Tesi sul tema "Small mammals"

During peak lactation female mammals reach a limit in their maximal sustained energy intake (SusEI). The causes of such limits is disputed. In this thesis, I examined the causes of the limits on SusEI at peak lactation, and then explored the consequences of such limits for reproductive performance. Finally I tested a possible physiological mechanism that may underpin the trade-off between reproduction and somatic protection (the oxidative stress theory). To answer these questions, I studied reproductive performance and oxidative stress in two lines of mice previously selected for high and low food intake (MH and ML, respectively). I found that these mice reached a plateau in their food intake around day 13 of lactation. In support of the heat dissipation limits theory, reproductive performance in the MH mice was significantly higher than that of the ML mice. Oxidative damage is expected to be higher among lactating individuals. Moreover, lactating mice with greater reproductive performance are also predicted to experience more oxidative damage. By measuring multiple-markers of oxidative damage and protection in different tissues, I found that lactation resulted in reduced oxidative damage in both brain and serum. Additionally, it did not increase oxidative damage to proteins and DNA in liver. Moreover, multiple measures of oxidative stress in the mammary gland were not significantly different between mice with different reproductive effort. Furthermore, I found that lactating mice with greater reproductive performance (litter size and litter mass) had reduced protein damage in their livers and upregulated protection (HSP70) in their brains. These results were inconsistent with the oxidative stress theory. Finally, I employed a novel approach to assess oxidative stress differences with metabolomics analysis. I found that lactation resulted in significant differences in the metabolome. By focusing on the metabolites that are related to vi oxidative stress, I found that most of these metabolites measured in livers and brains were not affected by lactation which provides more evidence against the oxidative stress theory. My results provide support for the heat dissipation theory as a mechanism explaining the limits on reproductive performance. Moreover it provides comprehensive information against oxidative stress as a mediator of life history trade-offs.

Master of Science
Department of Biology
Jack Cully, Jr.
Disturbance is defined as any discrete event that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment. Habitat use by an organism is based on its perception of where to maximize its own fitness, and can be altered in response to disturbance-induced changes in resources, substrate, or physical features modified by disturbance. Disturbance-induced changes to vegetation structure reshape a small mammal’s surrounding physical environment and/or resources, and may influence its utilization of an area. Effective wildlife and resource management is dependent on a thorough understanding of how individual species and communities utilize their surroundings and how disturbance affects a species’ response to changes in its surroundings. We investigated seasonal habitat associations of three small mammal species and for overall species diversity across a gradient of military combat-vehicle disturbance intensities at the Fort Riley Military Reservation, Kansas. Deer mouse (Peromyscus maniculatus) abundance did not vary across a categorical gradient of disturbance created by military-combat vehicles, regardless of season. Western harvest mouse (Reithrodontomys megalotis) abundance was associated with more highly disturbed areas irrespective of season. Prairie vole (Microtus ochrogaster) abundance was associated with habitat that was less disturbed in the spring but more highly disturbed in the fall. Shannon diversity of the small mammal community was higher in the more highly disturbed areas regardless of season. This research shows that small mammals respond to disturbances created by military training with combat vehicles in a species-specific manner, and indicates that there may be differences in the effects of military training versus natural or agricultural disturbances on the abundance and diversity of small mammals. This is an important consideration given that the Department of Defense manages more than 12 million ha of land in the United States, and is charged under the Sikes Act with conserving natural resources on these lands, including biological diversity. Thus, the findings of other ecological research on the effects of disturbance on small mammals may not be directly applicable to the types of disturbances that occur on military lands, which underscores the need for further research on the specific effects of military-training activities on species’ responses.

This thesis examines the effect of diet, photoperiod and perceived predation risk on the body composition and energy balance of voles (Clethrionomys sp and Microtus sp).  These rodents are able to regulate their fat mass in response to the changeable environment in which they live by adjusting components of their energy intake and expenditure; thus making them potential candidates for the study of obesity.  Throughout, body composition was determined using both destructive (dissections, Soxhlet) and non-destructive techniques (total body electrical conductivity (TOBEC), morphometrics), whilst energetic variables measured included food intake, assimilation efficiency, resting metabolic rate and daily energy expenditure (DEE). In addition, the usefulness of four non-destructive methods of measuring body composition in voles was assessed and compared to chemical analysis. When fed a diet high in fat (45 %), bank voles (Clethrionomys glareolus) reduced their food intake such that the amount of energy assimilated was equal to that on the control diet and increased fat oxidation to match intake almost immediately.  On a standard diet, these voles gained approximately 10% body mass when switched from short to long photoperiod without corresponding adjustments in energy intake or expenditure, even during the period of most weight gain.  When weasel (Mustela nivalis) faeces was introduced to simulate predation risk, male bank voles reduced the amount of body mass gained in response to photoperiod change, concurrent with a reduction in food intake and an increase in DEE. Both male and female voles exhibited elevated levels of faecal corticosterone when exposed to weasel faeces, indicating increased stress. In a field experiment, male field voles (Microtus agrestis) from sites with low weasel activity were heavier than those from sites with high weasel activity.  There were no differences in body mass between sites with differing vole density.

Thesis (M.S.)--Southern Oregon State College, 1994.
Typescript. Includes bibliographical references (leaves 73-80). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

The ecology of small mammal communities found in set-aside and adjacent farm land was investigated to determine the ecological consequences of set-aside land to small mammals. Field work was carried out for two years at three study sites in NE Scotland. First Aldroughty farm, a mosaic of set-aside, crop and semi-natural land. The two remaining study sites; Ythan Lodge at Newburgh, and Fraser's farm near Aldroughty, were whole fields of set-aside. Wood mice Apodemus sylvaticus, bank voles Clethrionomys glareolus and field voles Microtus agrestis were trapped in the habitat mosaic at Aldroughty, and wood mice and field voles in the set-aside at Newburgh. Wood mice had higher densities, greater survival, heavier weights, longer breeding seasons and more juveniles at Aldroughty than Newburgh. These differences were thought to be due to a difference in habitat productivity between the two sites. Field voles showed less of a difference in population dynamics between Aldroughty and Newburgh, and both species of vole maintained populations at low density. The home range size of 33 wood mice was measured using radiotelemetry. At both study sites home range size was smaller than in other habitats revealed by other studies. The apparently anomalous results obtained, of low population densities and small home range sizes of wood mice in the set-aside at Newburgh, may have been due to predation from cats Felis catus. Wood mice showed no clear habitat preference, nesting and foraging in all habitat types, while both vole species showed almost exclusive preference for rough grassland. An assessment of the habitat characteristics of the study sites showed that there was heterogeneity in the vegetation communities found in set-aside.

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references.
This thesis explores two aspects of small regulatory RNAs in mammals: (1) the genomic origin of mammalian piwi-interacting RNAs (piRNAs), (2) the evolutionary and functional implication of the seed-based target recognition mechanism of microRNAs (miRNAs). First, we participated in the discovery of mammalian piRNAs from adult rat testes. Our initial characterization of mammalian piRNAs by high-throughput sequencing revealed the peculiar features of their genomic origin: they predominantly derive from long singlestranded RNA precursors that are encoded at ~100 loci with no preferential association to repeat elements. Second, we measured the efficacy of polymorphic miRNA target sites in mammals. A large part of the miRNA-target recognition is determined by the 7-8-nt match between the seed region of miRNAs and the 3'UTR of mRNAs. Because of the small informational complexity of the specificity, spontaneous point mutations in 3'UTRs often create or disrupt miRNA target sites. The resulting polymorphisms in the target sites may contribute to gene expression diversity. By experimentally measuring the efficacy of such polymorphic target sites, we were able to conclude that between two unrelated mammalian individuals of the same species more than 100 genes are likely differentially regulated due to the target-site polymorphisms. Some of the expression diversity might translate into phenotypic diversity, providing substrates for the natural selection to act upon. We also constructed a miRNA library covering nearly all ~-16,000 theoretically possible seed sequences. Under the assumption that the functionality of a miRNA is approximately defined by the identity of the seed, the library is a resource that may enable the systematic exploration of the phenotypic consequences of nearly all possible functionally distinct miRNA species.
by Jinkuk Kim.
Ph.D.

Estimates of animal abundance or density are fundamental quantities in ecology and conservation, but for many species such as rare, small mammals, obtaining robust estimates is problematic. In this thesis, I combine elements of two standard abundance estimation methods, capture-recapture and distance sampling, to develop a method called trapping point transects (TPT). In TPT, a "detection function", g(r) (i.e. the probability of capturing an animal, given it is r m from a trap when the trap is set) is estimated using a subset of animals whose locations are known prior to traps being set. Generalised linear models are used to estimate the detection function, and the model can be extended to include random effects to allow for heterogeneity in capture probabilities. Standard point transect methods are modified to estimate abundance. Two abundance estimators are available. The first estimator is based on the reciprocal of the expected probability of detecting an animal, ^P, where the expectation is over r; whereas the second estimator is the expectation of the reciprocal of ^P. Performance of the TPT method under various sampling efforts and underlying true detection probabilities of individuals in the population was investigated in a simulation study. When underlying probability of detection was high (g(0) = 0:88) and between-individual variation was small, survey effort could be surprisingly low (c. 510 trap nights) to yield low bias (c. 4%) in the two estimators; but under certain situations, the second estimator can be extremely biased. Uncertainty and relative bias in population estimates increased with decreasing detectability and increasing between-individual variation. Abundance of the Key Largo woodrat (Neotoma floridana smalli), an endangered rodent with a restricted geographic range, was estimated using TPT. The TPT method compared well to other viable methods (capture-recapture and spatially-explicit capture-recapture), in terms of both field practicality and cost. The TPT method may generally be useful in estimating animal abundance in trapping studies and variants of the TPT method are presented.

This project aimed to reanalyse two large historical data sets from two different locations in New Zealand (Fiordland in the South Island and Pureora Forest Park in the North Island). The data describe populations of mice (Mus musculus), rats (Rattus rattus and R. norvegicus), and stoats (Mustela erminea) collected using standard monitoring techniques from five distinct types of forest habitat. The new analysis methods selected were an index of patchiness and Site Occupancy analysis. The objectives of the analysis were (1) to evaluate whether the patchiness index and Site Occupancy analysis methods might contribute to improved protocols for monitoring small mammal populations in the future, and (2) to use formal tests of five hypotheses to evaluate two of the assumptions made by the conventional density index often used in small mammal studies. I describe the results of the analyses for each species, including any problems encountered (such as the inability of the Site Occupancy method to analyse very sparse data sets). I also describe the results pooled from each of the two study locations and potential consequences for small mammal monitoring and control. This analysis has suggested that in most cases the density index is not a rigorous measure of small mammal populations. However, both the index of patchiness and Site Occupancy analysis provided useful, new information about these populations of rodents and stoats, despite the fact that these historical data sets were not designed for use with modern methods of analysis. Please note: some figures and tables were printed separately and added to the thesis as unnumbered pages. These can be found in the file 03Plates_and_Tables.pdf.

