Made available in DSpace on 2014-06-11T19:30:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-09-02Bitstream added on 2014-06-13T20:00:11Z : No. of bitstreams: 1 estrada_fab_me_rcla.pdf: 2848739 bytes, checksum: 7762a98a6409bfe1118c630b45226509 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Scinax fuscomarginatus, S. parkeri, S. trilineatus e a recentemente descrita S. lutzorum são espécies muito similares morfologicamente que ocorrem em formações abertas da America do Sul ao leste dos Andes. Scinax parkeri e S. trilineatus tiveram sua validade taxonômica questionada enquanto S. fuscomarginatus é considerada por vários autores como um complexo de espécies. Levando em conta a similaridade morfológica e a incerteza taxonômica, nesse trabalho revisamos a taxonomia de Scinax fuscomarginatus, S. trilineatus, S. parkeri e S. lutzorum usando dados de morfologia externa, cantos de anúncio e sequências moleculares. Os principais objetivos foram investigar a existência de outras espécies sob o nome S. fuscomarginatus e avaliar o status taxonômico de S. parkeri, S. trilineatus, S. lutzorum e Hyla madeirae (único sinônimo de S. fuscomarginatus). Nas análises filogenéticas com dados moleculares encontramos uma profunda e rica estrutura genética tanto intra quanto inter-especifica. As amostras incluídas formaram um grupo monofilético bem suportado que está estruturado em vários clados e subclados. Hyla madeirae e a população da Serra do Cachimbo correspondem a subclados distintos enquanto as espécies atualmente válidas (S. fuscomarginatus, S. parkeri, S. trilineatus e S. lutzorum) se agrupam em um único clado. Este clado apresenta subestrutura marcada, mas a concordância entre subclados e as espécies reconhecidas é limitada. A alta variação intraespecífica e intrapopulacional encontrada nos caracteres morfológicos usados para a diagnose original das espécies não permitiu a diferenciação entre S. parkeri, S. trilineatus, S. lutzorum e S. fuscomarginatus. Entretanto, alguns caracteres permitem a distinção de Hyla madeirae e dos espécimens da Serra do Cachimbo / Scinax fuscomarginatus, S. parkeri, S. trilineatus and the recently described S. lutzorum are morphologically very similar species that occur in open formations of South America east of the Andes. Scinax parkeri and S. trilineatus had its taxonomic validity questioned, and S. fuscomarginatus is considered by many authors as a species complex. Given the morphological similarity and taxonomic uncertainty, we review the taxonomy of Scinax fuscomarginatus, S. parkeri, S. trilineatus, and S. lutzorum using data from external morphology, advertisement calls and molecular sequences. The main goals were to investigate the existence of other species under the name S. fuscomarginatus and assess the taxonomic status of S. parkeri, S. trilineatus, S. lutzorum and Hyla madeirae (the only synonym within S. fuscomarginatus). In the phylogenetic analysis obtained with the molecular data we found rich and deep genetic structure both within and between species. The samples included formed a well supported monophyletic group that is divided into several clades and subclades. The specimens of Hyla madeirae and those from Serra do Cachimbo corresponded to distinct subclades while the currently valid species (S. fuscomarginatus, S. parkeri, S. and S. trilineatus lutzorum) were grouped into a single clade. This clade showed marked substructure, but the concordance of the recognized species to subclades were limited. The high intrapopulation and intraspecific variation found in morphological characters used for the original diagnoses did not allow us to differ among S. parkeri, S. trilineatus, S. lutzorum and S. fuscomarginatus. However, some characters support the distinction of Hyla madeirae and specimens from Serra do Cachimbo. Similarly, none of valid species were distinguishable in morphometric analysis while Hyla madeirae and the specimens from Serra do Cachimbo showed a trend in having wider heads

The distribution and abundance of organisms is influenced by historical, abiotic, and biotic factors. The goal of my dissertation was to determine the distribution of anurans in the Big Bend region of the Chihuahuan Desert and to examine how abiotic and biotic factors shape the composition and structure of anuran communities at multiple spatial scales. My approach relied on extensive field surveys, laboratory and field experiments, and GIS modeling. Results from field surveys and reciprocal transplant studies of tadpoles indicate that abiotic conditions of the breeding site most likely do not play a significant role in causing the segregation of species among individual breeding pools. I used laboratory and mesocosm experiments to test for indirect and direct effects of predators on growth and survival of S. couchii tadpoles. I found that S. couchii tadpoles do not alter their behavior in the presence of predators and are very susceptible to predation. Although tadpoles reared with predators suffered high mortality rates, they metamorphosed significantly faster than tadpoles reared without predators. The reduced time to metamorphose is likely a result of the thinning of intraspecific competitors. Because the primary cause of death for S. couchii tadpoles is desiccation due to pond drying, predators may play an important role in facilitating metamorphosis by decreasing competitors and thus increasing per capita resources, therefore decreasing time to metamorphosis for the surviving tadpoles. At the landscape level anuran distributions seem to be influenced by environmental factors that influence the survival of the adult stage. At the level of the breeding site, microhabitat and abiotic components of the aquatic environment do not seem to play an important role in influencing breeding site use by different species. Rather, it seems likely that predation on tadpoles by predators is important in limiting the distribution of some species and that the fast-developing S. couchii may exclude other species from using sites via oophagy and predation on small tadpoles. My research elucidates the fact that in order to understand factors important in regulating ecological communities it is important to examine both abiotic and biotic factors at multiple spatial scales.

