Dissertations / Theses on the topic 'Lizard'

Male growth is best described by a von Bertalanffy growth model and female growth by a logistic growth model. This sexual dimorphism is correlated with greater relative surface activity and lower survivorship of juvenile males when compared to juvenile females. Early-hatching (first clutch) offspring exhibit greater body size and survivorship compared to late-hatching (second clutch) offspring. (Abstract shortened with permission of author.)

An assemblage of lizards was studied in a remote part of the Colombian Amazon. Thirty-one species were collected and identified, making the study site the second highest area for species richness within Amazonia, and the third most diverse In the world. The study site could be classified as 'virgin' forest, practically untouched by man. Structurally Intact, and with flora and fauna present at few remaining sites within Amazonia the Caparü field site promised to be an interesting location to study the ecology of a little studied group. The autecology of each species present at the study site was investigated: species abundance, spatial distribution, diet, activity patterns and reproduction patterns. The results presented here show that the lizard assemblage Is both highly organized and complex Finally, the biogeography of both the Capani lizard assemblage, and that of the Amazon as a whole was also considered. Uzards were found in very low abundances, similar to other studied Amazonian localities (some species only collected once over the two year sampling period). The most abundant species where found to be those with both a generalist lifestyle and a wide distribution. The rarest species were often the most specialized, although extremely limited data was available and such conclusions are preliminary. Most species were dietary generalists, and where specialization occurred it focused on ants. All but one species present at the study site were diurnal. Uzard activity appears to follow the general diurnal lizard pattern, which is highly correlated with both temperature and rainfall. The assemblage was comprised of both heliotherms and non-heliotherms and basking species were most abundant in forest gap areas. The limited reproductive data available shows that the lizards present are aseasonal breeders, breeding throughout the year. All but one species was oviparous, and the other being ovoviviparous. Different methods were used to identify the individual niches of each lizard species. Niche breadths were highest in the most common species and overlap generally quite low. A positive correlation was also identified between niche breadth and body size. Micro habitat was found to be the most important structuring factor in the community, followed by diet. Interspecific competition is predicted to be very low. The Capard lizard assemblage was found to be most similar to other Upper Amazonian sites, although several similarities were shared with Guianan saurofaunas. In general, similarity decreased with increased distance between site pairs. Multivarlate analysis of locality data identified several regions of high species community similarity, and a major division between lizard faunas from eastern and western Amazonia was evident. Local endemism and areas of high diversity were compared with data from other groups such as birds and butterflies found in the literature. Such distribution patterns (including those identified here) suggest a reduction In forest cover and subsequent spedation in the Quaternary period. Biogeographical analysis based on combined distribution maps was performed and fourteen general distribution patterns were selected, adding to those already identified in the literature.

In this project I have investigated how a set of rules can be applied to a particular sight and program. Inspired by the rules of the ’divine ‘proportion I applied its system of repetition and algorithm in a particular site and created a bridge with a diverse program beyond the simple intention of bridging two ends. This project is a way of approaching the complexity of designing an architectural space. It is a helping guide on how, through a system I could evaluate and pay attention to spatial qualities. My system is based on the divine proportion and its parts. I have broken up the divine rectangle and used the parts to create a structure that connects the tow ends on this specific sight. In this project I have been investigating and testing how a sett of rules can be applied on a sight to crate proportion, composition and rhythm. The classic rule that is about movement in space, giving function to the space, the relation to the human body and a space being more diverse. These rules are the basics of the foundation of or field. The metaphor I have used is the broken tail of a lizard, that from the point of where it brakes takes another shape and creates a new structure, overlapping and connecting the old and the new. I have called this ”the nature’s broken proportions”. By that I mean, when the symmetry in the creation in the new tail is broken or reduced, it no longer is a continuation of the lizard’s body in that time and space, but an individually separated continuity with its own symmetry. It exist in parallel and as an extension of its past. The system I have created have helped me to define the boundaries and provided a clear structure of my design.  This project is to me about connecting my intuition on how life is withe how I design space. The structure and boundaries provided by this system of ”broken proportions”, has given me the tools to evaluate the quality of the spaces I created. I found freedom in my abstraction of this system by breaking up the logarithmic spiral, which is about continuity. This is a designing tool I used to create my bridge. My work is an illustration of a subjective idea, of breaking the continuity in space and time. Through using this system I could evaluate qualities like dimension, proportion, composition, rhythm, direction, sectioning and levels. All these quality’s given by this system, creates an abstract interpretation about my personal view of movement of this bridge.

Thesis (MSc)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: Cordylus giganteus is the largest lizard species of the family Cordylidae and is restricted in distribution to the highveld grasslands of the Free State, South Africa. Previous work on life history and physiological ecology suggested the need for further investigation into the social structure of C. giganteus, with the aim of improving knowledge on South African herpetofauna and contributing towards better conservation plans. Observations, recaptures, behavioural experiments and chemical analyses were made to investigate chemical communication, movements around and between burrows, spatial distribution and response to intruders. Sexual variation was found in both femoral gland proteins and lipids, while seasonal variation was found in lipids. Femoral gland proteins do not vary intra-individually. These results suggest alternate roles in communication for femoral gland proteins and lipids. Female C. giganteus showed a possible discriminatory ability between their own femoral gland secretion and that of other individuals. Burrow movements were characterised by very little time spent between burrows, high burrow fidelity and limited dispersal during seasons, other than movements associated with mating activity. Lizards remained in very close proximity to burrows. Male and female burrows were distributed in a clumped fashion, while male burrows were distributed randomly and female burrows were distributed randomly with respect to one another. There was a high degree of spatial association of male and female burrows. Male and female resident lizards responded aggressively to experimentally introduced conspecifics of the same sex, but exhibited no differential response towards neighbours or non-neighbours. Males and females exhibited similar levels of aggression towards intruders. The social system of C. giganteus can be defined as site defence, with very low frequencies of agonistic interactions. The social system of C. giganteus seems to be well suited to other aspects of its life history.
AFRIKAANSE OPSOMMING: Cordylus giganteus is die grootste akkedis spesie van die familie Cordylidae en is beperk in verspreiding tot die hoeveld graslande van die Vrystaat, Suid Afrika. Vorige werk oor die lewensgeskiedenis en fisiologiese ekologie het aangedui dat verdere inligting oor die sosiale struktuur van C. giganteus nodig is, met die doelom kennis oor Suid-Afrikaanse herpetofauna te verbeter, en om beter bewaringsstrategieë daar te stel. Observasies, hervangs, gedragseksperimente en chemise analyses was uitgevoer om aspekte oor kommunikasie, bewegings tussen en om gate, gat verspreiding en reaksie teenoor indringer akkedisse, te bestudeer. Femorale klier afskeidings het seksuele variasie in beide die proteiene en die lipiede getoon, terwyl net die lipide seisoenale variasie getoon het. Femoral klier proteiene het nie seisoenale variasie binne individue getoon nie. Hierdie resultate dui op alternatiewe funksies vir die femoral klier proteiene en lipiede. Wyfie C. giganteus het moontlik tussen hule eie femoral klier sekreet en die van ander wyfies onderskei. Baie min tyd tussen gate, hoë lojaliteit teenoor gate en beperkte bewegings weg van gate het gat bewegings gekarakteriseer. Net gedurende die paarseisoen was daar meer bewegings tussen gate. Andersins, het akkedisse baie naby hul eie gate gebly. Mannetjie en wyfie gate was naby mekaar versprei, terwyl mannetjies ewekansig teenoor mekaar versprei was, en wyfies ewekansig teenoor mekaar versprei was. Die verspreiding van mannetjies en wyfies het baie van die verspreiding van die ander geslag afgehang, sodat daar 'n groot assosiasie tussen hulle was. Akkedisse wat gate bewoon het, was baie aggressief teenoor indringer akkedisse, maar het geen verskil in reaksie teenoor naburige akkedisse of nie-naburige akkedisse getoon nie. Mannetjies en wyfies het dieselfde aggressiwiteit teenoor indringers getoon. Die sosiale struktuur van C. giganteus kan geklassifiseer word as skuilings-beskerming, maar met baie lae frekwensies van sosiale interaksies. Dit blyk dat die sosiale struktuur van C. giganteus baie goed pas by ander aspekte van sy lewensstyl.

A critical mechanism underpinning current biological diversity is the extent to which one species mates with, or avoids mating with, another. However, little is known about the factors that mediate hybridisation, especially during the initial and rarely observed stages of secondary contact when interspecific interactions have not responded to selection. In particular, whilst hybridisation is ultimately a behavioural phenomenon, the role of behaviour in mediating hybridisation and how it is influenced by environmental and circumstantial factors is rarely investigated. Recently introduced species provide us with unequalled opportunities to study these factors. In this thesis I examine the role of behavioural mechanisms, in particular male-male competition and mate choice, in mediating mating patterns between two genetically and phenotypically distinct lineages of European wall lizard (Podarcis muralis) that have come into recent secondary contact through human introductions. In Chapter Two, I investigated how sexual selection during allopatry is responsible for creating stark differences in phenotypic traits such as body size and weapon performance evident in the two lineages today, ultimately explaining the strong biases in dominance during territorial disputes between males. However, I also show that even given this asymmetry in male competitive ability, the extent to which it extrapolates into greater access to females in naturalistic, outdoor enclosures depends strongly on the spatial clustering of basking sites, a critically important resource for many ectotherms. In contrast to initial predictions suggested by asymmetries in male competition outlined in the previous chapter, in Chapter Three I show that both paternity and courtship behaviour was strongly assortative in the outdoor enclosures. Further investigation through staged experiments on olfactory mate choice, mating trials and analyses on specific behavioural data obtained in an enclosure experiment, I show that lineage based dominance actually contributes to assortative mating patterns in conjunction with weak conspecific male choice. In contrast, female choice seems to play no role in mediating the mating patterns observed between the two lineages. In Chapter Four I had the rare opportunity to examine the morphological and behavioural factors that predict why animals should hybridise in the first place, using the data obtained in the enclosure experiment above. I found that hybridisation was particularly common between small individuals of the larger lineage and large individuals of the smaller lineage; a result that corroborates the mechanisms determining the assortative patterns uncovered in Chapter Three. Additionally, hybridisation rates were particularly high in less dominant individuals, which I suggest is due to subordinate males having reduced opportunities for courting conspecific females due to male-male competition, requiring them to become less ‘choosy’ and therefore more likely to mate with heterospecifics. Finally, secondary contact cannot occur without at least one lineage coming into a new environment, and yet relatively little attention is paid to how this environmental change can affect the signals involved in intraspecific communication and mate choice. In Chapter Five I show that a change in the amount of time male lizards spend thermoregulating (a likely consequence of arriving in a new environment) significantly changes the chemical composition of their scent marks. However, whilst female lizards were able to detect these effects, they did not seem to base their mating decisions on them. Nevertheless, this result raises interesting questions about the potential function and consequences of this plasticity, and highlights the importance of considering plasticity in chemical communication in heterogeneous environments. Overall, this thesis shows the critically important role of behaviour in mediating intra- and interspecific mating patterns during recent secondary contact. In particular, it highlights how the direction and extent of hybridisation and competition are influenced by the degree to which differing morphological and behavioural phenotypes interact over a heterogeneous environment, particularly during the initial stage of secondary contact when mate choice has not had the chance to respond to the selective pressures of hybridisation.

Nonmammalian vertebrates possess some unusual features in their hormonal systems/ when compared to mammals. As a consequence, they can make an important contribution in investigations concerning the fundamental mechanisms operating in endocrinology. Such studies concerning androgens include inter alia their effects on developmental aspects in the brain of birds and related singing behaviour; the role of neural enzymes in reproductive processes in fish; and the relation between androgens and the stages of spermatogenesis in amphibia, The present thesis examines the biochemistry of androgens in the Australian lizard Tiliqua rugosa. The major compounds studied were testosterone and epitestosterone, which are known to be present in high concentrations in the plasma of the male animal. Previous investigations are expanded, particularly in the areas of steroid identification and testicular biosynthesis. In addition, preliminary studies on the metabolism in the brain (and other tissues) and plasma protein binding are reported. The presence of epitestosterone as a major free androgen in the plasma of the male lizard was confirmed. Other steroids were found in the sulphate fraction. Testosterone sulphate was the most rigorously identified compound, while some evidence was also found for the presence of conjugated 5-androstene-3β,17-diols, etiocholanolone and dehydroepiandrosterone (DHA). Epitestosterone does not appear to be extensively conjugated in this animal. Steroids were not found to be conjugated as glucuronides. The identification studies employed a novel method of electrochemical detection of steroids. This technique was investigated and extended in the current thesis. Biosynthetic studies were carried out on androgen interconversions in the testis, in vitro. The major enzyme activities detected were 17α-arid 17β-oxidoreductases (17α-OR and l7β-OR) and 3β-hydroxysteroid dehydrogenase (3β-HSD)/isonerase. No evidence was found for the presence of a steroid-17-epimerase that would directly interconvert testosterone and epitestosterone. The 17-oxidoreductases were found to be dependent on the cofactor NBDFH. Testosterone appears to be formed mainly via the 4-ene pathway, whereas epitestosterone is formed from both the 4- and 5-ene routes. The compound 5-androstene-3β, 17α-diol was found to be an intermediate in the synthesis of epitestosterone from DHA. Temperature was found to significantly affect 17α-OR activity (maximum at 32°C). In contrast,17β-OR activity was independent of this factor in the testis. Androgen metabolism in the testis was found to be regulated by cofactors, temperature and season. The major enzyme activities found in the male brain were 17α- and 17β-OR. 3βHSD/isomerase was not found; however a low activity of 5α-reductase was identified. Aromatase activity was not positively identified, but preliminary results suggest that it may be present at low levels. The 17-oxidoreductases were widespread throughout the brain. The 17α-OR was significantly lower in the forebrain than other brain sections. The 170-OR activity did not vary significantly throughout the organ, although there was a trend for its activity to be higher in the midbrain region (containing the hypothalamus in these sections). The concentration of endogenous steroids in brain tissue was estimated by radioimmunoassay. Epitestosterone was found throughout the organ structure, whereas testosterone was found mainly in the midbrain (containing hypothalamic regions in these sections). Correlations between enzyme activities and steroid concentrations in brain regions suggested that the main function of 17α-OR is to produce epitestosterone, whereas the 17β-OR may catalyse a more reversible reaction in vivo. Temperature was found to significantly affect both 17α- and 17β-OR activities in the brain. In contrast to the testis, the maximum activity of the brain enzymes occurred at 37°C. The level of 17α-OR activity in the male lizard (100 nmol/g tissue/h) is the highest reported for this enzyme in vertebrates. Both activities were found to be quantitatively similar in the whole brain homogenates of male and female animals, and did not vary seasonally when examined in the male. The 17-oxidoreductases were also found in most other tissues in T.rugosa, including epididymis, adrenal, kidney and liver (but not blood). This suggests that the high activities of both 17α-OR and 17β-OR are dominant features of the steroid system in this animal. The formation of 11-oxygenated compounds was found in the adrenal, in addition to the formation of polar metabolites in the kidney and liver (possibly polyhydroxylated and conjugated steroids). A preliminary investigation into the plasma binding of androgens was carried out. The insults suggest that there are several binding sites for testosterone; one with high affinity and low capacity; the other with low affinity and high capacity. Binding experiments were carried out at 32°C. At this temperature, specific binding was greater than at 25 or 37°C. From the results of competition studies it was suggested that epitestosterone (with a K(i)= 3 X 10 (-6)M for testosterone binding) regulates the binding of testosterone (K(i)=10(-7)M) and hence the concentrations of the latter steroid as a free compound in plasma. In general, the study has shown that the biochemistry of androgens in the reptile T.rugosa is largely similar to that found in other vertebrates. The major difference is a greatly increased activity of 17α-OR, which causes a higher concentration of 17α-compounds to be present in the tissues of this lizard. The physiological roles for epitestosterone are not yet clear. However it appears from this study that this steroid regulates testosterone concentrations in several tissues by either steroidogenic or binding mechanisms. Several major influences on this regulation include temperature, availability of cofactors and seasonal effects.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.
Includes bibliographical references (leaves 44-46).
by Henry E. Chung.
M.Eng.

