A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 3 May 2018. / The movement ecology of a species can dictate their survival and success. Animals are motivated to move depending on resource priorities and in turn their movements are influenced by the surrounding environment. Natural habitats are being increasingly disturbed by anthropogenic changes which often creates several implications for the existing wildlife. One of these changes include extensive road networks that may fragment landscapes and increase mortality risks for local fauna. This current and global issue is often researched with the aid of road kill statistics which can create a biased view. My study highlights a more realistic method for understanding how organisms interpret and react to road infrastructure by using the movement patterns of 109 telemetered Puff Adders (Bitis arietans). To assess the effect of roads on these snakes within Dinokeng Game Reserve (Gauteng, South Africa) over eight years, Puff Adder lie-up locations (to the nearest road) and movement paths were analysed. Sex, season, years, and the types of roads within the reserve were included to evaluate the motivation for movement and if roads were inhibiting or aiding movement patterns. Compared to random, Puff Adders were closer too, and crossed roads more often. Males crossed roads more frequently than females and during non-mating season, both sexes were closer to roads. Narrow roads with low levels of traffic were also crossed more often. Overall, the roads in Dinokeng Game Reserve do not inhibit movement and patterns suggest that roads may be advantageous for Puff Adders. Roads appear to be foraging hotspots because of micro habitats created along the verges. However, these positive attributes could result in a potential risk when road usage is intensified by traffic. Understanding how species interact with changes to their environment is essential for appropriate management and mitigation and this study illustrates the necessity for unbiased research to properly evaluate these changes and reactions. / EM2018

Thesis (M.A.) - Carleton University, 2005. / Includes bibliographical references (p. 126-138). Also available in electronic format on the Internet.

Thesis (Ph. D.)--Carleton University, 2001. / Includes bibliographical references. Also available in electronic format on the Internet.

Thesis (Ph. D.)--Washington State University, May 2010. / Title from PDF title page (viewed on June 7, 2010). "School of Biological Sciences." Includes bibliographical references.

With reference to anatomical studies it appears that the aerpents are indeed a neglected group ot reptiles. Although some early writers recorded a few fragmentary obser-vations on the anatomy of snakes, no attempt was made to undertake a complete comprehensive study. Cole (1944) has rightfully referred to this section of vertebrate anatomy as "almost virgin field." The serpent area of reptilian anatomy is deserving ot a more intensive investigation because of the considerable number ot adaptations demonatrated by this group of reptiles in relation to their peculiar types ot locomotion and methods ot feeding. It is important to understand the anatomical specializations of this group of animals if we are to understand more completely the evolutionary trends among the vertebrates. It is also quite evident that compara-tive descriptions of certain serpents, which have been based mainly on external characteristics, need to be supplemented by accounts of their internal anatomy.

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.

A dissertation submitted to the School of Animal, Plant and Environmental Sciences, Faculty of Science, University of the Witwatersrand, Johannesburg, South Africa in fulfilment of the requirements of the degree of Masters of Science. Johannesburg, South Africa. July, 2016. / A central goal in macroecology is understanding the factors that have shaped broad-scale patterns among extant natural communities. Diet is widely cited as a key factor involved in shaping snake diversification. Amongst serpents, the adaptive radiation of elapids is unparalleled in terms of their sheer global distribution. My study was aimed at evaluating the variation in diet and how trends evolved throughout the radiation of the elapids. Based on the published natural history data of 303 elapid species, a cluster analysis revealed seven groups of species within which diet types were similar. The broad diet clusters included snake consumption, feeding on fish, ectotherms, endotherms, lizards, a generalist diet and lastly, a terrestrial invertebrate group that was the least prevalent diet type. Maximum Parsimony, Maximum Likelihood and Stochastic Character Mapping were used to trace the ancestral dietary condition in the Elapidae. Reconstructions demonstrated that starting from an ophiophagous ancestor, elapids still largely retain their early feeding habits. Despite the emergence of novel feeding patterns in the group, the predominantly conservative diet patterns suggest that niche conservatism has shaped elapid foraging dynamics. Members of the lineage characteristically feed on elongate ectothermic prey (e.g., squamates, caecilians, eels, earthworms) possibly owing to morphologically-mediated gape constraints. Phylogenetically corrected comparative methods were used to assess the influence of differences in body size, lifestyle and global scale spatial distribution of diet evolution. While lifestyle and distribution considerably influenced how diet patterns evolved, body size was not a significant determinant of the prey types taken. The lack of body size-diet association may be because larger-bodied elapids also opportunistically supplement their diet with smaller prey items. Overall, the findings indicate that recent ecological factors (e.g., lifestyle) coupled with long established factors (phylogeny, biogeography) have shaped elapid natural history patterns. This study is the first of its kind to offer a family-level, phylogenetically-based analysis on the evolutionary and contemporary feeding dynamics of the world’s most widespread snake family. / LG2017

Thesis (M.Sc.)--Chinese University of Hong Kong, 1975. / Bibliography: l. 157-179.

Issued also as Thesis (M.S.), University of Florida, under title: The cranial anatomy of Heterodon, with reference to Xenodon and the solenoglypha. / Cover title. Includes bibliographical references (p. 302-304).