Dissertations / Theses on the topic 'Lizards'

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.

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.)

[Truncated abstract] In ecomorphological or ecophysiological studies, variation in `design? traits (e.g. size, morphology and physiology) is thought to determine variation in ecologically-relevant performance traits, which in turn determines fitness in a particular habitat (Arnold 1983). Thus, natural selection is thought to act most directly on intermediate traits such as measures of locomotory performance. This thesis examined this process in the closely related group of Australian varanids lizards (Squamata: Varanidae). Phylogenetically, varanids are divided into three major clades. Size (mass and snout-to-vent length) is strongly correlated with these three clades. Two clades, (Gouldii and Komodoensis) are large, while the third clade (Odatria) has a smaller body size. Thus, there is considerable variation in size for various species. Size varied for species by three orders of magnitude. Size is also related to two ecological characteristics, foraging mode and habitat openness. Widely-foraging species were larger than sit-and-wait strategists, while species from open habitats were larger than species from semi-open or closed habitats. However, given the tight link between size and phylogeny we cannot separate adaptation of size to ecological traits from that of phylogenetic patterns. Of interest throughout this thesis was how variations in design (e.g. morphology and physiology) were related to ecological characteristics. Since body size also influences many of these morphological and physiological characteristics it is often necessary to remove the effects of size. Three design traits were examined in detail: body dimensions, vertebral number and metabolic rates. …Curiously, no performance variable linked differences in size-free body dimensions to retreat sites. This suggests that there is either a direct link between design and ecology (e.g. dorso-ventral compression), or some unmeasured performance variable related to retreat site. Given that most performance traits are thought to involve kinematic movements of the hindlimb limb and pelvis, and these were not best related to retreat site, then a direct link between design and ecology with respect to retreat site seems possible. In summary, this thesis provides evidence not only for links between design and ecology mediated by locomotory performance traits, but also direct links between design and ecology, for Australian varanid lizards.

The transition between terrestrial varanoid lizards and aquatic mosasaurs through the intermediate, semi-aquatic aigialosaurs is fully documented. Aigialosaurs are shown to possess a mosaic of mosasaurian (configuration of the skull, jaw and tail) and terrestrial varanoid characters (appendicular skeleton and trunk).
The taxonomic position of the Aigialosauridae within the superfamily Varanoidea is evaluated. Based on character states previously used to define the Varanoidea, neither the specific affinities of aigialosaurs nor the sister-group relationships of earlier members of the terrestrial varanoid assemblage can be securely established. For this reason, the specific character states involved have been reexamined and alternative hypotheses of relationship have been considered.

The phenotypes of hatchling reptiles are influenced by the environmental conditions that embryos experience during incubation, by yolk invested into the egg, and by the genetic contributions of the parents. Phenotypic traits are influenced by these factors in ways that potentially affect the fitness of hatchlings. The physical conditions that embryos experience within the nest affects development, hatching success, and hatchling phenotypes. Thus, the nest site that a female selects can influence the survival of her offspring as well as her overall fitness. In Chapter 1, I addressed this issue through a nest site selection experiment designed to determine the substrate temperature and moisture conditions that female eastern fence lizards (Sceloporus undulatus) select when provided a range of conditions from which to choose. In general, I found that females selected nest sites with conditions that yield high hatching success. In Chapter two, I investigated the relative contributions of incubation moisture conditions, maternal yolk investment, and clutch (genotype) to variation in hatchling phenotypes and survival under field conditions. Eggs from 28 clutches were distributed among two moisture treatments; wet (-150 kPa) and dry (-530 kPa). In another treatment, yolk was removed from eggs to determine the affect of yolk quantity on hatchling phenotypes. After hatching, several phenotypic traits (mass, snout-vent length, tail length, body shape, thermal preference, running speed, desiccation rate, and growth rate) were measured. Hatchlings were subsequently marked and released at a field site in southwest Virginia. Hatchlings were recaptured twice weekly prior to winter and the following spring to monitor growth and survival. I found that incubation moisture and yolk removal affected only hatchling body size; individuals from the dry and yolk removed treatments were smaller in body size than those from the wet treatment. However, clutch was the most important source of phenotypic variation; all phenotypes were affected by clutch. Significant clutch effects suggested the possibility that phenotypic variation had at least some genetic basis. In the field, survival was not affected by incubation moisture and yolk removal, and overall survival was not associated with hatchling body size. Survivors and nonsurvivors differed only in growth rate in the field and running speed measured in the laboratory. Survivors ran faster and grew more slowly than nonsurvivors. To examine the association of clutch with survival, I used clutch mean values to look at the relationship between phenotype and survival. Clutches that produced relatively slow growing individuals and fast runners had higher survival rates than clutches that produced relatively rapid growing individuals and slow runners. In order to grow rapidly, an individual must eat more than slowly growing individuals. Thus, rapid growth rate may increase risk of predation through its association with foraging activity. Individuals that run fast should be capable of capturing prey and evading predators more effectively than individuals that run slowly. Overall, these results emphasize the importance of clutch to variation in phenotypes and survival in hatchling Sceloporus undulatus.
Master of Science

The integument is the body organ interfacing between the internal and external environments of a lizard. This study explores aspects of its structure, texture, and coloration, relating them to survival strategies of horned lizards. The dermal chromatophore structure of Phrynosoma modestum is described. Color change depends on two cell types, melanophores and iridophores. This cellular arrangement may be typical of lizards utilizing color change for thermoregulation. Color pigment cells (xanthophores and erythrophores) function in pattern formation and background color matching. Experiments on the regulation of color change revealed that (1) -MSH is the prime skin darkening agent, (2) - and -adrenergic receptors also play a role in color change, and (3) temperature is a factor in in vitro and in vivo darkening and lightening responses. Apparently the primary role of color change is thermoregulation. Intraepidermal mechanoreceptors on dorsal body, limb, and head scales were studied, their ultrastructure is described, and their role in defense and survival is explored. The use of the integument for "rain-harvesting" of drinking water by P. cornutum is described, including stereotyped behavior, stereoscopic SEM examination of interscalar channels, experiments on capillary water flow, and an evaluation of micro-ornamentation. Comparisons are made with the putative use of the integument for the collection of rain, fog, or dew for drinking by Moloch and Phrynocephalus. A stereotypic behavior that utilizes positioning of occipital horns and dorsal scale armament is described and hypothesized to be an ophidian antipredator defense. Attacks by Onychomys torridus on P. cornutum and P. modestum were studied to further evaluate the role of occipital horns, dorsal scalation, and dermal collagen as antipredator defenses. Attack behaviors of the grasshopper mice and defense behaviors of the lizards are detailed. The use of color pattern, integumental structures, and mimetic behavior by P. modestum in avoidance of predator detection, through "stone-mimicry," is hypothesized and supported. Aspects of social communication in four species were studied. The importance of olfaction for intraspecific communication and lack of visual color signals is related to the need for chromatic crypticity in order to avoid detection by predators.