In this thesis I set out to further our understanding of the causes and consequences of genetic variation after colonisation events. Specifically, I focused on how historical processes shape genetic diversity and to what extent we can link colonisation history, genetic diversity, individual fitness and population viability. To achieve this, I used a combination of molecular markers, analytical tools and the common wall lizard, Podarcis muralis as a study system. I first infer the origin and genetic architecture of isolated population on islands at the range margin, in relation to mainland populations, to determine whether their current distribution and genetic structure are a result of a historical colonisation event or a more recent introduction. I then unravel the details of human-mediated introductions of P. muralis in England to further test which factors affect their genetic structure. I ask about the contribution of multiple introductions and admixture, the importance of number of founders and the year since their introduction and whether bottleneck events during primary and /or secondary introduction predict the level of genetic diversity in the non-native range. Throughout this study I obtain information on population genetic structure and composition from both native and non-native ranges. This is essential since the (complex) phylogeographic structure of P. muralis in the native range determines the distribution and structure of genetic diversity from which colonists are drawn and the details of colonisation will then reflect in the genetics of non-native populations. Lastly, I assess the consequences of colonisation on reproductive fitness and test for heterozygosity fitness correlations at the individual and population level. Overall, this thesis demonstrates why reconstructing the colonisation history is important when aiming to understand the causes and consequences of genetic variation during colonisation. This information is critical when assessing the relationship between genetic diversity and establishment success. Whether non-native populations have retained sufficient evolutionary potential to adapt to their new climate their long-term viability will be dictated by availability of suitable habitat rather than by internal population factors.

The Lizard Complex consists of a poorly exposed assemblage of serpentinites, gabbros, amphibolites, basic dykes, metasediments and gneisses. As an alternative approach to conventional mapping of the inland area, the geochemistry of the residual soils of the area are used to identify the underlying lithologies. Using multi-element geochemical data obtained by X-ray fluorescence spectrometry, an identification scheme is established which allows the recognition of over a dozen mappable units with a high rate of success. This scheme evolved from a training set of samples collected during an orientation survey from areas of undisputed geology immediately adjacent to coastal exposure. At approximately 250 sites it has been possible to confirm the geological predictions directly against material obtained from the base of power auger holes. A non-hierarchical K-means clustering technique is developed and used to recluster data from over 800 samples into gabbroic and ultrabasic groups. The results of this classification produced more sensitive discriminatory parameters which in turn are used on 1500+ samples collected during the project. The soil identification procedure combines the use of a variety of numerical techniques and the algorithm designed to use them operates in a sequential manner. The most distinct units are identified at an early stage whilst those samples which are less distinct chemically take longer to isolate and as a final stage of treatment are separated using a modified K-means technique. This approach to mapping has allowed the recognition of units not found outcropping on coastal sections and for an improved geological map of the Lizard Complex to be drawn. In particular the Crousa gabbro is shown to be a smaller body than previously considered and to comprise several different bodies. As a result of this work the evolutionary history of the Complex is revised.

Thesis (Ph.D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 2002.
Includes bibliographical references (p. 219-235).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
The sensitivity and frequency selectivity of the hearing sense are determined primarily by mechanical properties of the cochlea. These mechanical properties are poorly understood in any species. This thesis contributes to our understanding of cochlear mechanics by presenting measurements of sound-induced motion of the alligator lizard cochlea. Novel methods were developed to maintain the cochlea in vitro for the time required to measure three-dimensional motions. Three-dimensional images of cochlear motion were taken by illuminating the cochlea with a light-emitting diode stroboscopically at predetermined phases of the acoustic stimulus. The resulting images were analyzed using computer vision algorithms to extract three-dimensional motions of all visible structures with nanometer precision. The sound-induced motion of the entire basilar papilla and of individual hair bundles of hair cells were simultaneously measured. The basilar papilla, in which the hair cells reside, moved as a rigid body, exhibiting simultaneous translational and rotational modes of motion. Both modes apply shearing forces to hair bundles. A simple mechanical model of the basilar papilla, based on these measurements, provides a physical basis for a mechanical low-pass filter hypothesized in previous models. In the tectorial region of the cochlea, motion of the tips of hair bundles and of the tectorial membrane (TM) were in phase with motion of the basilar papilla. None of the motions had significant frequency dependence, suggesting that this region does not exhibit appreciable mechanical frequency selectivity. In the free-standing region, which has no TM, hair bundle deflection depended on stimulus frequency and hair bundle height.
(cont.) At high frequencies, hair bundle deflection was proportional to basilar papilla displacement. At low frequencies, hair bundle deflection was proportional to a linear combination of basilar papilla velocity and acceleration. Measured hair bundle deflections were well fit by a simple hydrodynamic model (Freeman and Weiss, 1990) of this region of the cochlea. The measurements in this study provide the first characterization of the three-dimensional motion of all structures in a vertebrate cochlea.
by Alexander James Aranyosi.
Ph.D.

Thesis (MSc)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: Cordy/ us cataphractus and C macropholis naturally occur in groups on a year round basis. I examined whether limited shelter availability might be responsible for this phenomenon. Individuals were provided with an excess of shelter sites and the observed pattern of shelter occupation was contrasted to that obtained for the solitary living species C polyzonus. Cordy/us cataphractus consistently occupied fewer shelters than its two congeners. Results suggest that grouping behaviour in this species is not the result of a limitation in refuge sites. In contrast, the pattern of shelter occupation by C macropholis did not differ significantly from that of C polyzonus, thus the aggregative behaviour observed in the former species may partially be attributed to limited shelter availability in its natural habitat. Conspecific recognition by means of pheromonal detection has been reported in many lizard families, but only for one member of Cordylidae, namely Cordy/us cordy/us. Cordylus cataphractus individuals were exposed to ceramic tiles that had been labeled by conspecific male and female substrate deposits. Labeling was achieved by using ceramic tiles as the bottom half of a shelter in a lizard's home cage for ten consecutive days. Washed tiles were used as controls. Labeled tiles did not elicit significantly more tongue-flicks than control tiles from test specimens in a series of trials. The apparent lack of conspecific recognition via pheromonal detection might be attributable to the group-living nature of this species, which primarily use visual cues for identification purposes. Tongue-flicking is generally utilized in C cataphractus in the detection of novel stimuli. Spatial dynamics of the group-living cordylid, C cataphractus, were investigated by studying patterns of intergroup movement. To date, literature has assumed that C cataphractus groups represent family units, implying low or delayed dispersal rates and high group fidelity. A mark-recapture experiment on six groups included three recaptures outside of and three recaptures within the mating season. High percentages of male, female and juvenile lizards left their groups, but might be an artifact of microhabitat disturbance. High proportions of males, females and juveniles entering the groups, both outside of mld within the mating season, clearly implied a high rate of intergroup movement. Activity and foraging patterns were studied in group-living C. cataphractus lizards by conducting direct field observations between September 1998 and October 1999. The influence of general weather patterns as well as the effect of group size on these patterns were investigated by observing a small-sized, medium-sized and large group. Each group was observed for a minimum of three sunny days per season, with scans conducted every 30 minutes between the hours of 08:00 and 20:00. There was a high rate of activity during the mating season in spring (September). Activity declined sharply mld foraging ceased at the onset of warm, dry conditions (February). Virtually no activity occurred just prior to the first winter rains (July), after which the lizards emerged to forage and replenish energy stores before onset of the next mating season. Selective inactivity might be employed to reduce energy expenditure in this group-living lizard, where intraspecific competition is stringent. Groups of different sizes display different thresholds at which it becomes energetically viable for group members to emerge, as well as different patterns of spatial use around their respective home crevices. Members of larger groups perched further from their crevices, ran further to catch prey mld had less potential prey capture events per individual. Lizards in the larger groups also displayed sporadic lengthy foraging excursions. Such movements might explain the evolution of tail-biting behaviour and heavy armour, which are defensive strategies associated with open areas.
AFRIKAANSE OPSOMMING: Cordylus cataphractus en C. macropholis word dwarsdeur die jaar in groepe in hul natuurlike habitat aangetref. Daar is nagevors of 'n beperking in aantal beskikbare skuilplekke vir hierdie verskynsel verantwoordelik is. Individue is van 'n oormaat skuilings voorsien en die waargenome patroon van skuilplekbesetting is gekontrasteer met dié verkry vir '11 enkelwonende species, naamlik C. polyzonus. Cordylus cataphractus het voortdurend minder skuilplekke beset as sy kongeneriese species. Groepsgedrag in C. cataphractus is dus nie die resultaat van 'n tekort aan beskikbare skuilplekke nie. In teenstelling hiermee het die patroon van skuilplekbesetting vertoon deur C. macropholis nie noemenswaardig verskil van dié van C polyzonus nie. Dus mag die groepsgedrag wat gewoonlik in C. macropholis waargeneem word 'n uitvloeisel wees van 'n beperking op die beskikbaarheid van skuilplekke in sy natuurlike habitat. Herkenning van speciesgenote deur waarneming van ferornone is vir verskeie akkedisfamilies gerapporteer, maar slegs vir een lid van Cordylidae, naamlik C. cordylus. Cordylus cataphractus individue is blootgestel aan keramiekteëls wat gemerk is met substraat-neerleggings van manlike en vroulike speciesgenote. Sodanige merking is uitgevoer deur die keramiekteëls vir tien dae lank te gebruik as die onderste helfte van akkedisse se skuilplekke in hul tuishokke. Gewaste teëls is as kontroles gebruile Gemerkte teëls het nie statisties beduidend meer tongskiete van die akkedisse uitgelok as kontrole teëls in 'n reeks toetse nie. Die klaarblyklike afwesigheid van speciesgenootherkenning deur middel van feromoon waameming kan moontlik toegeskryf word aan die groeplewende gedrag van C. cataphractus, wat primêr visuele informasie vir identifikasie gebruik. Cordylus cataphractus gebruik tongskiete oor die algemeen vir die waarneming vannuwe omgewingsstimuli. Die ruimtelike dinamika van 'n groeplewende gordelakkedis, C. cataphractus, is ondersoek deur die patroon van intergroepbeweging na te vors en groepsgetrouheid te meet. Tot op datum is daar in die literatuur aanvaar dat C cataphractus groepe familie-eenhede verteenwoordig, wat lae of vertraagde verpreidingstempo' sasook' n hoë mate van groepsgetrouheid impliseer. 'n Merk-hervang eksperiment is op ses groepe uitgevoer, insluitend drie hervang episodes buite en drie binne die paarseisoen. 'n Hoë persentasie manlike, vroulike en onvolwasse akkedisse het hul groepe verlaat, maar dit mag bloot 'n uitvloeisel van versteuring van die mikrohabitat wees. 'n Hoë proporsie mannetjies, wyfies en onvolwassenes het egter by die groepe aangesluit, beide buite en binne die paarseisoen, wat onteenseglik op 'n hoë mate van intergroep beweging dui. Daar kom derhalwe veel vryer bewegingspatrone in hierdie species voor as voorheen vermoed en dit is hoogs onwaarskynlik dat groepe familie-eenhede verteenwoordig. Aktiwiteits- en voedingspatrone van die groeplewende akkedis, C cataphractus, is bestudeer in 'n reeks veldobservasies tussen September 1998 en Oktober 1999. Afgesien van die invloed van algemene weerspatrone. is die effek van groepgrootte op hierdie patrone ondersoek deur 'n klein, medium en groot groep te observeer. Elke groep is waargeneem oor . 'n minimum periode van drie dae per seisoen met opnames elke 30 minute, tussen 08:00 ten 20:00. 'n Hoë aktiwiteitsvlak is gedurende lente tydens die paarseisoen gehandhaaf (September). Met die aanvang van warm en droë kondisies (Februarie) het aktiwiteitsvlakke skerp begin daal en voedingsgedrag is gestaak. Feitlik geen aktiwiteit was waarneembaar kort voor die eerste winterreëns (Julie) nie, waamá akkedisse intensiefbegin voed het om energiestore op te bou voor die aanvang van paartyd. Selektiewe onaktiwiteit verminder moontlik energieverbruik in hierdie groeplewende akkedis, waar intraspesifieke kompetisie streng is. Verskillende groepgroottes beskik oor verskillende perke waar dit vir die individu energeties voordelig sou wees om uit die skeur te kom, asook 'n variasie in ruimtelike gebruik om die skeur. Individue van die twee groter groepe het nader aan hul rotsskeur gesit, het verder van die skeur af prooi vang en het beduidend minder potensiële voedingskanse gehad. Akkedisse in die groter groepe het voorts sporadiese lang voedingsekskursies getoon. Hierdie bewegings mag die evolusie van stertbytgedrag en 'n swaar pantser, verdedigingstrategieë wat met oop areas geassosieer word, verduidelik.

