A high proportion of amphibian species are threatened with extinction globally, and habitat loss and degradation are the most frequently implicated causes. Rapid deforestation for the establishment of agricultural production is a primary driver of habitat loss in tropical zones where amphibian diversity is highest. Land-cover change affects native assemblages, in part, through the reduction of habitat area and the reduction of movement among remnant populations. Decreased gene flow contributes to loss of genetic diversity, which limits the ability of local populations to respond to further environmental changes. The focus of this dissertation is on the degree to which common land uses in Sarapiquí, Costa Rica impede the movement of two common amphibian species. First, I used field experiments, including displacement trials, and a behavioral landscape ecology framework to investigate the resistance of pastures to movement of Oophaga pumilio. Results from experiments demonstrate that pastures do impede movement of O. pumilio relative to forest. Microclimatic effects on movement performance as well as limited perceptual ranges likely contribute to reduced return rates through pastures. Next, I linked local processes to landscape scale estimates of resistance. I conducted experiments to measure habitat-specific costs to movement for O. pumilio and Craugastor bransfodrii, and then used experimental results to parameterize connectivity models. Model validation indicated highest support for resistance estimates generated from responses to land-use specific microclimates for both species and to predator encounters for O. pumilio. Finally, I used abundance and experiment-derived resistance estimates to analyze the effects of prevalent land uses on population genetic structure of the two focal species. While O. pumilio did not exhibit a strong response to landscape heterogeneity and was primarily structured by distances among sites, C. bransfordii genetic variation was explained by resistance estimates from abundance and experiment data. Collectivity, this work demonstrates that common land uses can offer different levels of resistance to amphibian movements in Sarapiquí and illustrates the value of investigating local scales processes to inform interpretation of landscape-scale patterns.

Orientador: Shirlei Maira Recco Pimentel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-14T11:03:41Z (GMT). No. of bitstreams: 1 Egito_GabrielToselliBarbosaTabosado_M.pdf: 537508 bytes, checksum: e9fd34e6de85068aa05990a955acff88 (MD5) Previous issue date: 2009 / Resumo: Dendropsophus minutus está amplamente distribuído ao Leste dos Andes, na América do Sul e possui uma grande diversidade acústica e morfológica, o que sugere que possa haver mais de uma espécie sob esse nome. Sua coloração dorsal pode ser classificada em dois padrões principais, hourglass e bivittata. No presente estudo, 14 parâmetros morfométricos e seqüências de DNA com 357 pares de bases do gene citocromo b mitocondrial foram analisados objetivando um melhor entendimento acerca da variação de D. minutus no Brasil. Tanto os resultados moleculares quanto os fenotípicos revelaram a presença de uma alta estruturação da diversidade dessa espécie, mostrando que a divergência entre populações é, geralmente, proporcional à distância geográfica, exceto no estado de São Paulo, sudeste do Brasil. Nessa região, a Serra do Mar está aparentemente agindo como uma barreira geográfica para o fluxo gênico, isolando duas linhagens. A primeira, formada pelas populações da Mata Atlântica, tem padrão hourglass de coloração dorsal. A segunda, do interior de São Paulo, assim como a população do Rio Grande do Sul, possui padrão bivittata de coloração dorsal. Esses resultados corroboram a hipótese de que o táxon D. minutus contém duas linhagens crípticas. Apesar disso, uma amostragem maior se faz necessária, bem como um melhor estudo de caracteres para defini-las como espécies ou não. / Abstract: In despite of its complex reproductive behavior, Dendropsophus minutus has a large distribution at East of Andes, South America and show high acoustic and morphologic diversity, suggesting that possibly more than one species may exist under this name. Its dorsum coloration has basically two main patterns, hourglass or bivittata. Here, 14 morphometric parameters and partial mitochondrial cytochrome b gene sequences (357 base pairs) were analyzed aiming to understand more about Brazilian D. minutus variation. Both molecular and morphologic results agree with a high structuration of this species diversity, showing population divergence generally proportional to their geographic distance, except in São Paulo State, southeastern Brazil. At this region, Serra do Mar high mountains are apparently acting as a barrier for dispersion, isolating two lineages. The first of them, formed by populations from Atlantic Rainforest domain, has an hourglass dorsum pattern, whereas the second, comprising inner São Paulo State populations gathered with D. minutus from Rio Grande do Sul (South Brazil), shows bivittata dorsum coloration pattern. These results corroborate the hypothesis that D. minutus could comprise more than one species, revealing two cryptic lineages. However, these lineages should not be defined as different species before sampling enlargement to the present study. / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural

Para analisar os efeitos da perda de habitat e fragmentação da Mata Atlântica sobre as espécies de anfíbios anuros e lagartos de serapilheira amostramos 15 fragmentos florestais e seis localidades de mata contínua na região de Tapiraí e Piedade, Planalto Atlântico de São Paulo. Apesar de abrigar alta riqueza de espécies em comparação com outros estudos realizados no planalto, fragmentos florestais apresentaram menor diversidade em relação a localidades de mata contínua. Diferenças na composição de espécies entre as localidades podem ser explicadas pela distância geográfica, estrutura da vegetação e disponibilidade de microambientes. Os efeitos da redução de área e isolamento dos remanescentes sobre anfíbios de serapilheira variam de acordo com aspectos de história natural das espécies, e constituem características muito importantes para a conservação da diversidade na região. Nossos resultados sugerem que a distribuição de anfíbios e lagartos em paisagens fragmentadas deve ser determinada por uma interação entre os efeitos da fragmentação e alterações ambientais. / In order to investigate the effects of habitat loss and fragmentation of the Atlantic Rain Forest in leaf-litter anuran and lizards we sampled 15 fragments and six localities of continuous forest in the Tapiraí and Piedade region, Atlantic Plateau of São Paulo. Forest fragments supports a higher species richness in comparison to other studies developed in the Atlantic Plateau, but mainteined lower diversity than continuous forest localities. Differences in species composition among localities can be explained by geographic distance, forest and vegetation structure and microhabitat disponibility. The effects of isolation increase and area reduction in leaf-litter anurans were correlated to species natural history, and constituted important characteristics to diversity conservation in this region. Our study suggests that leaf-litter anurans and lizards distribution and persistence in fragmented landcapes could be determined by an interaction of fragmentation effects and ambiental disturbance.

O risco de extinção e o declínio populacional de muitas espécies animais na região neotropical estão fortemente relacionados aos processos antrópicos, como a conversão ambiental, mas também aos fatores intrínsecos aos próprios indivíduos, como os atributos. Os anuros correspondem ao grupo vertebrado mais ameaçado atualmente, sofrendo com sérios declínios populacionais. Este trabalho buscou avaliar quais os atributos dos anfíbios neotropicais podem predizer: i) as categorias de ameaça e tendências populacionais destas espécies e ii) a ocorrência de anuros em um ambiente modificado, de matriz agrícola. Para a predição de categorias de ameaça e tendências populacionais utilizamos um banco de dados com atributos de habitat e modos reprodutivos de 3196 espécies de anuros neotropicais. Verificamos que espécies com modos reprodutivos terrestres e desenvolvimento direto tem uma maior tendência a estarem em declínio. Além disso, verificamos que embora os atributos sejam filogeneticamente estruturados, o grau de ameaça parece ser independente de suas histórias evolutivas. Para identificar possíveis relações entre atributos ecológicos e morfológicos de anuros em uma paisagem agrícola no sul do Brasil, registramos a anurofauna com uso de armadilhas de interceptação e queda e procuras ativas em três diferentes distâncias da borda em um ambiente florestal e em uma matriz agrícola. Verificamos que principalmente os atributos ecológicos, como o modo reprodutivo (tanto terrestre como aquático) e o hábito estão relacionados com a ocorrência destas espécies no sistema agrícola, assim como encontramos diferenças entre os atributos morfológicos ao longo do gradiente de distância. Ambos os resultados podem auxiliar na tomada de decisões em planos e projetos de conservação de anuros neotropicais. / The extinction risk and population decline of many animal species in neotropical region are strongly related to anthropic processes, such as environmental conversion, but they are also related to intrinsic factors such as traits. Anurans correspond to the most endangered vertebrate group, suffering serious population declines. This work aimed to evaluate which neotropical anurans traits can predict: i) the categories of threat and population trends of species, and ii) the occurrence of anuran species in modified environments, such as the agricultural matrix. First, we compiled data to 3196 neotropical anuran species. We emphasized the importance of habitat and reproductive modes in threat classifications, as well as verified that species with terrestrial reproductive modes and direct development are more likely to be declining. We also found that although anurans traits being phylogenetically structured, the degree of threat seems to be independent from their evolutionary histories. In addition, to identify possible relation among ecological and morphological anuran traits with agricultural landscape in southern Brazil, we studied the anurofauna using pitfall traps and active searches at three different border distances in a forest environment and in an agricultural matrix. We verified that mostly of the ecological traits, such as the reproductive mode (both terrestrial and aquatic) and the habit, are related to the occurrence of determined species in the agricultural system. And we also found differences among the morphological traits observed through the distance gradient from the border. Therefore, both results present practical importance since it can help herpetologists to making decision about neotropical anurans conservation.

