<p>Nearly one-third of the world&rsquo / s tortoises live in South Africa, but little is known about their habitat requirements and feeding ecology. Chersina angulata, the angulate tortoise, is endemic to&nbsp / southern Africa, with a wide distribution along the western and southern coasts. Because this tortoise occupies a number of different habitat types, it has always been considered a generalist&nbsp / herbivore, although little is known about its&nbsp / diet and other needs. This study evaluates the habitat characteristics and feeding ecology of C. angulata at two study sites in the southwestern&nbsp / &nbsp / &nbsp / Cape, the West Coast National Park (WCNP) and Dassen Island (DI). The WCNP is a large conserved area in the Fynbos biome, along the southwestern coast of South Africa, whereas DI is a&nbsp / small offshore island with low floral and faunal diversity, just south of the WCNP. The efficacy of three methods used to study the feeding ecology of herbivores, focal observations, macroscopic faecal analysis and histological analysis of scats, was evaluated. Plant cover, species diversity, and the variety of growth forms were substantially larger at the WCNP than on DI.&nbsp / In the WCNP, shrubs and grasses were the dominant growth forms but the vegetation also included herbs, succulents, restios, sedges and parasitic plants. A few perennial species such as&nbsp / the grass Ehrharta villosa, shrubs such as Helichrysum niveum, Nylandtia spinosa and Rhus spp., and succulents such as Carpobrotus edulis and Ruschia spp., provided most of the plant&nbsp / cover. DI had a depauperate flora, consisting of succulents and herbs, and ephemeral plants contributed more than perennials did to plant cover throughout the year. The succulents Mesembryanthemum crystallinum and Tetragonia fruticosa provided most of the cover on DI. Angulate tortoises are herbivores and 72 diet plants in 32 plant families were identified to the&nbsp / species or genus level. Several diet species, however, could not be identified. In&nbsp / addition to angiosperms, the tortoises&rsquo / diet included mosses, mushrooms, insects,snails and animal faeces.&nbsp / The most important growth forms in the diet were herbs and grasses. The diet of the WCNP tortoises was more diverse than the diet of DI tortoises, but the number of principal food items in&nbsp / the diet did not differ between the two sites. Over an annual cycle, WCNP tortoises had four principal food plants while DI tortoises had five principal food plants. At both sites, principal food&nbsp / &nbsp / plants changed with the season and few plants remained principal food items in more than one season. Cynodon dactylon was a principal food item in three of the four seasons in the WCNP, whereas Trachyandra divaricata was a principal food plant each season on DI. Most principal food plants were grass or herb species but the sedge Ficinia nigrescens, and a succulent that&nbsp / could be identified only to the family level (Aizoaceae), featured strongly in the spring diets of DI and WCNP tortoises, respectively.&nbsp / The three study methods did not provide the same type or quality of information about the feeding ecology of angulate tortoises. The small size and wary nature of angulate tortoises compromised focal studies because it was often not possible to see&nbsp / what the tortoises ate. This method, however, provided the interesting observation that rabbit&nbsp / faecal pellets contributed nearly 30% to summer and autumn diets on DI when food was scarce.&nbsp / Rabbit faeces may not only provide a source of nutrients but may also supplement the microflora, required to digest cellulose, in the tortoises&rsquo / guts. Macroscopic evaluation of the tortoises&rsquo / &nbsp / scats appeared to be an ineffective method to identify diet plants, and the bulk of the scat mass could not be identified. This indicates&nbsp / that angulate tortoises either selected food low in fibrous&nbsp / content or that the digestive system of the tortoises dealt efficiently with tough plant material. The macroscopic method was the only method that highlighted the large contribution of&nbsp / fruits / seeds to the diet of angulate tortoises. Since the tortoises digested many seeds only partially, or not at all, C. angulata is potentially an important agent of seed dispersal in the southwestern Cape. The macroscopic study showed that on DI, sand made up 28% of the scat mass in spring, whereas sand never made a substantial contribution to the scat composition of WCNP tortoises. Lithophagy may be an important strategy in a depauperate habitat, such as DI, because the abrasive action of sand may help with the digestion of tough plants, or the sand may&nbsp / provide the tortoises with important minerals that are deficient in their food plants.The histological analysis of scats provided the most comprehensive diet list for C. angulata. Selection indices&nbsp / based on data from the histological analysis indicated that angulate tortoises were highly selective in their food choice. Most of the principal food items were selected out of proportion to their&nbsp / availability and the tortoises avoided the most abundant plants in their habitats. Several factors, such as palatability, accessibility and profitability, may have influenced their food choice. The proportional similarity indices for WCNP and DI tortoises, respectively, were 0.31 and 0.16, confirming that C. angulata is a food specialist and not a food generalist as was previously thought. This factor should be considered in the management of this species and in future conservation planning of its habitat.&nbsp / &nbsp / </p>