The increasing popularity of snakes and lizards as pets has led to an increasing demand of specialised veterinary duties in these animals. Diagnostic imaging is often a fundamental step of the clinical investigation. The interpretation of diagnostic images is complex and requires a broad knowledge of anatomy, physiology and pathology of the species object of the clinical investigation. Moreover, in order to achieve a correct diagnosis, the comparison between normal and abnormal diagnostic images, for all the diagnostic imaging modalities, is mandatory. In this PhD thesis the diagnostic imaging features of some snake and lizard species are described. The aim of all the works presented is to provide some normal atlases matching the normal gross and cross-sectional anatomy with the normal radiographic, ultrasonographic, CT features of some of the most popular pet lizard and snake specie. In Chapter I a review of literature regarding snakes and lizards is presented. The aim of this chapter is to review the most commonly used diagnostic imaging modalities as well as to make an updated collection of the available international references describing the normal and pathological imaging features in snakes and lizards. Most of papers describing radiography, ultrasonography, computed tomography, magnetic resonance imaging and other imaging modalities have been collected in order to overcome the lack of a unique reference regarding diagnostic imaging in snakes and lizards. The scientific aims and the outline of this thesis are presented in Chapter II. The general aim of this PhD thesis is to provide some useful anatomical and diagnostic imaging references in snakes and lizards. The first part of this work (Chapters III and IV) is focused on the description of the normal radiographic and computed tomographic features of the head of some snakes and lizards species. The second part (Chapters V to VII) is focused on the diagnostic imaging of the coelomic cavity; the description of the normal contrast enhanced computed tomographic features of the coelomic cavity of some lizards, the normal ultrasonographic features of the coelomic cavity of some snake species and the normal upper gastro-intestinal examination in the ball python are presented. In Chapter III the normal stratigraphic and cross sectional anatomy is matched with the normal radiographic and computed tomographic features of the head of the Boa constrictor. 4 boa constrictor’s cadavers head where used in this study. Radiographs of the head were taken in LL and DV projections using a high detail screen-film combination. CT scans scans of the head where performed in a CC and a LL direction with a slice thickness of 1,5mm and displayed in a bone window. 2 heads where dissected following a stratigraphic approach and 2 heads frozen for 24h (-20°C) and then sectioned into 3mm slices respecting the imaging protocol. All anatomical structures have been identified and labelled with the aid of available literature in the anatomical images and then matched on the corresponding radiographic and computed tomographic images. Radiographic and CT images provided a high detail for the visualisation of bony structures; soft tissues were not easily identified on radiographic and CT images. In Chapter IV the normal radiographic and contrast enhanced computed tomographic features of the head of the green iguana, common tegu and bearded dragon are described. The study included 4 cadavers for each considered species and 6 adult green iguanas, 4 tegus, 3 bearded dragons. Prior to the beginning of the radiographic and computed tomographic studies 2 cadavers were dissected following a stratigraphic approach and 2 cadavers were cross-sectioned for each species. Anatomical studies were performed following the same approach described in Chapter III. Both the radiographic and the computed tomographic studies were performed only in live animals. Radiographic studies included a LL and a DV projection. Pre- and post- contrast computed tomographic studies of the head were performed in a CC direction. CT images were displayed in both bone and soft tissue windows. Individual anatomical structures were first recognised and labelled on the anatomic images and then matched on radiographs and CT images. Radiographic studies provided a good detail both of the soft tissues (especially in the green iguana) and of the bony structures. CT images provided an excellent detail of the bony structures in all the considered species. The soft tissues were clearly outlined only in the green iguana. In the common tegu and the bearded dragon only the eyes were clearly outlined from the remaining soft tissues. In Chapter V the normal contrast enhanced computed tomographic features of the coelomic cavity of the green iguana, black and white tegu and the bearded dragon are described. 4 cadavers and 4 live animals for each considered species were object of this study. The cadavers were frozen for 24 hours and then cross sectioned at 5mm intervals. The slices have been cleaned with water and photographed on both sides. In order to reduce the duration of the procedure only contrast enhanced CT scans have been performed. The CT scans have been performed in a CC direction. The CT scans have been displayed in a soft tissue and, when appropriate, in a lung window. Individual organs have been recognised and labelled on the anatomical images and then matched on the corresponding CT images. Most of the coelomic organs have been identified in all the considered species. Results provide an atlas of the normal cross sectional and CT features of the coelomic cavity of lizards. In Chapter VI the normal ultrasonographic features of the coelomic cavity of the Boa constrictor, Python molurus, Python curtus and Python regius are described. Moreover, normal reference ultrasonographic measurements of the scent glans, the colonic, gastric and pyloric wall thickness are reported. 46 live snakes (16 Python regius, 10 Python molurus, 12 Python curtus and 8 Boa constrictor) and 23 cadavers (6 Python regius, 4 Python molurus, 10 Python curtus, 3 Boa constrictor) where object of this study. Anatomical studies where performed prior to the beginning of the ultrasonographic studies in order to characterise the normal anatomical features of the above mentioned species. In previous ultrasonographic studies of the coelomic cavity of the Boa constrictor studies a ventral approach on sedated animals was proposed. We have decided to use a lateral approach on unsedated animals. Although, especially in larger animals, the shadowing effect produced by the ribs was evident in some images, most of the coelomic organs (scent glands, hemipenes, cloaca, ureters, colon, small intestine, pylorus, stomach, pancreas, liver, gallbladder and oesophagus) have been recognised. The rate of ultrasonographic recognition of individual organs is reported. Results provide a description of the normal ultrasonographic features of coelomic cavity of boid snakes along with a series of tables matching the gross and cross sectional anatomy with corresponding normal ultrasonographic images. In Chapter VII the technique and the normal features of upper gastro-intestinal examination in ball pythons are described. 10 ball python's cadavers have been dissected and cross sectioned prior to the the beginning of the study in order to characterise the normal features of the intestine in this species.18 healthy ball pythons where object of this study. All animals where not fed for at least 7 days before the beginning of the study. The animals have been divided into three groups (A, B, C). Contrast medium (barium sulphate) at the dose of 25 ml/kg has been administered through an esophageal probe at an increasing concentration (25%, 35% and 45 wt/vol) to three groups. An initial animal (Group A , 25% wt/vol) was used to verify the feasibility and establish a time course for the procedure. Imaging quality was evaluated by 3 investigators who assigned a grading score on the basis of predetermined criteria. Results of present study revealed that the 35% wt/vol concentration of contrast medium provided the best imaging quality. Moreover, three pattern of distribution of the contrast medium in the small intestine, independent from the concentration, have been described.
Negli ultimi anni ofidi e sauri sono diventati sempre più diffusi come animali da compagnia. Questa crescente diffusione ha comportato un aumento della richiesta di servizi veterinari specializzati in questi animali. L’imaging diagnostico spesso è una parte fondamentale dell’indagine clinica. La corretta interpretazione delle immagini diagnostiche implica una conoscenza approfondita dell’anatomia, fisiologia e patologia della specie oggetto dell’indagine clinica. Il confronto tra immagini normali e immagini patologiche spesso è di vitale importanza per una corretta interpretazione delle immagini diagnostiche. Lo scopo di questa tesi di dottorato è quella di fornire degli atlanti che mettano in relazione l’anatomia normale e per sezioni con le corrispondenti immagini radiografiche, tomografiche e ecografiche di alcune delle specie più popolari di ofidi e sauri. Il Capitolo I è riportata una revisione della letteratura corrente sull’imaging in ofidi e sauri. Al momento manca un riferimento univoco su questo argomento e la letteratura presente è spesso frammentaria a volte difficile da reperire. L’obiettivo di questo capitolo, quindi, è quello di fare il punto sullo stato dell’arte della diagnostica per immagini in ofidi e sauri. Molti articoli internazionali riguardanti la radiologia, l’ecografia, la tomografia computerizzata, la risonanza magnetica e altre tecniche di imaging sono stati citati in modo da creare un riferimento utile ai clinici che si occupano di animali esotici. Nel Capitolo II vengono presentati gli obiettivi scientifici e la struttura di questa tesi. L’obiettivo generale è quello di fornire una descrizione dell’anatomia e dell’imaging normale in ofidi e sauri. La prima parte (Capitoli III e IV) è incentrata sul confronto tra la l’anatomia normale e per sezioni della testa alcune specie di ofidi e sauri con i normali aspetti radiografici e tomografici. La seconda parte (Capitoli dal V al VII) è incentrata sull’imaging della cavità celomatica. In questi capitoli sono descritti: gli aspetti normali valutati in tomografia computerizzata della cavità celomatica di alcune specie di sauri, l’ecografia normale in alcune specie di ofidi e il Nel Capitolo III sono descritti i normali aspetti anatomici, radiografici e tomografici della testa del Boa constrictor. Per questo studio sono stati impiegate le teste di 4 cadaveri di Boa constrictor. Utilizzando una combinazione pellicola-casetta ad alta definizione sono state ottenute proiezioni latero-laterali e dorso-ventrali di tutte le teste. L’esame tomografico è stato eseguito in direzione cranio-caudale e latero-laterale con uno spessore di fetta di 1,5mm. Le immagini sono state visualizzate in una finestra da osso. 2 teste sono state dissezionate con un approccio stratigrafico. 2 teste invece sono state congelate per 24 ore a -20°C e poi sezionate in fette di 3mm rispettando il protocollo utilizzato in tomografia computerizzata. Le strutture anatomiche sono state identificate nelle immagini anatomiche e poi accoppiate con le corrispondenti immagini radiografiche e tomografiche. I tessuti ossei sono ben definiti sia nelle immagini radiografiche che tomografiche; i tessuti molli risultano poco definiti in entrambe. Nel Capitolo IV l’anatomia stratigrafica e per sezioni della testa dell’iguana, del tegu e del drago barbuto vengono messi in relazione con il loro normale aspetto radiografico e tomografico. Per realizzare questo studio sono stati usati 4 cadaveri per specie e 6 iguane, 4 tegu e 3 draghi barbuti adulti. Prima di iniziare gli studi di imaging 2 cadaveri per specie sono stati dissezionati con un approccio stratigrafico e 2 sono stati sezionati. Gli studi anatomici sono stati eseguiti con la stessa metodica riportata nel Capitolo III. Gli studi radiografici e tomografici sono stati eseguiti solo sugli animali vivi. Le radiografie sono stata scattate in proiezione latero-laterale e dorso-ventrale. Le scansioni tomografiche sono state effettuate pre e post contrasto scansionando gli animali in direzione cranio-caudale. Le immagini tomografiche sono state quindi visualizzate sia in finestra da tessuti molli che da osso. Le strutture anatomiche sono state individuate prima nelle immagini anatomiche e poi correlate con le corrispondenti immagini radiografiche e tomografiche. Gli studi radiografici hanno permesso di visualizzare in maniera ottimale sia i tessuti duri che i tessuti molli (specialmente nell’iguana). Negli studi tomografici le strutture ossee sono state visualizzate in modo ottimale in tutte le specie. I tessuti molli sono chiaramente delineati solo nell’iguana; nel tegu e nel drago barbuto si riescono a distinguere chiaramente solo gli occhi. Nel Capitolo V i normali aspetti anatomici della cavità celomatica dell’iguana verde, del tegu bianco e nero e del drago barbuto sono messi in relazione con i normali aspetti tomografici di queste specie. Per questo studio sono stati usati 4 cadaveri e 4 animali vivi per specie. I cadaveri sono stati congelati per 24 ore e poi sezionati a intervalli di 5mm. Le fette così ottenute sono state lavate da entrambi i lati e poi fotografate. Per ridurre la durata delle procedure diagnostiche sono state effettuate solo procedure post-contrasto. Le scansioni tomografiche sono state effettuate in direzione cranio-caudale. Le immagini tomografiche sono state visualizzate in finestra da tessuti molli e da polmoni. La maggior parte degli organi celomatici sono stati individuati sia nelle immagini anatomiche che nelle immagini tomografiche. Il risultato di questo lavoro è un atlante degli aspetti anatomici e tomografici normali della cavità celomatica di queste specie di sauri. Nel Capitolo VI vengono descritti gli aspetti ultrasonografici normali della cavità celomatica del Boa constrictor, Python molurus, Python curtus e Python regius. Inoltre vengono fornite le misure ecografiche di riferimento delle scent glands e delle mucose gastica, pilorica e del colon nelle suddette specie. Per questo lavoro sono stati utilizzati 46 serpenti vivi (16 Python regius, 10 Python molurus, 12 Python curtus and 8 Boa constrictor) and 23 cadaveri (6 Python regius, 4 Python molurus, 10 Python curtus, 3 Boa constrictor). Gli studi anatomici sono stati effettuati prima di iniziare gli studi ecografici in modo da caratterizzare i normali aspetti anatomici di queste specie. In un lavoro precedente, nel quale vengono descritti i normali aspetti ecografici del Boa constrictor, viene proposto un approccio ventrale al paziente. In questo studio proponiamo un approccio laterale. In alcune immagini ecografiche i coni d’ombra prodotti dalle coste di questi animali, specialmente nei soggetti di maggiori dimensioni, degradavano leggermente la qualità dell’esame. Nonostante ciò è stato possibile riconoscere la maggior parte degli organi celomatici (scent glands, emipeni, cloaca, ureteri, colon, piccolo e grosso intestino, piloro, stomaco, pancreas, fegato, cistifellea ed esofago). Il numero di animali nei quali i singoli organi sono stati visualizzati è stato riportato. Questo lavoro ha prodotto una descrizione completa degli aspetti ecografici normali in alcune specie di boidi oltre a una serie di tavole che mettono in relazione l’anatomia normale e per sezioni con le corrispondenti immagini ecografiche. Nel Capitolo VII è riportata la tecnica e gli aspetti normali dello studio radiografico dell’esofago, stomaco e piccolo intestino nel Python regius. Per caratterizzare l’aspetto normale del piccolo intestino di questa specie i cadaveri di 10 Python regius sono stati dissezionati prima dei iniziare procedure diagnostiche. Per questo lavoro sono stati utilizzati 18 Python regius. Tutti gli animali utilizzati non sono stati nutriti nella settimana precedente lo studio. Gli animali sono stati divisi in 3 gruppi (A, B, C). Il mezzo di contrasto (bario solfato) è stato somministrato alla dose di 25ml/kg tramite una sonda esofagea a concentrazione crescente (25%, 35%, 45% p/v) nei tre gruppi. Un soggetto appartenente al gruppo A (25% p/v) è stato usato per verificare la fattibilità della procedura e per stabilire una timeline radiografica approssimativa per gli studi successivi. La qualità delle immagini diagnostiche è stata valutata da tre autori in basi a criteri pre-definiti. I risultati di questo studio suggeriscono che la concentrazione ideale di mezzo contrasto per questo tipo di indagine diagnostica è del 35%. Inoltre, sono stati descritti tre pattern di distribuzione del mezzo di contrasto nel piccolo intestino, indipendenti dalla concentrazione.

