In the past 400 years, there has been a drastic decline in the number of endemic species on mainland Mauritius, with the island losing 69% of its original reptile community. Of 17 endemic species, only five mostly Phelsuma species survived the human mediated disturbances on mainland Mauritius. These remaining arboreal endemic geckos still play important ecological roles in the Mauritian ecosystem. However, habitat fragmentation and introduction of invasive species have increased the threats to these endemic geckos. The recent invasion of the bigger Phelsuma grandis (giant Madagascar day gecko) has increased the threats posed to the existence of endemic geckos, while habitat loss and fragmentation is also playing a major role in gecko decline, particularly for Phelsuma guimbeaui (lowland forest day gecko). In this thesis, I studied the ecological effects of P. grandis on endemic geckos at a landscape and local scale using species .distribution and binomial mixture models. I also designed markers from microsatellite and mitochondrial DNA to research the population. genetics of P. guimbeaui in response to habitat fragmentation. Finally, I explored habitat selection of P. guimbeaui to find suita~le sites for potential translocations. First, I showed that P. grandis shared many characteristics of an invasive species and could persist in a relatively large range of environmental conditions. The results highlight that P. grandis and endemic gecko distributions can overlap. Where P .. grandis has invaded areas occupied by endemic geckos, the abundance of the Mauritian species has declined by an average of 89%. This study provides strong evidence that P. grandis and endemic geckos are unlikely to coexist in sympatry. Second, I designed arid amplified 44 markers from an enriched-microsatellite genomic library. They were tested on ten subpopulations and 20 were selected to examine the population genetics of the fragmented population of P. guimbeaui. Here, the microsatellite results suggested that most subpopulations were genetically different, with low effective population sizes and no migrations, while simulations showed that the different subpopulations were at high risks of losing genetic diversity and extinction. Mitochondrial DNA showed that the fragmented subpopulations used to be part of a panmictic population. Using the findings of this genetic study, 12 subpopulations were identified as viable and 18 subpopulations were at high risk. Third, I showed that P. guimbeaui males had a larger home range than females and males overlap more with females than males and geckos selected habitats with higher plant diversity, with trees that had taller and larger trunks and a higher cavity density. Adult geckos selected different habitat features compared to sub-adults and juveniles. The findings of this research were synthesised into a review to formulate the conservation assessment of the endemic geckos on mainland Mauritius.

No description available.

The slow-worm, Anguis fraqilis, is a legless lizard in the family Anguidae. The ecology of the species was studied by weekly visits to two sites on the Isle of Purbeck, Dorset, England from 1981 to 1988. Other sites were visited less often. Animals were found under pieces of corrugated iron sheet that had been placed on the ground. Adults were photographed and identified on recapture by the pattern on the underside of the head. Pregnant females were retained in captivity until the birth of the young. A total of 3456 slow-worms were found. Capture rates of known individuals were low, often less than once a year. There were differences in rate of captures of four sex and size class over the season. Males predominated in spring, females were found most often in summer and sub-adults and juveniles were commonest in autumn. Rates of movement were low. There was no evidence of territory formation. Mating was only observed once. Females with sperm in the cloaca were found in May. The litters of 1 to 18 (average 8) were born in late summer. Larger females had larger litters but not larger young. In 1986, litter sizes were small with many of the young deformed. The sex ratios were not equal. The bias was to females at one site and to males at the other. Cloacal temperatures, low for a temperate reptile, ranged from 9.8 to 33.2 "C, with a median of 24.9 °C. There was little evidence of precise thermoregulation. Cloacal temperatures were highest in summer on sunny days, but varied little with time of day. The distribution in the Iberian peninsula was shown by discriminant function analysis to be correlated with cooler, wetter climates.

A field study of the behaviour and bioeconomics of the West African lizard Agama agama agama L., has been made at Ibadan, Nigeria. A marking method, depending upon individual variation of colour pattern. has been used to establish identities in the field. The overt, diurnal habits of this lizard together, with its preference for human habitations, make it an ideal subject for study. The males exhibit a marked territorial behaviour during the breeding season, which resembles that of passerine birds more closely than that of any other species of lizard so far described. The Territories are well defined, and are only defended against intrusion of other adult males; females and juveniles are tolerated in the territory. An essential element of male fighting is colour change : this is also accompanied by various displays. The tail alone is used as the offensive weapon in actual combat. Female fighting is directed at establishing a hierarchy. The spacing of territories is dependent upon the general, configuration of' the environment and the availability of suitable sites for colonization. The major function of territorial behaviour in this species appears to be the acquisition of a mate and maintaining the sexual bond during the breeding season. Colouration fulfils several functions. The light and dark reticulate colour phases, and possibly the reproductive colouration of males, is considered to be of importance in thermoregulation. Threat colouration is important in territorial behaviour as an element of fighting. The brightest hues are displayed in the reproductive colour phase. This colouration is of importance in advertising ownership of territory, and possibly has an attractive influence on the female. It is the colouration in which mating takes place. Sex discrimination in Agama agama agama is based upon the marked sexual dichromatism of these lizards, and does not involve any form of recognition display. Colour plays an important part in the stimulus situation releasing certain aspects of territorial and courtship behaviour. An attempt has been made to show how these two aspects of the lizard behaviour consist of a chain of activities, each section of which requires its own specific releaser.

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

Lacerta lepida is a lizard species that occurs throughout the Iberian Peninsula. Detailed phylogeographic analysis of the species using mitochondrial DNA and nuclear sequence data revealed a history of population fragmentation and diversification in allopatry. Diversification within the species was estimated to have started in the Miocene probably related to geological events of the region, nevertheless a strong influence of Pleistocene climatic oscillations were also detected. Several glacial refugia and demographic range expansions after diversification in allopatry were detected leading to the establishment of several secondary contact zones. Detailed analysis of two secondary contact zones within the species was carried out.

No description available.

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

No description available.

Lizard skulls vary greatly in shape and construction, and radical changes in skull form during evolution have made this an intriguing subject of research. The mechanics of feeding have surely been affected by this change in skull form, but whether this change in feeding is the driving force behind the change in skull shape is the underlying question being addressed throughout this project. Here the skull of 'Uromastyx hardwickii', an akinetic herbivorous lizard has been analysed using advanced computer modelling techniques. This study aimed to perform a multibody dynamics analysis (MDA) on a biting lizard skull so that bite forces, joint forces, ligament forces and muscle forces could be accurately predicted. Then, using this MDA load data stresses and strains within the skull were assessed using finite element analysis (FEA). These FE analyses were used to assess biting performance and to test hypotheses that consider biomechanical optimization of bone as the main reason behind the modification of skull shape during its evolution. Sutures were modelled and their effect on skull strains was assessed through a series of investigative studies. Finally, representative basal skull forms were examined to highlight potential implications of specific skull variations. To assist in validation of the computational modelling experimental strain gauging was conducted. The MDA provided detailed information on cranial biomechanics and associated cranial forces in this animal. It is believed that this technique will play a pivotal role in the analysis of skulls in the future and this study has demonstrated its definite potential. Cranial kinesis was seen to be mechanically significant in reducing joint reaction forces acting upon the skull, and specific groups of sutures (i.e. the frontal-parietal suture) in the Uromastyx skull played a substantial role in relieving strain compared to the other sutures, raising the questions about the original role of mesokinesis in squamate evolution.