Anoxia is an environmental stress that few air-breathing vertebrates can tolerate for more than a few minutes before extensive neurodegeneration occurs. Some facultative anaerobes, including the freshwater western painted turtle Chrysemys picta bellii, are able to coordinately reduce ATP demand to match reduced ATP availability during anoxia, and thus tolerate prolonged insults without apparent detriment. To reduce metabolic rate, turtle neurons undergo channel arrest and spike arrest to decrease membrane ion permeability and neuronal electrical excitability, respectively. However, although these adaptations have been documented in turtle brain, the mechanisms underlying channel and spike arrest are poorly understood. The aim of my research was to elucidate the cellular mechanisms that underlie channel and spike arrest and the neuroprotection they confer on the anoxic turtle brain. Using electrophysiological and fluorescent imaging techniques, I demonstrate for the first time that: 1) the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) undergoes anoxia-mediated channel arrest; 2) delta opioid receptors (DORs), and 3) mild mitochondrial uncoupling via mitochondrial ATP-sensitive K+ channels result in an increase in cytosolic calcium concentration and subsequent channel arrest of the N-methyl-D-aspartate receptor, preventing excitotoxic calcium entry, and 4) reducing nitric oxide (NO) production; 5) the cellular concentration of reactive oxygen species (ROS) decreases with anoxia and ROS bursts do not occur during reoxygenation; and 6) spike arrest occurs in the anoxic turtle cortex, and that this is regulated by increased neuronal conductance to chloride and potassium ions due to activation of γ–amino-butyric acid receptors (GABAA and GABAB respectively), which create an inhibitory electrical shunt to dampen neuronal excitation during anoxia. These mechanisms are individually critical since blockade of DORs or GABA receptors induce excitotoxic cell death in anoxic turtle neurons. Together, spike and channel arrest significantly reduce neuronal excitability and individually provide key contributions to the turtle’s long-term neuronal survival during anoxia. Since the turtle is the most anoxia-tolerant air-breathing vertebrate identified, these results suggest that multiple mechanisms of metabolic suppression acting in concert are essential to maximizing anoxia-tolerance.

Anoxia is an environmental stress that few air-breathing vertebrates can tolerate for more than a few minutes before extensive neurodegeneration occurs. Some facultative anaerobes, including the freshwater western painted turtle Chrysemys picta bellii, are able to coordinately reduce ATP demand to match reduced ATP availability during anoxia, and thus tolerate prolonged insults without apparent detriment. To reduce metabolic rate, turtle neurons undergo channel arrest and spike arrest to decrease membrane ion permeability and neuronal electrical excitability, respectively. However, although these adaptations have been documented in turtle brain, the mechanisms underlying channel and spike arrest are poorly understood. The aim of my research was to elucidate the cellular mechanisms that underlie channel and spike arrest and the neuroprotection they confer on the anoxic turtle brain. Using electrophysiological and fluorescent imaging techniques, I demonstrate for the first time that: 1) the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) undergoes anoxia-mediated channel arrest; 2) delta opioid receptors (DORs), and 3) mild mitochondrial uncoupling via mitochondrial ATP-sensitive K+ channels result in an increase in cytosolic calcium concentration and subsequent channel arrest of the N-methyl-D-aspartate receptor, preventing excitotoxic calcium entry, and 4) reducing nitric oxide (NO) production; 5) the cellular concentration of reactive oxygen species (ROS) decreases with anoxia and ROS bursts do not occur during reoxygenation; and 6) spike arrest occurs in the anoxic turtle cortex, and that this is regulated by increased neuronal conductance to chloride and potassium ions due to activation of γ–amino-butyric acid receptors (GABAA and GABAB respectively), which create an inhibitory electrical shunt to dampen neuronal excitation during anoxia. These mechanisms are individually critical since blockade of DORs or GABA receptors induce excitotoxic cell death in anoxic turtle neurons. Together, spike and channel arrest significantly reduce neuronal excitability and individually provide key contributions to the turtle’s long-term neuronal survival during anoxia. Since the turtle is the most anoxia-tolerant air-breathing vertebrate identified, these results suggest that multiple mechanisms of metabolic suppression acting in concert are essential to maximizing anoxia-tolerance.