Thesis (MSc)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: The foraging mode of the Cape grass lizard, Chamaesaura anguina, was determined by using three criteria: 1) the number of movements per minute (MPM) and the percentage of time spent moving (PTM) during periods of activity; 2) the amount of tongueflicking directed at cotton applicators labelled with prey chemicals as a measure of prey chemical discrimination; 3) the stomach contents of the lizards as an indication of the natural diet. Observations were made by means of binoculars from an observation tower using a seminatural outdoor enclosure, and through a one-way glass panel using a seminatural indoor enclosure. Each lizard was observed for aIO minute period during peak activity and the times it was moving and the times it was stationary were recorded. Data obtained in the indoor- and outdoor enclosures did not differ significantly and were pooled. "MPM(0.37 ± 0.21 SD) and PTM (1.92 % ± 0.93 SD) values recorded for C. anguina (N = 10) fall within the range given as characteristic for sit-and-wait foragers. Nine C. anguina individuals were habituated in glass terraria to accept mealworms offered to them. When all lizards accepted food without hesitation, they were tested for their ability to discriminate among three different odours presented to them in a randomized block design: prey odours consisting of mealworm surface odours, distilled water as an odourless control stimulus, and cologne as a pungency control. The number of tongue-flicks directed at the cotton applicator containing the stimulus odour during 60 s was recorded. No statistically significant differences were found among the responses to the three treatment odours (Kruskal-Wallis, H = 2.41, dj = 2, P = 0.30). An analysis of the stomach contents of21 C. anguina specimens revealed a diet of mostly diurnally active arthropod prey species. The preferred body temperatures selected by 12 grass lizards in a thermal gradient were measured six times during a 48 hour period, using a copper-constantan thermocouple inserted into the cloaca. The measured body temperatures (N = 72) ranged from 22.62 oe - 27.07 oe with a mean of24.82 oe ± 2.27 SD. The low preferred body temperature exhibited by C. anguina as compared to other cordylids may be attributed to the combined influence of vegetative cover, high altitude, and high surface-volume ratio. To determine movement patterns and microhabitat use, six lizards were observed in a seminatural outdoor enclosure (4 x 4 m). The location of the grass tufts in the enclosure was mapped, and the position of each lizard within the enclosure was noted on 17 mornings. Observations of lizard behaviour during periods of activity were made by means of binoculars from an observation tower. Although C. anguina did not show reliance on a specific shelter site, the taller, broader tufts were generally preferred as refuges during inactivity. There were significant differences between the heights (student's z-test; P < 0.001) and the diameters (Mann-Whitney; P < O.00 1) of the preferred grass tufts, and those grass tufts that were not preferred as refuges, respectively. The lizards usually sheltered in a coiled-up position in the middle of the grass tufts close to the ground. During active periods, the lizards perched in an elevated position in the vegetation by entangling their elongated bodies and tails in the grass for efficient weight distribution. Locomotion was mainly restricted to the strike action when attacking prey. Fynbos and grassland, which are the main habitat of grass lizards of the genus Chamaesaura, are fire-prone. With their serpentiform morphology, grass lizards differ markedly from other cordylids, the majority of which are rock-dwelling. One aim of this study was to determine whether grass lizards make use of refuges like burrows or crevices within their grasslrestioid habitat during periods of inactivity or when threatened by fire. Refuge selection during inactivity was determined experimentally. Twelve lizards were offered different refuge options, namely grass tufts, crevices, burrows and loose sand. All twelve lizards preferred to shelter in the grass tufts. When the grass tufts were removed, only two lizards made use of the burrows and crevices provided, the other 10 not sheltering at all. Refuge selection when threatened by fire was tested by placing the 12 lizards in an enclosure provided with grass tufts and two types of refuges, burrows and crevices. The grass was set alight at one end of the enclosure and the fire was fanned on towards the other end with the aid of a high-speed fan. Precautions were taken to ensure the safety of all the lizards and to intervene when they were in direct danger. Only two of the 12 lizards sought shelter in the refuges provided. Of the remaining 10, six fled and four were trapped by the flames, requiring intervention. The results of these experiments, as well as field observations, suggest that C. anguina seldom makes use of shelter options other than grass and restio tufts, even when threatened by fire. In the case of fire, it flees by 'grass-swimming'. Field observations also suggest that mortality during and after a fire is considerably higher than in the case of rock-dwelling cordylids. The reproductive status of adult females (N = 85) were determined on the basis of the developmental stage of ovarian follicles and the presence or absence of oviductal eggs. Females were grouped into four reproductive categories: pre-vitellogenic, early vitellogenic, pre-ovulatory and gravid. To determine the reproductive cycle exhibited by the males (N = 46), testicular volume and seminiferous tube diameter were measured, as well as the spermatogenic activity assessed qualitatively. Spermatogenic activity was assessed by using Licht's (1967) classification system. The snout-vent length (SVL) of 144 specimens was measured. Sexual size dimorphism (SSD) recorded for C. anguina was quantified by a size dimorphism index (SDI). Reproductive activity was asynchronous among females, differing from the normal cordylid cycle of autumn/winter vitello genic activity, followed by winter/spring ovulation and gestation in late summer to autumn. The significant seasonal variation that existed in testes volume (ANOVA; F (7,22) = 3.70; P < 0.05) and seminiferous tubule diameter (ANOVA; F (10,25) = 4.90; P < 0.05), as well as sermatogenic activity as observed by histological examination, indicated that C. anguina males follow an annual spermatogenic cycle that can be described as post-nuptial. The cycle is characterized by summer/autumn spermiogenesis, associated with sperm storage throughout winter. Chamaesaura anguina males differ from other cordylids following a post-nuptial cycle, by starting with spermatogenesis in spring. The mean SVL of female grass lizards (109.51 mm ± 20.60 SD) was significantly larger (Mann-Whitney; P < 0.001) than that of males (84.77 mm ± 9.39 SD). A positive SDI of 1.29 and a SDImax of lAO were determined. Female-biased dimorphism in SVL recorded for C. anguina corresponds with the general pattern recorded for terrestrial cordylids, but contrasts with male-biased dimorphism in rupicolous forms. The longer SVL of C. anguina females facilitates higher fecundity. This, in turn, might be an adaptive survival strategy for this lizard species in the fire-prone environment where it occurs, because successful recruitment is facilitated by high fecundity. KEYWORDS: Chamaesaura anguina; serpentiform body; cryptic colouration; grass/restio habitats; undulatory locomotion; foraging mode; preferred body temperature; movement patterns; microhabitat use; fire susceptibility; refuge selection; reproductive cycle; sexual size dimorphism. 4
AFRIKAANSE OPSOMMING: Die voedingswyse van Chamaesaura anguina is bepaal deur drie kriteria: 1) die getal bewegings per minuut (BPM) en die persentasie tyd wat aan beweging bestee word (PTB) tydens aktiewe periodes; 2) die hoeveelheid tongskiete wat gerig word na wattepluisies bedek met prooi chemikalieë as 'n maatstaf van prooi chemiese diskriminasie; 3) die maaginhoud van die akkedisse as 'n indikasie van hul natuurlike diëet. Waarnemings is met 'n verkyker vanaf 'n waarnemingstoring langs 'n buitemuurse kampie gemaak, terwyl dit deur 'n eenrigting glaspaneel in die geval van 'n binnemuurse opstelling gemaak is. Elke akkedis is vir 'n periode van 10 minute tydens piek-aktiwiteit dopgehou, en die tye wat dit beweeg het en nie beweeg het nie, is aangeteken. Data verkry in die binnemuurse - en buitemuurse opstellings het nie statisties van mekaar verskil nie en is saamgevoeg. BPM (0.37 ± 0.21 SD) en PTB (1.92 % ± 0.93 SD) waardes aangeteken vir C. anguina (N = 10) val binne die reeks waardes wat as kenmerkend vir sit-en-wag voeders beskou word. Nege C. anguina individue is in glas terraria gewoond gemaak om meelwurms te aanvaar wat hul aangebied is. Toe al die akkedisse die kos sonder huiwering aanvaar het, is hul vermoë getoets om tussen drie verskillende geure wat hul aangebied is in 'n ewekansige blokontwerp, te diskrimineer: prooigeur bestaande uit die reuk van meelwurms, gedistilleerde water as 'n geurlose kontrole stimulus, en reukwater as 'n skerp kontrole. Die hoeveelheid tongskiete gerig na die gegeurde wattepluisie gedurende 'n 60 s periode, is aangeteken. Geen statisties-beduidende verskille is gevind tussen die reaksies tot die drie geure nie (Kruskal-Wallis, H = 2.41, df= 2, P = 0.30). 'n Analise van die maaginhoude van 21 C. anguina individue het meestal dag-aktiewe arthropoda prooispesies onthul. Die voorkeur liggaamstemperature wat deur 12 akkedisse in 'n termiese gradiënt geselekteer is, is ses maal gemeet gedurende 'n 48 uur periode, deur van 'n termo-koppel wat in die kloaka geplaas is, gebruik te maak. Die bepaalde liggaamstemperature (N = 72) het gevariëer van 22.62 oe - 27.07 oe met 'n gemiddeld van 24.82 oe ± 2.27 SA. Die lae voorkeur liggaamstemperatuur van C. anguina mag dalk toegeskryf word aan die gekombineerde invloed van plantbedekkingskadu, hoë hoogte bo seevlak, en hoë oppervlakte-volume verhouding. Die bewegingspatrone en mikrohabitat-gebruik van C. anguina is bestudeer deur ses akkedisse in 'n buitemuurse kampie aan te hou. Die ligging van die graspolle binne die kampie is op 'n kaart aangeteken, en die posisie van elke akkedis binne in die kampie is op 17 oggende aangeteken. Verdere waarnemings is gemaak met 'n verkyker vanaf 'n waarnemingstoring terwyl die akkedisse aktief was. Alhoewel die C. anguina individue nie herhaaldelik 'n spesifieke skuilplek gebruik het nie, het hul die langer, breër graspolle as skuilplek gedurende onaktiwiteit verkies. Daar was 'n hoogs beduidende verskil tussen onderskeidelik die hoogtes (studente z-toets; P < 0.001) en die deursnitte (studente I-toets; P < 0.001) van die verkose graspolle, en die graspolle wat nie gekies is as skuilplekke nie. Hulle het gewoonlik in 'n opgerolde wyse, in die middel en na aan die bodem van die graspolle, geskuil. Daar is gevind dat C. anguina vanaf 'n verhewe posisie voed deur sy verlengde liggaam en stert in die grass te vervleg om doeltreffende gewigsverspreiding te verseker. Beweging was hoofsaaklik tot die vangaksie van prooi beperk. Vuur is 'n algemene verskynsel in fynbos en graslande, wat die hoof habitat van grasakkedisse van die genus Chamaesaura uitmaak. Met hulle slangagtige morfologie, verskil grasakkedisse drasties van ander lede van die Cordylidae, waarvan meeste rotsbewonend is. Die doelwit van hierdie studie was om te bepaal of die grasakkedisse gebruik sal maak van skuilplekke, soos gate en klipskeure binne die grashabitat, gedurende periodes van onaktiwiteit of wanneer bedreig word deur vuur. Twaalf akkedisse is verskillende skuilopsies aangebied, naamlik graspolle, klipskeure, gate en los sand. Al twaalf het verkies om in die graspolle te skuil. Toe die graspolle verwyder is, het slegs twee akkdisse die klipskeure en die gate benut, terwyl die ander 10 nie geskuil het nie. Skuilplek-seleksie wanneer bedreig word deur vuur, is getoets deur 12 akkedisse in In afskorting te plaas wat met graspolle en twee tipes skuilplekke, gate en klipskeure, voorsien is. Die gras aan die een kant van die afskorting is aan die brand gesteek en is aangehelp m.b.v. 'n hoë-spoed waaier. Voorsorgmaatreëls om die veiligheid van al die akkedisse te verseker en om in te gryp as hulle in direkte gevaar sou verkeer, is getref. In twee van die 12 gevalle het die akkedisse skuiling gesoek in die beskikbare skuilings. In die oorblywende 10 gevalle het ses akkedisse gevlug, terwyl vier deur die vlamme vasgevang was en daar ingegryp moes word. Die resultate van hierdie eksperimente, sowel as waarnemings wat in die veld gemaak is, dui daarop dat C. anguina selde van skuilopsies, anders as graspolle en restio's, gebruik maak as hulle deur vuur bedreig word. In die geval van vuur, vlug hulle deur te "swem" deur die gras. Veldwaarnemings dui ook daarop dat mortaliteit gedurende en na die vuur heelwat hoër is as in die geval van rotsbewonende gordelakkedisse. Die reproduktiewe status van volwasse wyfies (N = 85) is bepaal deur die ontwikkelingsfase van ovarium follikels te ondersoek en deur die teenwoordigheid of afwesigheid van eiers in die oviduk. Wyfies is in vier reproduktiewe kategorieë gegroepeer: pre-vitellogenies, vroeg vitellogenies, pre-ovulatories en dragtig. Testikulêre volume en saadbuisdeursnit is gemeet, en spermatogeniese aktiwiteite soos histologies vasgestel, is gebruik om die reproduktiewe siklus van die mannetjies (N = 46) te bepaal. Spermatogeniese aktiwiteit is bepaal deur van Licht (1976) se klassifikasie sisteem gebruik te maak. Die snoet-kloaak lengte (SKL) van 144 individue is gemeet en die seksuele grootte-dimorfisme (SGD) soos bepaal vir C. anguina, is gekwantifiseer deur middel van In grootte-dimorfisme-indeks (GDI). Voortplantingsaktiwiteit in die wyfies was nie gesinchroniseerd nie, en verskil dus van die normale gordelakkedissiklus met herfs/winter vitellogeniese aktiwiteit, winter/lente ovulasie en swangerskap in die volgende laat somer tot herfs. Die beduidende seisoenale verskil wat bestaan het in die testesvolume (ANOV A; F (7.22) = 3.70; P < 0.05) en die saadbuisdeursnit (ANOVA; F (10,25) = 4.90; P < 0.05), asook testis histologie, het aangedui dat C. anguina mannetjies 'n jaarlikse spermatogeniese siklus volg, beskryf as "post-nuptial". Hierdie siklus word gekenmerk deur somer/herfs spermiogenese, geassosieer met spermstoring gedurende die winter. In teenstelling met ander gordelakkedisse wat hierdie siklus volg, begin spermatogenese in C. anguina alreeds in die lente. Die gemiddelde SVL van die wyfies (109.51 mm ± 20.60 SA) was beduidend groter (Mann-Whitney; P < 0.001) as dié van die mannetjies (84.77 mm ± 9.39 SA). In Positiewe GDI van 1.29 en In GDImax van 1.40 is gemeet. Wyfie-plus dimorfisme in SKL bepaal vir C. anguina, stem ooreen met die algemene patroon waargeneem by terrestriële gordelakkedisse, maar is in kontras met mannetjie-plus dimorfisme by rotsbewonende vorme. Die langer SKL by wyfies van C. anguina kan In hoër fekunditeit fasiliteer. Dit mag dalk In oorlewingstrategie vir die species wees wat in In vuurgeteisterde omgewing voorkom, omdat suksesvolle rekolonisering deur In hoë fekunditeit aangehelp word. TREFWOORDE: Chamaesaura anguina, slangagtige liggaam; kriptiese kleuring; graslrestio habitatte; kronkel beweging; voedingsrnetode; voorkeurtemperatuur; bewegingspatrone; mikrohabitat-gebruik; vatbaarheid vir vuur; skuilplekseleksie; voortplantingsiklus; seksuele dimorfisme.

