No description available.

The coloration is a significant animal attribute which can be examined from the view of phylogenesis, ontogenesis, ecology or life-history parameters. In this thesis the method of coloration quantification and pattern complexity was developed, with the focus on Leopard gecko (Eublepharidae) family. are one of the most commonly breeded lizards, the great part of their popularity being due to their attractive "leopard" coloration. Yet we only know a little about their "wild" coloration. They have become an important organism for many etological and physiological experiments, the distinct color pattern change during ontogenesis being especially unusual. These aspects make them an ideal subject for coloration change and affecting parameters analysis. The results of this work show clear ekological pattern for coloration. The amount of black color correlates with the humidity and abundance of vegetation in the habitat of the species. The coloration quantification was also verified using spectrophotometry, which confirmed the original assumptions for colors included in the pattern. Given the absence of UV reflectance in the Leopard gecko pattern, we can assume that the UV spectrum pattern is not an essential parameter. Therefore, the photographies can be used for quantification as well. It is apparent...

Several parthenogenetic lineages occur within the lizards of the genus Darevskia (Sauria: Lacertidae) which are endemic to southern Transcaucasus. High level of heterozygosity, cause by thein hybrid origin, is one of the crucial aspects of thein evolutionary potential, as well as the asexual reproduction. Heterosis on one side is in the opposition to the outbreeding depression and genetic uniformity of the clones on the other side. Aim of this work is to evaluace if these aspects influence viability of parthenogenetic species and differ them from the sexual ones. We chose the amount of asymmetries as a measure of developmental instability, which we studied on three meristic characters. We also evaluated the pattern of asymmetries in lateral blue spots, which are of signaling importace in lacertid lizards. Our results suggest that there isn't significant difference between parthenogenetic and sexual species in developmental stability, but the sexual ones are more sensitive to population changes. Absence of males may have perhaps the greatest influence on coloration, resulting in loss of symmetry in the blue spots.

The sagebrush swift, Sceloporus graciosus graciosus, is abundant in the transitional zone of the Great Basin. As an intermediate link the the food chain, sagebrush swifts are preyed upon by snakes and hawks, and in turn are predators of small arthropods.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Masters of Science, Johannesburg 2018 / The morphology and functionality of surface microornamentation in southern African snakes is well-established in terms of resulting optical effects. Velvet-blackness, a type of optical effect is produced when light incident on a scale is scattered by microornamentation. I tested microornamentation from Bitis arietans dorsal exuvia for these optical effects. Scales were excised from shed skins of B. arietans and sputter coated with 15 nm Gold-Palladium to control the effect of pigment. Spectral intensity (SI) of three scale regions of known micro topography was recorded using spectrophotometry over the visible spectrum only as a measure of reflectivity of the scales. Given that surface roughness (the deviation of a membrane’s surface topography from an ideal surface) is a product of the size of surface asperities and its degree of randomness, the three scale regions in order of decreasing surface roughness were dark (dorsal) scales, pale (dorsal) scales, and ventral scales. Measures of SI on dorsal and ventral scale regions revealed lowest SI on dark dorsal scales and highest on ventral scales. In general, the level of micro-structuring was inversely proportional to SI. To test if optical effects are angle-dependent, I measured differences in SI between normal (90) and oblique (45) angles of incidence. Differences in SI between 90 and 45 were significant for all scale regions which revealed that while microornamentation produces optical effects at both normal and oblique incidence, the effect is greater at 45. Given that SI varies with surface roughness such that dark scales have a lower SI than pale scales, I conclude that scale colour in B. arietans is a product of optical effects created by microornamentation. The optical effect may improve the visual camouflage of B. arietans during ambush. While microornamentation is best known for its optical effects, it may have other functions. I examined the microornamentation in Bitis schneideri (Namaqua Dwarf Adder) using electron microscopy and found small, tooth-like protuberances distributed uniformly across the scales and across all body regions. I measured the distance between adjacent denticles which I 5 compared to the mean dimensions of sand grains from two study sites: Noup, within the distribution of B. schneideri, and Tswalu, outside of it but with significantly smaller grains. The space between denticles is smaller than sand grains from both sites. Due to its physical characteristics, microornamentation in B. schneideri has the potential to restrict sand grains from direct contact with the scale surface. These results suggest that microornamentation can function to shield the integument from sand abrasion in B. schneideri. This study demonstrates specific functions of microornamentation in the ecology of two species of Bitis. / XL2019

No description available.