This PhD thesis deals with fossil small mammals from Quaternary deposits from Sicily (Italy) and Flores (Indonesia). It is well known that evolutionary dynamics on islands are quite different than on mainland, because of, amongst the others, the shortage of resources, the reduced interspecific competition and predation, the difficultness in reaching/leaving the island. Therefore many species undergo strong size variation, giving rise to phenomena of gigantism (small mammals) or dwarfism, and a variation in the structure of mammalian communities takes place. In this thesis faunal associations of two very different islands have been taken into account, in order to record the difference in the effects that distance from the mainland, area of the island, introduction of new species and time have on small mammals community. Sicily is in fact the largest Mediterranean island and is very close to the mainland, so close that periodically, during low-standing phases of sea level it was connected to Southern Italy and mammals could reach it. Thus the analysis of the material from Isolidda 3 (Trapani), a Middle - Late Pleistocene paleontological site, could record phases of isolation from the mainland, with a very impoverished (only three rodents and one insectivore) and unbalanced fauna, whilst Oriente Cave (Favignana Island) (Late Pleistocene – Holocene) and Cala Mancina Cave (Trapani) (Holocene), two archeological sites, provided evidence of the arrival of small mammals during the LGM or with man. The abundance of the fossil remains collected allowed also the taxonomical and phylogenetical study of the Microtus (Terricola) and Crocidura in Sicily. The study of small mammals of these archeological deposits facilitates, in conjunction with other disciplines, the reconstruction of the palaeo-environment in which Late Paleolithic and Mesolithic people lived . On the other hand, Liang Bua (Flores, Indonesia) (Late Pleistocene – Holocene), the well-known site for the discovery of Homo floresiensis, is located on an oceanic island. It has never been connected to the mainland and the faunal association displays high degrees of endemism, with the presence of three giants rats (Papagomys armandvillei, Papagomys theodorverhoeveni and Spelaeomys florensis), two middle size rats (Paulamys naso and Komodomys rintjanus) and two small rats (Rattus hainaldi and Rattus exulans). Despite the apparent high number of species, the great part of them is strictly related, confirming the long period of isolation. Since Liang Bua represents the richest deposit for many of these species, it was possible to provide an accurate morphometrical description of upper and lower toothrow of the murids. Moreover, it was possible to record the extinction of Spelaeomys florensis, the severe diminution of the other giant rats (P. armandvillei and P. theodorverhoeveni), Paulamys naso and Rattus hainaldi, and the introduction (intentional or accidental) by Neolithic agriculturists of Rattus exulans.

Thesis (M.S.)--Georgia Southern University, 2007.
"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." In Biology, under the direction of C. Ray Chandler. ETD. Electronic version approved: December 2007. Includes bibliographical references (p. 68-74) and appendices.

Within the Australian wet tropics bioregion, only 900 000 hectares of once continuous rainforest habitat between Townsville and Cooktown now remains. While on the Atherton Tableland, only 4% of the rainforest that once occurred there remains today with remnant vegetation now forming a matrix of rainforest dispersed within agricultural land (sugarcane, banana, orchard crops, townships and pastoral land). Some biologists have suggested that remnants often support both faunal and floral communities that differ significantly from remaining continuous forest. Australian tropical forests possess a relatively high diversity of native small mammal species particularly rodents, which unlike larger mammalian and avian frugivores elsewhere, have been shown to be resilient to the effects of fragmentation, patch isolation and reduction in patch size. While small mammals often become the dominant mammalian frugivores, in terms of their relative abundance, the relationship that exists between habitat diversity and structure, and the impacts of small mammal foraging within fragmented habitat patches in Australia, is still poorly understood. The relationship between foraging behaviour and demography of two small mammal species, Rattus fuscipes and Melomys cervinipes, and food resources in fragmented rainforest sites, were investigated in the current study. Population densities of both species were strongly related with overall density of seed resources in all rainforest fragments. The distribution of both mammal species however, was found to be independent of the distribution of seed resources. Seed utilisation trials indicated that M.cervinipes and R.fuscipes had less impact on seed resources (extent of seed harvesting) than did other rainforest frugivores. Experimental feeding trials demonstrated that in 85% of fruit species tested, rodent feeding increased seed germination by a factor of 3.5 suggesting that in Australian tropical rainforest remnants, small mammals may play a significant role in enhancing germination of large seeded fruits. This study has emphasised the role of small mammals in tropical rainforest systems in north eastern Australia, in particular, the role that they play within isolated forest fragments where larger frugivorous species may be absent.

Within the Australian wet tropics bioregion, only 900 000 hectares of once continuous rainforest habitat between Townsville and Cooktown now remains. While on the Atherton Tableland, only 4% of the rainforest that once occurred there remains today with remnant vegetation now forming a matrix of rainforest dispersed within agricultural land (sugarcane, banana, orchard crops, townships and pastoral land). Some biologists have suggested that remnants often support both faunal and floral communities that differ significantly from remaining continuous forest. Australian tropical forests possess a relatively high diversity of native small mammal species particularly rodents, which unlike larger mammalian and avian frugivores elsewhere, have been shown to be resilient to the effects of fragmentation, patch isolation and reduction in patch size. While small mammals often become the dominant mammalian frugivores, in terms of their relative abundance, the relationship that exists between habitat diversity and structure, and the impacts of small mammal foraging within fragmented habitat patches in Australia, is still poorly understood. The relationship between foraging behaviour and demography of two small mammal species, Rattus fuscipes and Melomys cervinipes, and food resources in fragmented rainforest sites, were investigated in the current study. Population densities of both species were strongly related with overall density of seed resources in all rainforest fragments. The distribution of both mammal species however, was found to be independent of the distribution of seed resources. Seed utilisation trials indicated that M.cervinipes and R.fuscipes had less impact on seed resources (extent of seed harvesting) than did other rainforest frugivores. Experimental feeding trials demonstrated that in 85% of fruit species tested, rodent feeding increased seed germination by a factor of 3.5 suggesting that in Australian tropical rainforest remnants, small mammals may play a significant role in enhancing germination of large seeded fruits. This study has emphasised the role of small mammals in tropical rainforest systems in north eastern Australia, in particular, the role that they play within isolated forest fragments where larger frugivorous species may be absent.

The relationship of vegetation and disturbance factors to the distribution, abundance and diversity of small mammals in the eastern Otway region, Victoria were investigated. Antechinus stuartii, Rattus fuscipes and Rattus lutreolus were widely distributed and occurred in the majority of the eleven floristic vegetation groups identified. Antechinus minimus, Antechinus swainsonnii and Pseudomys novaehollandiae had restricted distributions and were recorded in only two or three vegetation groups. New information on the distribution of the rare species P. novaehollandiae, was obtained and two floristically rich vegetation groups that it preferred were identified. Species-rich small mammal communities occurred in vegetation communities with high numbers of sclerophyll plant species and high structural diversity. Maximum food resources were considered to be provided in these communities. Local habitat diversity was also correlated with species-richness. Small mammal abundance was maximum in non-sclerophyllous canmunities, where high plant productivity was considered to be important. For the first time, the presence of the plant pathogen Phytophthora cinnamomi was shown to affect small mammals. It was associated with small mammal communities of low species richness and abundance, Recovery of small mammal populations after wildfire was slow until the fourth year. Mus musculus reached peak abundance from 2-3 years and then declined rapidly. P. novaehollandiae was the only native species that achieved maximum abundance early in the succession. A. stuartii, R. fuscipes and R. lutreolus approached maximum abundance in mid-succession, while Isoodon obesulus was a mid- to late-successional species. A. minimus survived the fire, but did not persist after one year. The pattern of succession was influenced by attributes of species, such as survival after fire, their ability to disperse and reproduce.

Cervids are a widespread family of ungulates, native to the Americas, Europe and Asia and introduced to Australia. Densities of cervids have increased in North America, Europe and Japan during the last couple of decades, due to changes in land use, reduced hunting, lack of large carnivores and changes in management practices. Where they occur at high densities, native and introduced cervids may have profound effects on vegetation, causing knock-on effects on other taxa. Cervids are in some instances managed towards changing the local distribution through supplemental feeding. These supplemental feeding stations are causing localized areas of high cervid abundance in the landscape, and may have effects on plants and animal species. In this thesis I investigate how high cervid densities and the practice of supplemental feeding impact birds and small mammals through effects on; 1) food resources, and 2) habitat structure. Utilizing a simulated moose (Alces alces) browsing experiment, I tested how varying moose densities and varying site productivity affects vole preference for bilberry. I found that voles preferred unbrowsed bilberry at low productivity sites, while they preferred lightly browsed bilberry at high productivity sites, I was however unable to explain the preference pattern with the chemical composition of the bilberry. However, moose do impact vole food preferences and this could, depending on the productivity of the site, potentially affect food selection and population dynamics over large geographical areas. Moose browsing pressure and nutrient input gradually decline with distance from supplemental winter feeding stations. I utilized this gradient to test how moose activity affects reproduction in pied flycatchers (Ficedula hypoleuca) and great tits (Parus major). The two species showed contrasting responses to moose feeding stations, great tits preferred to nest away from feeding stations where they showed higher feeding frequency and also produced more fledglings compared to close to feeding stations. Pied flycatchers on the other hand preferred to nest close to feeding stations where they had higher feeding frequency and fledgling mass was higher compared to further away. Hence, for both species moose browsing is affecting food availability that subsequently affects reproductive performance. Moose supplemental feeding stations also changed the habitat for small mammals from dwarf shrub dominated to grass and forb dominated. This did not have any effect on reproductive performance of the small mammals, but it did affect species composition along a gradient from the feeding stations. There was higher abundance of Microtus spp. and common shrews (Sorex araneus) close to feeding stations, while bank voles (Myodes glareoleus) had higher abundance away from feeding stations, the latter however was not statistically significant. Small mammals in Australian coastal heath were generally negatively associated with introduced rusa deer (Cervus timorensis), however one species responded positively to historical densities of rusa deer. It was however not possible to confirm these effects as being due to changes in habitat structure for the small mammals. However they may be explained by qualitative changes in the vegetation or alternatively by direct effects of deer through trampling or predation. Cervids and their management have an impact on other fauna, however the effects vary depending on small mammal and bird species. The effects of cervids also depend on the habitat requirements and foraging preferences of the small mammals and birds. Effects may be mediated through both food resources and habitat structure and are dependent on site productivity and cervid density.