With the maturity of conventional industrial robots, there has been increasing interest in designing robots that emulate realistic animal motions. This discipline requires careful and systematic investigation of a wide range of animal motions from biped, to quadruped, and even to serpentine motion of centipedes, millipedes, and snakes. Collecting optical motion capture data of such complex animal motions can be complicated for several reasons. Often there is the need to use many high-quality cameras for detailed subject tracking, and self-occlusion, loss of focus, and contrast variations challenge any imaging experiment. The problem of self-occlusion is especially pronounced for animals. In this thesis, we walk through the process of collecting motion capture data of a running lizard. In our collected raw video footage, it is difficult to make temporal correspondences using interpolation methods because of prolonged blurriness, occlusion, or the limited field of vision of our cameras. To work around this, we first make a model data set by making our best guess of the points' locations through these corruptions. Then, we randomly eclipse the data, use Gappy POD to repair the data and then see how closely it resembles the initial set, culminating in a test case where we simulate the actual corruptions we see in the raw video footage.
Master of Science

Thesis (MSc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: As ectotherms, lizards are particularly vulnerable to changes in the thermal landscape and face extinction risk if they lack the capacity to rapidly adapt or behaviourally mitigate increasingly altered thermal environments. Theoretical models that predict lizards‟ response to climate change often fail to take into account the thermal characteristics of the microenvironment, the ability of lizards to behaviourally buffer climate variation in the habitat and the plastic nature of both behaviour and physiology over ecologically relevant time-scales. Here, I address this major knowledge gap using two separate research chapters in an experimental physiology approach. In Chapter 1, I investigated the temperature-dependence and plasticity of resting metabolic rate, water-loss rate and preferred body temperature of Cordylus oelofseni at several temporal scales (within and between seasons) and incorporated field observations to acquire a better understanding of this species‟ adaptive potential to buffer thermal changes in the habitat. Cordylus oelofseni showed plasticity of both behaviour and physiology in response to thermal acclimation, but relied on distinct strategies depending on the time-scale investigated. These results highlighted the complexity of underlying mechanisms used by these organisms to buffer temperature variation. In Chapter 2, I used an experimental approach to examine the energetic costs of thermoregulation in C. oelofseni and test the cost-benefit model of thermoregulation. This model‟s primary prediction states that lizards should thermoregulate carefully only when the associated costs are low. Using four enclosures that simulated different thermal qualities (temporal and spatial distributions of operative temperatures) in the habitat, I found limited support for the cost-benefit model. Lizards in the low-quality heterogeneous enclosures invested the same energetic effort and thermoregulated with similar overall accuracy as lizards in the high-quality heterogeneous enclosure. The costs incurred were not necessarily energetic, but reflected missed opportunities (e.g. less time to forage), something that, along with important interaction effects with body mass, deserves further attention when testing this model. Together, these results illustrate the importance of incorporating ecological reality at various time and spatial scales in order to make relevant predictions regarding the fate of lizards with projected climate change.
AFRIKAANSE OPSOMMING: As ektotermiese diere, is akkedisse veral sensitief vir veranderinge in die termiese landskap en staar uitsterwingsrisiko in die gesig as hulle nie die vermoë het om vinnig aan te pas of gedragsveranderinge te maak in omgewings wat toenemend verwarm nie. Teoretiese modelle wat akkedisse se reaksie op klimaatsverandering voorspel, neem dikwels nie die termiese eienskappe van die mikro-omgewing, die vermoë van akkedisse om met gedragsveranderinge klimaat variasie in die habitat te buffer en die plastieke aard van beide gedrag en fisiologie oor ekologies relevante tydskale in ag nie. Hier bespreek ek hierdie groot kennisgaping met behulp van twee afsonderlike navorsingshoofstukke in 'n eksperimentele fisiologie benadering. In Hoofstuk 1 het ek ondersoek ingestel na die temperatuur-afhanklikheid en plastisiteit van rustende metaboliese tempo, waterverlies tempo en voorkeur liggaamstemperatuur van Cordylus oelofseni by verskeie tydskale (binne en tussen seisoene) en inkorporeer veld waarnemings om 'n beter begrip te verkry van hierdie spesie se aanpasbare potensiaal om termiese veranderinge in die habitat te buffer. Cordylus oelofseni het plastisiteit van beide gedrag en fisiologie in reaksie op hitte-akklimatisering getoon, maar staatgemaak op verskillende strategieë, afhangende van die tyd-skaal wat ondersoek is. Hierdie resultate beklemtoon die kompleksiteit van die onderliggende meganismes wat gebruik word deur hierdie organisme om temperatuur verandering te buffer. In Hoofstuk 2 het ek 'n eksperimentele benadering gebruik om die energiekoste van termoregulering in C. oelofseni te ondersoek en die kostevoordeel model van termoregulering te toets. Hierdie model se primêre voorspelling verklaar dat akkedisse slegs versigtig moet termoreguleer wanneer die gepaardgaande koste laag is. Deur gebruik te maak van vier afskortings wat verskillende termiese eienskappe gesimuleer het (tyd en ruimtelike verspreiding van operatiewe temperature) in die habitat, het ek beperkte ondersteuning gevind vir die koste-voordeel model. Akkedisse in die lae-gehalte heterogene afskortings het dieselfde energieke moeite belê en getermoreguleer met soortgelyke algehele akkuraatheid as akkedisse in die hoë-gehalte heterogene kamp. Die kostes wat aangegaan is, is nie noodwendig energiek nie, maar weerspieël geleenthede wat gemis is (bv. minder tyd om kos te soek), iets wat, saam met belangrike interaksie effekte met liggaamsmassa, verdere aandag verdien wanneer hierdie model getoets word. Tesame illustreer hierdie resultate die belangrikheid van die integrasie van ekologiese werklikheid op verskillende tyd en ruimtelike skale, om relevante voorspellings oor die lot van akkedisse met geprojekteerde klimaatsverandering te kan maak.

This study arose from a conservation dilemma between the need to conserve a population of the endangered pink tailed legless lizard, Aprasia parapulchella and crucial upgrading of Canberra's sewerage treatment plant. The study focused on conservation biology and how it could be applied to the management of A. parapulchella. As little biological information was available on A. parapulchella, research was focused on obtaining data that would be beneficial in the conservation management of the species. This included the dietary and habitat requirements, population status and structure and population relocation and habitat restoration. A. parapulchella was found to occur in low relative densities at all sites (maximum 9.1 lizards per 1000 rocks turned, Mt Taylor). Populations of the species appear to be larger than has been considered previously, however numbers are still below 500 individuals per site. Sexual dimorphism is present in the species with females achieving longer snout-vent lengths than males. Sex ratios were equal in all sites, however average size of lizards was different at the four main study sites, indicating differences in population structure. The life history of A. parapulchella can be summarised as long-lived, late maturing (3rd or 4lh year of life) with a low reproductive rate (single clutch of two eggs per year). A. parapulchella is a dietary specialist feeding on about 11 different species of ants. Interestingly, the lizards also live with the same species that they feed upon. By far the most important species in the diet and homesite requirements of A. parapulchella is the ant Iridomyrmex rufoniger. A. parapulchella shows positive selection towards the species in homesite choice, is found most commonly in the nests of this ant, and selects its brood over the brood of other ant species in diet experiments. In addition this ant was represented in the diet of A. parapulchella more commonly than any other ant. The relationship between ants and A. parapulchella appears to be unique and the mechanisms of this specialisation require further investigation. The vegetation associations where A. parapulchella occur are different across the range of the species. Sites at Bendigo and West Wyalong support mallee communities, while in the ACT region, Bathurst and Tarcutta, A. parapulchella appears to be a habitat specialist, being found most commonly in sites dominated by grass species, both native and introduced. A. parapulchella lives beneath rocks in grassland sites. Rocks that the species uses for homesites are commonly between 100 and 150 mm wide, 120-220 mm long and 50 and 150 mm thick. There were significant differences between the sizes of rocks used at different sites and between different seasons. Rocks used by females were significantly larger than rocks used by juvenile lizards. Twelve other species of reptile were found to use rocks in grassland sites, with rocks partitioned within the community on the basis of size and shape. An experimental relocation of A. parapulchella was conducted to try to determine ideal habitat conditions for the survival of relocated individuals. Unfortunately of the 114 lizards released, only 15 were recaptured. Although recaptures were low, trends indicated that treatments of Themeda triandra and very high rock densities had the highest survival rates. Key habitat variables were reinstated at the Lower Molonglo Dam site however restoration is preliminary with more time needed for the habitat to be suitable for occupation by A. parapulchella. What started as a situation that was likely to have a deleterious impact on A. parapulchella has been turned into a conservation success story. Without the involvement of ACT Electricity and Water, much of the basic biology of A. parapulchella would still be unknown. The findings will now form a solid basis from which to effectively conserve A. parapulchella. The project provides an example of the conservation success that can be achieved between industry and conservation partnerships.

Bibliography: pages 243-268.
Cordylus giganteus is a large, terrestrial, viviparous lizard, endemic to the Highveld grasslands of South Africa. Its distribution is limited and its conservation status is vulnerable. Autopsy and mark-recapture methods were used to study the seasonal aspects of its reproductive cycle, diet, energy reserves, growth, population dynamics, daily activity and thermoregulation. Reproduction is distinctly seasonal in both sexes. Females may reproduce biennially. Vitellogenesis commenced in autumn (March), and continued through hibernation with ovulation in spring (October). Two or three young are born in autumn. A functional placenta is implicated. Seasonal steroid hormone profiles are presented. Males exhibit a postnuptial spermatogenetic cycle. Spermatogenesis commences in spring with peak spermiogenesis in autumn and testicular regression following in late autumn. Spermatozoa are stored in the epididymis and ductus deferens for seven to eight months. A bimodal plasma testosterone profile is reported, consistent with spermiogenesis in autumn and mating behaviour in spring. C. giganteus feeds during 8 months of the year and prefer Coleoptera as prey. Fat bodies are utilized for winter maintenance and reproduction. Hatchlings grow 20-30mm during the first year and maximum growth rates occur in summer. Males and females attain sexual maturity at about 165 mm SVL in the fourth year. Seasonal affects on growth rate resulted in poor fit by either logistic-by-length or von Bertalanffy models and a seasonal oscillating model was introduced. Adult males are smaller than females; head sizes are the same but allometric slopes differed significantly. Population size and structure remained stable in the study area. Densities ranged from 9 - 11 lizards/ha. The age structure is marked by the low relative abundance of juveniles. Survivorship during the first year varied among years. Mortality was highest during summer months rather than winter months. Average annual survival of adults 'was high, but varied with sex and years (ranged from 58%-80%). A life table yielded a net reproductive rate (Ro= 1) sufficient to sustain the population, if the reproductive life of an adult female is at least 12 years. Lizards remain in their burrows during winter. In summer, activity was bimodal on sunshine days but unimodal on cool overcast days. Body temperature is regulated by behavioural means (postural and orientation changes) and by shuttling to the cool burrow microclimate. The life history strategy corresponds partially to that of K-selection.

Recognizing how climate change will impact populations can aid in making decisions about approaches for conservation of endangered species. The Blunt-nosed Leopard Lizard (Gambelia sila) is a federally endangered species that, despite protection, remains in extremely arid, hot areas and may be at risk of extirpation due to climate change. We collected data on the field-active body temperatures, preferred body temperatures, and upper thermal tolerance of G. sila. We then described available thermal habitat using biophysical models, which allowed us to (1) describe patterns in lizard body temperatures, microhabitat temperatures, and lizard microhabitat use, (2) quantify the lizards’ thermoregulatory accuracy, (3) calculate the number of hours they are currently thermally restricted in microhabitat use, (4) project how the number of restricted hours will change in the future as ambient temperatures rise, and (5) assess the importance of Giant Kangaroo Rat burrows and shade-providing shrubs in the current and projected future thermal ecology of G. sila. Lizards maintained fairly consistent daytime body temperatures over the course of the active season, and use of burrows and shrubs increased as the season progressed and ambient temperatures rose. During the hottest part of the year, lizards shuttled among kangaroo rat burrows, shrubs, and open habitat to maintain body temperatures below their upper thermal tolerance, but occasionally, higher than their preferred body temperature range. Lizards are restricted from staying in the open habitat for 75% of daylight hours and are forced to seek refuge under shrubs or burrows to avoid surpassing their upper thermal threshold. After applying climatic projections of 1 and 2˚C increases to 2018 ambient temperatures, G. sila will lose additional hours of activity time that could compound stressors faced by this population, potentially leading to extirpation. Finally, temperature-based activity estimation (TBAE) is an automated method for predicting surface activity and microhabitat use based on the temperature of an organism and its habitat. In an attempt to lessen impacts on sensitive species and costs, we assessed continuously logged field active body temperatures as a tool to predict the surface activity and microhabitat use of an endangered lizard (Blunt-nosed Leopard Lizard, Gambelia sila). We found that TBAE accurately predicts whether a lizard is above or below ground 75.7% of the time when calculated using air temperature, and 60.5% of the time when calculated using biophysical models. While surface activity was correctly predicted about 93% of the time using either method, accuracy in predicting below ground (burrow) occupancy was 62% for air temperature and 51% for biophysical models. Using biophysical model data, TBAE accurately predicts microhabitat use in 79% of observations in which lizards are in the sun, 47% in the shade, and 51% in burrows. Heliotherms bask in the sun, and thus body temperatures can shift rapidly when the animal moves to a new microhabitat. This sensitivity, makes TBAE a promising means of remotely monitoring animal activity, particularly for specific variables like emergence time and surface activity.

Thesis (Ph. D.)--University of Sydney, 2004.
Title from title screen (viewed 5 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Biological Sciences, Faculty of Science. Degree awarded 2004; thesis submitted 2003. Appendices contains published articles co-authored by Robert. Includes bibliographical references. Also available in print form.