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.

Thesis (M.S.)--Marshall University, 2008.
Title from document title page. Includes abstract. Document formatted into pages: contains 61 p.: col. ill. Includes bibliographical references (p. 58-61).

The theory of adaptive radiation predicts that evolutionary diversification occurs when alternative phenotypes confer fitness advantages to different subsets of the same species facing divergent natural selection. A widespread outcome of this process is the evolution of new species (speciation). When natural selection imposes antagonistic fitness effects between the sexes of the same population, adaptive radiation may instead result in the evolution of ecological sexual dimorphism by disruptive selection.

Doutoramento em Biologia - Ecotoxicologia e Biologia Ambiental
Apesar do recente aumento no número de estudos, os lagartos persistem como um dos grupos menos estudados em ecotoxicologia e o desconhecimento em relação à sua resposta à contaminação ambiental é enorme. A nível europeu, os lacertídeos têm sido identificados como potenciais espécies modelo para a ecotoxicologia com répteis. O principal objectivo deste projecto era determinar se um lacertídeo abundante pertencente ao género Podarcis, podia ser utilizado como bioindicador de exposição e toxicidade em zonas agrícolas. Para atingir este objectivo, utilizámos uma estratégia integrada com três fases. Numa primeira fase realizou-se um estudo de campo para documentar o tipo de exposição e parâmetros populacionais de populações de lacertídeos que ocorrem em zonas de uso intenso de pesticidas e zonas de agricultura orgânica. A segunda fase consistiu num estudo de mesocosmo em que se expuseram juvenis a um conjunto de pesticidas em condições controladas durante um período de um ano. Finalmente, a terceira fase incluiu um estudo laboratorial sobre os efeitos do clorpirifos, um dos insecticidas mais utilizado a nível global, em lagartixas. No término de cada um dos estudos, analisaram-se diversos biomarcadores e parâmetros de exposição e toxicidade a pesticidas nos diferentes indivíduos. Este conjunto abrangente de parâmetros foi analisado em diferentes níveis de organização biológica, incluindo parâmetros populacionais, bem como comportamentais, fisiológicos, bioquímicos e histológicos. Em geral, detectaram-se poucas diferenças estatísticas significativas entre as populações dos campos expostos a pesticidas e populações referência. Confirmando a dificuldade que existe em isolar os efeitos de diferentes contaminantes sobre as populações de outros factores locais, ciclos sazonais ou eventos estocásticos. As populações de P. bocagei parecem ser capazes de lidar com o nível observado de exposição a pesticidas. No entanto, indivíduos que vivem em locais expostos a pesticidas parecem estar menos adaptados ecologicamente do que aqueles que vivem em locais referência, apresentando um estado de depleção nutricional e sinais de stress metabólico. Os resultados obtidos com os animais da experiência de mesocosmo parecem reforçar estes resultados. Os animais prosperaram relativamente bem em todos os mesocosmos, independentemente do tratamento ou não com pesticidas, apresentando uma ampla gama de comportamentos naturais. A abordagem laboratorial confirmou P. bocagei como um valioso indicador de exposição sub-letal a doses ambientalmente realistas de clorpirifos. De acordo, com o conjunto d resultados obtidos, P. bocagei parece ser um bioindicador adequado de exposição a pesticidas.
Lizards are among the least studied groups in ecotoxicology and despite a recent increase in the number of studies, there is still a lack of knowledge regarding their response to environmental contamination. In Europe, lacertid lizards have been identified as potential model species for reptile ecotoxicology. The main question of this project was to assess if a highly abundant lacertid lizard belonging to the genus Podarcis, could be used as a bioindicator of pesticide exposure and toxicity in agricultural areas. To achieve this end, we used a three-stage tiered approach. The first tier took the form of a field survey to document the nature of the exposure and the population parameters of lacertids occurring in areas of intensive pesticide usage as well as areas of negligible pesticide usage. The second tier consisted of a mesocosm study in which naïve lizards were exposed to pesticides in a controlled experiment. Finally, the third tier included a laboratory approach to the effects of one of the most common insecticides used worldwide, chlorpyrifos. We assessed pesticide impact in individuals from the different tiers using a comprehensive set of biomarkers applied at different levels of biological organization, including population parameters as well as behavioral, physiological, biochemical and histological biomarkers. We detected few statistically significant differences between reference and exposed populations in the field study. Confirming the difficulty to isolate the effects of contaminants on natural populations where other local factors, natural cycles or stochastic events occur. P. bocagei populations seem to be able to compensate with the observed level of pesticide exposure. Nevertheless, individuals living in exposed sites seem to be less ecologically fit than those living in reference sites, presenting a depleted nutritional status and signs of metabolic stress. The results from the mesocosm setting reinforce these results. Lizards prospered relatively well in all enclosures, treated or not with pesticides, presenting a broad range of natural behaviors. The laboratory approach confirmed P. bocagei as valuable indicator of sub-lethal exposure to environmental realistic doses of chlorpyrifos. According to our results, P. bocagei seems to be a suitable bioindicator of pesticide exposure.

Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The phenotype of an individual has often been used as the descriminating factor in distinguishing species. However, with the advent of more precise molecular techniques, the genotype of species is increasingly being used as the preferred method in taxonomic classifications. Many taxa have recently been demonstrated to be incongruent in terms of their genetic and morphological groupings, and this may due to the influence that the environment may have on the morphological and functional aspects of a species. Selective pressures often act upon the performance of a species within a particular habitat first, and then selection for the morphological characters that allow for optimal performance occurs. Should genetically disparate species inhabit a particular environment, convergence in morphologies and performance may evolve. Historically, lizard species descriptions were based primarily on external morphologies, and thus misclassfication of species may have occurred due to mistakenly grouping species with convergent morphologies together. In the current dissertation, the links between morphology, performance capacities, diet and behaviour is explored in comparison to the environment and genetic relationships of southern African lacertid lizards. The performance capacities and associated morphological traits were expected to be more closely linked with the environment, and not closely linked with genetic relationships. To investigate these expectations, a multidisciplinary approach was taken, and genetic, morphological and performance analyses were done and compared with dietary behavioural and environmental analyses. In the first chapter, the link between habitat openness and the lizard bauplans is investigated and the presence of convergent morphologies within this group of lizards is uncovered. These convergences are shown to have resulted in misclassification of two lacertid species, and taxonomic revisions within the family are discussed. The second chapter explores the link between performance and associated morphological traits, and the dietary composition of the members of the Nucras genus. The third chapter identifies the link between the predator escape strategies employed by the members of the Meroles genus, and their morphologies and performance capacities. The fourth chapter explores the intraspecific, inter-population differences in morphologies and investigates the link between the morphological groupings and the population genetic groupings within Pedioplanis lineoocellata. The final chapter identifies whether adaptation to a novel habitat can occur over a relatively short period of time, and the morphological traits, functional aspects, and population genetic structure is investigated in conjunction with environmental analyses of vegetation and substrate between the populations of Meroles knoxii. It was concluded that the morphological and functional aspects of the southern African lacertid lizards are more closely related to the environment, particularly the microhabitat structure, than to their genetic relationships, and that future work using this group of lizards should involve a multidisplinary approach as different selective pressures are playing a role in shaping the morphologies and performance capacities of these lizards, compared to those that are acting upon the genotypes of the lizards.
AFRIKAANSE OPSOMMING: Die fenotipe van 'n individu is dikwels gebruik as die diskriminerende faktor in kenmerkende spesies. Maar, met die ontwikkeling van meer akkurate molekulêre tegnieke, word die genotipe van spesies toenemend gebruik as die voorkeur-metode in taksonomiese klassifikasie. Die onversoenbaarheid van genetiese en morfologiese eienskappe kom voor in ‘n verskeidenheid taksa, dit kan wees as gevolg van die invloed wat die omgewing het op die morfologiese en funksionele aspekte van ‘n spesie. Selektiewe druk beїnvloed dikwels doeltreffende funktionaliteit van 'n spesie in 'n bepaalde habitat eerste, en gevolglik word morfologiese karakters wat voorsiening maak vir optimale funktionaliteit geselekteer. Indien geneties uiteenlopende spesies woon in 'n bepaalde omgewing, kan konvergensie in morfologie en soortgelyke werksverrigtinge ontwikkel. Histories, is akkedis spesiesbeskrywings hoofsaaklik gebaseer op eksterne morfologieë, en kan dus misklassifikasie tot gevolg hê wat kan lei tot foutiewe taksonomie van spesies met konvergente morfologieë. In die huidige verhandeling, is die verband tussen die morfologie, werksverrigtingsvermoë, dieët en gedrag ondersoek, in vergelyking met die omgewing en die genetiese verwantskappe van Suider-Afrikaanse sandakkedisse. Die werksverrigtingsvermoë en gepaardgaande morfologiese eienskappe word verwag om te meer verband te hou met die omgewing, en dus nie in noue verband te wees met die genetiese verwantskappe nie. Om hierdie verwagtinge te ondersoek, is 'n multi-dissiplinêre benadering geneem, en genetiese, morfologiese en werksverrigtingontledings is gedoen in vergelyking met dieët, gedrags-en omgewings-ontleding. In die eerste hoofstuk, is die skakel tussen die habitat openheid en die akkedis bauplans ondersoek en die teenwoordigheid van konvergente morfologieë binne hierdie groep akkedisse word ten toon gestel. Hierdie konvergensies het gelei tot foutiewe klassifikasie van twee sandspesies, en taksonomiese hersiening binne die gesin word bespreek. Die tweede hoofstuk ondersoek die verband tussen werksverrigting en gepaardgaande morfologiese eienskappe, en die samestelling van die dieët van die lede van die Nucras genus. Die derde hoofstuk identifiseer die verband tussen die roofdier ontsnapping strategieë, morfologieë en werksverrigtingsvermoë van die Meroles genus. Die vierde hoofstuk ondersoek die intraspesifieke, inter-bevolkingsverskille in morfologieë en ondersoek die verband tussen die morfologiese groepe en die bevolking genetiese groepe binne die Pedioplanis lineoocellata spesies kompleks. Die finale hoofstuk identifiseer hoe die aanpassings na 'n nuwe habitat kan plaasvind oor 'n relatief kort tydperk, en die morfologiese eienskappe, funksionele aspekte en die bevolking genetiese struktuur word ondersoek in vergelyking met die omgewingsanalise van plantegroei en substraat tussen die bevolkings van Meroles knoxii. Die gevolgtrekking is dat die morfologiese en funksionele aspekte van die Suider- Afrikaanse sandakkedisse nader verwant is aan die omgewing, veral die mikrohabitat struktuur, as aan hul genetiese verwantskappe. Toekomstige werk op hierdie groep akkedisse moet ‘n multidisiplinêre benadering behels siende dat verskillende selektiewe drukke 'n rol speel in die vorming van die morfologie en werksverrigtingsvermoë van hierdie akkedisse, in vergelyking met selektiewe drukke wat die genotipes van die akkedisse beinvloed.

At broad scales, community ecologists study how biogeographic factors like environmental dissimilarity and geographic distance influence community assembly and composition. At small scales, community ecologists study how one or several species interact to determine habitat partitioning and coexistence. In this dissertation, I present studies at both scales. Chapter One investigates community assembly across the Caribbean, Central, and South American radiations of Anolis lizards and Eleutherodactylid frogs to test whether oceanic islands are unique in their assembly processes. Such uniqueness is suggested by high levels of endemism on islands; however, comparable levels of endemism can be found in mainland communities. I modeled the rate of species turnover between mainland communities, with respect to geographic distance and environmental dissimilarity, and then used the mainland model to predict turnover among islands. Turnover among island communities was significantly higher than predicted from the mainland model, confirming the long-held but untested assumption that island assemblages accumulate biodiversity differently than their mainland counterparts. Chapter Two reviews the evidence for ecological character displacement (ECD), an evolutionary process whereby two resource competitors diverge from one another in phenotype and resource use, facilitating coexistence in a community. I find that, despite current scientific opinion, the evidence for ECD is equivocal; most cases of ECD pattern fail to rule out processes alternative to resource competition that could create the same pattern. I conclude that better evidence may come from real time tests of ECD. Chapters Three and Four describe just such a test in small island populations of Anolis carolinensis. In Chapter Three, I find that small island populations of A. carolinensis that have come into sympatry with a novel competitor, the invasive A. sagrei, shift their habitat use to become more arboreal, compared to allopatric populations. Consistent with prediction, individuals from sympatric populations have larger toepads with additional adhesive scales - a common adaptation to arboreality in Anolis. In Chapter Four, I describe a common garden experiment that finds that the observed toepad divergence is an evolved response, suggesting rates of divergence for toepad area and scale number on par with well known examples of contemporary evolution.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006.
Title from PDF t.p. (viewed Nov. 18, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: B, page: 6942. Adviser: Emilia P. Martins.

