Thesis (Ph.D)--Utah State University, 2008. / Title from title screen (viewed Jan. 15, 2008). Department: Biology Includes bibliographical references. Archival copy available in print.

Thesis (M.S.)--Marshall University, 2008. / Title from document title page. Includes abstract. Document formatted into pages: contains vii, 96 p. : col. ill. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Committee on Evolutionary Biology, August 2000. / Includes bibliographical references. Also available on the Internet.

These studies indicate that tetraethylammonium (TEA) is transported by saturable processes from bath to lumen and lumen to bath in isolated, perfused snake (Thamnophis spp.) proximal renal tubules and that the unidirectional flux from bath to lumen (Jᵇ¹(TEA)) exceeds the unidirectional flux from lumen to bath (J¹ᵇ (TEA)) at all TEA concentrations studied. In order to examine the transport process further, the effects of N¹-methylnicotinamide (NMN), temperature, sodium cyanide, and the removal of Na⁺ on TEA transport were studied. Steady-state Jᵇ¹(TEA) (103.2 ± 1.1 fmoles min⁻¹ mm⁻¹ at {TEA}(b) = 8.1 μM) was inhibited by 50% at {NMN}(b) = 4.0 mM. When TEA and NMN were present in the lumen, J¹ᵇ (TEA) was depressed initially (T < 8 min). However, at steady-state, the presence of NMN in the lumen appeared to stimulate J¹ᵇ (TEA). This suggests a trans-stimulation effect of NMN on J¹ᵇ (TEA). During some flux experiments tubules were perfused at room temperature (24°C) and then cooled to 2.8°C. Jᵇ¹(TEA) decreased approximately 25% when compared to control values. This effect was reversible. Other tubules were perfused in the presence of 2.5 mM sodium cyanide in the perfusate and bath. Cellular concentrations of TEA dropped from 67 to 27 times the bath concentration during Jᵇ¹(TEA) measurements and from 21 to 6 times the mean luminal concentration during J¹ᵇ (TEA) measurements. This indicates that little if any intracellular binding of TEA occurs, as passive accumulation should be 16.1 times the bath or lumen TEA concentration (assuming a -70 mV PD). To determine if TEA transport was dependent on the presence of Na⁺, Na⁺ in the bath and perfusate solutions was replaced isosmotically by sucrose. Jᵇ¹(TEA) was not significantly changed in the absence of Na⁺. J¹ᵇ (TEA) decreased to 56% of control in the absence of Na⁺. This effect was reversible. Thus, J¹ᵇ (TEA) is Na⁺-dependent and Jᵇ¹(TEA) is not. These data suggest that the transport characteristics of the carrier for TEA at the luminal and peritubular membranes of the distal-proximal tubules of garter snakes are dissimilar.

Thesis (Ph. D.)--University of Rhode Island, 2002. / Typescript. Includes bibliographical references (leaves 96-102).

Colours influence numerous aspects of an animal’s ecology and the adaptive significance of colour variation has been intensively studied in diverse taxonomic groups. This study was motivated by the question: Why do garter snakes vary in colour? To answer this question, I focused on Western Terrestrial Garter Snakes, Thamnophis elegans, which exhibit geographic variation in colouration (dark morph vs. light morph), and two different species of garter snake that occur in the same geographic region but vary in colour –light T. elegans and the Common Garter Snake, T. sirtalis. My work provides an objective quantification and analysis of snake colour and evaluates the influence of colour variation on ecological processes such as thermoregulation, crypsis, and antipredator behaviour. I compared body temperatures (Tbs) with available thermal opportunities, both in wild snakes and in a field experiment, to determine how snakes with contrasting colours differ in thermoregulation and temperature-dependent behaviours. Gravid females of the light and dark colour morphs of T. elegans exhibited comparable thermoregulatory behaviour at high temperatures; however, dark T. elegans maintained elevated Tbs when available temperatures dropped. In the field, dark-coloured snakes were more likely to be moving when first detected when Tbs were high, but this trend was reversed in light T. elegans. I quantified crypsis of snakes, in terms of colour and brightness, by measuring the spectral reflectance of snakes and the surrounding habitat. These data were visually modeled from the perspective of potential snake predators and human researchers. Overall, snakes selected basking sites that maximized crypsis and both colour morphs of T. elegans were equally cryptic. There was evidence suggesting that T. sirtalis was more cryptic than light T. elegans to snake predators. I collected a series of behavioural measurements for snakes pre- and post-capture. Light T. elegans were more likely to be moving when originally detected in the field than dark snakes. Distance to cover and injuries were important factors in explaining the antipredator behaviour of snakes in the field. Snakes became generally faster with increasing Tbs, but differences attributable to colour morph were not straightforward. A higher proportion of T. elegans of both colour morphs exhibited some type of movement when exposed to a simulated predatory attack. Thamnophis sirtalis, on the other hand, hung limp and motionless in the air. The less cryptic light T. elegans had a higher probability of having an injury than T. sirtalis but injury patterns between the equally cryptic light and dark T. elegans differed by sex. The relationships between colour and these various traits were complex, but, taken together, they highlighted how thermal ecology, crypsis, and anti-predator behaviours were related to a snake’s visual appearance. These results therefore provide an ecological underpinning for future genetic studies to identify potential candidate genes that may be responsible for the control of colour pattern in garter snakes. / Graduate / 0329 / 0306 / 0472

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.