The Diadectomorpha is a central taxon in understanding the origin and early evolution of amniotes. It is considered a sister taxon to Amniota and is so similar to amniotes that some researchers have placed it within the Amniota itself. This group is composed of three families: the Limnoscelidae, the Tseajaiidae, and the Diadectidae. Being the most basal member of this group, the family Limnoscelidae is especially important in these studies.

No description available.

Amphibians have been facing global declines over the last decades due to direct and indirect effects of anthropogenic activities. One of the leading causes is environmental contamination, particularly that of waterbodies which are used by many amphibian species for reproduction, development, and adult life. An important source of contamination comes from agricultural runoffs of pesticides such as neonicotinoids, which are known to alter anuran survival, behaviour, predation stress response, and development. However, few studies have investigated the possible interactions between neonicotinoids and natural environmental stressors which could alter the strength and direction of observed neonicotinoid effects. This study investigated how a concentration of imidacloprid (a neonicotinoid) measured in surface waters interacted with high population density, an important environmental stressor, to influence behaviour and development across metamorphosis in wood frogs (Lithobates sylvaticus) known to breed in agricultural landscapes. I reared tadpoles in a fully crossed design experiment, between two densities (0.33 and 1 tadpole/L) and clean vs contaminated water (10 µg/L imidacloprid). Behaviours were measured in the absence and presence of predation cues using open-field tests at three distinct developmental stages, up to the metamorph stage. I found that imidacloprid did not interact with population density or independently affect behaviours in the absence of predation cues. However, individuals raised at high density compared with low density were more active at an early developmental stage but less active at metamorphic climax. Furthermore, both density and imidacloprid independently decreased the natural behavioural response (i.e., “freezing”) of tadpoles to predation cues. Both treatments also slightly accelerated metamorphosis while only density altered final mass at metamorphosis. Finally, I found that distance travelled was weakly repeatable between aquatic stages but not repeatable across metamorphosis, a pattern that was not affected by treatments. This study provides novel insights on the ecotoxicology of imidacloprid in the presence of a natural stressor, highlighting the importance of including behavioural assays and stressors in studies of amphibian ecotoxicology.

No description available.

No description available.

The greenhouse frog, Eleutherodactylus planirostris, native to Cuba and the Bahamas, was recently introduced to Hawaii. Studies from other invaded habitats suggest that it may impact Hawaiian ecosystems by consuming and potentially reducing endemic invertebrates. However, there have been no studies on the greenhouse frog in Hawaii. The first component of this study was to conduct a diet analysis. We conducted a stomach content analysis of 427 frogs from 10 study sites on the island of Hawaii. At each site, we also collected invertebrates using two different sampling methods: leaf litter collection and sticky traps to characterize available resources. Greenhouse frogs consumed predominantly leaf litter invertebrates. Dominant prey items consisted of Hymenoptera: Formicidae (32.4%), Acari (19.2%), and Collembola (17.4%). Greenhouse frogs consumed more Formicidae than was measured in the environment. At one study site, we estimated there were 12,500 frogs ha-1 using mark-recapture methods and greenhouse frogs consumed 129,000 invertebrates ha-1 night-1 at this site. The second component of this study was to determine the distribution of the greenhouse frog on the island of Hawaii, with a male breeding call presence/absence survey at 446 points along the major road network. The greenhouse frog was detected at 61 sites (14%), and found mostly in lowland areas, in habitats of native shrublands and forests, nonnative forests, agricultural lands, and pastures on the southwestern and eastern sides of the island. We determined detection probabilities of the greenhouse frog and the invasive coqui frog, E. coqui. Detection probability of the greenhouse frog was low on the first two surveys and improved by the third survey. Detection probability of the coqui was higher than the greenhouse frog, but overall site occupancy estimates were similar for both species. Because the greenhouse frog appears to be as widespread as the coqui, we recommend that research be conducted to investigate its impacts ecologically to determine whether control efforts should also be aimed at this species.