Over 30 tetrapod groups have evolved a snake-like, elongate, limbless body plan. Studies of the patterns of limb reduction have revealed a close relationship between the reduction of the limbs and body elongation; however, the loss of the skeletal elements that support the limb, the pectoral girdle, has been less thoroughly examined. Here, I use computed tomography to generate three dimensional models of the pectoral girdles of an Australian skink genus, Lerista. This group contains pentadactyl species, fully limbless species and many species with intermediate morphologies. I employed a 3D geometric morphometric analysis to compare the shapes of these structures and revealed that the reduction of the pectoral girdle is correlated with the degree of loss in the limbs. The girdle in species with well developed limbs is longer and more narrow than the short, broad girdle of species with highly reduced or absent limbs, but the degree of reduction is only loosely correlated with the degree of reduction in the limbs. Certain events appear to occur concurrently such as the losses of the coracoid foramen and the humerus, but other events such as the loss of the epicoracoid are not consistently associated with any other event. The extent to which limb reduction is associated with the degree of pectoral girdle reduction and the morphology of the girdles appears to be closely associated with subclade, with individuals from closely related clades showing dramatically different degrees of girdle reduction despite similarities in the degree of limb loss. Despite these differences, the patterns in Lerista are generally more similar to each other than to those of other lizard groups, and more similar to those of other skinks than to those of other groups of lizards. Though some aspects of limb loss are common to all lizard groups that have evolved a serpentine body plan, this study shows that, even in closely related groups, this transition does not proceed in exactly the same way. / Master of Science / Over 30 tetrapod groups have evolved a snake-like, elongate, limbless body plan. Many studies of the patterns of limb reduction (evolutionarily losing fingers and toes) have revealed a close relationship between the reduction of the limbs and body elongation; however, the loss of parts of the internal skeleton that support the limb (e.g. shoulder blade, collar bone) have been less thoroughly examined. Here computed tomography was used to generate three dimensional models of the pectoral girdle, the array of limb support bones, of the Australian lizard genus Lerista. This group contains species that have five fingers, species which are fully limbless (and thus have no fingers), and some that have intermediate numbers of fingers. I quantitatively compared the pectoral girdle shapes, which revealed that the reduction of the pectoral girdle occurs gradually and in a series of steps that are loosely associated with how many fingers are present. The pectoral girdle as a whole shows a more obvious reduction in length than in width, with this length reduction being loosely associated with the number of fingers present. Certain events appear to occur concurrently such as the loss of a small hole in one of the bones through which nerves that control the arm pass and loss of the upper arm bone. However other events, such as the loss of a cartilaginous structure called the epicoracoid is not consistently associated with any other event. The extent to which limb reduction is associated with the extent of pectoral girdle reduction is group dependent, with individuals from closely related groups showing dramatically different degrees of pectoral girdle reduction despite a similarity in the degree of digit loss. Despite these differences, the patterns in Lerista are more similar to each other than to those of other lizard groups, and more similar to those of other skinks than to those of other groups of lizards. Though some aspects of limb loss are common to all lizard groups that have evolved a snake-like body plan, this study reveals that even in closely related groups, this transition does not proceed in exactly the same way.

No description available.

Pesticides are commonly used around the world for a multitude of different purposes and on diverse habitats, including agricultural fields, wetlands, and personal lawns and gardens. Currently, acetylcholinesterase (AChE)-inhibiting pesticides are among the most prevalently used chemical pesticides in the United States. A wealth of information exists on sub-cellular responses of organisms, primarily birds, mammals, and fish, exposed to these compounds. However, the effects of AChE-inhibiting pesticides at the whole-organism level, most importantly effects relevant to an individual's fitness, have received less attention. My Master's research focused on describing the effects of carbaryl, an AChE-inhibiting pesticide, on several fitness-related traits in the western fence lizard (Sceloporus occidentalis). Reptiles are the least studied vertebrate taxon in ecotoxicological studies even though contaminants are suspected in contributing to recent population declines. Using multiple dose concentrations within the range expected to occur in nature (based on EPA application rates and published pesticide residues on insects), I quantified the effects of carbaryl on sprint performance energy acquisition, and energy allocation, traits which could have important implications for the animal's ability to avoid predators, capture prey, and grow and reproduce. I found that at the highest dose concentration, lizards experienced a decrease in arboreal and terrestrial locomotor performance, a decrease in energy acquisition, and alterations in energy allocation. My findings suggest that acute exposure to high concentrations of carbaryl can have important sublethal consequences on fitness-related traits in S. occidentalis. Future studies should examine the consequences of multiple-pulse exposures to AChE-inhibiting pesticides on reptiles. / Master of Science