<p>Nearly one-third of the world&rsquo / s tortoises live in South Africa, but little is known about their habitat requirements and feeding ecology. Chersina angulata, the angulate tortoise, is endemic to&nbsp / southern Africa, with a wide distribution along the western and southern coasts. Because this tortoise occupies a number of different habitat types, it has always been considered a generalist&nbsp / herbivore, although little is known about its&nbsp / diet and other needs. This study evaluates the habitat characteristics and feeding ecology of C. angulata at two study sites in the southwestern&nbsp / &nbsp / &nbsp / Cape, the West Coast National Park (WCNP) and Dassen Island (DI). The WCNP is a large conserved area in the Fynbos biome, along the southwestern coast of South Africa, whereas DI is a&nbsp / small offshore island with low floral and faunal diversity, just south of the WCNP. The efficacy of three methods used to study the feeding ecology of herbivores, focal observations, macroscopic faecal analysis and histological analysis of scats, was evaluated. Plant cover, species diversity, and the variety of growth forms were substantially larger at the WCNP than on DI.&nbsp / In the WCNP, shrubs and grasses were the dominant growth forms but the vegetation also included herbs, succulents, restios, sedges and parasitic plants. A few perennial species such as&nbsp / the grass Ehrharta villosa, shrubs such as Helichrysum niveum, Nylandtia spinosa and Rhus spp., and succulents such as Carpobrotus edulis and Ruschia spp., provided most of the plant&nbsp / cover. DI had a depauperate flora, consisting of succulents and herbs, and ephemeral plants contributed more than perennials did to plant cover throughout the year. The succulents Mesembryanthemum crystallinum and Tetragonia fruticosa provided most of the cover on DI. Angulate tortoises are herbivores and 72 diet plants in 32 plant families were identified to the&nbsp / species or genus level. Several diet species, however, could not be identified. In&nbsp / addition to angiosperms, the tortoises&rsquo / diet included mosses, mushrooms, insects,snails and animal faeces.&nbsp / The most important growth forms in the diet were herbs and grasses. The diet of the WCNP tortoises was more diverse than the diet of DI tortoises, but the number of principal food items in&nbsp / the diet did not differ between the two sites. Over an annual cycle, WCNP tortoises had four principal food plants while DI tortoises had five principal food plants. At both sites, principal food&nbsp / &nbsp / plants changed with the season and few plants remained principal food items in more than one season. Cynodon dactylon was a principal food item in three of the four seasons in the WCNP, whereas Trachyandra divaricata was a principal food plant each season on DI. Most principal food plants were grass or herb species but the sedge Ficinia nigrescens, and a succulent that&nbsp / could be identified only to the family level (Aizoaceae), featured strongly in the spring diets of DI and WCNP tortoises, respectively.&nbsp / The three study methods did not provide the same type or quality of information about the feeding ecology of angulate tortoises. The small size and wary nature of angulate tortoises compromised focal studies because it was often not possible to see&nbsp / what the tortoises ate. This method, however, provided the interesting observation that rabbit&nbsp / faecal pellets contributed nearly 30% to summer and autumn diets on DI when food was scarce.