Orientador: Célio Fernando Baptista Haddad / Banca: Esteban Orlando Lavilla / Banca: Luciana Barreto Nascimento / Resumo: Scinax fuscomarginatus, S. parkeri, S. trilineatus e a recentemente descrita S. lutzorum são espécies muito similares morfologicamente que ocorrem em formações abertas da America do Sul ao leste dos Andes. Scinax parkeri e S. trilineatus tiveram sua validade taxonômica questionada enquanto S. fuscomarginatus é considerada por vários autores como um complexo de espécies. Levando em conta a similaridade morfológica e a incerteza taxonômica, nesse trabalho revisamos a taxonomia de Scinax fuscomarginatus, S. trilineatus, S. parkeri e S. lutzorum usando dados de morfologia externa, cantos de anúncio e sequências moleculares. Os principais objetivos foram investigar a existência de outras espécies sob o nome S. fuscomarginatus e avaliar o "status" taxonômico de S. parkeri, S. trilineatus, S. lutzorum e Hyla madeirae (único sinônimo de S. fuscomarginatus). Nas análises filogenéticas com dados moleculares encontramos uma profunda e rica estrutura genética tanto intra quanto inter-especifica. As amostras incluídas formaram um grupo monofilético bem suportado que está estruturado em vários clados e subclados. Hyla madeirae e a população da Serra do Cachimbo correspondem a subclados distintos enquanto as espécies atualmente válidas (S. fuscomarginatus, S. parkeri, S. trilineatus e S. lutzorum) se agrupam em um único clado. Este clado apresenta subestrutura marcada, mas a concordância entre subclados e as espécies reconhecidas é limitada. A alta variação intraespecífica e intrapopulacional encontrada nos caracteres morfológicos usados para a diagnose original das espécies não permitiu a diferenciação entre S. parkeri, S. trilineatus, S. lutzorum e S. fuscomarginatus. Entretanto, alguns caracteres permitem a distinção de Hyla madeirae e dos espécimens da Serra do Cachimbo / Abstract: Scinax fuscomarginatus, S. parkeri, S. trilineatus and the recently described S. lutzorum are morphologically very similar species that occur in open formations of South America east of the Andes. Scinax parkeri and S. trilineatus had its taxonomic validity questioned, and S. fuscomarginatus is considered by many authors as a species complex. Given the morphological similarity and taxonomic uncertainty, we review the taxonomy of Scinax fuscomarginatus, S. parkeri, S. trilineatus, and S. lutzorum using data from external morphology, advertisement calls and molecular sequences. The main goals were to investigate the existence of other species under the name S. fuscomarginatus and assess the taxonomic status of S. parkeri, S. trilineatus, S. lutzorum and Hyla madeirae (the only synonym within S. fuscomarginatus). In the phylogenetic analysis obtained with the molecular data we found rich and deep genetic structure both within and between species. The samples included formed a well supported monophyletic group that is divided into several clades and subclades. The specimens of Hyla madeirae and those from Serra do Cachimbo corresponded to distinct subclades while the currently valid species (S. fuscomarginatus, S. parkeri, S. and S. trilineatus lutzorum) were grouped into a single clade. This clade showed marked substructure, but the concordance of the recognized species to subclades were limited. The high intrapopulation and intraspecific variation found in morphological characters used for the original diagnoses did not allow us to differ among S. parkeri, S. trilineatus, S. lutzorum and S. fuscomarginatus. However, some characters support the distinction of Hyla madeirae and specimens from Serra do Cachimbo. Similarly, none of valid species were distinguishable in morphometric analysis while Hyla madeirae and the specimens from Serra do Cachimbo showed a trend in having wider heads / Mestre

Made available in DSpace on 2014-06-11T19:30:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-01Bitstream added on 2014-06-13T20:40:02Z : No. of bitstreams: 1 pupin_nc_me_rcla.pdf: 661234 bytes, checksum: e36615e4ab578d179fb41037bec04c78 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O gênero Physalaemus inclui 42 espécies distribuídas do norte da Argentina às Guianas. Uma característica interessante do gênero é a capacidade de ocupar uma ampla variedade de ambientes, desde a serrapilheira de florestas úmidas até ambientes sazonais tais como os encontrados no Cerrado, Chaco e Caatinga. Esta dissertação é apresentada em dois capítulos. No primeiro capítulo, dados sobre a biologia reprodutiva de Physalaemus crombiei, uma espécie endêmica da Mata Atlântica, são apresentados, juntamente com as relações tamanho-fecundidade, investimento reprodutivo da espécie, modos reprodutivos e uma comparação com dados obtidos na literatura para mais 12 espécies do gênero. No segundo capítulo foi verificado se fêmeas de diferentes espécies vivendo