Hypogeous fungi perform various functions in the forest ecosystems, they form the mycorrhizal relationship with plants and serve as the food source of some animals. Main aims of this dissertation were to ascertain the diversity and distribution of hypogeous fungi in Lithuania, to compare the communities of hypogeous and epigeous mycorrhizal fungi, and to explore the composition of fungi in small mammal diet. Using various research methods (an analysis of the literature data, the critical examination of the herbarium specimens, the search of the fruit-bodies by raking the soil, an examination of the fecal pellets of small mammals) in total 29 species of hypogeous fungi have been ascertained in Lithuania. The taxonomic structure, distribution and fructification phenology of hypogeous fungi has been analysed. The data on the structure and dynamics of communities of hypogeous and epigeous mycorrhizal fungi in spruce, oak and mixed tree stands were presented. The influence of abiotic and biotic factors on the species composition and fructification of fungi was assessed. The peculiarities of small mammal mycophagy in different tree stands were described.
Požeminiai grybai atlieka įvairias funkcijas miško ekosistemose, sudaro mikorizes su augalais ir yra kai kurių gyvūnų maisto šaltinis. Disertacinio darbo pagrindiniai tikslai buvo išaiškinti Lietuvos požeminių grybų rūšių įvairovę ir paplitimą, palyginti mikorizinių požeminių ir antžeminių grybų bendrijas, išaiškinti grybų sudėtį smulkiųjų žinduolių maisto racione. Pritaikius skirtingus tyrimo metodus (literatūros duomenų analizę, kritišką herbariuminių pavyzdžių tyrimą, grybų vaisiakūnių paiešką grėbliukais suardytame dirvožemyje, smulkiųjų žinduolių ekskrementų tyrimą), nustatyta, kad dabar Lietuvoje žinomos 29 požeminių grybų rūšys. Išnagrinėta požeminių grybų taksonominė struktūra, paplitimas ir fruktifikacijos fenologija. Pateikti duomenys apie požeminių ir antžeminių mikorizinių makromicetų bendrijų struktūrą ir dinamiką eglynuose, ąžuolyne ir mišriame medyne. Įvertinta abiotinių ir biotinių veiksnių įtaka grybų rūšių sudėčiai ir fruktifikacijai. Išnagrinėti kai kurių smulkiųjų žinduolių mikofagijos ypatumai skirtingos sudėties medynuose.

Thesis (Ph.D.)--Deakin University, Victoria, 1990.
Submitted to the Dept. of Biological Sciences of the School of Sciences, Deakin University. Appendices are separately published papers. Bibliography: leaves 274-302.

La mida corporal (o el seu proxy: pes corporal) té una posició central en la immensa web de variables biològiques interdependents d’un organisme. Mostra correlació amb moltes característiques fisiològiques, morfològiques, comportamentals, ecològiques i de life history, i, per tant, afecta a l’aptitud biològica dels individuals i, en última instància, a la biologia i evolució de les espècies. Els canvis de mida (o massa) des d’un punt de vista evolutiu són indicatius d’adaptacions als ecosistemes per selecció natural. Una de les tendències eco-geogràfiques més atractiva en variació de mida és la coneguda Regla d’Illes. Es descriure que en ecosistemes insulars els mamífers de talla petita evolucionen cap a formes gegants (en relació als seus ancestres continentals), mentre que els mamífers grans cap a formes nanes. Associat amb els canvis de mida, les biotes insulars també mostres adaptacions característiques en quan a morfologia, demografia, comportament i life history com a conseqüència dels diferents règims selectius de les illes (Síndrome d’Illes). Les possibles causes de la Regla d’Illes han estat sempre estudiades en biotes actuals, les quals manquen d’espècies nadiues veritablement endèmiques i han estat altament modificades per l’arribada de l’home i les espècies invasores. Les biotes extintes són les úniques que ens poden proporcionar una visió verdadera i donar-nos respostes genuïnes per explicar aquest fenomen. Els ecòlegs de comunitats han proposat diverses teories per explicar com les pressions ecològiques desencadenen el gegantisme operant directament sobre la mida de l’individu (hipòtesis de depredació, de viabilitat de recursos i socio-sexual). No obstant, recentment, altres autors han interpretat el gegantisme com a conseqüència de canvis en la life history dels individus als quals la mida corporal es sensitiva. L’objectiu principal de la present tesis doctoral és fer inferència en les pressions selectives que estan darrera la Regla d’Illes tenint en compte la massa corporal d’espècies extintes i els ecosistemes insulars (Illes Mediterrànies). Degut a la gran quantitat d’ordres de mamífers, la tesi doctoral es troba centrada en els micromamífers perquè la seva investigació ha estat més descuidada. Per conèixer el pes de les espècies fòssils, s’han mesurat dents, cranis i ossos postcranials de 1340 individus (170 espècies) de parents actuals (rosegadors, lagomorfs i sorícids). Amb aquestes dades, diversos models predictius han estat desenvolupats amb resultats satisfactoris. Analitzant la fiabilitat d’aquests models, s’ha observat que les mesures dels estilopodis (principalment diàmetres de fèmurs i húmers) són millors indicadors del pes corporal que altres elements esquelètics. Utilitzant aquests nous models, els pesos corporals de 22 espècies fòssils (2250 individus), incloent espècies insulars i els seus ancestres o parents continents, han estat estimats. Els resultats obtinguts contrasten amb prèvies aproximacions, on els autors van utilitzar models dentals no adequats. Quan comparem el pes corporal de les espècies insulars amb els dels seus ancestres continentals o parents actuals o extints, s’observa que la majoria d’ells mostra un morfotip gegant (amb l’excepció de les musaranyes de Creta i Sicília). Els resultats d’aquesta tesi evidencien que en petits mamífers l’absència de depredadors és un dels principals impulsors del canvi de mida corporal en règims insulars. Per això en illes petites i més aïllades és on es produeixen els màxims exponents de gegantisme. L’estudi també evidencia que en absència de depredació, la disponibilitat de recursos podria regular l’augment de mida. L’estudi sobre la life history d’aquestes espècies revela que aquests vivien molt més del que s’esperaria pel seu pes. Per tant, es mourien cap una life history lenta, implicant una major longevitat i una reproducció retardada. Els resultats d’aquesta tesi donarien suport al model proposat on el pes canviaria degut a la sensibilitat amb la life history.
El tamaño corporal (o su proxy: peso corporal) tiene una posición central en la inmensa web de variables biológicas interdependientes de un organismo. Muestra correlación con muchas características fisiológicas, morfológicas, ecológicas y de life history, y, por lo tanto, afecta a la aptitud biológica de los individuos y, en última instancia, a la biología y evolución de las especies. Los cambios de tamaño (o masa) des de un punto de vista evolutivo son indicativos de adaptaciones a los ecosistemas por selección natural. Una de las tendencias eco-geográficas más atractiva en variación de tamaño es la conocida Regla de Islas. Se describe que en ecosistemas insulares los mamíferos de tamaño pequeño evolucionan hacia formas gigantes (en relación a sus ancestros continentales), mientras que los mamíferos grandes hacia formas enanas. Asociado con los cambios de tamaño, las biotas insulares también muestran adaptaciones en referencia a su morfología, demografía, comportamiento y life history como consecuencia de los distintos regímenes selectivos de las islas (Síndrome de Islas). Las posibles causes de la Regla de Islas han estado siempre estudiadas en biotas actuales, las cuales carecen de especies nativas endémicas y han estado altamente modificadas por la llegada del hombre y las especies invasoras. Las biotas extintas son las únicas que nos pueden dar respuestas genuinas para explicar este fenómeno. Los ecólogos de comunidades han propuesto distintas teorías para explicar cómo las presiones ecológicas originar el gigantismo operando directamente sobre el tamaño del individuo (hipótesis de depredación, de viabilidad de reservas y socio-sexual). No obstante, recientemente, otros autores han interpretado el gigantismo como consecuencia de cambio en la life history de los individuos a los cuales el tamaño es sensitivo. El objetivo principal de la tesis es hacer inferencia en las presiones selectivas que están detrás de la Regla de Islas teniendo en cuenta la masa corporal de las especies extintas y los ecosistemas insulares (Islas Mediterráneas). Debido a la gran cantidad de órdenes de mamíferos, la tesis se centra en los micromamíferos. Para conocer el peso de las especies fósiles, se han medido dientes, cráneos y huesos postcraneales de 1340 individuos (170 especies) de parientes actuales (roedores, lagomorfos y sorícidos). Con estos datos, distintos modelos predictivos han estado desarrollados con resultados satisfactorios. Analizando la fiabilidad de estos modelos, se ha observado que las medidas de los estilopodios (principalmente diámetros de fémures y húmeros) son mejores indicadores de peso corporal que otros elementos esqueléticos. Utilizando estos nuevos modelos, los pesos corporales de 22 especies fósiles (2250 individuos) han sido predichos. Los resultados obtenidos contrastan con estimaciones previas, donde los autores usaron modelos dentales no adecuados. Cuando comparamos el peso corporal de las especies insulares con los de sus ancestros contientales o parientes actuales o extintos, se observa que la mayoría de ellos muestra un morfotipo gigantes (con la excepción de las musarañas de Creta y Sicilia). Los resultados de esta tesis evidencian que en pequeños mamíferos la ausencia de depredadores es uno de los principales impulsores de cambio de tamaño en regímenes insulares. Por esto en las islas pequeñas y más aisladas es donde se producen los máximos exponentes de gigantismo. El estudio también evidencia que en ausencia de depredación, la disponibilidad de reservas podría regular el aumento de tamaño. El estudio sobre la life history de estas especias revela que éstas viven mucho más de lo que esperaríamos por su peso. Por lo tanto, se moverían hacia una life history lenta, implicando una mayor longevidad y una reproducción retardada. Los resultados de esta tesis darían soporte al modelo propuesto donde el peso cambiaría debido a la sensibilidad con la life history.
Body size (or its proxy: body mass) has a central position in the colossal web of interdependent biological variables of an organism. It shows correlation with lots of physiological, morphological, behavioral, ecological and life history features, and, thus, it affects the fitness of individuals and, ultimately, the biology and evolution of species. The shifts in size (or mass) from an evolutionary point of view are indicative of adaptations to ecosystems through natural selection. One of the most attractive and awesome ecogeographical trends in variation of body size is the well-known Island Rule. It is described that in island ecosystems small mammals evolve towards giants (relative to their mainland ancestors), while large mammals towards dwarf morphotypes. Associated with these size shifts, the insular biotas also show characteristic morphological, demographic, behavioral, and life history adaptations consequence of the different selective regimens of island (Island Syndrome). The possible causes of Island Rule have always been studied in extant biotas, which lack true endemic native species and have been highly modified by the arrival of humans and invasive species. The extinct biotas are the only ones that can provide a true view and genuine answers for explaining this phenomenon. Community ecologists have proposed several hypotheses to explain how ecological pressures trigger gigantism operating directly on the size of individual (predation hypothesis, food availability hypothesis or social-sexual hypothesis). However, recently other authors have interpreted the gigantism as a consequence of changes in the life history of individuals to which the body size is sensitive. The main objective of the present PhD Thesis is to make inference on the selection pressures behind the Island Rule taking into account the body mass of the extinct species and the island ecosystem (Mediterranean Islands). Due to the large amount of mammalian orders, the PhD Thesis is centered in micromammals because the knowledge of gigantism remains widely neglected. For knowing the weight of fossil species, it has been measured teeth, skulls and postcranial bones of 1340 individuals (170 species) of current relatives (rodents, lagomorphs and soricids). With this data, several predictive models have been developed with satisfactory results. Assessing the reliability of these models, it has been observed that the measurements of stylopods (principally diameters of femora and humeri) are better proxies of BM than other skeletal elements. Using these new models, the body masses of 22 fossil species (2250 individuals), including insular species and their mainland ancestor or relatives, were estimated. The results obtained contrast with previous approximations, where the authors used not suitable teeth predictive models. When the BM of insular species was compare with their mainland ancestor or extinct and extant relatives, it is observed that the most of them show a giant morph (with the exception of shrews from Crete and Sicily). The results of this PhD Thesis evidence that in small mammals the absence of predators is a primary driver in the body size shift in insular regimes. Thus, in small and more isolated islands is where the most incredible gigantism cases are observed. The study also evidences than in a total absence of predators, the resource availability can regulate the size increase. The study of the life history of these species reveals that they lived more than expected from their size. Thus, they move towards a slow life history, implying a longer lifespan and delayed reproduction. The results of this PhD Thesis give support to the model proposed where the mass changes due to their sensitive with life history changes.

