As serpentes da tribo Pseudoboini apresentam grande diversidade quanto à sua ecologia, são consideradas um grupo monofilético e possuem uma filogenia conhecida. A partir disso, tornou-se possível a análise, sob um contexto evolutivo, das possíveis associações entre a morfologia e a ecologia neste grupo. Neste estudo, analisamos a dieta da tribo, bem como, testamos hipóteses de possíveis relações adaptativas entre a morfologia e a dieta e entre a morfologia e o uso do ambiente arborícola, e exploramos a evolução destes aspectos em serpentes da tribo. Nove espécies foram consideradas generalistas e 13, especialistas, sendo seis em lagartos, três em pequenos mamíferos, duas em serpentes, uma em ovos de lagarto e uma em ovos de ave. Um aumento no consumo de pequenos mamíferos, não esteve associado com um aumento da robustez e do volume da cabeça. Especializações em lagartos, pequenos mamíferos e serpentes surgiram independentemente em táxons terminais ao menos duas vezes durante a história evolutiva da tribo. A especialização em ovos de ave é uma autapomorfia de Rhachidelus brazili. A robustez decresceu no ancestral do gênero Siphlophis, e aumentou substancialmente em R. brazili. O tamanho da cabeça decresceu no ancestral do gênero Siphlophis e em Oxyrhopus petola e aumentou substancialmente em Phimophis guianensis, no ancestral de O. trigeminus e O. rhombifer e em R. brazili. Siphlophis cervinus, S. compressus, S. pulcher e D. anomalus foram consideradas espécies semi arborícolas. A reconstrução do hábito semi-arborícola indica que este surgiu independentemente pelo menos duas vezes durante a diversificação do grupo. Não foram encontrados indícios de efeito da freqüência do uso da vegetação sobre o tamanho do corpo, a robustez, o formato da cabeça e o número de vértebras por unidade corporal. Entretanto, o hábito arborícola parece ter levado a um aumento no tamanho da cauda. O tamanho corporal diminuiu substancialmente em P. guianensis e aumentou substancialmente em Clelia rustica e no ancestral de C. clelia e C. plumbea. Já o número de vértebras por unidade corporal diminuiu substancialmente em C. rustica, no ancestral de C. clelia e C. plumbea, e em Pseudoboa haasi; aumentou substancialmente no ancestral de O. trigeminus e O. rhombifer, e em O. melanogenys e P. guianensis. O tamanho da cauda diminuiu significativamente em C. rustica, Boiruna maculata e P. haasi e aumentou consideravelmente no ancestral do gênero Siphlophis, O. petola, D. anomalus, R. brazili e no ancestral do gênero Pseudoboa. A largura da cabeça diminuiu substancialmente em Pseudoboa neuwiedii e aumentou substancialmente em S. compressus, P. guianensis e em B. maculata. As ausências de relações possivelmente adaptativas podem estar ligadas a uma forte inércia filogenética e/ou ao efeito de outros agentes seletivos. Um ancestral morfologicamente adequado a uma dieta baseada em pequenos mamíferos e ao uso da vegetação também pode ter influenciado os resultados. O conhecimento do grupo externo da tribo Pseudoboini ajudaria a esclarecer ainda mais as relações entre morfologia e ecologia nestas serpentes. / Snakes of the tribe Pseudoboini are ecological diversity, considered as a monophyletic group and have a known phylogeny. Thus, the analyses of possible associations between the morphology and the ecology of this group in an evolutionary framework became possible. In the present study, we analyze the diet of pseudoboine species, and we test hypotheses of possible adaptative relationships between morphology and diet, and between morphology and microhabitat use in pseudoboine snakes. We also explore how these traits evolved during the diversification of the tribe. Nine species were considered as diet generalists and 13, as diet specialists, being six lizard specialists, three small mammal specialists, two snake specialists, one a lizard egg specialist, and one a bird egg specialist. An increase in the consumption of small mammals was not associated with an increase in robustness and head volume. Lizard, small mammal and snake specializations occurred independently at least twice in terminal taxa during the diversification of the tribe. A specialization in bird eggs seems to be an autapomorphy of Rhachidelus brazili. Robustness decreased in the ancestor of Siphlophis species, and increased substantially in R. brazili. Head volume descreased in the ancestor ofSiphlophis species and in Oxyrhopus petola, and increased substantially in Phimophis guianensis, in the ancestor of O. trigeminus and O. rhombifer and in R. brazili. Siphlophis cervinus, S. compressus, S. pulcher and D. anomalus were considered as semi-arboreal. The semi-arboreal habit reconstruction indicates that this habit evolved independently at least twice during the diversification of the group. We did not find indications of the effect of vegetation use on body size, robustness, head shape and the number of ventral scales per body unit. However, vegetation use seems to have led to an increase in tail length. Body size substantially decreased in P. guianensis and substantially increased in Clelia rustica and in the ancestor of C. clelia and C. plumbea. The number of vertebrae per body unit decreased substantially in C. rustica, in the ancestor of C. clelia and C. plumbea, and in Pseudoboa haasi. It substantially increased in the ancestor of O. trigeminus and O. rhombifer, and in O. melanogenys and P. guianensis. Tail length significantly decreased in C. rustica, Boiruna maculata and P. haasi, and increased substantially in the ancestor of the genus Siphlophis, in O. petola, D. anomalu ,R. brazili and in the ancestor of Pseudoboa spp.. Head width decreased substantially in Pseudoboa neuwiedii and increased significantly in S. compressus, P. guianensis and in B.maculata. Strong influence of phylogenetic inertia and/or the effect of alternative selective agents could be related to the absences of these possible adaptative 69 relationships. An ancestor with a morphology adequate to a diet based on small mammals and to arboreality could also have influenced the results. Knowing the outgroup of the tribe Pseudoboini would help to further clarify the relationships between morphology and ecology of these snakes.