em ambientes contrastantes investem diferentemente em reprodução. Estas comparações foram feitas entre fêmeas de quatro espécies de Physalaemus associados a áreas florestadas e quatro espécies de área aberta. Neste contexto, as correlações entre os componentes de história de vida destas espécies foram investigadas, bem como a existência de variação no tamanho dos ovos dentro das desovas. Physalaemus crombiei se reproduz ao longo do ano, com seu pico de reprodução nos meses mais chuvosos. Exibe o modo de reprodução típico para o gênero (modo 11), mas pode exibir modos reprodutivos alternativos (modos 14 e 28), assim como outras espécies do grupo de P. signifer. As espécies do grupo de P. signifer depositam desovas com ovos maiores e em menor número do que as outras espécies do gênero. Esta diferença pode ser explicada não apenas pelo menor tamanho destas espécies, mas também por depositarem desovas terrestres. Na comparação entre espécies de mata e área aberta, o tamanho do corpo da fêmea foi correlacionado com o número de ovócitos em apenas duas dentre as sete espécies analisadas / The genus Physalaemus includes 42 species distributed from northern Argentina to the Guyanas. An interesting attribute of the genus is the ability to occupy a wide variety of environments, from the leaf litter of rainforests to seasonal environments, such as those found in the Cerrado, Chaco and Caatinga. This work presents two chapters. In the first chapter, data on the reproductive biology of Physalaemus crombiei, an endemic species of the Atlantic Forest, are presented along with the size-fecundity relationships, reproductive modes, and species reproductive investment (RI). A comparison with data from the literature for other 12 Physalaemus species was also made. In the second chapter, we verified if females of different species living in contrasting environments invested differently in reproduction. These comparisons were made between females of four species of Physalaemus associated with forested areas and four species from open areas. In this context, correlations between species’ life history components were investigated, as well as intra-clutch variation in egg size. Physalaemus crombiei reproduces throughout the year with a peak in the rainy months, exhibits the typical mode of reproduction for the genus (mode 11), but also presents alternative reproductive modes (modes 14 and 28), such as other species in the P. signifer group. Females in the P. signifer species group produce larger eggs but fewer in number than other species in the genus. This difference can be explained by the smaller size of these species, but also by the ability to place terrestrial clutches. In the comparison between forest and open area species, female body size correlated with the number of oocytes in only two out of seven species analyzed

Temporal features in the vocalizations of animals and insects play an important role in a diverse range of species-specific activities such as mate selection, territoriality, and hunting. The neural mechanisms underlying the response to such stimuli remain largely unknown. Two species of anuran amphibian provide a starting point for the investigation of the neurological response to species-specific advertisement calls. Neurons in the anuran midbrain of Rana pipiens and Hyla regilla exhibit an atypical response when presented with a fixed number of advertisement calls. The general response to these calls is mostly inhibitory; only when the correct number of calls is presented at the correct repetition rate will this inhibition be overcome and the neurons reach a spiking threshold. In addition to rate-dependent call-counting, these neurons are sensitive to missed calls: a pause of sufficient duration—the equivalent of two missed calls—effectively resets a neuron to its initial condition. These neurons thus provide a model system for investigating the neural mechanisms underlying call-counting and interval specificity in audition. We present a minimal computational model in which competition between finely-tuned excitatory and inhibitory synaptic currents, combined with a small propagation delay between the two, broadly explains the three key features observed: rate dependence, call counting, and resetting. While limitations in the available data prevent the determination of a single set of parameters, a detailed analysis indicates that these parameters should fall within a certain range of values. Furthermore, while network effects are counter-indicated by the data, the model suggests that recruitment of neurons plays a necessary role in facilitating the excitatory response of counting neurons—although this hypothesis remains untested. Despite these limitations, the model sheds light on the mechanisms underlying the biophysics of counting, and thus provides insight into the neuroethology of amphibians in general.