Within-island geographic variation in three character systems (body dimensions, scalation, colour pattern) and in life history is described in the Gran Canarian skink (Chalcides sexlineatus). Numerical methods used to describe patterns of geographic variation include contouring, principal components analysis, multiple group principal components analysis and canonical variates analysis. The primary patterns of geographic variation are north-east/south-west clines, although altitudinal variation is also evident in some characters. Several hypothesized causes of the variation are erected and tested using Mantel Tests and partial correlation. This points to lush/arid ecotone adaptation as the cause. A suggestion by previous workers that there are two species on the island is rejected. Patterns of geographic variation in Chalcides viridanus on the neighbouring island of Tenerife are described and tested against hypotheses using similar methods. Tenerife shows similar lush/arid variation to that in Gran Canaria. Parallel patterns of geographic variation in morphology are found, most notably in colour pattern. This strongly suggests that adaptation to current ecological conditions, rather than ancient population vicariance, is the cause. Geographic variation in anti-predator strategy can explain the colour pattern microevolution. Ecological differences between populations of C. sexlineatus are investigated to elucidate the actual selection pressures acting on different aspects of the animals' morphology. Some thermoregulatory and also dietary and prey size differences are found among populations. Daily energy expenditure and water flux are compared among skinks from northern and southern populations in the field, using the doubly-labelled water technique. Between-population differences in energy expenditure can be attributed to body size differences.

Thesis (MSc)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Geographic variation in the presence/absence of generation glands in females of the cordylus-niger-oelofseni complex was described and correlated with climatic variables. Preserved and live specimens from 96 localities in the area south of 32°30' S and west of 19°45' E in the Western Cape, South Africa, were examined for the presence or absence of generation glands. Females from western coastal localities and from the Cape Fold Mountains generally lack generation glands, while females from inland lowland localities generally possess glands. A GIS analysis was performed to determine mean annual minimum temperature, mean annual maximum temperature, potential evaporation, mean annual precipitation, mean annual fog and mean annual cloud cover measured at 14:00 for each locality. Discriminant function and canonical analyses showed a highly significant correlation between the presence and absence of generation glands and five of the six climatic variables. It is suggested that the high incidence of fog and lower temperatures experienced along the west coast as a result of the cold Benguela Current, and the high incidence of orographic fog and cloud cover in the Cape Fold Mountains may affect energy allocation in females. In order to maintain their reproductive output, females may be forced to invest less energy in secondary sexual characters such as generation glands. Interspecific variation in the location, occurrence, number, and age of gland differentiation was investigated for cordylid lizards. For several species, data were obtained from the literature and for others data were obtained from material housed in the Ellerman Collection of the University of Stellenbosch. Cordylus cordylus and C. cataphractus were used for an evaluation of inter- and intrapopulation variation. Data for C. cordylus were obtained from five populations on the coastal lowlands of the Western Cape, while data on C. cataphractus come from the literature. The sex, snout-vent length, and number of generation glands were recorded for a representative sample of lizards at each locality. While in all species generation glands were located in the femoral region, Cordylus giganteus and C. microlepidotus had additional generation glands elsewhere on the body. It is suggested that additional generation glands in these species may be related to an increased need for chemical communication in a low-visibility environment in the case of C. giganteus, and in low population densities in the case of C. microlepidotus. Generation glands are present in all cordylid males, but females of some species may lack these glands. All cordylids display sexual dimorphism with regards to the presence and number of generation glands, with males having significantly more glands than females, indicating that these glands may play a more important role in males than in females. Low sexual dimorphism in at least two species suggests that generation glands may be equally important in both sexes of these species. In females, the presence of generation glands is closely regulated by climate. There is no indication of differences in generation gland profile between ground-dwelling and rock-dwelling species, except that in at least three ground-dwelling species, generation glands are already present at birth. In other species these glands differentiate only later in life. In the males of most species, generation glands start to differentiate prior to or at sexual maturity with a drastic increase in number when asymptotic body size is reached. The considerable inter- and intrapopulation variation in gland number in females, but not in males, underscores the hypothesis that the presence of generation glands in females is energy-linked and closely regulated by climate. An opposite geographic pattern of generation gland number in C. cataphractus, suggests that other factors than climate must be responsible for a difference in gland number and a difference in population density is suggested as explanation. To test for differences in aggression levels, females with and those without generation glands were staged in two experiments. In one experiment, females from different localities were staged against each other, while females from the same locality were paired in another experiment. No significant difference in aggression levels between females with and those without generation glands were observed in both experiments. It is suggested that generation glands do not exclusively function in territorial marking, but rather as a scent enhancer for femoral gland secretions. Inorder to elucidate the functional significance of generation glands, male response to female gland stimuli was investigated for 12 male C. cordylus. Males were presented with different female gland secretions (femoral, generation, and femoral and generation gland secretion combined) and water was used as a control. Total number of tongue-flicks and number of tongue-flicks directed at the secretion were counted. No significant difference was observed in the number of tongue-flicks between the different treatment groups. Males did, however, display leg-waving and head-rubbing behaviour. At present, the behaviour displayed by male C. cordylus in the presence of female gland stimuli, is unclear. The general absence of tongue-flicking of sandpaper labelled by female gland stimuli may be because of a flaw in the experimental design or because the experiment was conducted outside the breeding season. The display ofleg-waving and head-rubbing behaviour, however, suggests that cordylids do not exclusively rely on tongue-flicking for detection of conspecifics. The real function of generation glands thus still remains unresolved and further studies are needed to clarify this.
AFRIKAANSE OPSOMMING: Geografiese variasie in die aan-/afwesigheid van generasiekliere in wyfies van die cordylus-niger-oelofseni kompleks is beskryf en met klimaatsveranderlikes gekorreleer. Gepreserveerde en lewende materiaal, afkomstig van 96 lokaliteite in die area suid van 32°30' S en wes van 19°45'0 in die Wes-Kaap, Suid-Afrika, is vir die aan- ofafwesigheid van generasiekliere ondersoek. Generasiekliere is oor die algemeen afwesig in wyfies van westelike kuslokaliteite en die Kaapse Plooiberge, terwyl dit aanwesig is in wyfies van die binnelandse laagland lokaliteite. 'n GIS-analise is gedoen om die gemiddelde jaarlikse minimum temperatuur, gemiddelde jaarlikse maksimum temperatuur, potensiële verdamping, gemiddelde jaarlikse neerslag, gemiddelde jaarlikse mis en gemiddelde jaarlikse wolkbedekking, gemeet teen 14:00, vir elke lokaliteit te bepaal. Diskriminantefunksie en kanonieke analises toon 'n hoogs beduidende korrelasie tussen die aan- en afwesigheid van kliere en vyf van die ses klimaatsveranderlikes. Daar word voorgestel dat die hoë voorkoms van mis en lae temperature wat langs die weskus ervaar word as gevolg van die koue Benguela Seestroom, en die hoë voorkoms van orografiese mis en wolkbedekking in die Kaapse Plooiberge, die energie-toekenning in wyfies beïnvloed. Om hulle voortplantingsuitset te handhaaf, word wyfies moontlik gedwing om minder energie in sekondêre geslagskenmerke, soos generasiekliere, te belê. Interspesifieke variasie in die posisie, voorkoms, aantal en tyd van klierontwikkeling is vir verskeie gordelakkedisspesies ondersoek. Data vir verskeie spesies is vanuit die literatuur verkry, terwyl data vir ander spesies vanafmaterial in die Ellerman-versameling van die Universiteit van Stellenbosch verkry is. Cordylus cordylus en C. cataphractus is vir 'n evaluering van inter- en intrapopulasie variasie gebruik. Data vir C. cordylus is vanafvyfpopulasie wat op die kuslaaglande van die Wes-Kaap voorkom, ingesamel, terwyl data oor C. cataphractus vanuit die literatuur verkry is. Geslag, snoet-kloaak-lengte en die aantal generasiekliere is aangeteken vir 'n verteenwoordigende aantal individue van elke populasie. Terwyl generasiekliere in die femorale wyk van alle spesies aangetref word, het Cordylus giganteus en C. microlepidotus ook addisionele generasiekliere in ander dele van die liggaam. Daar is tot die gevolgtrekking gekom dat addisionele generasiekliere in hierdie spesies moontlik verwant is aan 'n groter behoefte aan chemiese kommunikasie in 'n lae sigbaarheidsomgewing in die geval van C. giganteus, en in 'n lae populasiedigtheid in die geval van C. microlepidotus. Generasiekliere word in alle gordelakkedis mannetjies aangetref, maar kan afwesig wees in wyfies van sommige spesies. Alle gordelakkedisse toon geslagsdimorfisme met betrekking tot die aanwesigheid en aantal generasiekliere, en mannetjies het beduidend meer kliere as wyfies, wat daarop dui dat hierdie kliere moontlik 'n meer belangrike rol by mannetjies as by wyfies speel. Lae geslagsdimorfisme inten minste twee spesies stel voor dat generasiekliere moontlik ewe belangrik in beide geslagte van hierdie spesies kan wees. In wyfies word die aanwesigheid van generasiekliere sterk deur klimaat gereguleer. Daar is geen aanduiding van verskille in generasieklierprofiel tussen grondbewonende en rotsbewonende spesies nie, behalwe dat generasiekliere reeds by geboorte teenwoordig is in ten minste drie grondbewonende spesies. In ander spesies ontwikkel hierdie kliere eers later. In mannetjies van die meeste spesies, begin generasiekliere voor oftydens geslagsrypheid ontwikkel, met 'n drastiese toename in aantal kliere wanneer asimptotiese liggaamsgrootte bereik word. Die aansienlike inter- en intrapopulasie variasie in aantal kliere in wyfies, maar nie in mannetjies nie, ondersteun die hipotese dat die teenwoordigheid van generasiekliere in wyfies aan energie gekoppel is en deur klimaat gereguleer word. 'n Teenoorgestelde geografiese patroon in die aantal generasiekliere in C. cataphractus, stel voor dat ander faktore as klimaat vir die verskil in aantal kliere verantwoordelik is en 'n verskil in populasiedigtheid word as verklaring voorgestel. Om vir verskille in aggressievlakke te toets, is wyfies met en wyfies sonder generasiekliere is teenoor mekaar getoets in twee eksperimente. In een eksperiment is wyfies van verskillende lokaliteite teenoor mekaar getoets, en in 'n ander eksperiment is wyfies van dieselfde lokaliteit teenoor mekaar getoets. Inbeide eksperimente is geen beduidende verskille is in die aggressievlakke van wyfies nie waargeneem nie. Daar word voorgestel dat generasiekliere nie uitsluitlik in gebiedsafbakening funksioneer nie, maar dat dit eerder as reukversterker vir die femorale kliere dien. Om die funksie van generasiekliere vas te stel, is die reaksie van 12 mannetjie C. cordylus op klierstimuli van wyfies getoets. Verskillende kliersekresies (femoraal, generasie, en femoraal en generasie gekombineerd) van wyfies is mannetjies voorgelê, en water is as 'n kontrole gebruik. Totale aantal tongskiete en aantal tongskiete wat na die sekresie gerig is, is getel. Geen beduidende verskil in die aantal tongskiete is tussen die verskillende groepe waargeneem nie. Mannetjies het egter beenwaai- en kopvryfgedrag getoon. Die rede vir die gedrag wat deur C. cordylus mannetjies in die teenwoordigheid van klierstimuli van wyfies vertoon word, is egter tans onduidelik. Die algemene afwesigheid van tongskiete na skuurpapier wat met klierstimuli van wyfies gemerk is, mag moontlik wees as gevolg van 'n fout in die eksperimentele ontwerp of omdat die eksperiment buite die paarseisoen uitgevoer is. Die vertoning van beenwaai- en kopvryfgedrag stel egter voor dat gordelakkedisse nie uitsluitlik op tongskiete staatmaak om lede van dieselfde spesie waar te neem nie. Die ware funksie van generasiekliere is dus steeds onopgelos en verdere studies word benodig om dit duidelikheid hieroor te kry.