Natural history is a cornerstone of both theoretical and applied ecology, and provides the context for comparative and experimental studies. I studied the natural history of the Plains Garter Snake (Thamnophis radix) near the northern limit of its range in Miquelon Lake Provincial Park. Alberta, Canada. As is typical of garter snakes, T. radix at Miquelon were sexually dimorphic as adults - females grew faster, reached larger sizes and had relatively shorter tails than males. Mating occurred in spring and females gave birth in August; litter size ranged from 8-50 and was correlated with size of female. These snakes were generalist predators, but fed mainly on anurans when small, adding mammals and other prey as they grew. Despite sexual size dimorphism, I found no difference in diet between adult males and females. Feeding frequency was low overall (22%). especially in gravid females. In summer, snakes were found mainly near cover on south-facing field edges or in marshes, but not in forests, and moved relatively little. However, movement distances increased in fall as snakes sought hibernating sites. Snakes hibernated for up to eight months, either individually or in pairs, in rodent burrows. This study also revealed the importance of radiotelemetry when studying movements of small, secretive animals, as there were significant differences between the results obtained through opportunistic captures versus telemetry: habitat descriptions from opportunistic captures therefore were biased, although they still captured some elements of microhabitat use by T. radix. The data from this study will be important for comparative studies of the ecology of garter snakes and for the management of this species on the human-altered landscape surrounding Miquelon Lake.

Movements of animals presumably reflect their changing needs and the changing availability of necessary resources. In cold climates, snakes often make long seasonal migrations between hibernacula and summer habitats, Finding suitably deep hibernacula with minimal delay could be critical. I hypothesized that such animals should have highly developed navigational ability. By contrast, snakes living in mild climates can hibernate in shallow sites and probably do not migrate; if so, they might be expected to show poorly developed orientation mechanisms!. The objectives of this study were to determine movement patterns and navigational ability of garter snakes (Thamnophis) living in a mild climate and compare them with a congeneric population known to be migratory. From 1986 - 1988 I examined, using mark-recapture, movement behaviour of two populations of garter snakes at Spectacle Lake Provincial Park (SLPP) on Vancouver Island, British Columbia, focusing on several components typically associated with migratory behaviour - distances travelled, population directionality, fidelity to seasonal sites, distinctness of seasonal habitats, and route directness. Thamnophis sirtalis, the common garter snake, is the most widely distributed North American snake species and high latitude populations are migratory. Thamnophis ordinoides, the northwestern garter snake, is restricted to the Pacific northwest and migratory behaviour has never been reported. Both species displayed combinations of traits clearly suggesting nonmigratory behaviour. These included short-distance (< 500 m), random movements, a lack of den fidelity, and variation in the maintenance of specific home ranges between successive years. Home ranges overlapped between individuals, averaged less than 0.3 ha measured over a single active season, and were not clearly distinct from denning areas. Although some directionality of movement was evident, it was likely related to foraging strategy and unlike the typical unidirectional movements undertaken by migrating snakes, Sexual and reproductive differences in any of these traits generally were not significant. The navigational abilities of a migratory population of T. sirtalis from Wood Buffalo National Park (WBNP) in northern Alberta were examined as were those of the nonmigratory populations of snakes from SLPP. Displacement studies were carried out during the active seasons of 1986 - 1988 to determine the level of orientational abilities present in each population and to examine potential orientation cues. Snakes were displaced from their home range and tested in an arena under a variety of conditions, The results demonstrated that T. sirtalis from both SLPP and WBNP possessed advanced navigational abilities. Advanced skills may be absent in T. ordinoides. Thamnophis sirtalis at both study sites demonstrated time-compensated solar orientation as determined by 6 hr phase-delayed tests. Pheromone trails produced by recently copulated females (but not unmated females) also provided an orientation guide for displaced WBNP males, but results from SLPP were less conclusive. Thamnophis ordinoides did not respond in a discernible way to either cue. Navigational skills thus vary relatively little between migrating and nonmigrating populations of the same species but may be poorly developed in completely nonmigratory species. / Graduate

Thesis (M.S.)--State University of New York at Binghamton, Biology Department, 2006. / Includes bibliographical references.