by Lee Heung Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 189-203.

by Kareen Kar-lit Wong. / Thesis (M.Phil.)--The Chinese University of Hong Kong. / Bibliography: l. 134-146.

Thesis (M. Ph.)--Chinese University of Hong Kong. / Bibliography: l. 73-78.

Os viperídeos estão entre as serpentes de menor custo energético de manutenção, o que é, geralmente, relacionado a seus baixos níveis de deslocamento e a tática de forrageio por emboscada. Dois importantes componentes do alocamento energético destes animais são: 1) o metabolismo de repouso padrão, que está relacionado ao custo de manutenção visceral durante o repouso e 2) o aumento metabólico pós-prandial (AMPP), que está relacionado ao custo do processo digestório. O presente trabalho teve como objetivos estudar as variações da TMRP (taxa metabólica de repouso padrão) e do AMPP em 5 espécies pertencentes ao gênero Bothrops levando em conta aspectos filogenéticos, ontogenéticos e testando hipóteses acerca de possíveis variações destes componentes em função de características ecológicas. Além disso, o presente trabalho testou, através de ferramentas de ponderação filogenética, a hipótese atualmente aceita que prediz que as TMRPs em serpentes estão essencialmente ligadas a estratégia alimentar e não a filogenia. O trabalho está dividido em quatro capítulos, sendo o primeiro devotado a uma introdução geral acerca dos assuntos que serão abordados nos demais. Os resultados e discussões específicas estão divididos em dois capítulos redigidos em forma de artigo, primeiro referente aos estudos das taxas metabólicas de repouso (capítulo 2) e o segundo sobre o AMPP (capítulo 3). Por fim, a conclusão final acerca dos achados e as perspectivas para pesquisas futuras estão presente no capítulo 4. / The viperids are among the snakes with the lowest energetic maintenance costs which are generally related to the low mobility and ambush foraging mode. Two important components of energy allocation in these animals are 1) standard metabolic rates (SMR), related to the cost of keeping visceral components during resting and 2) specific dynamic action (SDA) , which is related to the cost of digestion. The present work aimed to study the variations of SMR and SDA in 5 species of the genus Bothrops taking into account aspects of phylogeny and ontogeny plus testing hypotheses about possible variations in these metabolic rates related to ecological characteristics. Furthermore, the present study used phylogenetic weighting tools to test the currently accepted hypothesis that predicts that SMR in snakes is related to the feeding strategy and not to phylogeny. The work is divided into four different chapters. Chapter 1 is devoted to a general introduction about the issues that will be addressed in the others chapters. The results and discussions are divided into two chapters presented as articles, the first referring to studies of SMR ( chapter 2 ) and the second to the SDA (chapter 3 ). Finally, in chapter 4 we include the final conclusion and prospects for future research

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

Thesis (Ph. D.)--University of Hong Kong.

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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