This study was based on the parasite fauna of three anuran systems. In two of the systems; the spadefoot toads, Scaphiopus bombifrons and S. multiplicatus and the fire and yellow-bellied toads, Bombina bombina and B.variegata, inter-species hybridisation occurs. In the third system an autopolyploid species complex involves the Gray treefrogs, Hyla chrysoscelis and H.versicolor. The status of the Scaphiopus hybrid zone in Arizona was re-assessed by cellulose-acetate gel electrophoresis. Genotypic frequencies were comparable to those previously documented, indicating that a region of 'balanced introgression' may exist. Specimens were collected in areas of host sympatry and the distribution of helminths within hosts of different genetic constitution investigated. From extensive surveys of all three systems, parasite frequency distributions were typically aggregated with no evidence of any change in host genetic predisposition to infection. In addition, the surveys have documented a number of new host and/or parasite locality records for each system. Of particular interest was the discovery of the digenean Clinostomum complanatum in a desert environment, an introduction related to human management of the ecosystem. Particular reference was made to the specificity of the polystomatid monogeneans, Polystoma nearcticum infecting members of the H.chrysoscelis- H.versicolor complex and Neodiplorchis scaphiopodis infecting S.bombifrons and S.multiplicatus. For Polystoma, worms from H.chlysoscelis and H.versicolor could not be separated by morphology, which was supported by preliminary crossinfections. This suggests that P.nearcticum infects both members of this complex. For Neodiplorchis, morphological similarity was confirmed by cross-infections which revealed that N.scaphiopodis can reach sexual maturity and produce fully developed larvae in heterospecific hosts. The neotenic development of P. nearcticum and the initial post-oncomiracidial stages of N.scaphiopodis were documented. Furthermore, certain aspects of transmission dynamics were examined by the experimental infection of H. versicolor tadpoles with P. nearcticum.

Temporal features in the vocalizations of animals and insects play an important role in a diverse range of species-specific activities such as mate selection, territoriality, and hunting. The neural mechanisms underlying the response to such stimuli remain largely unknown. Two species of anuran amphibian provide a starting point for the investigation of the neurological response to species-specific advertisement calls. Neurons in the anuran midbrain of Rana pipiens and Hyla regilla exhibit an atypical response when presented with a fixed number of advertisement calls. The general response to these calls is mostly inhibitory; only when the correct number of calls is presented at the correct repetition rate will this inhibition be overcome and the neurons reach a spiking threshold. In addition to rate-dependent call-counting, these neurons are sensitive to missed calls: a pause of sufficient duration—the equivalent of two missed calls—effectively resets a neuron to its initial condition. These neurons thus provide a model system for investigating the neural mechanisms underlying call-counting and interval specificity in audition. We present a minimal computational model in which competition between finely-tuned excitatory and inhibitory synaptic currents, combined with a small propagation delay between the two, broadly explains the three key features observed: rate dependence, call counting, and resetting. While limitations in the available data prevent the determination of a single set of parameters, a detailed analysis indicates that these parameters should fall within a certain range of values. Furthermore, while network effects are counter-indicated by the data, the model suggests that recruitment of neurons plays a necessary role in facilitating the excitatory response of counting neurons—although this hypothesis remains untested. Despite these limitations, the model sheds light on the mechanisms underlying the biophysics of counting, and thus provides insight into the neuroethology of amphibians in general.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-11Bitstream added on 2014-06-13T19:46:40Z : No. of bitstreams: 1 giasson_lom_dr_rcla.pdf: 2766767 bytes, checksum: 22e537abf2216690d23b729eaf8f2f38 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A Mata Atlântica é um dos biomas mais biodiversos e, ao mesmo tempo, mais ameaçados do planeta. Estudos com anuros têm corroborado este padrão de diversidade, demonstrando que há grande variação na composição de espécies, mesmo entre localidades próximas neste bioma. Sob estas condições estudos de comunidades com anuros são de alta relevância e oportunos para investigar os fatores que estruturam as comunidades. Deste modo, foram caracterizadas as espécies de anuros de uma área de Mata Atlântica, detalhando a estrutura da