&nbsp / Rabbit faeces may not only provide a source of nutrients but may also supplement the microflora, required to digest cellulose, in the tortoises&rsquo / guts. Macroscopic evaluation of the tortoises&rsquo / &nbsp / scats appeared to be an ineffective method to identify diet plants, and the bulk of the scat mass could not be identified. This indicates&nbsp / that angulate tortoises either selected food low in fibrous&nbsp / content or that the digestive system of the tortoises dealt efficiently with tough plant material. The macroscopic method was the only method that highlighted the large contribution of&nbsp / fruits / seeds to the diet of angulate tortoises. Since the tortoises digested many seeds only partially, or not at all, C. angulata is potentially an important agent of seed dispersal in the southwestern Cape. The macroscopic study showed that on DI, sand made up 28% of the scat mass in spring, whereas sand never made a substantial contribution to the scat composition of WCNP tortoises. Lithophagy may be an important strategy in a depauperate habitat, such as DI, because the abrasive action of sand may help with the digestion of tough plants, or the sand may&nbsp / provide the tortoises with important minerals that are deficient in their food plants.The histological analysis of scats provided the most comprehensive diet list for C. angulata. Selection indices&nbsp / based on data from the histological analysis indicated that angulate tortoises were highly selective in their food choice. Most of the principal food items were selected out of proportion to their&nbsp / availability and the tortoises avoided the most abundant plants in their habitats. Several factors, such as palatability, accessibility and profitability, may have influenced their food choice. The proportional similarity indices for WCNP and DI tortoises, respectively, were 0.31 and 0.16, confirming that C. angulata is a food specialist and not a food generalist as was previously thought. This factor should be considered in the management of this species and in future conservation planning of its habitat.&nbsp / &nbsp / </p>

O cultivo de Caiman yacare demanda grandes gastos com alimentação, deste modo, é necessário formular dietas mais baratas e mais eficientes para a engorda destes animais. Uma possibilidade de redução nos custos é o acréscimo de lipídeos de origem vegetal. Neste trabalho, analisou-se o processo de absorção de óleo de soja pelo intestino de Caiman yacare para avaliar possíveis alterações patológicas pelo uso deste óleo na mucosa intestinal de um animal carnívoro. A absorção de óleo de soja ocorreu massiçamente pelo intestino delgado, gerando esteatose intestinal temporária e formando quilomícrons pequenas, que foram transportadas pelo sistema linfático. Outros parâmetros que indicam ausência de patologias na mucosa intestinal, como alteração na proliferação celular, lesão tecidual, recrutamento de granulócitos, formação de heterófilos tóxicos e degranulação de mastócitos, não foram alterados, indicando o potencial uso de óleo de soja na dieta de Caiman yacare. / Cultivation of Caiman yacare demands large financial expenditures on food, so it is desirable to reduce costs by formulating cheaper and more efficient feedings. The soybean oil addition in the diet is an opportunity to reduce spending, but very little is known about the effects of vegetable-origin oils in this carnivore species health. Here we describe the process of soybean oil absorption by the intestine of Cayman yacare in order to evaluate possible intestinal pathologies caused by the soybean oil. Soybean oil absorption occurred massively across the intestine, caused temporary intestinal steatosis and produced small-sized chylomicrons that were carried away from the intestine by the lymphatics. Some mucosal integrity parameters analyzed such as enterocyte proliferation, epithelial damage, granulocyte recruitment, toxic heterophil formation and mast cell degranulation were not altered, suggesting soybean oil may potentially be used in Caiman yacare feedings.