Transposable elements account for the almost half of the sequence encoded by mammalian genomes, which become silenced during early embryonic development. This thesis sought to explore the hypothesis of the involvement of the RNAi pathway in the silencing of transposable elements in mammals, predominantly through the identification of transposon-associated RNA of -20-25nt using a gel blotting technique. Initially cell lines of embryonic and tumour origin were analysed. This lead to the identification of several previously unreported transposon-associated RNA ranging from 70-90nt. However, it was not until a more detailed analysis of the embryonic cell lines, with the induction of differentiation in cell culture that several discrete RNA of -20nt were detected for the mouse transposons L1 and B2. The differentiation of embryonic cell lines in culture also serendipitously lead to the detection of several short 55 rRNA of -22-26nt, these were also later detected in several human cell lines of breast cancer origin and healthy breast tissue. Intriguingly the -20-26nt repeat-associated identified were predominantly observed after two-days of differentiation in cell culture in several cell lines and often coincided with an ethidium bromide stainable band of -19nt. The latter may indicate a large proportion of these RNAs. Further analysis of the B2 and 55 rRNA repeat-associated short RNA revealed both to have reduce accumulation in Dicer-null embryonic stem cells, implicating a possible association with a known component of the RNAi pathway. Dicer was also observed to process the longer -50-80nt 55rRNA to -20-26nt in vitro. BLAST was also used to identify possible mRNA targets for the short B2 and 55 rRNA. One of these, the mRNA encoding sialic acid acetylesterase (SIAE) was consistently observed to be reduced with the accumulation of the short RNA using end-point RT-PCR, consistent with targeting through the RNAi or a similar pathway. However, no further links with the RNAi pathway were established, with no targeting detected for the short B2 or 55 rRNA using dual luciferase sensor assays. The repeat-associated RNA identified in this thesis are among the first of their type and further work will be required to establish what relevance they have to the RNAi pathway and transposon regulation.

Small mammals are a keystone guild in arid ecosystems; often exhibiting top-down control of the diversity and structure of plant communities. However, changing climate, shifting fire regimes, and the invasion of exotic plants are modifying the structure of arid systems. Environmental changes in these arid systems are likely altering small mammal communities, and therefore, their ecological role. We examined two aspects of the community composition of small mammals in the Great Basin: changes in community composition since large scale sampling of the region began in 1930, and the current population of a sensitive species of small mammal, the dark kangaroo mouse (Microdipodops megacephalus). In Chapter 1, we compared diversity and composition of present day small mammal communities to communities sampled between the years of 1930 and 1980. We sampled 234 historical locations across the eastern Great Basin region during the summers of 2014 and 2015. Our results indicated that diversity, richness, and evenness of small mammals in the Great Basin have declined significantly over the last century (P=0.002, P=0.03, P=0.002). The relative abundance of generalist species has increased, while specialist species have declined (P<0.001, P<0.001). Also, community composition at each site has changed significantly over the past century. Alterations in the community structure of small mammals may have cascading implications for the future of the Great Basin ecoregion. In Chapter 2, we conducted a region-wide survey for the dark kangaroo mouse in western Utah. Four teams sampled 232 locations across western Utah during the summers of 2014-2015. Of the 232 sites sampled, only 5 sites resulted in dark kangaroo mouse captures, totaling 15 individuals. These results could indicate a state-wide population decline for this species, both compared to historic population levels and to the populations surveyed less than ten years ago. The rapid decline may be a result of habitat degradation associated with invasive plant species and increasing fire frequency, the effects of which are exacerbated by the dark kangaroo mouse's life history as an ecological specialist. Unless large-scale habitat restoration and preservation is conducted for remaining populations, it is likely the dark kangaroo mouse will continue to decline within the state.

I examined small mammal demography and habitat associations in 4 forest cover types on Quantico Marine Corps Base, VA. Study sites included clearcut, shelterwood, mature-riparian, and mature-upland habitats. My primary objective was to determine whether the abundance, species composition and demographic characteristics (density, survival, reproductive effort) of small mammals varied with respect to forest cover type. Secondarily, I was interested in identifying patterns of small mammal habitat selection and the factors that influence those patterns at micro- and macroscales. Small mammals were captured from May 1997-January 1999 on 10 sites (2 clearcut, 4 shelterwood, 2 riparian, and 2 mature) using a combination of Sherman live-traps and pitfall traps. Small mammal abundance and demographic characteristics were examined across forest cover types using a combination of statistical analyses, including Chi-square tests, Kruskal-Wallis tests and repeated measures ANOVA. I surveyed microhabitat features at individual trap stations (n=1000) using variable sized plots and the point quarter method and used these data to determine macrohabitat characteristics for sites (n=10). I examined species-habitat relationships at micro- and macro-spatial scales using Kruskal-Wallis tests, Wilcoxon Rank Sum tests, simple linear regression, stepwise multiple regression and stepwise logistic regression. Fourteen species of small mammals were captured over 7 trapping occasions. Five species including white-footed mice (Peromyscus leucopus), northern short-tailed shrews (Blarina brevicauda), eastern chipmunks (Tamias striatus), meadow voles (Microtus pennsylvanicus), and woodland voles (Microtus pinetorum), accounted for approximately 95% of the total number of individuals captured. Overall relative abundance and species composition of small mammals differed significantly across forest cover types. Catch per unit effort was greatest in shelterwoods followed by riparian, clearcut and mature forest cover types. I found significant differences in the abundances of white-footed mice and eastern chipmunks across forest cover types but not in those of northern short-tailed shrews, meadow voles or woodland voles. Shelterwood stands provided the highest quality habitat for white-footed mice and eastern chipmunks while clearcut stands provided high quality habitat for northern short-tailed shrews. Assessments of habitat quality for other species were based on weak evidence or inconclusive. Microhabitat preferences for the 5 small mammal species with > 100 captures were generally consistent with those previously reported in the literature. White-footed mice, eastern chipmunks and northern short-tailed shrews were associated with woody debris and brushy microsites, while meadow voles were associated with grassy vegetation and woodland voles with the presence of soft mast and woody stem densities. For each of these species, microhabitat was able to predict presence at individual trapping stations at a level better than expected by chance. For white-footed mice and woodland voles, however, habitat selection was found to be dependent upon macrohabitat, suggesting that habitat selection for these species is dynamic. Macrohabitat features were related to the abundance of several small mammal species. In general, the habitat characteristics important to individual species at microscales tended to be important at macroscales as well. The results of this study suggest that current even-aged forest management practices on Quantico Marine Corps Base are compatible with the maintenance of native populations of small mammals. Disturbances created by harvesting, at least temporarily, resulted in favorable microhabitat conditions for a variety of small mammal species. Species such as southern flying squirrels, however, were sensitive to disturbance, although it is likely that successional changes allow rapid recolonization of disturbed sites.
Master of Science

Thesis (M.S.)--Georgia Southern University, 2005.
"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science" ETD. Includes bibliographical references (p. 53-60) and appendices.