Abstract There are a remarkable variety of sex determination systems among different animal taxa. In most animals, sex is determined chromosomally. Although in an increasing number of animals sex determination has been found to be influenced primarily by the environment. Species with genotypic sex determination (GSD) have their sex determined at the time of fertilization, by genetic factors alone and those with environmental sex determination (ESD) have their sex determined by environmental factors that act after fertilization. Temperature-dependent Sex Determination (TSD), whereby the sex of the developing embryos depends on the temperature at which they develop is widespread in oviparous reptiles and occurs in all crocodilians, marine turtles and tuatara examined to date and is common in many freshwater turtles and lizards. SECTION ONE Temperature-dependent sex determination (TSD) was never expected to occur in viviparous reptiles, as thermoregulation by pregnant females would result in relatively stable gestation temperatures. Temperature-dependent sex determination and viviparity goes against all the basic assumptions that TSD occurs in oviparous reptiles where temperatures within a nest vary widely. However, skewed sex ratios as a result of incubation temperature indicated the possibility of TSD in the viviparous lizard Eulamprus tympanum. In my first experiments I show the first recorded case of a viviparous reptile with TSD. The developing embryos of the viviparous skink E. tympanum are subject to TSD, with gestation temperature having a highly significant effect on sex and warmer temperatures giving rise to male offspring (Chapter 1). Sex is fully determined at the time of birth and can be differentiated histologically into testes or ovaries (Chapter 2). The morphology and histological characteristics of the gonads of neonatal E. tympanum resulting from the treatment temperatures described in chapter 1 illustrate that sex in E. tympanum is easily distinguished at the time of birth and corresponds with the presence or absence of hemipenes. Males are histologically characterised by an elongated gonad consisting of seminiferous tubules with either no cortical epithelium or, if present at all, in a very thin band. If they are present, Mϋllerian ducts, showing signs of degeneration, are attached to the kidney by a shortened mesosalpinx. Females are histologically characterised by an irregularly shaped gonad consisting of a thick cortical epithelium that occasionally contains oocytes. The Mϋllerian ducts are obvious structures attached to the kidney by a fibrous mesosalpinx. The presence or absence of hemipenes is a reliable technique for determining sex in newborn E. tympanum. Sex determination is easiest to perform on neonates within the first few days of birth as hemipenes become increasingly difficult to evert as neonates age, however, with practice they are easily identified without full eversion. SECTION TWO The thermal biology of E. tympanum in the field is restricted by both the thermal properties of their habitat (Chapter 3) and behavioural modifications when faced with a predation threat (Chapter 4). The available temperatures in the field suggest that TSD is biologically relevant in the species and not just a laboratory artefact; E. tympanum can attain mean selected temperatures achieved in the laboratory but the proportion of time at the temperature is restricted. Females actively thermoregulate in the field, although they are restricted in their efficiency of thermoregulation by environmental constraints, for example, microhabitat structure, weather conditions, predator avoidance and social ranking. The highly territorial nature and high densities of E. tympanum present in Kanangra Boyd National Park potentially force less dominant individuals into less favourable habitats that are significantly cooler. An important point is that gravid females in more favourable habitats in the period encompassing the middle third of development (the assumed sex determining period) are selecting higher temperatures, with lower variance and have greater thermoregulatory efficiency than during the rest of pregnancy, therefore, thermoregulating more precisely during this thermosensitive period (Chapter 3). Chemosensory cues provide important information on the risk of predation. Hence, chemoreception is a common mechanism used by many species to detect the presence of, and subsequently respond to, a potential predator. The perceived risk of predation may force retreat to sub-optimal conditions, forcing a trade-off between the risk of predation and the ability to acquire resources. The basking regime maintained by gravid female E. tympanum, can directly alter sex ratios of offspring produced through temperature-dependent sex determination (Chapter 1). The avoidance of predator scents may restrict basking ability and in turn alter the sex of offspring produced. I measured responsiveness to chemical cues using tongue flicks as an indicator of chemical discrimination in females of different reproductive condition. I then measured activity and basking behaviour of gravid and non-gravid females in experimental enclosures in the presence of various chemical stimuli to determine if basking opportunity is compromised by the presence of a predator scent. Females respond differently depending upon reproductive condition, with gravid females responding most significantly to a predator scent. Activity, basking frequency, and time spent in the open (basking duration) are significantly reduced in gravid females in the presence of a predator stimulus. Under laboratory conditions, gravid females modify their behaviour and forego the opportunity to bask when there is a perceived predation risk (Chapter 4). SECTION THREE As female viviparous reptiles can regulate the temperature of the embryo by maternal temperature selection (Chapter 1), the occurrence of TSD in E. tympanum opens the possibility for females to select the sex of offspring. Reproducing females may benefit by facultatively adjusting their investment into sons over daughters or vice versa, in response to population wide shifts in adult sex ratios. Female E. tympanum, can manipulate the sex of their offspring in response to sex imbalances in the population using temperature-dependent sex determination (Chapter 5). When adult males are scarce, females produce male-biased litters and when adult males are common, females produce female-biased litters. The cues used by a female to assess the adult population are not known, but presumably depends upon the female's experience throughout the breeding season and is the subject of further investigation (Chapter 6). The maternal manipulation of offspring sex ratio in E. tympanum suggests a selective advantage of temperature-dependent sex determination. Any facultative sex ratio response needs to recognise the scarcity of one sex in order to overproduce that sex in the next generation; offspring sex ratio will vary inversely with adult sex ratio. Maternal sex allocation in E. tympanum is linked with population (or adult) sex ratio (Chapter 5), and one of the mechanisms by which females recognise an imbalance may be linked to visual recognition of males (Chapter 6). Females maintained throughout pregnancy without any male stimulus produce entirely male offspring (Chapter 5). In contrast females exposed to male stimulus produce both sexes (Chapter 5). Females respond differently to varying degrees of male stimulus and visual recognition of males in a population may be more important than chemoreception. In the absence of visual cues, females produce more male offspring, even when chemosensory cues are present (Chapter 6). The study system presented here offers many advantages over oviparous species with TSD, due to E. tympanum being relatively short lived and fast maturing. Thus, the fitness consequences over multiple generations as a result of gestation can be investigated. Viviparity allows maternal control of embryonic temperature during gestation and a means of maternal sex allocation. Until now the maternal side of TSD and sex allocation has been where the mother deposits her eggs and the allocation of sex steroid hormones at oviposition, both of which have been difficult to study. The work presented and the study system itself should inspire great interest in TSD and viviparous reptiles.

Abstract There are a remarkable variety of sex determination systems among different animal taxa. In most animals, sex is determined chromosomally. Although in an increasing number of animals sex determination has been found to be influenced primarily by the environment. Species with genotypic sex determination (GSD) have their sex determined at the time of fertilization, by genetic factors alone and those with environmental sex determination (ESD) have their sex determined by environmental factors that act after fertilization. Temperature-dependent Sex Determination (TSD), whereby the sex of the developing embryos depends on the temperature at which they develop is widespread in oviparous reptiles and occurs in all crocodilians, marine turtles and tuatara examined to date and is common in many freshwater turtles and lizards. SECTION ONE Temperature-dependent sex determination (TSD) was never expected to occur in viviparous reptiles, as thermoregulation by pregnant females would result in relatively stable gestation temperatures. Temperature-dependent sex determination and viviparity goes against all the basic assumptions that TSD occurs in oviparous reptiles where temperatures within a nest vary widely. However, skewed sex ratios as a result of incubation temperature indicated the possibility of TSD in the viviparous lizard Eulamprus tympanum. In my first experiments I show the first recorded case of a viviparous reptile with TSD. The developing embryos of the viviparous skink E. tympanum are subject to TSD, with gestation temperature having a highly significant effect on sex and warmer temperatures giving rise to male offspring (Chapter 1). Sex is fully determined at the time of birth and can be differentiated histologically into testes or ovaries (Chapter 2). The morphology and histological characteristics of the gonads of neonatal E. tympanum resulting from the treatment temperatures described in chapter 1 illustrate that sex in E. tympanum is easily distinguished at the time of birth and corresponds with the presence or absence of hemipenes. Males are histologically characterised by an elongated gonad consisting of seminiferous tubules with either no cortical epithelium or, if present at all, in a very thin band. If they are present, M�llerian ducts, showing signs of degeneration, are attached to the kidney by a shortened mesosalpinx. Females are histologically characterised by an irregularly shaped gonad consisting of a thick cortical epithelium that occasionally contains oocytes. The M�llerian ducts are obvious structures attached to the kidney by a fibrous mesosalpinx. The presence or absence of hemipenes is a reliable technique for determining sex in newborn E. tympanum. Sex determination is easiest to perform on neonates within the first few days of birth as hemipenes become increasingly difficult to evert as neonates age, however, with practice they are easily identified without full eversion. SECTION TWO The thermal biology of E. tympanum in the field is restricted by both the thermal properties of their habitat (Chapter 3) and behavioural modifications when faced with a predation threat (Chapter 4). The available temperatures in the field suggest that TSD is biologically relevant in the species and not just a laboratory artefact; E. tympanum can attain mean selected temperatures achieved in the laboratory but the proportion of time at the temperature is restricted. Females actively thermoregulate in the field, although they are restricted in their efficiency of thermoregulation by environmental constraints, for example, microhabitat structure, weather conditions, predator avoidance and social ranking. The highly territorial nature and high densities of E. tympanum present in Kanangra Boyd National Park potentially force less dominant individuals into less favourable habitats that are significantly cooler. An important point is that gravid females in more favourable habitats in the period encompassing the middle third of development (the assumed sex determining period) are selecting higher temperatures, with lower variance and have greater thermoregulatory efficiency than during the rest of pregnancy, therefore, thermoregulating more precisely during this thermosensitive period (Chapter 3). Chemosensory cues provide important information on the risk of predation. Hence, chemoreception is a common mechanism used by many species to detect the presence of, and subsequently respond to, a potential predator. The perceived risk of predation may force retreat to sub-optimal conditions, forcing a trade-off between the risk of predation and the ability to acquire resources. The basking regime maintained by gravid female E. tympanum, can directly alter sex ratios of offspring produced through temperature-dependent sex determination (Chapter 1). The avoidance of predator scents may restrict basking ability and in turn alter the sex of offspring produced. I measured responsiveness to chemical cues using tongue flicks as an indicator of chemical discrimination in females of different reproductive condition. I then measured activity and basking behaviour of gravid and non-gravid females in experimental enclosures in the presence of various chemical stimuli to determine if basking opportunity is compromised by the presence of a predator scent. Females respond differently depending upon reproductive condition, with gravid females responding most significantly to a predator scent. Activity, basking frequency, and time spent in the open (basking duration) are significantly reduced in gravid females in the presence of a predator stimulus. Under laboratory conditions, gravid females modify their behaviour and forego the opportunity to bask when there is a perceived predation risk (Chapter 4). SECTION THREE As female viviparous reptiles can regulate the temperature of the embryo by maternal temperature selection (Chapter 1), the occurrence of TSD in E. tympanum opens the possibility for females to select the sex of offspring. Reproducing females may benefit by facultatively adjusting their investment into sons over daughters or vice versa, in response to population wide shifts in adult sex ratios. Female E. tympanum, can manipulate the sex of their offspring in response to sex imbalances in the population using temperature-dependent sex determination (Chapter 5). When adult males are scarce, females produce male-biased litters and when adult males are common, females produce female-biased litters. The cues used by a female to assess the adult population are not known, but presumably depends upon the female�s experience throughout the breeding season and is the subject of further investigation (Chapter 6). The maternal manipulation of offspring sex ratio in E. tympanum suggests a selective advantage of temperature-dependent sex determination. Any facultative sex ratio response needs to recognise the scarcity of one sex in order to overproduce that sex in the next generation; offspring sex ratio will vary inversely with adult sex ratio. Maternal sex allocation in E. tympanum is linked with population (or adult) sex ratio (Chapter 5), and one of the mechanisms by which females recognise an imbalance may be linked to visual recognition of males (Chapter 6). Females maintained throughout pregnancy without any male stimulus produce entirely male offspring (Chapter 5). In contrast females exposed to male stimulus produce both sexes (Chapter 5). Females respond differently to varying degrees of male stimulus and visual recognition of males in a population may be more important than chemoreception. In the absence of visual cues, females produce more male offspring, even when chemosensory cues are present (Chapter 6). The study system presented here offers many advantages over oviparous species with TSD, due to E. tympanum being relatively short lived and fast maturing. Thus, the fitness consequences over multiple generations as a result of gestation can be investigated. Viviparity allows maternal control of embryonic temperature during gestation and a means of maternal sex allocation. Until now the maternal side of TSD and sex allocation has been where the mother deposits her eggs and the allocation of sex steroid hormones at oviposition, both of which have been difficult to study. The work presented and the study system itself should inspire great interest in TSD and viviparous reptiles.

Area used by male and female Phrynosoma mcallii (Hallowell) was studied in a population locted on the Barry M. Goldwater Aerial Gunnery Range near Yuma, Arizona. Area used by males and females shifted through time and did not fit the definition of home range. Summer male and female area used was not significantly different (F=2.625, df=1, P=0.131), but male areas used were significantly larger for 15-day time periods (F=9.67, P=0.0003). Males overlapped the area they occupied in consecutive 15-day time periods more often than did females. Female area used never overlapped within a 15-day time period. Male area used overlapped those of other males and females within a 15-day time period.

Among vertebrates, oviparity, a condition in which young at least partially develop outside the mother's body and are supported by yolk, is the ancestral state to viviparity, the reproductive mode in which embryos are fully developed at birth. Viviparity in reptiles is found only in the squamates. Among the more than 100 origins of viviparity in squamates, many have occurred fairly recently and as a result some species contain populations of both reproductive modes, i.e., are reproductively bimodal. The evolution of viviparity is associated with many changes including an increase in oviductal egg retention times, a decrease in thickness of the eggshell and a decrease in secretion of the uterine shell glands that are responsible for eggshell secretion. The uterine morphology of the oviparous Saproscincus mustelinus and the reproductively bimodal Saiphos equalis were compared to study the uterine shell gland cycle.