comunidade. Investigou-se a organização sazonal das espécies, o padrão de uso do ambiente e a partilha dos recursos e a similaridade com outras taxocenoses do Sul e Sudeste. Para tanto, foram feitas 25 amostragens no Núcleo Santa Virgínia do Parque Estadual da Serra do Mar. As espécies em atividade vocal e demais evidências de reprodução foram registradas e as vocalizações gravadas. Nas excursões, durando de quatro a oito dias, eram amostrados e registrados os ambientes usados pelos anuros. Foram registradas 50 espécies de anuros sendo a ampla maioria tipicamente associada à Mata Atlântica. Na atividade sazonal ocorreu uma gradação entre espécies restritas aos meses do verão, passando por espécies com período mais amplo de atividade, até espécies restritas ao inverno. O padrão de uso do ambiente em geral refletiu a filogenia e a maior sobreposição nesta dimensão do nicho ocorreu entre espécies aparentadas, apesar de também ocorrerem convergências entre espécies pouco aparentadas. Restrições herdadas são mais razoáveis para explicar os padrões gerais de uso do ambiente do que competição interespecífica ou predação ocorrendo no presente. A taxocenose de anuros deste estudo se assemelhou àquelas situadas em áreas serranas da Mata Atlântica. A similaridade na composição de espécies entre as localidades está fortemente relacionada às distâncias geográficas entre elas. / The Atlantic forest is one the world’s most diverse biomes and at the same time on of the most threatened. Studies on frogs are confirming this pattern, showing great variance in species composition, even among close localities in this biome. From this perspective, studies on frog communities are of extreme importance to elucidate the factors structuring these communities. Thus, herein we characterize the frog species from a locality in the Atlantic Forest, providing details on community structure. Seasonal activity of species, pattern of habitat use, resource partitioning, and species composition similarity between regions in the South and Southeast Brazil were investigated. Twenty-five samples were carried out at Núcleo Santa Virgínia, at the Serra do Mar State Park, São Paulo state, southeast Brazil. Calling activity of species, other reproductive evidences, and vocalizations were registered. During the surveys, which lasted from four to eight days, habitats used by the species were sampled and characterized. A total of 50 anuran species was registered; the great majority typical of the Atlantic Forest. Regarding seasonality, we detected a continuum from species with activity during the summer, to species exhibiting a more prolonged season, up to species restricted to the winter. Habitat use, in general, reflected the phylogeny and the greater overlap occurred among close related species, although convergence among distant species was also observed. Restrictions related to phylogeny are more plausible to explain the general pattern of habitat use observed here, than are present interspecific competition or predation. Community composition at the study site was more similar to those from montane areas located in the Atlantic Forest and species composition similarity was strongly related to the geographic distances among them. Localities under the influence of the Atlantic Forest are less similar among them than are those ...

Made available in DSpace on 2014-06-11T19:35:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-01Bitstream added on 2014-06-13T19:25:16Z : No. of bitstreams: 1 thome_mtc_dr_rcla.pdf: 1133050 bytes, checksum: d966bd8e88261194600516cb733c8e17 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Nessa tese, utilizamos uma série de métodos filogeográficos para investigar a diversificação em Rhinella gr. crucifer, um grupo de espécies próximas de sapos endêmicos da Mata Atlântica. No primeiro capítulo fizemos uma primeira abordagem da estrutura genética no grupo utilizando amostragem grosseira. Foram analisadas seqüências de DNA mitocondrial e nuclear de DNA de 65 indivíduos representando as cinco espécies atualmente válidas. Encontramos que a diversidade genética é geograficamente estruturada. A divergência mais antiga, datada do Plioceno, separa as populações mais ao sul do bioma enquanto que o restante das populações estão distribuídas em clados que divergiram desde o Pleistoceno. Modelos de distribuição paleoecológica suportam fragmentação de habitat associada a ciclos glaciais, mas a congruência de padrões filogeográficos com os refúgios inferidos é limitada. Algumas quebras genéticas coincidem geograficamente com barreiras associadas à atividade neotectônica. Os dados refutam a hipótese recentemente proposta de colonização Holocênica do sul da Mata Atlântica, sugerindo persistência de habitat nessa região. No segundo capítulo, utilizamos amostragem em nível populacional para delimitar melhor as unidades genéticas no grupo. Utilizamos seqüências de DNA mitocondrial e nuclear de 404 indivíduos, métodos baseados em árvores e