A goal of efforts to restore altered ecosystems is to reestablish natural disturbance processes, such as fire, that govern ecosystem structure and function. In ecosystems where structure has changed in response to human activities, however, ecosystem drivers may function differently and their reestablishment could yield unexpected or undesired consequences. Lehmann lovegrass, Eragrostis lehmanniana, a perennial bunchgrass from Africa, was introduced to grasslands in the southwestern United States in the 1930s and has since increased in distribution and dominance. Reintroducing fire has been proposed as a mechanism by which to restore semi-desert grasslands by reducing the dominance of nonnative plants, despite the altered plant community.To assess the effect of nonnative grass on animals, between 2000 and 2004 we sampled 54 plots across a gradient of invasion by nonnative grass and quantified variation in presence, abundance, and richness of insects and small mammals. For small mammals, we used a framework we developed to estimate abundance when data are sparse. The number of insect orders, families, and morphospecies, as well as overall abundance decreased as nonnative grass increased. Many insect families that decreased in abundance as nonnative grass increased were comprised of herbivorous species, suggesting that increases in nonnative grass may have reduced abundance and quality of plant foods. Abundance of several species of murid rodents increased and several species of heteromyid rodents decreased as nonnative grass increased, indicating clear changes in habitat for these species of small mammals.To assess the interactive effects of prescribed fire on small mammals in these altered ecosystems, we performed a randomized experiment where we applied prescribed fire on 36 of 54 plots. The effects of fire on many small mammal populations and the composition of the small mammal community varied along the invasion gradient, suggesting that fire functions differently inareas dominated by nonnative plants relative to those dominated by native plants. Invasion by this nonnative grass has clearly shifted the composition of faunal communities in semi-desert grasslands and has altered ecosystem processes, therefore reestablishing fire is not likely to be an omnibus solution for restoration.

In 2007, Rogan et al. reported the rare occurrence of the digenean Plagiorchis muris from the wood mouse Apodemus sylvaticus at Malham Tarn Nature Reserve in North Yorkshire, UK. The life cycle of this trematode is not well understood. Therefore, in order to investigate the occurrence of this digenean and attempt to understand its transmission ecology at Malham Tarn, 180 rodents (117 A. sylvaticus, 54 Myodes glareolus and 9 Microtus agrestis) trapped between January 2010 and October 2011 were examined for helminths by dissection. The following helminth species were identified, including the following nematodes (overall prevalence rates and mean intensity in parentheses): Heligmosomoides polygyrus (67.5%, 9.2±12.7), Heligmosomoides glareoli (3.17%, 44±55.2), Syphacia stroma (29.1%, 32.5±37.2), Syphacia sp. (11.1%, 15.2±13.2) and Aoncotheca murissylvatici (7.6%, 3.0±2.7), the following cestode: Hymenolepis diminuta (7.9%, 1.0±0) and the following digeneans: Brachylaemus recurvum (1.7%, 2.0±1.4), Plagiorchis elegans (23%, 26.6±61.5) and Notocotylus malhamensis (14.3%, 65.6±104.6). The use of DNA sequencing of the partial 28S rRNA gene and the complete Internal Transcribed Spacer (ITS1-5.8SrDNA-ITS2) region confirmed the presence of Plagiorchis elegans at this location and not P. muris as originally reported. P. elegans was recorded in the wood mouse population but was not identified from any of the vole species despite careful observations. P. elegans was dispersed across the study site and demonstrated seasonal variation that is thought to be linked to the development of intermediate host species involved in transmission. Both mouse age and sex were determined to be associated with prevalence, with adult male mice carrying a statistically higher worm burden and prevalence. These significant differences are likely to be due to differences in the foraging behaviour between the sexes and age cohorts of the wood mouse. My. glareolus and Mi. agrestis were infected with N. malhamensis; this digenean was identified as a new species based upon morphological inspection and DNA analyses of the 28S rRNA gene and the complete ITS region. N. malhamensis was not identified from the wood mouse despite thorough examination. The N. malhamensis ITS sequence (GenBank: JQ766940) is the first to be published for a Notocotylus species and infection of My. glareolus furthermore represents a new UK host record. N. malhamensis appeared to be site-specific, being identified only from a wetland location with a prevalence of 66.7% and mean intensity of 94.6±119.4 in the bank vole and 50% prevalence and mean intensity of 4.3±2.9 in the field vole. This digenean did not demonstrate seasonality, rather infection is considered to be related to the ecology of this site and its associated flooding. Finally, PCR-based methodologies for detecting larval digeneans within their intermediate host were developed in an attempt to identify the invertebrate species involved in the transmission of both P. elegans and N. malhamensis. The use of morphological analysis, coupled with DNA sequencing, identified the larval stages of Haplometra cylindracea and Notocotylus sp. from Lymnaeid snails. However, the larval stages of P. elegans and N. malhamensis were not identified despite careful observations and the limitations encountered during this process are discussed.

I piccoli mammiferi sono un gruppo non tassonomico estremamente diversificato che fornisce numerosi servizi ecosistemici e svolge una serie di importanti ruoli ecologici. Roditori ed insettivori sono generalmente caratterizzati da piccole dimensioni corporee, abitudini fossorie o arboricole e dalla dieta spesso altamente specializzata. Queste caratteristiche rendono alcune specie appartenenti a questo gruppo sensibili ai cambiamenti climatici e alle trasformazioni ambientali, quali le alterazioni di copertura ed uso di suolo. Malgrado i piccoli mammiferi vengano considerati dei buoni indicatori ecologici, ad oggi, sono pochi gli studi che hanno esplorato questo loro ruolo applicativo negli ecosistemi mediterranei. Il mio studio si è focalizzato sulla raccolta di un ampio set di dati di piccoli mammiferi nelle regioni dell’Italia centro-meridionale, sulla comprensione di come specie e comunità di piccoli mammiferi vengano influenzate dalle attività umane a diverse scale spaziali, partendo dalla scala locale (gestione forestale) a quella più ampia (land-use /land-cover) ed infine, come, queste specie possano essere utilizzate per monitorare cause e processi dei cambiamenti ambientali indotti dall’uomo. In dettaglio il mio progetto ha seguito i seguenti obiettivi: i) Raccolta e archiviazione di presenze, abbondanze e tratti ecologico-funzionali di piccoli mammiferi tramite dati provenienti da borre di rapaci notturni; ii) Analisi dell'influenza delle caratteristiche di microhabitat e delle pratiche di gestione forestale su due specie di roditori arboricoli nelle foreste del Bacino della Vandra (centro Italia); iii) Studio delle relazioni tra la diversità dei piccoli mammiferi ed eterogeneità di paesaggio su larga scala geografica. In particolare, è stata indagata l’influenza della configurazione spaziale del paesaggio su tali comunità. Nello specifico, il mio progetto di dottorato ha permesso di archiviare un ampio data set di presenze, abbondanze e tratti ecologico-funzionali per 23 specie di piccoli mammiferi coprendo un range temporale di 45 anni (1972 al 2017). Sono stati georeferenziati circa 50.000 individui in 190 siti dell'Italia centro-meridionale (Lazio, Abruzzo, Molise). La creazione del database relazionale openMICE ha colmato parte del gap conoscitivo per l’area mediterranea: ha permesso di sviluppare un database storico di informazioni potenzialmente utile alla comunità scientifica; ha reso fruibili ad un ampio pubblico numerosi dati di solito accessibili solo a specialisti; ha reso disponibili dati ecologici utili per future ricerche interessate a quantificare la perdita di biodiversità. A scala fine il mio studio ha sottolineato come l’uso dei modelli di “occupancy” possa migliorare la significatività statistica e l'interpretabilità della nicchia ecologica e del “niche overlap” (sovrapposizione della nicchia ecologica). Tale approccio ha permesso di discriminare strategie ecologiche alternative tra le due specie studiate. Il ghiro ha esibito una relazione significativa con le foreste ad alto fusto, mentre il moscardino ha mostrato preferenze per una varietà di tipi forestali. Queste differenze potrebbero essere dovute principalmente alle diverse abitudini alimentari e al grado di specializzazione delle due specie. In un contesto di gestione forestale, un'accurata quantificazione della sovrapposizione di nicchia permette di progettare pratiche mirate ad un uso sostenibile delle foreste che permetta di mantenere un’elevata diversità animale al loro interno. Poiché alcuni taxa sono più sensibili al cambiamento dell'habitat rispetto ad altri, un approccio multi-tassonomico potrebbe essere utile per valutare la risposta della biodiversità e per pianificare strategie di conservazione in paesaggi modificati dall'uomo. Il mio studio ha consentito di identificare e quantificare, come e se le comunità di piccoli mammiferi sono influenzate dalla composizione del paesaggio o dalla sua configurazione e se queste caratteristiche possono essere collegate al declino della ricchezza o dell’abbondanza specifica dei piccoli mammiferi stessi. I risultati del mio progetto, costituiscono una base di partenza per focalizzare aree prioritarie di conservazione per i piccoli mammiferi, guidare i futuri sforzi di campionamento e conservazione e sono un valido strumento per la gestione adattativa di specie e habitat nell’area Mediterranea.
Small mammals are an extremely diverse non-taxonomic group, which provide many ecosystem services and play important ecological roles. Rodents and insectivores are generally characterized by small body size, high litter size, high prolificity, arboreal or fossorial habits. Some of them possess a specialized diet, a trait linked to climate and land-use changes vulnerability. Despite these characteristics make small mammal communities’ make good candidates as ecological indicators, few studies have explored this aspect, i.e. environmental factors affecting species composition and abundance, especially in Mediterranean ecosystems. My Ph.D. project was aimed at collecting and archiving a large data set on small mammal occurrences in south-central Italy, and investigating how they are affected by human activities at different spatial scales, from local (i.e. stand scale - forest management) to broad scale (i.e. landscape scale-land-cover/land-use change), and thus how this diverse group could be used as ecological indicator of human driven environmental changes. The specific aims of my Ph.D. project were: i) Developing of an open-access georeferenced database of small mammal occurrences, abundance, and functional traits based on owl-pellet data; ii) Analyzing the influence of micro-habitat characteristics and sustainable forest management practices on arboreal rodents to evaluate how these species could act as bio-indicator of alternative forest management practices. This project has a focus on a Molise region’ forested areas; iii) Investigating the relationships between small mammal communities and landscape heterogeneity at large geographic scale in three south-central Italian regions (Lazio, Abruzzo, and Molise). During my research project, I implemented and designed the first standardized and accessible georeferenced database of small mammal communities based on owl pellets covering the years 1972 to 2017, including nearly 2000 records for 190 sites of south-central Italy. The relational OpenMICE database has made more widely available a remarkable amount of small mammal data to the scientific community that usually are accessible only to a restricted audience. OpenMICE will likely help in gaining a better understanding of ecological processes occurring in human-impacted landscapes. It also filled part of the knowledge gap on small mammals’ occurrence in the study area to guide future sampling and conservation efforts. The results of my project may serve to prioritize conservation areas for small mammals and to design adaptive management of EU habitats and species. At a fine-scale, I investigated niche similarity of two forest dormice (Muscardinus avellanarius and Glis glis) in a mixed deciduous forest of Molise, and how accounting for imperfect detection can improve the statistical significance and interpretability of niche overlap estimates based on occurrence data. I combined two different modelling approaches: ‘Occupancy models’ and ‘General Linear Mixed Models’. Arboreal rodents were surveyed in a forest of south-central Italy, and relative abundances were compared to a set of forest structural factors and habitat requirements. The key output was the definition of species-specific habitat relationships that refined information on arboreal rodent species and their distribution, and their response to forest structure and practices. In such a perspective, our findings offered a methodological framework to assess the degree of forests naturalness and to explore effects of alternative forest management systems, highlighting the importance of sustainable use of forest products in maintaining crucial biodiversity resources. In a forest management context, our quantification of niche overlap provided useful information to assess the effects of different management practices on the occurrence of these arboreal species. At a broad-scale, the research project was focused on the effect of landscape composition and structure (i.e. measured by landscape metrics) on small mammal communities. This study will provide insights on the small mammal complex responses to habitat change from the community-level of view and represents a baseline to future predictions of possible trends under future scenarios. Finally, results may potentially provide a powerful method in support of management and planning options for land-use change mitigation and adaptation.