L’excepcional registre fòssil d’escamosos a la Península Ibèrica representa una oportunitat inestimable per revelar la història evolutiva de llangardaixos i amfisbenes al llarg d’un llarg lapse de temps (Juràssic-Quaternari) en una zona clau de contacte intermitent entre Europa i Àfrica. Pel que fa als llangardaixos, només les associacions mesozoiques (principalment les del Juràssic Superior i Cretaci Inferior) i quaternàries s’han descrit sistemàticament amb anterioritat. La descripció de nou material del Cretaci Inferior millora el coneixement existent quant a les notables associacions mesozoiques, permetent l’erecció de Pedrerasaurus latifrontalis de La Pedrera de Meià i Jucaraseps grandipes de Las Hoyas, així com la descripció del segon exemplar conegut de l’interessant Scandensia ciervensis provinent de la segona localitat. La diversa asssociació de Sossís (Eocè superior) proporciona informació sobre els primers llangardaixos descrits d’aquesta edat al sud d’Europa, i inclou el nou tàxon Pyrenasaurus evansae, aixi com exemplars que amplien el rang geogràfic i/o temporal de diversos grups, com els iguànids pleurodonts, gekkos, lacèrtids, possibles scíncids, cordiliformes, glyptosaurins, anguins i amfisbenes. L’associació de Sossís proporciona noves dades des d’un punt de vista paleobiogeogràfic i paleoecològic, assemblant-se molt a les localitats contemporànies de França, recolzant hipòtesis prèvies basades en les faunes de mamífers. Quant al Miocè, la diversitat de varanins queda reduïda al gènere Varanus mitjançant la sinonimització d’Iberovaranus amb el primer. Es descriu també una nova espècie del blànid Blanus basada en el primer crani fòssil d’amfisbena recuperat a Europa. Ambdós estudis contribueixen a un refinament del coneixement més aviat parcial que es té dels llangardaixos i amfisbenes miocens, resultat d’un tractament superficial d’aquest tipus de faunes en treballs anteriors. El coneixement previ sobre llangardaixos i amfisbenes fòssils de la Península Ibèrica és revisat a la llum d’aquestes noves troballes i sota un enfocament modern, incrementant el coneixement existent sobre la composició de les associacions i proporcionant informació paleobiogeogràfica i paleoecològica, esdevenint una de les visions més completes disponible de la evolució del grup al llarg de la major part de la seva existència en una zona determinada, en aquest cas, la Península Ibèrica.
The remarkable squamate fossil record from the Iberian Peninsula represents an invaluable opportunity to unveil the evolutionary history of lizards and amphisbaenians during a long time span (Jurassic-Quaternary) in a key area of intermittent contact between Europe and Africa. Only Mesozoic (mainly Late Jurassic and Early Cretaceous) and Quaternary lizard assemblages had been systematically described previously. The description of new material from the Early Cretaceous improves our knowledge of the exceptional Mesozoic assemblages through the erection of Pedrerasaurus latifrontalis from La Pedrera de Meià and Jucaraseps grandipes from Las Hoyas, as well as the description of the second known specimen of Scandensia ciervensis. The diverse assemblage from Sossís (late Eocene) represents the first late Eocene lizard assemblage from Southern Europe, and includes the highly characteristic new taxon Pyrenasaurus evansae, as well as specimens that increase geographical and/or temporal ranges of several groups in the Iberian Peninsula, such as pleurodont iguanians, gekkotans, lacertids, scincids, cordyliformes, glytposaurines, anguines and amphisbaenians. The assemblage of Sossís provides insights from paleobiogeographical and paleoecological viewpoints, and compares well with contemporaneous French localities, supporting previous hypotheses based on mammals. In the Miocene, the diversity of varanines is reduced to the genus Varanus through the synonymization of Iberovaranus with the former. A new species of Blanus, based on the first amphisbaenian skull from the European fossil record, is described. Both studies contribute to an ongoing refinement of a rather incomplete knowledge on Miocene squamate faunas resulting from a superficial treatment received by many preceding works. Previous knowledge of fossil Iberian lizards and amphisbaenians is reviewed in the light of these new findings, and placed in a modern framework, shedding light on issues such as the composition of the assembages, paleobiogeography and paleoenvironment. The result is one of the most complete visions of their evolution most of its time of existence in a given area, in this case, the Iberian Peninsula.