In the group of reptiles, the ability to form memories is still much discussed and neuroanatomical data have suggested the existence of homologies between the areas of the hippocampus and amygdala of mammals and correlated structures of the telencephalon of reptiles. However, there is little functional evidence of these structures in reptiles to give support to this proposal homology. Faced with this situation, this study aimed to conduct a behavioral and neurobiological evaluation of memory in lizards species Tropidurus hispidus. For this, were used 50 lizards adult males, which after 4 days of accommodation were distributed in two experiments: the Experiment 1, aversive memory (n = 40); and the Experiment 2, spatial memory (n = 10). In Experiment 1, the animals were divided into three groups (Control, n = 8; Neutral Stimulus, n = 16; Aversive Stimulus, n = 16). The Control group did not participate in the behavioral steps, since the Neutral Stimulus group was exposed to an empty metal cage, while the Aversive Stimulus group was exposed to a domestic cat. Then all the animals in the Control group and half of the animals Neutral Stimulus and Stimulus Aversive groups had their brains perfused with paraformaldehyde 4% for subsequent analysis. The remaining animals of Neutral and Aversive Stimulus groups returned to the accommodation terrarium and, after 24 hours, passed by a rechallenge to local display of the stimulus, then also had their brains perfused with paraformaldehyde 4%. After fixation, brains were all collected subjected to a imustotoquímica detection technique the ZIF-268, a protein involved in mediating plasticity which occurs during memory formation. We found that during exposure to cat lizards of Aversive Stimulus group had a higher freezing time (p <0.001) and a smaller number of initiated movements (p <0.001) and visited quadrants (p <0.001) when compared with Neutral Stimulus group. Also found that during the re-exposure to aversive environment, the animals Aversive Stimulus group had a higher freezing time (p <0.001) and a smaller number of initiated movements (p <0.001) and visited quadrants (p <0.001), suggesting so that exposure to cat served adequately as an aversive stimulus. There was also an increase in the number of Zif-268 positive cells in regions of the reptilian hippocampus and amygdala lizards Stimulus Aversive group during exposure to cat (p = 0.005 and p = 0.039, respectively) and on re-exposure to aversive context (p = 0.001 and p = 0.009, respectively). In experiment 2, lizards underwent an adaptation of the Morris water maze, where 3 times a day for 19 days, the animals had performed attempts to find a submerged platform. We found a negative correlation (p = 0.012) the time to reach the platform and over the days, indicating an improvement in the performance of lizards in the task. Thus, the present study provided evidence that males of T. hispidus are capable of forming aversive and spatial memories, and that there is an involvement of the hippocampus and amygdala in aversive memory. / No grupo dos répteis, a capacidade de formar memórias é ainda muito discutida e dados neuroanatômicos têm sugerido a existência de homologias entre as áreas do hipocampo e amígdala de mamíferos e estruturas correlatas no telencéfalo de répteis. Contudo, existem poucas evidências funcionais dessas estruturas reptelianas para que forneçam suporte a essa proposta de homologia. Diante de tal conjuntura, esse trabalho teve como objetivo realizar uma avaliação comportamental e neurobiológica da memória em lagartos da espécie Tropidurus hispidus. Para isso foram utilizados 50 lagartos machos adultos, que após 4 dias de acomodação, foram distribuídos em dois experimentos: o Experimento 1, de memória aversiva (n=40); e o Experimento 2, de memória espacial (n=10). No Experimento 1 os animais foram divididos em três grupos (Controle, n=8; Estímulo Neutro, n=16; Estímulo Aversivo, n=16). O grupo controle não participou das etapas comportamentais, já o grupo Estímulo Neutro foi exposto a uma gaiola metálica vazia, enquanto o grupo Estímulo Aversivo foi exposto a um gato doméstico. Em seguida, todos os animais do grupo Controle e metade dos animais dos grupos Estímulo Neutro e Estímulo Aversivo tiveram seus cérebros perfundidos com paraformaldeido 4% para posterior análise. Os animais restantes dos grupos Estímulo Neutro e Estímulo Aversivo foram colocados de volta no terrário de acomodação e após 24 horas passaram por uma reexposição ao local da exibição dos estímulos, então também tiveram seus cérebros perfundidos com paraformaldeido 4%. Após a fixação, todos os cérebros coletados foram submetidos a uma técnica de detecção imustotoquímica de Zif-268, uma proteína envolvida na mediação da plasticidade que ocorre durante a formação de memórias. Verificamos que, durante a exposição ao gato, os lagartos do grupo Estímulo Aversivo apresentaram um maior tempo de congelamento (p<0,001) e um menor número de deslocamentos iniciados (p<0,001) e de quadrantes visitados (p<0,001), quando comparados com o grupo Estímulo Neutro. Verificamos também que, durante a reexposição ao contexto aversivo, os animais do grupo Estímulo Aversivo apresentaram um maior tempo de congelamento (p<0,001) e um menor número de deslocamentos iniciados (p<0,001) e de quadrantes visitados (p<0,001), sugerindo assim que a exposição ao gato atuou adequadamente como um estímulo aversivo. Observou-se também um aumento do número de células Zif-268 positivas nas regiões do hipocampo reptiliano e na amígdala dos lagartos do grupo Estímulo Aversivo, durante a exposição ao gato (p=0,005 e p=0,039, respectivamente) e na reexposição ao contexto aversivo (p=0,001 e p=0,009, respectivamente). No experimento 2, os lagartos foram submetidos a uma adaptação do labirinto aquático de Morris, onde, 3 vezes por dia, durante 19 dias, os animais realizaram tentativas de encontrar uma plataforma submersa. Constatamos uma correlação negativa (p=0,012) do tempo para chegar à plataforma e o passar dos dias, indicando uma melhoria no desempenho dos lagartos na tarefa. Assim, o presente estudo forneceu indícios que machos de T. hispidus são capazes de formar memórias aversivas e espaciais, e que há um envolvimento do hipocampo e amígdala na memória.