The conservation of biological diversity has become one of the most important goals of managing forests in an ecologically sustainable way. In this thesis, I report a comprehensive study designed to examine the long-term effects of commercial logging and high-intensity fire, and the ability of Population Viability Analysis (PVA) models to predict these effects to aid in the conservation and management of multiple species. Initially, I compared the abundance of small mammals (A. agilis, R. fuscipes, A. swainsonii), and lizards (L. delicata, L. guichenoti, E. heatwolei), in sites with different disturbance histories: 18-19 yearold logging regrowth, 28-29 or 33-34 year???old clearfelling regrowth and unlogged forest. All sites had previously been burnt by bushfires. No evidence of long-term effects of logging or fire was found for A. agilis, R. fuscipes, L. delicata or L. guichenoti, and there were not enough data to make conclusions for A. swainsonii and E. heatwolei. Then the effects of a hazard-reduction burn were investigated. There was variation between the species in the effects of the burn, with interactions between year, aspect and burning for A. agilis and R. fuscipes, and interactions between year, disturbance and topography for the Lampropholis species. A. swainsonii became extremely scarce in the forest after the burn and E. heatwolei were generally unaffected. Next, PVA metapopulation models were used to predict the likely abundance and patch occupancy of these species based on historical data. Retrospective testing showed the models were accurate for all species, but best for A. agilis and R. fuscipes. Lastly, PVA modelling was used to rank management options; no management action, a hazard-reduction burn in 2005 or a logging event in 2005. The models predicted that future management is likely to result in the extinction of A. agilis, R. fuscipes and L. guichenoti by 2010. However, no one management scenario was most detrimental to all species. The current management regime for this forest involves commercial logging on a 40-year cycle and regular hazard-reduction burning. PVA modelling predicts that A. swainsonii and L. delicata are at the greatest risk of extinction under this regime, but that it is also likely to lead to the extinction of A. agilis, R. fuscipes and L. guichenoti in the near future. The results of this research indicate that the conservation of multiple species under one management regime is unlikely to be successful.

Natural habitat in the eastern United States has diminished over the past century because of the effects of invasive species. Both plant and animal invaders can alter habitat structure and may decrease survival of native species. The degree to which an invasive species alters ecosystem function depends on the functional characteristics of affected species and the resulting cascading effects. The loss of important native species, such as foundation species, can potentially influence the structure and distribution of animal communities because of the foundation species' unique ecosystem roles. The foundation species concept is relatively new to the terrestrial ecology and the impact on animal communities resulting in the loss of terrestrial foundation species is generally unknown. Eastern hemlock (Tsuga Canadensis), a foundation species in the eastern United States, is declining in abundance due to the invasive sap-sucking insect, hemlock woolly adelgid (Adelges tsugae, Annand). The loss of hemlock may impact the distribution and microhabitat associations of dependent species such as small mammals. I hypothesized that the distribution, population size, community composition, and microhabitat associations of small mammal species differ in response to canopy disturbance from the effects of logging and invasive species. In this dissertation, Chapter One provides an exploration of the past research conducted on 1) invasive species and how they affect habitat structure, 2) foundation species and how they affect ecosystem function, 3) small mammal habitat associations and population cycling, 4) occupancy modeling and its usefulness and limitations in the analysis of local occupancy, colonization rates, and extinction rates. Chapter Two presents a large-scale experiment on how the hemlock woolly adelgid impacts distribution and community assembly of small mammals. Chapter Three presents how forest disturbance, food resources, and habitat structure effects local colonization and extinction patterns of southern red-backed voles. Chapter Four presents how a paper published in 2005 brought the foundation species concept to terrestrial research and how the foundation species concept can be misleading in research.

MHC genes encode proteins that are responsible for the recognition of foreign antigens and the triggering of a subsequent, adequate immune response of the organism. Thus they hold a key position in the immune system of vertebrates. It is believed that the extraordinary genetic diversity of MHC genes is shaped by adaptive selectional processes in response to the reoccurring adaptations of parasites and pathogens. A large number of MHC studies were performed in a wide range of wildlife species aiming to understand the role of immune gene diversity in parasite resistance under natural selection conditions. Methodically, most of this work with very few exceptions has focussed only upon the structural, i.e. sequence diversity of regions responsible for antigen binding and presentation. Most of these studies found evidence that MHC gene variation did indeed underlie adaptive processes and that an individual’s allelic diversity explains parasite and pathogen resistance to a large extent. Nevertheless, our understanding of the effective mechanisms is incomplete. A neglected, but potentially highly relevant component concerns the transcriptional differences of MHC alleles. Indeed, differences in the expression levels MHC alleles and their potential functional importance have remained unstudied. The idea that also transcriptional differences might play an important role relies on the fact that lower MHC gene expression is tantamount with reduced induction of CD4+ T helper cells and thus with a reduced immune response. Hence, I studied the expression of MHC genes and of immune regulative cytokines as additional factors to reveal the functional importance of MHC diversity in two free-ranging rodent species (Delomys sublineatus, Apodemus flavicollis) in association with their gastrointestinal helminths under natural selection conditions. I established the method of relative quantification of mRNA on liver and spleen samples of both species in our laboratory. As there was no available information on nucleic sequences of potential reference genes in both species, PCR primer systems that were established in laboratory mice have to be tested and adapted for both non-model organisms. In the due course, sets of stable reference genes for both species were found and thus the preconditions for reliable measurements of mRNA levels established. For D. sublineatus it could be demonstrated that helminth infection elicits aspects of a typical Th2 immune response. Whereas mRNA levels of the cytokine interleukin Il4 increased with infection intensity by strongyle nematodes neither MHC nor cytokine expression played a significant role in D. sublineatus. For A. flavicollis I found a negative association between the parasitic nematode Heligmosomoides polygyrus and hepatic MHC mRNA levels. As a lower MHC expression entails a lower immune response, this could be evidence for an immune evasive strategy of the nematode, as it has been suggested for many micro-parasites. This implies that H. polygyrus is capable to interfere actively with the MHC transcription. Indeed, this parasite species has long been suspected to be immunosuppressive, e.g. by induction of regulatory T-helper cells that respond with a higher interleukin Il10 and tumor necrosis factor Tgfb production. Both cytokines in turn cause an abated MHC expression. By disabling recognition by the MHC molecule H. polygyrus might be able to prevent an activation of the immune system. Indeed, I found a strong tendency in animals carrying the allele Apfl-DRB*23 to have an increased infection intensity with H. polygyrus. Furthermore, I found positive and negative associations between specific MHC alleles and other helminth species, as well as typical signs of positive selection acting on the nucleic sequences of the MHC. The latter was evident by an elevated rate of non-synonymous to synonymous substitutions in the MHC sequences of exon 2 encoding the functionally important antigen binding sites whereas the first and third exons of the MHC DRB gene were highly conserved. In conclusion, the studies in this thesis demonstrate that valid procedures to quantify expression of immune relevant genes are also feasible in non-model wildlife organisms. In addition to structural MHC diversity, also MHC gene expression should be considered to obtain a more complete picture on host-pathogen coevolutionary selection processes. This is especially true if parasites are able to interfere with systemic MHC expression. In this case advantageous or disadvantageous effects of allelic binding motifs are abated. The studies could not define the role of MHC gene expression in antagonistic coevolution as such but the results suggest that it depends strongly on the specific parasite species that is involved.
Die Hauptaufgabe von MHC-kodierten Proteinen ist die Erkennung von körperfremden Molekülen sowie das Einleiten einer adäquaten Immunantwort, womit sie eine Schlüsselrolle im Immunsystem der Wirbeltiere einnehmen. Man nimmt an, dass ihre außergewöhnliche Vielfalt eine Antwort auf die sich ständig anpassenden Parasiten und Krankheitserreger ist, durch adaptive Selektion erhalten wird und dass die individuelle Allelausstattung einen Großteil der Parasitenbelastung erklärt, wofür bereits zahlreiche MHC-Studien Hinweise gefunden haben. Trotzdem ist unser Verständnis über die wirkenden Mechanismen teilweise noch lückenhaft. Ein stark vernachlässigter Aspekt hierbei sind z.B. eventuelle Unterschiede in der Genexpression der MHC-Allele und eine geringere Expression wäre gleichbedeutend mit einer geringeren Aktivierung des Immunsystems. Ich habe hierzu zwei frei lebende Kleinsäugerarten (Delomys sublineatus, Apodemus flavicollis) unter natürlichen Selektionsbedingungen untersucht. Dabei habe ich neben der genotypischen Diversität von MHC-Genen auch deren Expression, sowie die Genexpression immunregulativer Zytokine mit in Betracht gezogen und in Relation zur individuellen Belastung mit gastrointestinalen Helminthen gesetzt. Anhand von Leber und Milzproben beider Arten habe ich die Methode der ‚real-time PCR‘ zur relativen Quantifizierung von mRNA im Labor etabliert. Bereits für die Labormaus etablierte PCR-Primersysteme wurden an beiden Arten getestet und so konnten stabile Referenzgene gefunden werden, die Grundvoraussetzung für zuverlässige Genexpressionsmessungen. Für D. sublineatus konnte gezeigt werden, dass Helminthenbefall eine typische Th2 Immunantwort induziert, und dass der Zytokin Il4 Gehalt mit Befallsintensität strongyler Nematoden zunimmt. Es wurde für D. sublineatus kein signifikanter Zusammenhang zwischen MHC Expression oder anderen Zytokinen mit Helminthenbefall gefunden. In A. flavicollis wurde ein negativer Zusammenhang zwischen haptischer MHC-Expression und dem parasitären Nematoden Heligmosomoides polygyrus festgestellt, was auf eine Immunvermeidungsstrategie des Nematoden hindeutet. Ich fand typische positive und negative Assoziationen zwischen MHC-Allelen und anderen Helminthenarten, sowie Zeichen eines positiven Selektionsdruckes auf den MHC-Sequenzen, was sich durch eine erhöhte Rate aminosäureverändernder Mutationen zeigte. Diese nicht-synonymen Veränderungen waren auf Positionen innerhalb des zweiten Exons des DRB-Genes beschränkt, wohingegen die untersuchten Bereiche des ersten und dritten Exons stark konserviert vorlagen. Diese variablen Positionen kodieren Schlüsselstellen im Bereich der Antigenbindungsstelle im MHC Molekül. Zusammenfassend zeigt diese Arbeit, dass Genexpressionsstudien auch an Wildtieren durchgeführt und verlässliche Daten erzeugt werden können. Zusätzlich zur strukturellen Vielfalt sollten zukünftig auch mögliche Genexpressionsunterschiede bei MHC-Studien berücksichtigt werden, um ein kompletteres Bild der koevolutiven Wirt-Parasiten-Beziehungen zeichnen zu können. Dies ist vor allem dann von evolutiver Bedeutung, wenn die Parasiten in der Lage sind die MHC Expression aktiv zu beeinflussen. Die Studien konnten nicht die exakte Bedeutung von MHC-Genexpression in der antagonistischen Koevolution definieren, aber sie konnten zeigen dass diese Bedeutung stark von den jeweils beteiligten Partnern abzuhängen vermag.