Adaptive radiations, or evolutionary diversifications, are the evolutionary divergence of a single lineage into many different adaptive forms. They play a critical role in the history of life as groups of organisms speciate and fill new ecological roles over geologically rapid time intervals. There is currently no agreed upon operational unit, timeframe, or amount of divergence for organisms to be considered to have undergone an adaptive radiation. Additionally, the paucity of both comparative and fossil studies has limited the utility of the adaptive radiation in framing macroevolutionary questions, such as, is ecological and morphological diversification simultaneous? An ideal fossil clade to test this question is the Archosauriformes (crocodylians, birds, and their closest relatives). Archosauriforms radiated following the end-Permian mass extinction and their lineage diversification through the Early to Late Triassic is well documented in the literature. Prior to the end-Permian mass extinction, these reptiles were both species poor and ecologically limited, but by the Late Triassic they dominated terrestrial ecosystems in both species abundance and ecological breadth. However, continued environmental instability following the end-Permian extinction has led to the hypothesis that ecological expansion of archosauriforms lagged behind the diversification of lineages. The first chapter of my dissertation uses a Middle Triassic archosauriform tooth assemblage from Tanzania to reconstruct dietary specialization, estimated by morphological disparity of teeth. In addition to comparing tooth disparity of isolated and in situ teeth, this also provides a lens for comparing the timing of dietary specialization and species diversification. I found the archosauriforms to be faunivorous with little morphological disparity amongst the teeth. The second chapter uses an Early Triassic reptile tooth assemblage from South Africa to reconstruct the dietary specialization of archosauriforms early in their radiation to compare the amount of morphological disparity and lineage diversity. I use methods from Chapter 1 and integrate 3D morphometrics to better capture shape. I described several tooth morphotypes including six new to the locality. The morphological and dietary differences were minimal, indicating a greater species diversity than ecological diversity. The third chapter is a description of a new pseudosuchian archosaur taxon from the Middle Triassic of Tanzania. As species descriptions form the basic data unit of macroevolutionary analyses, this assists future studies of the archosauriform radiation. I recover this new taxon as the oldest known aetosaur. This species provides insights into the evolution of an armored carapace in crocodylian-line archosaurs and shows morphology related to armor evolved prior to the evolution of an herbivorous diet. / Doctor of Philosophy / There is an incredible diversity of life on Earth, but this is a small fraction of the life that once existed on our planet. The fossil record provides us a window into the past to reconstruct the history of life on our planet. Two of the patterns we see in the fossil record are rapid drops in biodiversity called mass extinctions, and rapid increases in biodiversity called biological radiations. Both of these events are often related and mass extinctions are followed by biological radiations throughout earth history. A particularly interesting case is the end-Permian mass extinction, not only because it is the largest extinction event, but also because the subsequent radiation was delayed by continuing environmental instability. An ideal group of animals to study in this time period are the archosaurs, the group of reptiles including crocodylians, birds, and their extinct relatives. Archosaur reptiles went from very few species before the extinction, to dominate ecosystems for the next 200 million years. However, we do not know if the radiation of many archosaur species occurred at the same time as they filled new roles in their communities. The first two chapters of my dissertation focus on using fossil teeth to reconstruct the diets of archosaurs at a single location. My first chapter describes teeth from the Middle Triassic (247-237 million years ago) of Tanzania. I measured the shapes of these teeth and used that to help assign them to diets. Doing this I found there were more species than types of diets indicating the radiation of species may have occurred before specialization of life habits. In the second chapter where I describe a reptile tooth assemblage from the Early Triassic (252-247 million years ago) of South Africa. I added additional methods for measuring tooth shape, found several different types of teeth (likely different species) but mostly similar diets, indicating again a delay in life habit specialization. In my third chapter I name a new species of archosaur reptile from the Middle Triassic of Tanzania. This new species helps us to understand how heavily armored plant eaters evolved in early crocodylian relatives during the archosaur radiation.

Call number: LD2668 .T4 1986 M46 / Master of Science / Biology

This thesis has investigated skeletal muscle fibers and neuromuscular junctions of the reptile Anolis carolinensis. The extensor digitorum communis and gastrocnemmius externus were used for observations and characterization. Cross sections were stained for oxidative and glycolytic activities and for contractile properties by the use of four histochemical stains. This revealed the extensor digitorum communis to be composed of predominately fast glycolytic fibers, with a central core of fast oxidative-glycolytic and slow oxidative fibers. The gastrocnemius externus exhibited a majority of fast oxidative-glycolytic fibers and random slow oxidative fibers.Ultra structural examination of the extensor digitorum communis revealed the nerve terminal of the neuromuscular junction to be smaller than that of the gastrocnemius externus, with junctional folds longer and straighter, and synaptic vesicles smaller and more closely packed. In both muscles, the nerve fibers terminated in a shallow groove of the muscle fiber. The characteristics and heterogeneity that exist are very similar to the homologous mammalian extensor digitorum longus and soleus skeletal muscle.Ball State UniversityMuncie, IN 47306

The non-game wildlife trade poses a risk to our natural landscape, natural heritage, economy, and security. Specifically, the trade in non-game reptiles and amphibians exploits native populations, and is likely not sustainable for many species. Exotic amphibian and reptile species pose risk of invasion and directly or indirectly alter the native landscape. The extent of non-game amphibian and reptile trade is not fully understood and is poorly documented. To quantitatively describe the trade in Texas, I solicited data from the United States Fish and Wildlife Service's (USFWS) Law Enforcement Management Information System (LEMIS) and Texas Parks and Wildlife Department's (TPWD) non-game dealer permits. I surveyed amphibian and reptile pet owners, breeders, Internet sites, pet shops, and meat and seafood establishments by visits, electronic surveys, and observations. The trade in exotic species of amphibians and reptiles in the state of Texas was found to be popular in two ways; the importation of wildlife products and sale of live specimens for pets. Persisting in the pet trade were species known to be exotic, a problem made worse by lack of regulations governing the import, export, and keeping of exotic species. Trade in wild collected native species was primarily for export to foreign countries. Collection of turtles from the wild in Texas was heavy until 2008, when TPWD restricted collection to private waters. Collection of other species from the wild was minimal, with the exception of the Western Diamond-backed Rattlsnake (Crotalus atrox) for rattlesnake roundups. Native species were found to exist in the pet trade, but primarily as genetic color variants that do not occur in the wild, an indication that captive breeding may be relieving pressures on wild caught specimens. Minor changes in reporting requirements and permitting systems at the state and federal level would improve the management of exotic and native amphibians and reptiles that persist in the trade. Changes that include standardized taxonomic reporting requirements at state and federal level, streamlined permitting system for individuals wishing to collect from the wild in Texas, bag limits and seasons for wild collection, increased reporting requirements for owners of exotics, and enforcement of reporting errors would aid in management of exotic and native amphibians and reptiles in the trade.