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

Within the Sceloporus scalaris species group, some species are oviparous while others are viviparous, suggesting the origin of viviparity is relatively recent. This interpopulation comparison focused on Sceloporus scalaris in Arizona because low elevation (1500 m) and high elevation (2500-2900 m) populations exhibit short and long periods of egg retention, respectively, and increased periods of egg retention are presumably an intermediate step in the evolution of viviparity. Low elevation populations had life histories typical of lowland Sceloporus: eggs are laid at embryonic stages 32-33, clutch sizes are relatively large, hatchlings are relatively small, and more than one clutch is produced per season. In contrast, montane populations retain eggs to embryonic stages 36-38, clutch sizes are relatively small, hatchlings are relatively large, and only one clutch is produced per season. In accord with their lengthy retention, eggshells of montane populations were thinner than those of lowland populations. The assumption that prolonged egg retention is mechanistically associated with relatively thin eggshells was tested by comparing the development of embryos in eggs retained in utero with that of control embryos in eggs incubated in Simulated nests where water and gases were presumably not limited. For the low elevation population, growth rates of embryos retained in utero as long as stage 39 were identical to those of control eggs at the same stages. However, water uptake by retained eggs was confined to the embryo whereas water uptake of control eggs was associated with both the embryo and extraembryonic tissues. These results suggest that the length of egg retention by S. scalaris is not constrained by eggshell thickness, and that the capacity to regulate the water balance of eggs may be an important component of the evolution of viviparity. / Master of Science

Rates and energy equivalents of consumption (C), egestion+ excretion (FU) , assimilation (A), respiration (R) and production (P) were measured in two groups of Sceloporus olivaceus: 1) a laboratory group acclimated at four seasonally encountered temperatures (15, 20, 25 and 30°C) ; and 2) four acclimatization groups collected at different seasons when ambient temperatures corresponded to 15, 20, 25 and 30°C.

No description available.

Embora os escamados sejam comumente encontrados em sítios fossilíferos cenozóicos sul−americanos, materiais esqueléticos completos são raros. Apenas alguns poucos exemplares assim foram registrados, com a maioria dos achados representando materiais fragmentários de crânio e mandíbulas ou vértebras isoladas. Dentre as localidades provedoras de vertebrados fósseis na América do Sul, a Formação Chichínales se destaca pela recente descoberta, em seus sedimentos, de um crânio quase completo de um lagarto teiídeo previamente desconhecido. Dada a fauna associada, a idade da formação é definida como Mioceno Temprano (Colhuehuapense). No presente estudo, conclui−se, através de uma análise filogenética contendo 39 espécies viventes e fósseis de escamados e 149 caracteres osteológicos, que este material pertence a uma nova espécie do gênero contemporâneo Callopistes. Uma descrição morfológica detalhada do fóssil, obtida através de análises estereoscópicas e de microtomografia computadorizada de alta resolução (CT Scan), também é apresentada. A matriz morfológica foi analisada com o auxílio do software TNT Versão 1.1, seguindo o princípio de máxima parcimônia, com todos os caracteres tratados com a mesma pesagem, resultando em quatro árvores igualmente parcimoniosas, que foram então utilizadas para a construção de uma árvore de consenso estrito. Em todas as quatro árvores, o novo táxon posicionou−se dentro da família Teiidae como um membro do clado formado pelas demais espécies viventes de Callopistes. Entretanto, não foi possível estabelecer uma relação de grupo−irmão inequívoca entre as duas espécies de Callopistes presentes na análise e o fóssil. A atual distribuição das duas espécies viventes de Callopistes e a localidade de onde foi recuperado o fóssil em estudo indicam que esse gênero possuía uma distribuição muito mais ampla no passado, chegando a áreas patagônicas cis−Andinas, diferentemente das áreas trans−Andinas de altitude onde as duas espécies atuais estão restritas / Although squamates are commonly found in most Caenozoic south american fossil beds, complete skeletal materials are rare. Only a few examples exist, with most findings representing fragmentary cranial or jaw materials or isolated vertebrae. Among the known South American vertebrate fossil localities, the Chichínales formation rendered recently a mostly complete skull of a previously unknown teiid lizard. Given the associated fauna, the age of the formation is defined as Early Miocene (Colhuehuapense). Here, I show that this fossil represents a new species of the extant genus Callopistes through a phylogenetic analysis of extant and extinct squamates that includes 39 taxa and 149 osteological characters. I also provide a detailed description of the new fossil teiid based on both stereoscopical and high-resolution X−ray computed tomography (CT Scan) analyses. The data matrix was analyzed performing a equally weighted parsimony analysis using the software TNT Version 1.1 that resulted in four equally most parsimonius trees, which were then used to built a strict consensus tree. In all four trees, the fossil lizard was recovered within the Callopistes lineage, nested inside the family Teiidae. Nevertheless, I was unable to establish which of the two Callopistes species present in the analysis were more closely related to the fossil. The present distribution of the two extant species of Callopistes and the locality from where the fossil was recovered indicate that this genus had a much broader distribution in the past, reaching cis−Andean areas of Patagonia, apart from the trans−Andean areas where the two extant species are restricted