Studies in agricultural landscapes have shown that anthropogenic environments may be relevant to wildlife species. Given the extent of these areas efficient research methods are needed to assess its ecological value in terms of local diversity, such as the use of biological indicators. The main goal here was to evaluate the possible relationship between the native vegetation biomass and diversity of small mammals in a silvicultural landscape of São Paulo. The study was developed at Fazenda Três Lagoas, which is part of the \"Programa de Pesquisa em Biodiversidade\" (PPBio), at Angatuba municipality, State of São Paulo, and lasted nine months. From May 2015 to March 2016 nine sampling campaigns were carried over a grid of 15 pitfall traps, five in Eucalyptus plantations, five in native vegetation and five in abandoned pastures. In the Chapter 1 the distribution and abundance patterns of small mammals on a silvicultural landcape during the early second cycle of Eucalyptus plantation in Southeastern Brazil was evaluated. A total of 672 individuals from 15 species of the orders Rodentia (9 spp.) and Didelphimorphia (6 spp.) were captured and five new species were detected in the study area in comparison to the first cycle. Although these species are predominantly generalists, there were differences in the abundance of small mammals in the three environments. The presence of native vegetation patches associated with riparian areas and abandoned pastures and the role of small mammals as a food resource for predators on a trophic structure, gives a certain conservation value to silvicultural landscapes in southeastern Brazil. In the Chapter 2 the relationship between landscape metrics and patterns of diversity, distribution and abundance of small mammals in a silvicultural landscape were evaluated. The species richness and family diversity of small mammals have been predominantly determined by the percentage of native vegetation. However, the abundance of small mammals can be determined by an indirect estimate of the native vegetation biomass (i.e., NDVI), which can be considered a 3D landscape metric as it is related to volume. Therefore, to succeed in assessing the value of agricultural landscape, future studies should consider landscape context, as well as the landscape metrics associated with geospatial data analysis and the distinct responses of species.
Estudos em paisagens agrícolas têm mostrado que ambientes antrópicos podem ser relevantes para muitas espécies selvagens. Dada a extensão destas áreas, são necessários métodos eficientes de pesquisa para avaliar seu valor ecológico em termos de diversidade local, tais como o uso de indicadores biológicos. O presente estudo teve como objetivo geral avaliar a possível relação entre a biomassa de vegetação nativa e a diversidade de mamíferos de pequeno porte em uma paisagem silvicultural do estado de São Paulo. O estudo foi desenvolvido na Fazenda Três Lagoas, que é parte do Núcleo Angatuba do Programa de Pesquisa em Biodiversidade (PPBio), no município de Angatuba, Estado de São Paulo e teve a duração de nove meses. De maio de 2015 a março de 2016, foram realizadas campanhas mensais de amostragem em uma grade amostral com 15 conjuntos de armadilhas de interceptação e queda (pitfall), sendo cinco nas plantações de Eucalyptus spp., cinco em vegetação nativa e cinco em pasto abandonado. No Capítulo 1 foram avaliados os padrões de distribuição e abundância de pequenos mamíferos em uma paisagem silvicultural ao início do segundo ciclo de plantações de Eucalyptus no Sudeste do Brasil. Um total de 672 indivíduos de 15 espécies das ordens Rodentia (9 spp.) e Didelphimorphia (6 spp.) foram capturados e cinco novas espécies foram detectadas na área de estudo em relação ao primeiro ciclo. Embora as espécies presentes sejam predominantemente generalistas, houve diferença na abundância de pequenos mamíferos nos três ambientes. A presença de fragmentos de vegetação nativa associados a áreas ripícolas e pasto abandonado e o papel dos pequenos mamíferos como recurso alimentar para predadores em uma estrutura trófica, atribui um valor de conservação às paisagens silviculturais no sudeste do Brasil. No Capítulo 2, o objetivo foi avaliar a relação entre métricas da paisagem e padrões de diversidade, distribuição e abundância de pequenos mamíferos em uma paisagem silvícultural. A riqueza de espécies e a diversidade de famílias dos pequenos mamíferos tem sido predominantemente determinada pela área porcentual de vegetação nativa. No entanto, a abundância de pequenos mamíferos pode ser determinada por uma estimativa indireta da biomassa da vegetação nativa (e.g., NDVI), que pode ser considerada uma métrica de paisagem 3D, pois está relacionada ao volume. Portanto, para ter sucesso na avaliação do valor da paisagem agrícola, os estudos futuros devem considerar o contexto da paisagem, bem como as métricas da paisagem associadas à análise dos dados geoespaciais e as distintas respostas das espécies.

The small mammal communities of central Africa are not well understood, and the southwestern section of Gabon has not been previously surveyed except for some recent work in Monts Doudou. At five sites within the Gamba Complex we set out to 1) document the species of terrestrial rodents (Muridae) and shrews (Soricidae) weighing less than 100 g, 2) compare the community composition between inland and coastal sites, and 3) evaluate our sampling protocols. Using a combination of pitfall lines, Sherman live traps, and snap traps we captured 721 individuals of 12 rodent and 10 shrew species in 15,792 trap-nights. The rodent community was dominated by Hylomyscus stella and the shrew community by Sylvisorex johnstoni, in agreement with nearby studies. The coastal sites were less diverse with 3 rodent species and 1 shrew species only found at inland sites. The inland Rabi site had the most diverse small mammal community due to 2 species captured in secondary forests and fields near the oil facility. Our use of pitfalls was essential to our capture of shrews, and our protocol of switching from live to snap traps midway through the trapping period resulted in more species than expected. The ecological factors influencing distribution patterns of small mammals in central Africa is not well understood. We evaluated the role of disturbance at paired inland and coastal sites using landscape variables generated from satellite imagery. Regression analyses revealed that while the amount of forest present at a site was strongly correlated with rodent richness (F = 16.437; df = 1; p = 0.001), shrew richness was negatively correlated with the amount of roads (partial F = 12.232; df = 1; p = 0.007) and rainfall (partial F = 6.035; df = 1; p = 0.036) and positively with elevation (partial F = 6.832; df = 1; p = 0.028). Our results suggest that while disturbance at Rabi has created additional habitats for rodents, the loss of specialist rodents from coastal sites reflects their inability to tolerate the edge-affected, fragmented, and less diverse forests in that region.