Baited pitfall traps were used to sample the lizard fauna at Birdlings Flat on Kaitorete Spit, Canterbury. Four species had been recorded previously from this area; Leiolopisma maccanni Patterson and Daugherty, Leiolopisma nigriplantare polychroma Patterson and Daugherty, Leiolopisma lineoocellatum (Dumeril and Dumeril) and Hoplodactylus maculatus (Gray). Three of these species (L. maccanni, L. n. polychroma and H. maculatus) were captured during the course of the study. The aim of this present study was to examine the nature of the ecological relationship among these three species at Birdlings Flat. Capture data indicated that L. maccanni was almost entirely confined to the dunelands while L. n. polychroma was associated exclusively with shrublands on old dune ridges behind the sand dunes. H. maculatus' distribution encompassed both of these major habitats. Separation on the basis of habitat was thought to be the most important niche variable for these two diurnal skinks. There was some temporal separation in activity of these two species, with L. maccanni active earlier in the day than L. n. polychroma. However, there was a high degree of overlap in the activity periods of these two species. Temporal differentiation between the nocturnal gecko H. maculatus and the two diurnal skinks is thought to be an important means by which these species coexist. The most common prey items consumed by all three species were Diptera, Araneae, C. propinqua seeds, Hemiptera, unidentified arthropod eggs, Coleoptera and Hymenoptera. Dietary differences between the two skink species were apparent although these differences appeared to be related to the preferred habitats of the respective species. Density estimates for L. maccanni varied between 1050/ha and 1850/ha while L. n. polychroma density varied between 200/ha and 400/ha. The density of H. maculatus was not calculated but appeared to be intermediate to the density of the two skink species. The apparent disappearance of L. lineoocellatum from an area where they were once relatively common is cause for concern. There is no obvious reason for this decline although it may be related to the combined impacts of predation, collection and habitat disturbance.

Baited pitfall traps were used to sample the lizard fauna at Birdlings Flat on Kaitorete Spit, Canterbury. Four species had been recorded previously from this area; Leiolopisma maccanni Patterson and Daugherty, Leiolopisma nigriplantare polychroma Patterson and Daugherty, Leiolopisma lineoocellatum (Dumeril and Dumeril) and Hoplodactylus maculatus (Gray). Three of these species (L. maccanni, L. n. polychroma and H. maculatus) were captured during the course of the study. The aim of this present study was to examine the nature of the ecological relationship among these three species at Birdlings Flat. Capture data indicated that L. maccanni was almost entirely confined to the dunelands while L. n. polychroma was associated exclusively with shrublands on old dune ridges behind the sand dunes. H. maculatus' distribution encompassed both of these major habitats. Separation on the basis of habitat was thought to be the most important niche variable for these two diurnal skinks. There was some temporal separation in activity of these two species, with L. maccanni active earlier in the day than L. n. polychroma. However, there was a high degree of overlap in the activity periods of these two species. Temporal differentiation between the nocturnal gecko H. maculatus and the two diurnal skinks is thought to be an important means by which these species coexist. The most common prey items consumed by all three species were Diptera, Araneae, C. propinqua seeds, Hemiptera, unidentified arthropod eggs, Coleoptera and Hymenoptera. Dietary differences between the two skink species were apparent although these differences appeared to be related to the preferred habitats of the respective species. Density estimates for L. maccanni varied between 1050/ha and 1850/ha while L. n. polychroma density varied between 200/ha and 400/ha. The density of H. maculatus was not calculated but appeared to be intermediate to the density of the two skink species. The apparent disappearance of L. lineoocellatum from an area where they were once relatively common is cause for concern. There is no obvious reason for this decline although it may be related to the combined impacts of predation, collection and habitat disturbance.

Lacerta agilis is a widespread lizard which reaches the western edge of its range in Britain where it is restricted to three geographically separated areas. Recent habitat loss and fragmentation have resulted in a significant decline and it is now a UK conservation priority. Sand lizards from across the Britain were genotyped at 15 microsatellite loci and the resulting dataset used to address questions regarding the conservation genetics, phylogeography and influence of landscape on patterns of genetic diversity. Genetic diversity of Dorset populations compared favourably to European examples. However, diversity was significantly lower in Surrey and Merseyside. Significant genetic structuring occurred across small geographical distances even in relatively unfragmented landscapes. Lacerta agilis colonised Britain via a land bridge across the North Sea and reached the limits of its current distribution approximately 5,000 years BP. Subsequent climate cooling has resulted in a range contraction to areas where the habitat is suitable for the successful incubation of eggs. A resistance surface was used to investigate the effect of landscape configuration on patterns of genetic diversity at multiple scales in Dorset. At a local scale, habitat type and rivers were the best predictors of genetic diversity. At a regional scale, rivers were most important, whereas habitat type and artificial barriers were less important. Artificial barriers may be more significant than the results suggest as their true effect has not yet been realised due to a genetic time-lag. Male lizards from Merseyside exhibited significant differences in colour and pattern to the Dorset and Surrey populations. However, despite difference in colour, all populations were equally green, which is in keeping with the importance of ‘greenness' as a sexual signal. The implications of these findings for the conservation of L. agilis are discussed in the context of current challenges and predicted future global climate change.

Thesis (MSc) -- Stellenbosch University, 2004.
ENGLISH ABSTRACT: Standard histological procedures revealed that there are two types of glands in the cloacal complex of the viviparous Cordylus cataphractus. These occur in the urodeal region of the complex (called urodeal glands), and in the posterior proctodeum region (called proctodeal glands). Urodeal glands are found in females only and differentiate at sexual maturity. Proctodeal glands occur in both sexes and the dorsal and ventral proctodeal glands are identical in structure. Seasonal activity in cloacal gland structure and secretory was studied. Urodeal glands show distinct seasonal variation in development and secretory activity, they become enlarged in vitellogenic females, remain active during pregnancy, with glandular activity peaking around parturition. Proctodeal glands, in contrast, show little or no seasonal variation in development or secretory activity in both sexes. Secretion quantity, however, is highly variable among individuals of the same sex, time of year, as well as reproductive stage, but evidently much less in females than in males. Although the possible functions of the cloacal glands are still unclear, two main functions are suggested: a) mechanical function such as lubrication or a substrate for genital products and b) pheromonal communication. I propose that urodeal glands are involved in some reproductive function rather than in social communication, because very little secretion is found during the mating season and peak glandular activity are evident around parturition. The opposite may be true for proctodeal glands, but further investigation is needed, particularly chemical analysis of secretion and behavioural manipulation, to determine the role of these glands in social communication.
AFRIKAANSE OPSOMMING: Standaard histologiese tegnieke dui aan dat daar twee tipes kliere voorkom in die kloakale kompleks van die lewendbarende akkedis, Cordylus cataphractus. Die een kliertipe word in die urodeale omgewing aangetref en staan bekend as die urodeaalkliere, terwyl die ander groep in die posterior area van die proktodeum voorkom en proktodeaalkliere heet. Urodeaalkliere word slegs in wyfies aangetref en ontwikkel eers na volwassenheid bereik is. Proktodeaalkliere kom in albei geslagte voor en dorsale en ventrale aspekte van hierdie kliere is identies aan mekaar. Die seisoenale aktiwiteit in struktuur en sekresie-aktiwiteit van hierdie kloakale kliere is ondersoek in mannetjies en wyfies wat gedurende verskillende maande van die jaar versamel is en dus in verskillende voorplantingstadia was. Urodeaalkliere het duidelike seisoenale variasie vertoon wat beide ontwikkeling van die klier en sekretoriese aktiwiteite betref. Die klier vergroot tydens vitellogenese, bly aktief tydens swangerskap en bereik maksimale aktiwiteitsvlakke rondom geboorte. In teenstelling hiermee het die proktodeaalkiere van beide geslagte weinig of self geen seisonale variasie in hul ontwikkeling of sekretoriese aktiwiteit getoon nie. Die hoeveelheid sekreet vrygestel was merkbaar minder in wyfies as in mannetjies, maar hoogs veranderlik tussen individue van dieselfde geslag of voortplantingstadium; of wat in dieselfde tydperk van die jaar versamel is. Alhoewel funksies van kloakale kliere steeds onduidelik bly, word twee hooffunksies voorgestel: a) ‘n meganiese funksie, byvoorbeeld as smeermiddel of as ‘n substraat vir geslagsprodukte en b) ‘n kommunikasie funksie, byvoorbeeld in die vrystelling van feromone. Ek stel voor dat die urodeaalkliere eerder by ‘n voortplantingsfunksie betrokke is, aangesien baie min sekreet gedurende die paarseisoen vervaardig word terwyl klieraktiwiteit rondom geboorte ‘n piek bereik. Die teenoorgestelde mag geld vir proktodeaalkliere, maar vereis verdere ondersoek. Veral ‘n chemiese analise van die sekresie en gedragsmanipulasie sal nuttig wees om ‘n moontlike rol van hierdie kliere in sosiale kommunikasie te bepaal.

I evaluated possible constraints on the evolution of viviparity in the lizard genus Sceloporus by experimentally extending the length of egg retention past the normal time of oviposition for a number of oviparous species. Observations also included a representative of the genus Urosaurus, the sister genus to Sceloporus. I determined the effects of retention on embryonic development, hatchlings, and gravid females. Results indicated that the proximate constraints on longer retention times and viviparity are 1) embryonic development becomes arrested or severely retarded in utero, and 2) the ability to maintain gravidity past the normal time of oviposition is limited in some species. Observations on Urosaurus further showed that extended egg retention results in hatchlings with traits that are associated with lower fitness. I also tested the hypothesis that reproductive Sceloporus lower their body temperatures during activity because their normal body temperatures are detrimental to embryos. Observations on a viviparous species of Sceloporus indicated that the normal body temperature of the female was detrimental to embryonic development. This result is indicates that viviparity would be constrained in some squamate lineages if maternal body temperatures are too high for successful embryonic development. I also evaluated the hypothesis that the evolutionary transition from oviparity to viviparity involves a "reduction" of the eggshell concurrent with longer durations of egg retention. If this hypothesis is correct, then attributes of eggshells that should enhance exchange of respiratory gases (i.e., thickness, density, permeability to water vapor) would be correlated with the maximal developmental stage that embryos are able to attain in the oviducts (i.e., stage of developmental arrest). The results of this study indicated that these features of shells do not determine the stage at which development becomes arrested. Thus, the results do not support the hypothesis that shell reduction occurs concurrently with longer periods of egg retention. The results are consistent with the alternative hypothesis that reduction of the eggshell occurs after viviparity has evolved.
Ph. D.

Ticks are haematophagous arthropods and major vectors of pathogenic microorganisms. In Australia, over 74 species of ticks have been described, of which 13 are known to parasitise reptiles. While only three tick borne diseases are formally recognised, Rickettsia honei, the causative agent of Flinders Island spotted fever, has been long associated with the reptile tick, Bothriocroton hydrosauri, despite this tick rarely reported to parasitise people. More recently, a novel Rickettsia species, Rickettsia gravesii, was reported in the ornate kangaroo tick (a common human biting tick), Amblyomma triguttatum, on Barrow Island in Western Australia. In addition, a number of overseas tick-associated microbes (taxa of interest) have been identified in Australian human-biting ticks using an advanced molecular technique, next generation sequencing (NGS). Therefore, the aims of this study were to morphologically and molecularly identify ticks that parasitise reptiles, specifically the bobtail lizard, Tiliqua rugosa, and to employ NGS to profile the bacterial 16S rRNA gene (16S) within the ticks. The taxa identified would then be phylogenetically compared to known taxa of interest. A total of 306 ticks from Western Australia were morphologically identified and 30 were removed from the data set and the remaining 276 included all developmental stages comprising males 43.1% (n=119); nymphs 40.6% (n=112); females 15.2% (n=42) and three larvae (1.1%). Using Australian-specific morphological keys, ticks were identified as A. albolimbatum. To provide more accurate species identification, molecular barcoding of the cytochrome C oxidase 1 (CO1) gene was employed on 17 nymphal and two larval ticks, along with Northern and Southern WA A. albolimbatum ticks as representative specimens. However, only one nymph (5.8%) and two larvae (100%) generated clean chromatograms and all were identified as A. albolimbatum; the two larvae were genetically identical to the Southern representative sample and the nymph more genetically similar to the Northern representative sample (0.48% genetic difference). The genetic distance between the two A. albolimbatum sequences was 4.79%. A total of 116 ticks and six controls were processed for 16S metabarcoding to profile the bacterial communities. A total of 9,706,920 reads were generated using an Illumina V3 600 cycle run on the MiSeq platform. A final quality filtered data set consisted of 4,823,227 reads, with a total of 1,385 zero operational taxonomic units (ZOTUs) generated. The bacterial diversity of the ticks was observed to be statistically different between life stage, with males exhibiting the highest diversity. The bacterial microbiome of the tick samples was dominated by the phylum Proteobacteria (90.94%) and also included Actinobacteria (3.81%) and Firmicutes (3.71%). Interestingly, orders Rickettsiales and Legionellales, which contain known taxa of interest, were identified. BLAST analysis of ZOTUs associated with taxa of interest revealed the most abundant ZOTU as Rickettsia endosymbiont (100% similarity; GenBank accession MK00580); ZOTU2 was 99% genetically similar to Francisella hispaniensis (GenBank accession KT28184); while ZOTU10 and ZOTU19 were most closely related to a Spotted Fever Rickettsia raoultii (99.7% similarity; GenBank accession MK30454) and Coxiella burnetii (100% similarity; GenBank accession LC464975), respectively. Importantly, while R. raoultii does not exist in Australia, literature supports that species delimitation for Rickettsia cannot be based on 16S alone and requires a multi-loci approach. Therefore, the Rickettsia identified in this study may in fact represent a novel endemic species. However, the presence of C. burnetii is intriguing and represents the first evidence within A. albolimbatum ticks supported by phylogenetic analysis. While ticks are rarely implemented in the zoonotic transmission of C burnetii, further research is required to investigate the vector competency of this tick and to determine if reptiles, particularly T. rugosa, are viable reservoirs for this bacterium and determine if reptiles pose a risk to wildlife carers. Overall, this study provides new molecular data for A. albolimbatum and requires further research to investigate the validity of the Northern and Southern morphotypes identified. Furthermore, for the first time in Australia, this study presents the bacterial communities within the bobtail tick, A. albolimbatum, and showcases a rich diversity of microbes, including endosymbionts and known tick-associated pathogens.