The paleontology of reptiles in the Caribbean is a topic of great interest to understand how the current fauna of the area was constituted from colonization and extinction of their groups. The largest number of fossils belongs to Squamata, ranging from the Eocene to our days. The registry covers all the islands of the Greater Antilles, most of the Lesser Antilles, and of the Bahamas. Cuba, the largest island of the Antilles, has a relatively sparse Squamata fossil record, with 11 known species from 10 locations, distributed in the West and Center of the Country. However, there are many other fossils deposited in biological collections without identification that could better clarify the history of their reptile fauna. A total of 328 fossils from three paleontological collections were selected for their analysis, searching osteological characteristics that would serve to diagnose them at the lowest possible taxonomic level, and compare them with other fossils and recent species. In the present work, the Squamata fossil record is increased, both in the number of species and in the number of localities. The registry is extended to practically all of the Cuban territory. Fossil remains belonging to previously reported species are confirmed, such as Leiocephalus cubensis, L. carinatus, Tarentola americana, Chilabothrus angulifer, and Cubophis cantherigerus. Fossils of Amphisbaena, Pholidoscelis auberi, and Leiocephalus macropus are described for the first time. Besides, other fossils belonging to the genera Tarentola, Leiocephalus, and Chilabothrus but different from the species that currently inhabit the archipelago, are described. These results show that the Squamata fossil record in Cuba is broader than what was previously considered, despite being composed of very fragile and small fossils with little potential for fossilization. For the paleontology of Squamata the description of new taxa and record of new localities in Cuba, are the first steps for more integrating studies on biological diversity, evolution, biogeography, paleoenvironment among others that contribute to the understanding of the fauna in the Caribbean region. / A paleontologia de répteis no Caribe é um tema de grande interesse para entender como a fauna atual da área foi constituída a partir da colonização e extinção dos seus grupos. O maior número de fósseis pertence a Squamata, que vai desde o Eoceno até nossos dias. O registro abrange todas as ilhas das Grandes Antilhas, a maioria das Pequenas Antilhas e as Bahamas. Cuba, a maior ilha das Antilhas, tem um registro fóssil de Squamata relativamente escasso, com 11 espécies conhecidas de 10 localidades, distribuídas no oeste e centro do país. No entanto, existem muitos outros fósseis depositados em coleções biológicas sem identificação, que poderiam esclarecer melhor a história de sua fauna de répteis. Um total de 328 fósseis de três coleções paleontológicas foi selecionado para sua análise, buscando características osteológicas diagnosticas do menor nível taxonômico possível, e comparando-os com outros fósseis e espécies recentes. No presente trabalho, o registro fóssil de Squamata foi aumentado, tanto em número de espécies quanto em número de localidades. O registro foi estendido a praticamente todo o território cubano. Restos fósseis pertencentes às espécies relatadas anteriormente são confirmados, como Leiocephalus cubensis, L. carinatus, Tarentola americana, Chilabothrus angulifer e Cubophis cantherigerus. Fósseis de Amphisbaena, Pholidoscelis auberi e Leiocephalus macropus foram descritos pela primeira vez, bem como de outros fósseis pertencentes aos gêneros Tarentola, Leiocephalus e Chilabothrus, mas diferentes das espécies que atualmente habitam o arquipélago. Esses resultados mostram que o registro fóssil de Squamata em Cuba é mais amplo do que era considerado anteriormente, apesar de ser composto de fósseis muito frágeis e pequenos, com pouco potencial para a fossilização. Para a paleontologia de Squamata, a descrição de novos táxons e registro de novas localidades em Cuba são os primeiros passos para estudos mais integradores sobre diversidade biológica, evolução, biogeografia, paleoambiente entre outros que contribuam ao entendimento da fauna na região do Caribe.

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