Explaining spatial and temporal variation in the abundance of species is one of the primary goals of ecology. Habitat selection, the behaviour that organisms use to choose habitat patches that maximize fitness, can explain patterns in abundance between patches at small spatial scales within the dispersal capacity of the species. However, habitat selection models assume there is a reduction in individual fitness as population density increases due to increased competition between individuals. Ectotherms, which often select habitats based on temperature, a density-independent resource, may not display density-dependent responses if temperature limits energy assimilation more than finite food resources limit energy acquisition. As predicted by their dependence on environmental temperatures, some ectotherms select habitat largely independently of population density when temperatures are far from the optimal temperature for performance. But, is density-dependence prevalent in ectotherm populations when temperatures are close to the optimal temperature for performance? Habitat selection models also assume that all individuals of a population exhibit the same strategy for maximizing fitness through habitat selection. However, differences in morphology and behaviour (e.g., reproductive strategy) can modify the optimal habitat selection strategy for different phenotypes. Finally, observed patterns in habitat selection and abundance can also be modified by competition with other species. Quantifying the relative importance of these different factors that affect habitat selection behaviour will improve our ability to predict the spatial distribution and relative abundance of organisms. The objective of my thesis was to explain spatial variation in the abundance of ectotherms, using the ornate tree lizard (Urosaurus ornatus) as a study species. In chapter one, I tested whether density-dependent habitat selection explained patterns in abundance and fitness of lizards between two habitats differing in suitability. In chapter two, I tested whether density dependent habitat selection in tree lizards was caused by intraspecific competition for food that limited body size and growth. In chapter three, I tested whether variation in reproductive strategy, as indicated by throat colour phenotype, affected space use and habitat selection in male tree lizards. Finally, in chapter four, I tested whether interspecific competition with another lizard species affected habitat selection, fitness, and abundance of tree lizards. My thesis emphasizes the importance of intraspecific competition in shaping patterns of habitat selection and abundance in terrestrial ectotherms. I show that habitat selection is strongly density-dependent despite differences in thermal quality between habitats. I show that density-dependent mortality and growth lower the fitness of individuals when populations reach high densities, and this likely caused habitat selection to be density-dependent. Despite this evidence for density-dependent habitat selection, I show considerable variation between individuals in habitat selection and space use. Males with different throat colour phenotypes select habitats differently, demonstrating that variation in morphology can influence habitat selection patterns within a population. Finally, I show that interspecific competition with another lizard affects space use and how frequently tree lizards switch habitats, but this does not lead to differences in fitness or in the relative abundance of tree lizards in habitats. Therefore, intraspecific competition for resources was the dominant force shaping the relative abundance of tree lizards in different habitats.

l evaluated the hypothesis that juveniles of species whose tail is important for predator deflection should allocate energy preferentially to tail growth at the expense of body growth. Relative linear tail growth (linear tail growth/linear body growth) and relative mass tail growth (tail mass growth/body mass growth) were measured for juveniles of two species of skinks: Eumeces Fasciatus that use the tail for predator deflection, and Chalcides ocellatus that does not use the tail for predator deflection. Experimental conditions produced an energy limiting situation under which the priority of energy allocation to tail regeneration should be exhibited. For E. fasciatus, relative linear tail growth was higher for the energy limited than control group and for the tail-removal than the tailed lizards. For C. ocellatus, relative linear tail growth was not affected by energy level but was lower for tail-removal than tailed lizards. For both species, relative tail mass growth was lower for the tail-removal than tailed lizards. The greater relative linear tail growth of regenerating than normal tails of E. fasciatus supports the hypothesis that rapid tail regeneration is important for a species whose tail is used for predator deflection. However, the low rate of tail regenerartion in mass suggests that mass gains in the regeneration process. In contrast, lower relative linear and mass tail growth of C. ocellatus that were regenerating tails suggests that tail regeneration has a low priority for this species.

Master of Science

The evolutionary relationships of three Canary Island lizard species of the genus: Gallotia, G.stehlini, G.atlantica and G.galloti, were analysed by examining mitochondrial DNA sequence variation in eight Canary Island populations. Initially, restriction endonucleases were the method of choice for examining mitochondrial DNA variation within Gallotia. A number of fragment visualisation techniques, both radioactive and non-radioactive, were utilised during the course of the study. However, mitochondrial DNA probe hybridisation was used to examine restriction fragment length polymorphism (RFLP) for the majority of samples. The advent of the polymerase chain reaction (PCR) enabled sequence variation at two mitochondrial loci, to be studied directly. Conserved primers for regions of the cytochrome b and 12s ribosomal RNA (rRNA) genes were used to examine five hundred and forty base pairs of sequence information. As a by-product of the 12s rRNA amplification, five hundred and thirty-six base pairs of the 18s rRNA gene were also obtained. Mitochondrial genetic distance data was examined for evidence of founder effects, and for the reliability of a molecular clock in the evolution of Gallotia. In order to test the reliability of the mitochondrial DNA phylogenies, variation in nuclear DNA was also examined. RFLP analysis was carried out by 18s rRNA probe hybridisation on DNA samples digested with a number of restriction endonucleases. This analysis revealed little variation between the species examined. In addition six primers were utilised in the recently developed molecular technique: the random amplified polymorphic DNA assay (RAPD). Although the phylogenies reconstructed using this technique are supportive of the mitochondrial phylogenies, they must be treated with caution due to the possible errors inherent in this assay. The evolutionary relationships suggested by the molecular data sets were used to suggest a potential consensus phylogeny for Gallotia. The tree reconstructed was then compared to morphological phylogenies, and to the existing fossil and geological data in order to discuss a possible colonisation sequence for the species examined.

My studies undertaken over the past 30 years have identified the existence of an exceptionally rich and highly diverse scincid lizard fauna in New Caledonia, one typified by regional and localised endemism at a level not indicated by earlier studies. The patterns of broad and finer-scale endemism revealed in the phylogenetic studies indicate a complex evolutionary history for the scincid lizard fauna, one which reflects the historical complexity of the island’s environment, and provides a window into the likely processes that shaped the present day biota. Further, it places the evolution of the New Caledonian lizard fauna in a broader regional context, identifying it as intimately linked with the endemic New Zealand skink fauna, and challenging current conventional theories of a recent post emersion Oligocene origin for the New Caledonia biota.
Thesis (PhD Doctorate)
Doctor of Philosophy by Publication (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

Fossil Agamidae from Western Australia have been the subject of limited study. To aid in fossil agamid identification, Hocknull (2002) examined the maxilla and dentary of several extant species from Australia and determined diagnostic characters for various species groups. In the study here, fossil agamids from two localities in Western Australia, Hastings Cave and Horseshoe Cave, were examined, grouped, and identified to the lowest unambiguous taxonomic level. Morphometric analyses were conducted to compare morphotypes, and find additional diagnostic characters. From Hastings Cave there were two maxilla morphotypes and three dentary morphotypes. Based on identifications, taxa present at this locality were Pogona and Ctenophorus. Horseshoe Cave contained three maxilla morphotypes and two dentary morphotypes; taxa present were Pogona, Tympanocryptis, and Ctenophorus. Morphometric analyses showed separation between groups; however, the dentary morphotype separation was not as clear. Each morphotype identification matched a species in the respective localities today, but identifications are cautious.

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.

Body temperature affects physiological processes and, consequently, has a large impact on fitness. Lizards need to thermoregulate behaviourally to maintain their body temperature within a range that maximizes performance, but there are costs associated with thermoregulation. The thermal quality of an environment is a major cost of thermoregulation because it directly affects the time and energy that must be invested by an individual to achieve and maintain an optimal body temperature for performance. According to the cost-benefit model of thermoregulation, lizards should only thermoregulate when the benefits outweigh the costs of doing so. Thus, in habitats of poor thermal quality, individuals should thermoregulate less. Using two systems, an elevational gradient and a pair of habitats that vary in the amount of solar radiation they receive, I tested the hypothesis that investment in thermoregulation by lizards is dictated by the associated costs of thermoregulating. Temperature, and thus thermal quality, decreases with elevation. I found a significant positive relationship between elevation and effectiveness of thermoregulation of Yarrow’s spiny lizards (Sceloporus jarrovii). When comparing thermoregulation of ornate tree lizards (Urosaurus ornatus) living in the thermally superior open-canopy wash habitat or the closed-canopy upland habitat, I found that habitat type was a significant predictor of accuracy of body temperature. In the poorer quality habitat, lizards had smaller deviations of body temperature from their preferred temperature range. Overall, I conclude that the thermal quality of a lizards’ environment impacts their thermoregulation in the opposite direction than predicted by the cost-benefit model of thermoregulation. This suggests that the disadvantages of thermoconformity may be greater than the costs thermoregulating as habitats become more thermally challenging.