Viviparity (live birth) and placentation have evolved in more than 100 lineages of squamate reptiles. However, highly placentotrophic species in which embryos receive the majority of nutrients for development via maternal transport across a placenta are rare. Pseudemoia pagenstecheri is a viviparous Australian scincid lizard with extensive placental transfer of nutrients. For example, 90% of neonate calcium is received via placental transfer. This species has a regionally differentiated chorioallantoic placenta distinguished by an elliptical-shaped region, the placentome. The placentome is characterized by hypertrophied uterine and embryonic epithelial cells supported by dense vascular networks. The remainder of the chorioallantoic placenta is also highly vascularized but epithelia are thin. A yolk sac placenta with hypertrophied epithelia is located in the abembryonic hemisphere of the egg. We used immunohistochemistry and immunoblotting to test the hypothesis that the placenta has regional functional specializations for calcium transport. Calcium uptake by extraembryonic membranes of squamates is correlated with expression of the intracellular calcium binding protein, calbindin-D28K. Immunohistochemistry was used to localize calbindin-D28K expressing cells. Immunoblotting for calbindin-D28K and the plasma membrane calcium ATPase (PMCA, an additional marker for active calcium transport) was used to assess changes in protein expression levels through development. We found support for our hypothesis because calbindin-D28K was expressed in the embryonic epithelium of the yolk sac placenta and in the chorionic epithelium of the placentome, but not in the remainder of the chorioallantoic placenta. In addition, calbindin-D28K was expressed the chorioallantoic membrane in all embryonic stages studied, which encompassed both early and late development. Immunoblotting data show that calbindin-D28K expression was detectable at low levels in early stages of development and increased significantly prior to birth, when embryonic calcium demand peaks. Expression of PMCA also increases significantly throughout development, though less dramatically. Expression of calbindin-D28K and PMCA protein by the chorioallantoic placenta parallels the accrual of calcium in the embryo. These data suggest that placental calcium secretion occurs over an extended interval of gestation, with increasing activity as embryonic demand escalates in late development. In conclusion, our results support our original hypothesis that regional structural differentiation in the placenta reflects functional specializations for calcium transport to the embryo during development.

An investigation of the life history of the western chuckwalla, Sauromalus obesus, was undertaken in the Colorado Desert of southeastern California during a 7-year period. The study provided for a test of current life history theory and the modeling of population dynamics from environmental parameters. Colorado Desert S. obesus were mainly active February through September, but feeding occurred throughout the year. Coyotes were this species' primary predator. Home range sizes of males and females were correlated with adult female activity and nutrient requirements, respectively. The breeding status of females was determined by the presence of preovulatory follicles, oviductal eggs and copora lutea. The breeding status of males was best determined by the presence of sperm in the vas deferens and by levels of spermatogenic activity. Adult females always oviposited during the first half of July. Size at reproductive maturity for both sexes was about 125 mm snoutvent length. Age at maturity for males and females was 2 and 3 years, respectively. Mean annual reproductive frequency was 51%. Reproduction occurred in 6 of 7 years. Mean clutch size was 6.9 eggs. Clutch masses and egg masses averaged 34.3% and 5.3% of total body mass, respectively. For a given body size, there was no annual variation in clutch size, egg mass, or reproductive effort. The consistency of these traits indicates adaptation to a predictable environment. Relatively high egg masses are an adaptation to counter the harsh environment. Annual recruitment was about 20%, almost exclusively due to reproduction. First year and subsequent annual survivorship rates averaged 40% and 75%, respectively. Most individuals lived no longer than 10 years. Compared with Mojave Desert populations, Colorado Desert S. obesus demonstrated earlier maturity, higher reproductive rates, higher first year survival and lower adult survivorship. High reproductive rates and first year survival were attributable to the predictability of mild winters and summer rainfall. Such conditions promoted lower adult survivorship because of associated costs of reproduction and predation. Attempts were made to predict population age class structure from winter precipitation regression models. Such a procedure appears reliable for predicting age-specific fecundity and therefore is a useful tool for management practices.

Reptiles are polyphyletic, and previous studies of renal anatomy and physiology in reptiles have covered a wide diversity of species of different phylogeny and habitat. To date, no study has examined the renal morphology and function of a group of closely related reptiles from different environments, yet this design has a number of advantages. Firstly, phylogenetic effects are reduced while adaptive specialisations in renal function or structure can be elucidated, and secondly, the variation in renal form and function between closely related species may be quantified in an effort to appreciate better the variation between more distantly related species. In this thesis, kidney morphology and renal function were studied in three Western Australian agamid lizards inhabiting environments differing in the availability of water. These key species were Pogona minor, Ctenophorus nuchalis and Ctenophorus salinarum. The renal anatomy of the three key lizards was characterised by determining glomerular diameter, volume density, surface area and number in each. Allometric relationships between kidney, colon and body mass were investigated in these and an additional 11 species of agamid lizard. Patterns of response to osmotic challenge were recorded by measuring renal variables such as urine flow rate, glomerular filtration rate and fractional reabsorption of filtrate among the three key species, and concurrent measurements of circulating arginine vasotocin in P. minor and C. nuchalis allowed the response of this hormone to homeostatic imbalance in these species to be gauged. The gross morphology and the glomerular characteristics of the kidneys was remarkably similar between species. Glomerular number and other characters varied as a function of body size rather than species, contrasting with reports in the literature suggesting that a given species has a particular number of glomeruli. ... Thus, kidney morphology is constrained among species and the response of each species to osmotic perturbation is similar. However, the mechanisms underlying antidiuresis and the hormonal control of this process differ subtly between species, and there is some evidence to suggest that P. minor is more adapted to a mesic environment than the other two lizards examined in this study. The hypothesis that renal form and function reflect the environment in which a lizard lives therefore receives partial support, although the reptilian bauplan is able to mitigate many of the forces that could potentially lead to renal specialisation.

ABSTRACT Social relationships, habitat utilisation and life history characteristics provide a framework which enables the survival of populations in fluctuating ecological conditions. An understanding of behavioural ecology is critical to the implementation of Natural Resource Management strategies if they are to succeed in their conservation efforts during the emergence of climate change. Egernia whitii from Wedge Island in the Spencer Gulf of South Australia were used as a model system to investigate the interaction of life history traits, scat piling behaviour and chemosensory communication in social lizards. Juveniles typically took ¡Ý 3 years to reach sexual maturity and the results of skeletochronological studies suggested longevity of ¡Ý 13 years. Combined with a mean litter size of 2.2, a pregnancy rate estimated at 75% of eligible females during short-term studies, and highly stable groups, this information suggests several life history features. Prolonged juvenile development and adult longevity may be prerequisite to the development of parental care. Parental care may, in turn, be the determining factor that facilitates the formation of small family groups. In E. whitii parental care takes the form of foetal and neonatal provisioning and tolerance of juveniles by small family or social groups within established resource areas. Presumably, resident juveniles also benefit from adult territorialism. Research on birds suggests that low adult mortality predisposes cooperative breeding or social grouping in birds, and life history traits and ecological factors appear to act together to facilitate cooperative systems. E. whitii practice scat piling both individually and in small groups. Social benefits arising from signalling could confer both cooperative and competitive benefits. Permanent territorial markers have the potential to benefit conspecifics, congenerics and other species. The high incidence of a skink species (E. whitii) refuging with a gecko species (N. milii) on Wedge Island provides an example of interspecific cooperation. The diurnal refuge of the nocturnal gecko is a useful transient shelter for the diurnal skink. Scat piling may release a species ¡®signature¡¯ for each group that allows mutual recognition. Scat piling also facilitates intraspecific scent marking by individual members, which has the potential to indicate relatedness, or social or sexual status within the group. The discovery of cloacal scent marking activity is new to the Egernia genus. E. Whitii differentiate between their own scats, and conspecific and congeneric scats. They scent mark at the site of conspecific scats, and males and females differ in their response to scent cues over time. Scat piling has the potential to make information concerning the social environment available to dispersing transient and potential immigrant conspecifics, enabling settlement choices to be made. This thesis explores some of the behavioural strategies employed by E. whitii to reduce risks to individuals within groups and between groups. Scents eliciting a range of behavioural responses relevant to the formation of adaptive social groupings, reproductive activity, and juvenile protection until maturity and dispersal are likely to be present in this species. Tests confirming chemosensory cues that differentiate sex, kin and age would be an interesting addition to current knowledge. The interaction of delayed maturity, parental care, sociality, chemosensory communication and scat piling highlights the sophistication of this species¡¯ behaviour. An alternative method for permanently marking lizards was developed. Persistence, reliability and individual discrimination were demonstrated using photographic identification and the method was shown to be reliable for broad-scale application by researchers. Naturally occurring toe loss in the field provided a context against which to examine this alternative identification method and revealed the need to further investigate the consequences of routine toe clipping, as this practice appears to diminish survivorship.

Thesis (PhD (Zoology))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: The Cape Floristic Region (CFR) is a biodiversity hotspot in South Africa, threatened by climate change and various other processes. The Greater Cederberg Biodiversity Corridor (GCBC) is a conservation area incorporating both public and private land, providing a practical and effective solution to conserve biodiversity in the CFR. This area is also home to two of the eight melanistic cordylid lizard species found in south-western South Africa. One of the herpetological conservation targets identified for the GCBC was an understanding of the ecology of melanistic cordylid populations with particular reference to global environmental change. Most melanistic cordylids occur in cool coastal and montane localities, and it was suggested that melanism has a thermoregulatory function in these species. The first aim of this study was to determine the climatic conditions with which melanistic cordylids are currently associated. Several melanistic cordylid populations showed a distinct association with a high incidence of fog and cloud cover, underscoring the thermal melanism hypothesis, which predicts that melanistic lizards should occur in cool environments. Several other populations, however, did not show such an association. The next aim was thus to compare habitat use and morphology among 10 melanistic cordylid populations. Individuals of the northern population of Pseudocordylus capensis and the Cordylus peersi population occurred in the warmest environments, used significantly higher rock formations, and had relatively longer limbs than those of other melanistic populations. Having a morphology that allows for flexibility in habitat use, may enable species such as P. capensis to overcome the constraints of melanism in warm environments. Being melanistic may result in decreased activity times in warm environments. The variation in habitat thermal quality and daily activity patterns of two melanistic cordylid species with different morphologies and habitat preferences, occurring sympatrically, was investigated. During summer, high rocks provided a better thermal quality habitat to P. capensis than small rocks, and P. capensis had a longer activity period than C. oelofseni. This suggests that the thermal opportunities provided by high rock enables P. capensis to increase its activity time. The impact of terrestrial and aerial predators can help shape body armour in lizards, with those species more exposed to aerial predators being faster and less armoured, and those more exposed to terrestrial predators being more heavily armoured. The degree of body armour in melanistic cordylids and their non-melanistic relatives was investigated. Melanistic members of the cordylus-niger-oelofseni and C. polyzonus clades had less armour than their non-melanistic relatives, supporting the prediction that melanistic cordylids basked more and were more exposed to aerial predators than non-melanistic lizards. An increase in body armour in C. peersi indicated exposure to terrestrial predators, whereas P. capensis had a reduction in body armour, indicating exposure to aerial predators. Little body armour, together with a slender morphology and long limbs, may thus enable this species to move with ease on large boulders and scale vertical surfaces to successfully avoid predators. Pseudocordylus capensis displayed much greater movement rates during activity than other cordylids. A less sedentary foraging strategy may be a prerequisite for life on large, barren rock surfaces where food availability may be low or not uniformly distributed. Both males and females of this species also had large home ranges, a unique phenomenon for cordylids. Space use of males only overlapped marginally, but extensive overlap among males and females and among females, respectively, was observed. Due to the constraining effect of climate on the distribution of most melanistic populations, melanistic cordylids should be considered as priority species for conservation. While P. capensis is pre-adapted for survival in warm climates, it is dependent on the availability of suitable habitats. The GCBC would thus play an important role in the conservation of this species’ habitat.
AFRIKAANSE OPSOMMING: Die Kaapse Blommeryk (KBR) is ‘n “biodiversity hotspot” in Suid-Afrika wat deur klimaatsverandering en verskeie ander prosesse bedreig word. Die Groter Cederberg Biodiversiteitskorridor (GCBK) is ’n bewaringsarea wat beide openbare en privaatgrond inkorporeer, en ’n praktiese en effektiewe oplossing tot die bewaring van biodiversiteit in die KBR bied. Twee van die ag melanistiese gordelakkedisse wat in suidwestelike Suid-Afrika aangetref word, kom ook hier voor. Een van die herpetologiese bewaringsdoelwitte vir die GCBK was om insig oor die ekologie van melanistiese gordelakkedis populasies met verwysing na globale omgewingsveranderinge in te win. Die meeste melanistiese gordelakkedisse kom in koel kus- en berggebiede voor, en daar is voorgestel dat melanisme ‘n termoregulerende funksie by hierdie spesies het. Die eerste doel van die studie was om die huidige klimaatstoestande waarmee melanistiese gordelakkedisse geassosieer word, te bepaal. Verskeie melanistiese gordelakkedis-populasies het ‘n duidelike assosiasie met mis en wolkdekking getoon, wat die termiese melanisme hipotese se voorspelling dat melanistiese akkedisse in koue omgewings moet voorkom, ondersteun. Verskeie ander populasies, het egter nie so ‘n assosiasie getoon nie. Die volgende doel was om habitatgebruik en morfologie tussen 10 melanistiese gordelakkedispopulasies vergelyk. Individue van die noordelike populasie van Pseudocordylus capensis en Cordylus peersi het in die warmste omgewings voorgekom, het relatief langer ledemate gehad en beduidend hoër rotsformasies as ander melanistiese populasies benut. ’n Morfologie wat buigsame gebruik van die habitat toelaat, kan sommige spesies soos P. capensis in staat stel om die beperkinge van melanisme in ‘n warm omgewing te oorkom. In warm omgewings mag melanisme tot ’n afname in aktiwiteitstye lei. Variasie in termiese kwaliteit van die habitat en daaglikse aktiwiteitspatrone van twee melanistiese spesies, met verskillende morfologieë en habitatvoorkeure, wat simpatries voorkom is bestudeer. Gedurende somer het hoë rotse ‘n beter termiese kwaliteit habitat aan P. capensis verskaf as die klein rotse, en P. capensis het ‘n langer aktiwiteitsperiode as C. oelofseni gehad. Dit stel voor dat die termiese geleenthede wat deur hoë rotse verskaf word, P. capensis in staat stel om sy aktiwiteitsperiode te verleng. Die invloed van terrestriële en lugpredatore kan help om liggaamspantser in akkedisse te vorm. Spesies wat hoofsaaklik aan lugpredatore blootgestel is, is vinniger en het minder pantser, terwyl spesies wat hoofsaaklik aan terrestriële predatore blootgestel is, meer pantser het. Die graad van pantser in melanistiese gordelakkedisse en hulle nie-melanistiese naasverwantes is ondersoek. Melanistiese lede van die cordylus-niger-oelofseni en C. polyzonus klades het minder pantser as hulle nie-melanisties naasverwantes gehad, en ondersteun die voorspelling dat melanistiese gordelakkedisse meer in die son gebak het en meer aan lupredatore blootgestel was. ’n Toename in pantser by C. peersi dui op blootstelling aan terrestriële predatore, terwyl P. capensis die minste pantser van alle melanistiese gordelakkedisse het, wat dui op blootstelling aan lugpredatore. Min beskerming, tesame met ‘n lenige morfologie en lang ledemate, mag dus hierdie spesie toelaat om gemaklik oor groot rotse en vertikale oppervlaktes te beweeg en roofdiere suksesvol te vermy. Pseudocordylus capensis het groter bewegingstempo’s tydens aktiwiteit as ander gordelakkedisse getoon. ‘n Meer beweeglike voedingstrategie mag ook ‘n voorvereiste wees vir ‘n lewe op groot, leë klipoppervlaktes waar voedselbeskikbaarheid dalk laag kan wees en nie eweredig versprei is nie. Beide mannetjies en wyfies het ook groot tuisgebiede gehad, ’n unieke verskynsel by gordelakkedisse. Mannetjies se ruimtes het slegs marginaal oorvleuel, terwyl daar heelwat oorvleueling tussen mannetjies en wyfies se ruimtes was. As gevolg van die beperkende invloed van klimaat op die verspreiding van die meeste melanistiese populasies, moet melanistiese gordelakkedisse as prioriteitspesies vir bewaring beskou word. Terwyl P. capensis pre-aangepas is vir oorlewing in warm klimate, is hierdie spesie afhanklik van die beskikbaarheid van gepaste habitatte. Die GCBK sal dus ’n belangrike rol vervul in die bewaring van die habitat van hierdie spesie.