Thesis (PhD) - Stellenbosch University, 2011.
ENGLISH ABSTRACT: The Albertine Rift is characterized by a heterogeneous landscape which may, at least in part, drive the exceptional biodiversity found across all taxonomic levels. Notwithstanding the biodiversity and beauty of the region, large areas are poorly understood because of political instability with the inaccessibility of most of the region as a contributing factor. The majority of studies in the Albertine Rift have focussed on charismatic mega fauna, with other taxa receiving less attention. One of the taxonomically and numerically more abundant small mammal genera is the genus Praomys, an African endemic with a wide distribution range spanning most of west, central and east Africa. Four species are typically recognized from the Albertine Rift namely P. degraaffi, P. jacksoni, P. misonnei and P. verschureni. In this study I used a combination of DNA sequence data (mitochondrial control region, mitochondrial cytochrome b and 7th intron of the nuclear ß-fibrinogen gene) as well as morphometric data (traditional and geometric) to investigate the systematics of the Praomys taxa occurring in the Albertine Rift. To allow meaningful DNA assessments and in an attempt to identify potential drivers of diversifications, other Praomys species were also included from public sequence data bases for comparisons. The main focus was on P. jacksoni (the numerically most abundant taxon; also, up to 2005, all Praomys in the Albertine Rift were mostly collected as “jacksoni”) and P. degraaffi (an Albertine Rift endemic). A surprising finding was the presence of P. mutoni; this represents a range extension for this species into the Albertine Rift. Distinct evolutionary lineages were found in both P. jacksoni (confirmed by sequence data as well as morphometrics) as well as P. degraaffi (based only on sequence data; insufficient samples precluded a full morphometric investigation). These lineages (in both P. jacksoni as well as P. degraaffi) appear to be separated along a north – south gradient; however, further investigations should confirm this. To further investigate the genetic patterns at local scales across the Albertine Rift, as well as introgression between species as revealed by sequence data, a species-specific microsatellite library was developed for P. jacksoni. Twelve polymorphic markers were identified of which nine also amplified in P. degraaffi. Introgression was confirmed between the two focal species with almost 20% of the individuals analysed being jacksoni-degraaffi hybrids. This is perhaps not so surprising given that there is considerable overlap in their ranges (between ~ 1500 m a.s.l. to 2450 m a.s.l.) as well as the relative ages of the species (the divergence time between these two species were estimated at 3.8 Mya). The presence of distinct lineages within each of these species was confirmed by microsatellite analyses (these lineages diverged approcimately at same time at ca. 3.4 Mya). As suggested by sequence and morphometric data, these lineages had a largely north – south distribution but with considerable overlap in the central Albertine Rift in the vicinity of Lake Kivu. The phylogeographic patterns obtained for both focal species were not consistent with the physical barriers such as the rivers, lakes or mountains, nor were they exclusively associated with Pleistocene phenomena such as the change of the course of the rivers or uplift; rather, the lineages predate the Pleistocene and fall firmly in the Pliocene (>3 Mya). Biogeographically, the north - south location of lineages with a centrally - located contact zone could be a result of parapatric speciation due to habitat fragmentation or past climate change, followed by secondary contact. Barcoding using genetic information provides a useful tool to identify unknown taxa, cryptic diversity or where different life stages are difficult to identify. From an invasion biology perspective, it allows for the rapid identification of problem taxa against a known data base. By adopting such a barcoding approach (senso lato), the presence of three invasive rodents was confirmed in the Democratic Republic of the Congo (DRC); these are Rattus rattus (black rat), R. norvegicus (Norway rat) and Mus musculus domesticus (house mouse). A comparison with global data available for these species revealed two possible introduction pathways namely via the shipping port at Kinshasa/Matadi (with strong links to Europe) and via the slave trade routes in the east (strong links to the Arab world and the east). Of these three taxa, only R. rattus is currently documented from the DRC although the others have received mention in the gray literature. These findings draw attention to the lack of any official policy regarding biosecurity in the DRC, and argue for the development of strict control measures to prevent further introductions.
AFRIKAANSE OPSOMMING: Die Albertine Rift word gekenmerk deur 'n heterogene landskap wat kan, ten minste gedeeltelik, die uitsonderlike biodiversiteit wat oor al die taksonomiese vlakke gevind word teweeg bring. Nieteenstaande die biodiversiteit en die skoonheid van die streek, is groot gebiede onbekend as gevolg van politieke onstabiliteit met die ontoeganklikheid van meeste van die streek as 'n bydraende faktor. Die meerderheid van studies in die Albertine Rift het gefokus op die charismatiese mega fauna, met ander taxa wat minder aandag ontvang. Een van die taksonomies en numeries meer volop klein soogdier genera is die genus Praomys, 'n Afrika endemiese groep met 'n wye verspreiding wat strek oor die grootste deel van van wes-, sentraal en oos-Afrika. Vier spesies word tipies erken van die Albertine Rift naamlik P. degraaffi, P. jacksoni, P. misonnei en P. verschureni. In hierdie studie het ek 'n kombinasie van DNA volgorde data (mitochondriale beheer streek, mitochondriale sitochroom b en 7de intron van die kern ß-fibrinogeen geen) sowel as morfometriese data (tradisioneel en meetkundig) gebruik om die sistematiek van die Praomys taxa te ondersoek. Om betekenisvolle DNA aanslae toe te laat en in 'n poging om potensiële aandrywers van diversiteit te identifiseer, is ander Praomys spesies van openbare volgorde data basisse vir vergelykings ingesluit. Die hooffokus is op P. jacksoni (die numeries volopste takson, ook, tot en met 2005 is alle Praomys in die Albertine Rift meestal as "jacksoni" versamel) en P. degraaffi ('n Albertine Rift endemiese spesie). 'n Verrassende bevinding was die teenwoordigheid van P. mutoni, dit verteenwoordig' n verspreidingsuitbreiding vir hierdie spesie in die Albertine Rift. Bepaalde evolusionêre ontwikkelingslyne was in beide P. jacksoni (bevestig deur die volgorde data sowel as morfometrie) sowel as P. degraaffi (wat slegs gebaseer is op die volgorde data, onvoldoende monsters verhinder 'n volledige morfometriese ondersoek). Hierdie lyne (in beide P. jacksoni sowel as P. degraaffi) word geskei langs 'n noord - suid gradiënt, maar verdere ondersoeke moet dit bevestig. Om die genetiese patrone op plaaslike skaal oor die Albertina Rift verder te ondersoek, sowel as introgressie tussen spesies soos geopenbaar deur die volgorde data, is 'n spesie-spesifieke mikrosatelliet biblioteek ontwikkel vir P. jacksoni. Twaalf polimorfiese merkers is geïdentifiseer waarvan nege ook amplifiseer in P. degraaffi. Introgressie is bevestig tussen die twee brandpunt spesies met byna 20% van die individue wat ontleed is as jacksoni-degraaffi basters. Dit is miskien nie so verbasend gegee dat daar aansienlike oorvleueling is in hul gebiede (tussen ~ 1500 m bo seespieel tot 2450 m bo seespieel), sowel as die relatiewe ouderdomme van die spesies (die divergensie tussen hierdie twee spesies is geskat op 3,8 Mya). Die teenwoordigheid van verskillende lyne in elk van hierdie spesies is bevestig deur mikrosatelliet ontleding (hierdie lyne het gedivergeer ongeveer 3,4 Mya). Soos voorgestel deur die DNA volgorde en morfometriese data, het hierdie lyne 'n grootliks noorde – suid verspreiding, maar met 'n aansienlike oorvleueling in die sentrale Albertine Rift in die omgewing van die Kivumeer. Die filogeografiese patrone wat vir beide die brandpunt spesies gevind is nie in ooreenstemming met die fisiese struikelblokke soos die riviere, mere of berge nie, en hou ook nie uitsluitlik verband met die Pleistoseen verskynsels soos die verandering van die loop van die riviere nie; die afstammelinge is eerder veel ouer as die Pleistoseen en val binne die Plioseen (> 3 Mya). Biogeografies, die noorde – suid plasing van die lyne met 'n sentraal geleë kontak sone kan die gevolg wees van parapatriese spesiasie te danke aan habitatfragmentasie as gevolg van verandering in die klimaat, gevolg deur 'n sekondêre kontak. Strepieskodering met behulp van genetiese inligting verskaf 'n nuttige instrument om onbekend taxa, kriptiese diversiteit of waar verskillende lewensfases moeilik is om te identifiseer, te identifiseer. Vanuit 'n indringerbiologie perspektief, maak hierdie benadering dit moontlik om vinnige identifikasies van die probleem taksa teen' n bekende data basis te bekom. Deur gebruik te maak van so 'n strepieskoderingsbenadering (senso lato), is die teenwoordigheid van drie indringende knaagdiere bevestig in die Demokratiese Republiek van die Kongo (DRK), naamlik Rattus rattus (swart rot), R. norvegicus (Noorweë rot) en Mus musculus domesticus (huis muis). 'n Vergelyking met die globale data wat beskikbaar is vir hierdie spesies het aan die lig gebring dat twee moontlike betree-roetes bestaan, naamlik via die skeepshawe by Kinshasa / Matadi (met sterk skakels na Europa), en via die slawehandel roetes in die ooste (sterk skakels na die Arabiese wêreld en die ooste) . Van hierdie drie taxa, is tans slegs R. rattus van die Demokratiese Republiek van die Kongo gedokumenteer, hoewel die ander melding ontvang in die grys literatuur. Hierdie bevindinge vestig die aandag op die gebrek aan enige amptelike beleid ten opsigte van biosekuriteit in die Demokratiese Republiek van die Kongo, en argumenteer vir die ontwikkeling van streng beheermaatreëls om verdere indringerspesies te voorkom.

Scarce knowledge of Neotropical small mammal communities prevents experimental inquiry on the mechanisms structuring these communities. In this study, I examined patterns of local assembly of the small mammal communities on the eastern slopes of El Cielo Biosphere Reserve (ECBR) in Tamaulipas, Mexico, at two spatial scales. At the landscape level I tested patterns of species co-occurrences between four sites with a null model. At the local level I addressed floor microhabitat use, vertical structure use and temporal partitioning. I studied these niche axes at two adjoining forest types, Tropical Subdeciduous Forest (TSDF) and Cloud Forest (CF), that had different structural complexity. Total trapping effort consisted of 19,712 trapnights distributed over three years. In 1,365 capture events I recorded 789 individuals representing 14 species. Abundant species, mostly Peromyscus species that are of intermediate body size, co-occurred less often than expected by chance, whereas rare species, mainly Reithrodontomys species of small size, occurred at random over study sites. This pattern suggests that species interactions might be responsible for this non-random structure. Both the TSDF and CF had striking differences in both microhabitat use and temporal partitioning. In the TSDF common species (>8 individuals) organized along a microhabitat gradient from grassy/open areas to closed forest areas. Temporal partitioning for the whole community was less than expected by chance with use of an ad hoc null model. Species from ecotone/open areas avoided use of middle portions of the night whereas the single forest species concentrated activity in this period. So, it is plausible that predator avoidance strategies might have higher impact on temporal partitioning as compared to competitive interactions. In high contrast the CF community was codominated by two Peromyscus species that overlapped heavily in both their microhabitat use and diel activity patterns. Ecological separation of these two species probably occurs along a niche axis not considered in my study or might be facilitated by their body mass difference. Overall, I provide the first account of community patterns for small mammals at ECBR. These patterns can provide the basis for experimental manipulations to ascertain mechanisms responsible for structure at these communities.

Ticks are one of the most important zoonotic disease vectors globally. In Australia, tick bites can lead to bacterial infections, debilitating allergies, and paralysis. The use of repellent is currently the primary way to minimise the risk of tick bites, but novel strategies that focus on reducing tick abundance in the landscape by managing wildlife hosts or landscape features are increasingly desired. Yet little is known about the spatial patterns in urban tick encounters, which landscape traits may be important drivers, and which small mammals maintain urban tick populations. I used a combination of community surveys and field sampling to address these gaps. I found that tick encounters in residential yards were widespread and that broader landscape traits and the presence of hosts were important predictors of tick encounters compared to individual yard traits. By quantifying tick abundances on hosts, host abundances, and host behaviour at the urban fringe, I show that introduced black rats and native long-nosed bandicoots were the most important small mammal hosts of medically significant tick species. I found that introduced rabbits could also be important urban hosts in areas where they reach higher densities than native small mammals. Lastly, I show that generalist small mammals readily use both backyard and adjacent bushland habitat. But limited movement of black rats and a preference for bushland at low densities suggests they may be synanthropic rather than commensal at the urban fringe with important implications for management. Together, my findings 1) assist with identifying high-risk areas to target with public engagement on tick-bite prevention and 2) have refined hypotheses that can be tested with manipulative field studies. My research also suggests that tick management strategies focused on the key hosts are needed, and I suggest which strategies may be used for each species to facilitate the coexistence of humans and wildlife in urban areas.