Philosophiae Doctor - PhD (Biodiversity and Conservation Biology) / Nearly one-third of the world’s tortoises live in South Africa, but little is known about their habitat requirements and feeding ecology. Chersina angulata, the angulate tortoise, is endemic to southern Africa, with a wide distribution along the western and southern coasts. Because this tortoise occupies a number of different habitat types, it has always been considered a generalist herbivore, although little is known about its diet and other needs. This study evaluates the habitat characteristics and feeding ecology of C. angulata at two study sites in the southwestern Cape, the West Coast National Park (WCNP) and Dassen Island (DI). The WCNP is a large conserved area in the Fynbos biome, along the southwestern coast of South Africa, whereas DI is a small offshore island with low floral and faunal diversity, just south of the WCNP. The efficacy of three methods used to study the feeding ecology of herbivores, focal observations, macroscopic faecal analysis and histological analysis of scats, was evaluated. Plant cover, species diversity, and the variety of growth forms were substantially larger at the WCNP than on DI. In the WCNP, shrubs and grasses were the dominant growth forms but the vegetation also included herbs, succulents, restios, sedges and parasitic plants. A few perennial species such as the grass Ehrharta villosa, shrubs such as Helichrysum niveum, Nylandtia spinosa and Rhus spp., and succulents such as Carpobrotus edulis and Ruschia spp., provided most of the plant cover. DI had a depauperate flora, consisting of succulents and herbs, and ephemeral plants contributed more than perennials did to plant cover throughout the year. The succulents Mesembryanthemum crystallinum and Tetragonia fruticosa provided most of the cover on DI. Angulate tortoises are herbivores and 72 diet plants in 32 plant families were identified to the species or genus level. Several diet species, however, could not be identified. In addition to angiosperms, the tortoises’ diet included mosses, mushrooms, insects,snails and animal faeces. The most important growth forms in the diet were herbs and grasses. The diet of the WCNP tortoises was more diverse than the diet of DI tortoises, but the number of principal food items in the diet did not differ between the two sites. Over an annual cycle, WCNP tortoises had four principal food plants while DI tortoises had five principal food plants. At both sites, principal food plants changed with the season and few plants remained principal food items in more than one season. Cynodon dactylon was a principal food item in three of the four seasons in the WCNP, whereas Trachyandra divaricata was a principal food plant each season on DI. Most principal food plants were grass or herb species but the sedge Ficinia nigrescens, and a succulent that could be identified only to the family level (Aizoaceae), featured strongly in the spring diets of DI and WCNP tortoises, respectively. The three study methods did not provide the same type or quality of information about the feeding ecology of angulate tortoises. The small size and wary nature of angulate tortoises compromised focal studies because it was often not possible to see what the tortoises ate. This method, however, provided the interesting observation that rabbit faecal pellets contributed nearly 30% to summer and autumn diets on DI when food was scarce. Rabbit faeces may not only provide a source of nutrients but may also supplement the microflora, required to digest cellulose, in the tortoises’ guts. Macroscopic evaluation of the tortoises’ scats appeared to be an ineffective method to identify diet plants, and the bulk of the scat mass could not be identified. This indicates that angulate tortoises either selected food low in fibrous content or that the digestive system of the tortoises dealt efficiently with tough plant material. The macroscopic method was the only method that highlighted the large contribution of fruits / seeds to the diet of angulate tortoises. Since the tortoises digested many seeds only partially, or not at all, C. angulata is potentially an important agent of seed dispersal in the southwestern Cape. The macroscopic study showed that on DI, sand made up 28% of the scat mass in spring, whereas sand never made a substantial contribution to the scat composition of WCNP tortoises. Lithophagy may be an important strategy in a depauperate habitat, such as DI, because the abrasive action of sand may help with the digestion of tough plants, or the sand may provide the tortoises with important minerals that are deficient in their food plants.The histological analysis