Thesis (MSc)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: There is overwhelming evidence that the Armadillo Lizard, Cordylus cataphractus, forms permanent aggregations, and that termites are possibly the most important component of the diet of this species. In addition, the spinose morphology and defensive tail-biting behaviour displayed by this lizard species strongly imply that individuals move away from the crevice, where they are more vulnerable to predation. Therefore the aim of this part of the study was to investigate whether C. cataphractus harvest termites at the termite foraging ports and to discuss the likely ecological implications of termitophagy for this species. A quadrate at the Graafwater study site, including several crevices housing C. cataphractus groups, was measured out. All the foraging ports of the subterranean harvester termite (Microhodotermes viator) present in the quadrate, were located and their positions recorded in respect to the distance from the nearest crevice housing lizards. The presence of C. cataphractus tracks at the foraging ports was used to verify whether individuals visited specific termite foraging ports. Tracks were found at foraging ports located at an average distance of 6.1 m, but were also located at foraging ports up to 20 m from the nearest crevice. The results strongly support the hypothesis that C. cataphractus individuals move away from the crevice to feed on termites. Termitophagy and the heavy armature of C. cataphractus appear to be key factors in the group-living behaviour of this species. Termitophagy allows individuals to live in groups as competition for food at the home crevice will be limited. Theheavy armature of C. cataphractus renders it clumsy and slow-moving, compared to other cordylids. Group-living will, however, eliminate juvenile dispersal and mate-searching excursions, activities which, in the light of the heavy morphology of the species, may result in high predation impact. The global objective of the study was to investigate social structure and space-use in Cordylus cataphractus. For the correct interpretation of data on the latter, it was necessary to first establish an ethogram for the study animal. Members of a multi-male group located at the Graafwater site, including all age-sex classes, were observed in the field by telescope, for a total of 102 hours. All individuals were observed to predominantly display maintenance behavioural act systems, however, agonistic act systems were also observed. Aggression levels were determined for the respective agonistic behavioural acts observed. Males were highly aggressive and displayed the most aggression (67.42 %). Females and sub-adults displayed aggression for 34.97 % and 37.75 % of the total observation time, respectively. Juveniles did not display aggression at all. Mating behaviour was also observed and described. An ethogram was thus established for the first time for C. cataphractus, and was compared to the ethograms available for a few other cordylids. The spatial distribution of individuals within a population has an important impact on the social structure that ensues. Living in a group imposes several pressures on the individual and competition for mates is one. The main aim of the study was to determine the space-use of all theindividuals included in a multi-male Cordylus cataphractus group (n = 55), to elaborate on the mating system. Specific focus was on the adult males and females of the multi-male group, because, ultimately, the manner in which individuals, particularly the adult males and females, utilise space, determines the mating system. The mating system is an important aspect of social structure. A two-dimensional grid pattern was delineated at a free-living, multi-male group’s crevice, situated at the Graafwater study site, to be able to plot the position of each individual during observations. All marked individuals, that were visible, were scanned through a telescope and their respective positions were recorded at 30-minute intervals. Arcview 3.2 Geographical Information Software was used to create a computerised model replicate of the two-dimensional grid pattern at the crevice, and to graphically depict the recorded positions for each individual. The space-use of males overlapped greatly with the space-use of females (66.12 ± 31.81 %), but a 0 % overlap in space-use was observed among adult males. The space-use of sub-adults and juveniles overlapped highly among one another, as well as with the space-use of adult males and females. The results showed conclusively that adult male C. cataphractus are territorial, defending specific sites at the crevice. The territory of each male included in the multi-male group incorporated at least one female. The space-use of several females incorporated the space-use of two or more males. Males were observed to mate with one or more females, and one female was observed to mate with two different males on more than one occasion. Thus the evidence strongly suggests that C. cataphractus males display typical territorial polygyny whereas females may be promiscuous.
AFRIKAANSE OPSOMMING: Daar is oorweldigende bewyse dat die pantsergordelakkedis, Cordylus cataphractus, permanent in groepe bly en dat termiete waarskynlik die belangrikste komponent in die dieet van hierdie spesie is. Die stekelrige morfologie en die stert-byt beskermingsgedrag is verder sterk aanduidings dat hierdie akkedisse tyd weg van hul klipskeure spandeer waar hulle meer gevoelig vir predasie is. Die doelwit van die eerste deel van die studie was om te bepaal of C. cataphractus termiete by die voedingspoorte van die termietneste oes en verder ook om die moontlike ekologiese implikasies wat termitofagie vir die spesie inhou, te bespreek. ‘n Kwadraat was by die Graafwater studielokaliteit uitgemeet om verskeie akkedisgroepe in te sluit. Al die voedingspoorte van die suidelike grasdraer termiet (Microhodotermes viator) binne die kwadraat is gevind en die afstande na die naaste klipskeur wat akkedisse huisves, is vir elke voedingspoort bepaal. Die teenwoordigheid van C. cataphractus spore in die sand by die voedingspoorte was gebruik om besoeke aan spesifieke voedingspoorte te bevestig. Spore is by voedingspoorte gemiddeld 6.1 m vanaf die naaste akkedisgroep gevind, maar tot so ver as 20 m vanaf die naaste akkedisgroep. Die resultate verleen sterk ondersteuning vir die hipotese dat C. cataphractus individue op termiete weg van hul klipskeur af voed. Termitofagie en die swaar pantser van C. cataphractus is waarskynlik sleutelfaktore in die groeplewe-gedrag van die spesie. Termitofagie laat groeplewe toe omdat kompetisie vir voedsel by die klipskeur beperk sal wees. Die swaar pantser van C. cataphractus het tot gevolg dat die spesie lomp en stadig is in vergelyking met ander gordelakkedisse. Groeplewe sal egter natale spreiding en maatsoek-ekskursies, aktiwiteite wat in die lig van die lompheid van die spesie swaar predasie impak tot gevolg kan hê, uitskakel. Die oorhoofse doelwit van die studie was om die sosiale struktuur en spesifiek ruimtebenutting by C. cataphractus te ondersoek. Vir korrekte interpretasie van data oor lg. was dit egter eers nodig om ‘n etogram vir die studiedier saam te stel. Lede van ‘n multi-mannetjie groep, wat alle ouderdomsgrootte klasse ingesluit het, is by die Graafwater studielokaliteit m.b.v. ‘n teleskoop vir ‘n totaal van 102 uur dopgehou. Al die individue in die groep het oorwegend instandhoudingshandelingsisteme vertoon, alhoewel agonistiese handelingsisteme ook vertoon is. Aggressievlakke is vir die verskeie agonistiese gedragshandelings bepaal. Mannetjies was hoogs aggressief en het die meeste aggressie vertoon (67.42 %). Wyfies en subvolwassenes het aggressie vir 34.97 % en 37.75 % van die totale observasietyd respektiewelik getoon. Jong individue het geen aggressie getoon nie. Paringsgedrag was ook waargeneem en beskryf. ‘n Etogram is dus vir die eerste keer vir C. cataphractus opgestel en is ook vergelyk met etogramme van ander gordelakkedisse. Die ruimtelike verspreiding van individue binne ‘n populasie het ‘n belangrike invloed op die sosiale struktuur wat daaruit voortvloei. Om in ‘n groep te lewe, plaas verskeie drukke op die individue binne die groep en kompetisie vir maats is een hiervan. The hoofdoelwit van die studie was om die ruimtebenutting van al die individue binne ‘n multi-mannetjie groep van C. cataphractus (n = 55) te bepaal en om die paringsisteem in so ‘n groep te ondersoek. Die spesifieke fokus was op die volwasse mannetjies en wyfies, omdat die paringsisteem deur die wyse waarop volwasse individue ruimte benut, bepaal word. Die studie is by die Graafwater studielokaliteit gedoen. Die oppervlak buite ‘n klipskeur wat deur ‘n multi-mannetjie groep bewoon word is opgedeel in sektore om die kartering van die posisies van die individue tydens observasietye moontlik te maak. Al die individue is vooraf met verfkodes langs die kant van die kop gemerk en op gegewe observasiedae is individuele posisies elke 30 min aangeteken. Arcview 3.2 Geographical Information Software was gebruik om ‘n tweedimensionele, gerekenariseerde replikaat van die klipskeur en onmiddelike omgewing te skep en om die waargenome posisies van individue grafies voor te stel. Die ruimtebenutting van mannetjies het grootliks met dié van wyfies oorvleuel, terwyl zero oorvleueling tussen mannetjies waargeneem is. Ruimtebenutting van subvolwasse en jong individue het ook grootliks onderling oorvleuel en ook met dié van volwasse mannetjies en wyfies. Die resultate toon duidelik aan dat volwasse mannetjies territoriaal is en dat spesifieke standplase rondom die klipskeur verdedig word. Die territorium van elke volwasse mannetjie het of ‘n gedeelte of die hele ruimtebenutting van ten minste een volwasse wyfie ingesluit. Ruimbenutting van verskeie wyfies het met dié van twee of selfs meer mannetjies oorvleuel. Mannetjies is waargeneem om met meer as een wyfie te paar en ten minste een wyfie het met meer as een mannetjie gepaar. Die resultate dui dus sterk daarop dat C. cataphractus mannetjies tipies terrotoriale poligenie vertoon terwyl wyfies weer promisku is.

Includes bibliographical references.
The field metabolic rate (FMR) and water flux of the herbivorous Namib sand-dune lizard, Angolosaurus skoogi, was measured during the summer non-breeding period (early January) by means of doubly labelled water. FMR was about half that expected for a lizard of this size. Water flux and laboratory measured standard metabolic rates were, however, typical of other desert lizards. It thus appeared a priori that this species was behaviourally reducing metabolic costs through reduced activity. This generated questions with regard to the ecological and physiological significance of low FMRs. Is the reduction forced by intolerable environmental conditions or the need to stay in positive water and energy balance? Alternatively, is activity reduction voluntary and geared towards optimizing growth and storage, possibly in preparation for periods of physiological stress ? The research required to answer these questions forms the basis of this thesis. There has been much discussion about the evolutionary and ecological significance of growth rates. The consensus seems to be that, under most circumstances, animals are adapted in ways that maximize growth or optimize growth in relation to realistically attainable rates of gross energy intake. Animal behaviour may be influenced by factors unrelated to growth considerations such as starvation, involuntary hypo/hyperthermia, predator evasion and social interactions. These factors may be difficult to identify and isolate, making this hypothesis difficult to test. Previous studies on the biology of A. skoogi have shown that this species has a perennially available food source, a wide range of potential body temperatures at its disposal and a low predation risk. Social interaction appear to be confined to the breeding season. This species is thus a particularly suitable subject for a scope for growth optimization study.

Habitat preference of the eastern fence lizard, Sceloporus undulatus, was investigated in southwestern Virginia. Habitat features were measured at 158 lizard-centered plots and at paired random plots. Landscape-level variables, southerly aspect and mixed forest type, distinguished lizard-centered from random sites. Hatchlings were associated with relatively high temperature at perch height (23 °C), relatively high amounts (per 1- m2) of coarse woody debris (15%) and bare ground (15%), and relatively low amount of litter (34%). Adults and juveniles were associated with a relatively high number of rocks (22 per 0.01 hectare) and amount of coarse woody debris (9% per 1- m2). Habitat preferences were modeled with a Geographic Information System (GIS) using landscape-level variables and with logistic regression and Akaikeâ s Information Criterion using site-level variables. The best-fitting site-level model for adults/juveniles included % CWD. The best-fitting model for hatchlings included % CWD and number of rocks, and the second best-fitting model also included % litter. Landscape (both classes) and site-level models (adult/juveniles only) were tested at 15 GIS-predicted â suitableâ study areas and at 15 GIS-predicted â unsuitableâ areas. Site-level models for hatchlings were tested with independent data collected at two study areas. Sixteen lizards were found at â suitableâ areas and one at an â unsuitableâ area; the GIS-based model was a good predictor of lizard presence at the landscape level. The best-fitting site-level models for adults/juveniles and hatchlings were poor predictors of lizard presence while the second best-fitting hatchling model was a good predictor of hatchling presence.
Master of Science

Uma notata in the Mohawk Dunes had population densities in good habitat of 15-17 lizards/ha. Testis volumes peaked in April-May and declined to low levels by August. Egg production peaked in May during 1995 but did not occur in spring 1996. Minimum convex polygon home range estimates were 530 (±70 SE) m² for 2 adult males and 228 (±82) m² for 8 adult females. Adjusted for sample size bias, these estimates were 994 (±422) and 774 (±302) m², respectively. Subadults had smaller home ranges. Uma notata actively used perennial plants as escape cover, preferentially selecting Ambrosia dumosa. I found significant use of plant materials in Uma notata diet with both ontogenetic and seasonal shifts in proportions of plant items. Their diet included 65 taxa of arthropods from 39 families, along with 13 plant species in 7 families. I also studied survival rates, tail loss, substrate selection, and thermal effects.