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.

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.

Foraging mode is repeatedly invoked as a powerful and pervasive force in snake evolution, because active foragers and ambushers differ in many significant morphological, physiological, and behavioural characteristics. However, foraging mode is highly conservative phylogenetically in snakes, and most taxa that have been studied in any detail belong to one of two families: viperids (which almost all hunt by ambush) and colubrids (which are mostly active searchers). Therefore, it is difficult to know if the observed differences result from disparate foraging modes or from divergent evolutionary histories.

In many reptile species, offspring sex is determined by the temperature these animals experience during embryogenesis, rather than by genetic factors passed from parents to offspring (e.g., sex chromosomes). The adaptive value of this unusual sex-determining mechanism (temperature-dependent sex determination, TSD) has eluded satisfactory explanation since its discovery four decades ago. The most plausible suggestion in this regard (the Charnov-Bull model) proposes that TSD enhances maternal fitness when nest temperature has a differential impact on the fitness of sons versus daughters, such that male-producing temperatures are optimal for the fitness of sons, and female-producing temperatures are optimal for the fitness of daughters. However, because most reptiles with TSD are long-lived and have delayed sexual maturation, no robust experimental test of this model has been conducted. The primary goal of my PhD research was to experimentally test the Chamov-Bull model using a_ short—lived, early-maturing lizard with TSD (the jacky dragon, Amphibolurus muricatus). By incubating eggs at a range of temperatures, and using hormonal manipulations to de-confound the effects of incubation temperature and sex on offspring fitness, my results directly address (and strongly support) major predictions of the Charnov—Bull model. Overall, males from eggs that were incubated at male-producing temperatures were more successful at siring offspring than those from eggs incubated under female-producing temperatures. This pattern was reversed for females; female reproductive success was lowest for individuals incubated at male-producing temperatures. In addition, incubation temperature had a strong effect on the seasonal timing of hatching, and the optimal time of hatching is likely to differ between sons versus daughters. Hatching early in the season provided individuals with a relatively long growing season, thereby enabling offspring to reach sexual maturity by age one. In A. muricatus, the fitness difference between early—maturing sons versus daughters depends upon the intensity of competition for mating opportunities. Early-maturing sons are unlikely to reproduce in their first year because of intense competition with larger territorial individuals from previous cohorts, whereas older females do not suppress breeding of younger females in the same way. These patterns suggest that a daughter's (but not a son’s) reproductive success would be enhanced if she hatched early enough to reach sexual maturity by age one. Thus, TSD should enhance maternal fitness by enabling the overproduction of daughters early in the season, and males late in the season. My second objective was to evaluate sex allocation patterns in A. muricatus, and especially to clarify the effects of maternal factors on offspring sex ratios. By rearing reproductive females and eggs under standardized conditions, my results suggested a strong maternal (perhaps genetic) component to sex determination. Clutch sex ratios varied substantially among females, and the degree of this variation depended upon the timing of clutch production. Moreover, this variation in clutch sex ratios (as well as other offspring phenotypes) was not associated with any non—genetic maternal effects, such as egg size, yolk steroid allocation, or nest-site selection. However, additional manipulative studies demonstrated that maternal sex allocation was responsive to the quality of the diet provided to reproducing females, as well as the operational sex ratios experienced prior to and during the reproductive season. Overall, these results challenge current paradigms of reptilian TSD, suggesting that offspring sex is likely the result of complex interactions among multiple factors, rather than that of a single overriding variable (i.e., temperature). My third objective was to complement my experimental studies with field-based observations, to provide insight into the ecological relevance of my laboratory-based results. A mark-recapture study in the field demonstrated that early hatching enhances offspring fitness in numerous ways. For example, individuals that hatched early in the season grew faster, dispersed farther, and had greater survival rates than those that hatched late. Moreover, early-hatched individuals attained sexual maturity by age one under natural field conditions, strongly supporting findings from my experimental work. I used radiotelemetry to track free-ranging gravid females and locate their nest sites, enabling me to evaluate nesting behaviour, as well as effects of natural nest conditions on offspring phenotypes and sex ratios. Females selected nest sites with lower canopy cover, and hence higher temperatures, than random. Moreover, seasonal shifts in ambient temperatures caused concomitant seasonal increases in nest temperature, suggesting that daughters will be over—produced early in the season and males produced later, as predicted by theory. Surprisingly, however, this expectation was not met: offspring sex ratios were not significantly associated with mean nest temperatures (but were linked to the mean daily thermal range). Overall, the field data corroborate many results from my experimental - studies, but suggests a hitherto-unrecognised complexity in the pathways by which sex is determined, and in the ways in which nest temperature affects offspring sex.

Thesis (Ph. D.)--University of Oregon, 2001.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 121-147). Also available for download via the World Wide Web; free to University of Oregon users.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-graduação em Estudos da Tradução
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Este trabalho de dissertação é fruto de estudos de teorias da tradução e teve como princípio norteador a aquisição de conhecimentos sobre aspectos relacionados com a produção da obra original, para só então definir a posição do tradutor. Somente após a contextualização da obra original e análise das características do autor concretizou-se a tradução do conto Lizards in Jamshyd's Courtyard de William Faulkner. Para manter a força do conto original não houve simplesmente a preocupação em conseguir encontrar equivalentes ou traduzir palavra por palavra, mas sim, em adentrar no jogo de significantes, de maneira a tornar a tradução o mais próximo possível do original, respeitando a heterogeneidade das situações lingüísticas e culturais existentes entre a língua inglesa do original e a língua portuguesa no Brasil, para a qual o conto foi traduzido. Muitos obstáculos foram encontrados ao longo desse processo, e a estes, foram apresentadas soluções. Tanto as hipóteses levantadas para a solução dos problemas, quanto as decisões tomadas descritas nesta pesquisa estão ancoradas nos princípios teóricos de Lawrence Venutti, Georges Mounin, John C. Catford e Antoine Berman. This essay has its origins in studies about translation theories and in the knowledge acquisition about the aspects related with the production of the original work. Just after those studies, was established the position as translator. And only after the contextualization of the original work and the analysis of the author characteristics it was started the translation process of the tale Lizards in Jamshyd's Courtyard written by William Faulkner, this tale is part of the novel Hamlet written by the same author. To maintain the strength of the original tale there was not just a concern about getting equivalents or translating word by word , but was to be very close to the characteristics of the original tale; considering what is heterogeneous in the linguistic and cultural situations between the English language in which the original tale was written, and the Portuguese language from Brazil where the tale has been translated. The hypothesis, the possible solutions to the problems found, and the decisions taken in this research are based on: Lawrence Venutti, Georges Mounin, John C. Cattford and Antoine Berman's theories.

Adaptive radiation – the proliferation of species from a single ancestor and diversification into many ecologically different forms – has long been heralded as an important process in the generation of phenotypic diversity. However, the early stages of adaptive radiation are notoriously elusive to observe and study. In this dissertation, I capitalize on communities of introduced non-native Anolis lizards as analogues of early stage adaptive radiations. In Chapter II, I begin by reviewing the concept of “ecological opportunity” – a classic hypothesis put forward as a potential key to understanding when and how adaptive radiation occurs. In Chapter III, I investigate the mechanisms which allow for coexistence and community assembly among ecologically-similar species. To do this I investigate range dynamics and assembly patterns of introduced anoles on the oceanic island of Bermuda. I discover that interspecific partitioning of the structural environment facilitates species coexistence, however the order of species assembly was an important predictor of final community composition. In Chapter IV, I then investigate how interspecific interactions between coexisting species may drive phenotypic divergence. This is the process of character displacement, which has been widely hypothesized to be an important mechanism driving phenotypic divergence in adaptive radiations. To do this I investigate sympatric and allopatric populations of introduced Cuban brown anoles (Anolis sagrei) and Puerto Rican crested anoles (A. cristatellus) in Miami FL, USA. I identify morphological shifts in sympatry, driven by divergence in habitat use and decreases in abundance. This study provides evidence of how selection on both ecologically and sexually-important traits can both drive phenotypic divergence during character displacement. Finally, in Chapter V, after taking advantage of non-native species as model eco-evolutionary systems in previous chapters, I investigate the potentially harmful effects that their presence may have on vulnerable native biodiversity. To do this I investigate the conservation risk posed by newly-discovered populations of A. sagrei on Bermuda to Critically Endangered endemic Bermuda skinks (Plestiodon longirostris). Through a detailed analysis of habitat use, diet, population size, and morphology of A. sagrei on Bermuda, we conclude it likely poses a high conservation threat to P. longirostris through interspecific competition.