of scats provided the most comprehensive diet list for C. angulata. Selection indices based on data from the histological analysis indicated that angulate tortoises were highly selective in their food choice. Most of the principal food items were selected out of proportion to their availability and the tortoises avoided the most abundant plants in their habitats. Several factors, such as palatability, accessibility and profitability, may have influenced their food choice. The proportional similarity indices for WCNP and DI tortoises, respectively, were 0.31 and 0.16, confirming that C. angulata is a food specialist and not a food generalist as was previously thought. This factor should be considered in the management of this species and in future conservation planning of its habitat. / South Africa

Chronic stress can result in elevated circulating levels of glucocorticoid hormones in vertebrates, which can affect their stress response, their immune function, and eventually their fitness. I tested the effect of chronic corticosterone (CORT) elevation on the acute stress responsiveness, immune function, and body condition of free-living painted turtles (Chrysemys picta) in Gatineau Park, using slow-release exogenous CORT administration. While Silastic implants did not predictably elevate circulating CORT concentrations in painted turtles, injections of CORT-laden cocoa butter kept circulating levels elevated for up to 3 weeks, to concentrations likely physiologically and ecologically relevant for the species. I measured the acute CORT stress response, parasitaemia, heterophil-to-lymphocyte ratios, and total leukocyte counts after 1 week and 3 weeks, and determined body condition after 1 week, 3 weeks, and 1 year. Compared to sham and control turtles, I observed no effect of treatment on these hormonal, immune, and body condition metrics of stress, possibly because CORT mediates resource allocation only in the presence of additional immune or energy challenges, because of the masking effect of extrinsic factors, or because free, not total, CORT appears to be biologically active.

No description available.

Insular fauna face disproportionate risks of extinction owing to direct human perturbation and intrinsic factors that are enhanced at small population sizes. Currently, our understanding of the processes that promote long-term persistence of naturally small populations and the cryptic processes that may contribute to accelerating their decline is limited by lack of empirical investigations across the range of natural conditions. Implementing effective protections for rare and understudied taxa requires the identification and examination of factors that limit recruitment at critical life stages. Predicting population health outcomes of future perturbations further necessitates an understanding a taxon’s behavioral ecology. Finally, cryptic threats to viability, such as inbreeding depression, must be investigated with an appreciation for taxon-specific life history, as these attributes can alter the context in which severe fitness reductions are expressed. In this project I enlist integrative and cross-disciplinary approaches to study the behavioral ecology and conservation genetics of a critically endangered West Indian Rock Iguana, Cyclura nubila caymanensis, on Little Cayman Island. I demonstrate how coastal communal nesting areas, a critical limiting resource on the island, serve a diverse population demographic and contribute to significantly enhanced nesting outcomes. These data emphasize the importance of expanding protections for major sites, as aggregative nesting appears to be perpetuated by both habitat suitability and adaptive fitness benefits. I next evaluate the possibility of evolved inbreeding avoidance strategies, including natal dispersal, non-assortative mate choice, and genetic bet-hedging. I conclude that the contribution of pre-reproductive dispersal to inbreeding avoidance likely outweighs that of active mate choice. Importantly, observed patterns of siring success imply constrained female choice and sexual conflict over genetic mating outcomes – a pattern that may extend to many territorial, male-driven mating systems and therefore should be an important consideration in genetic management. Finally, I investigate age-dependent inbreeding effects and the degree to which inbreeding depression may limit recruitment to the breeding population. I fail to reveal significant correlations of multi-locus heterozygosity with hatchling fitness; however, negative effects of parental inbreeding on fecundity and hatching success imply fitness consequences of inbreeding depression could be felt at other life stages.