freqüência alélica, considerando um cenário de divergências recentes e hibridação. Ambos marcadores apoiaram a existência de cinco unidades genéticas, três distribuídas na área núclear de distribuição do grupo, e duas com distribuições isoladas. Encontramos evidência clara da existência de zonas de contacto para dois pares de unidades genéticas... / In this dissertation, we used phylogeographic methods to investigate diversification in the Rhinella gr. crucifer, a group of closely related toads endemic to the Brazilian Atlantic Forest. In the first chapter we described the genetic structure in the group using coarse sampling. We analyzed mitochondrial and nuclear DNA sequences of 65 individuals representing the five currently valid species. We found that genetic diversity is geographically structured; the oldest divergence, dating from the Pliocene, separates the southernmost populations. The remaining population are distributed in clades that diverged throughout the Pleistocene. Palaeoecological distribution models support habitat fragmentation associated with glacial cycles, but the congruence of phylogeographic patterns and inferred refugia is limited. Some genetic breaks coincide geographically with barriers related to neotectonic activity. The data refute the recently proposed hypothesis of Holocene southern colonization of the biome, suggesting instead habitat persistence in this region. In the second chapter, we used sampling at the population level to delimit genetic units within the group. We used DNA sequences of mitochondrial and nuclear markers from 404 individuals. We combined tree and frequency– based methods, assuming a scenario of recent divergence and hybridization. Both marker types supported the existence of five genetic units, three being distributed within the core distribution of the group, and two with more isolated distributions. We found evidence of contact zones between two pairs of units... (Complete abstract click electronic access below)

Resumo: Nessa tese, utilizamos uma série de métodos filogeográficos para investigar a diversificação em Rhinella gr. crucifer, um grupo de espécies próximas de sapos endêmicos da Mata Atlântica. No primeiro capítulo fizemos uma primeira abordagem da estrutura genética no grupo utilizando amostragem grosseira. Foram analisadas seqüências de DNA mitocondrial e nuclear de DNA de 65 indivíduos representando as cinco espécies atualmente válidas. Encontramos que a diversidade genética é geograficamente estruturada. A divergência mais antiga, datada do Plioceno, separa as populações mais ao sul do bioma enquanto que o restante das populações estão distribuídas em clados que divergiram desde o Pleistoceno. Modelos de distribuição paleoecológica suportam fragmentação de habitat associada a ciclos glaciais, mas a congruência de padrões filogeográficos com os refúgios inferidos é limitada. Algumas quebras genéticas coincidem geograficamente com barreiras associadas à atividade neotectônica. Os dados refutam a hipótese recentemente proposta de colonização Holocênica do sul da Mata Atlântica, sugerindo persistência de habitat nessa região. No segundo capítulo, utilizamos amostragem em nível populacional para delimitar melhor as unidades genéticas no grupo. Utilizamos seqüências de DNA mitocondrial e nuclear de 404 indivíduos, métodos baseados em árvores e freqüência alélica, considerando um cenário de divergências recentes e hibridação. Ambos marcadores apoiaram a existência de cinco unidades genéticas, três distribuídas na área núclear de distribuição do grupo, e duas com distribuições isoladas. Encontramos evidência clara da existência de zonas de contacto para dois pares de unidades genéticas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this dissertation, we used phylogeographic methods to investigate diversification in the Rhinella gr. crucifer, a group of closely related toads endemic to the Brazilian Atlantic Forest. In the first chapter we described the genetic structure in the group using coarse sampling. We analyzed mitochondrial and nuclear DNA sequences of 65 individuals representing the five currently valid species. We found that genetic diversity is geographically structured; the oldest divergence, dating from the Pliocene, separates the southernmost populations. The remaining population are distributed in clades that diverged throughout the Pleistocene. Palaeoecological distribution models support habitat fragmentation associated with glacial cycles, but the congruence of phylogeographic patterns and inferred refugia is limited. Some genetic breaks coincide geographically with barriers related to neotectonic activity. The data refute the recently proposed hypothesis of Holocene southern colonization of the biome, suggesting instead habitat persistence in this region. In the second chapter, we used sampling at the population level to delimit genetic units within the group. We used DNA sequences of mitochondrial and nuclear markers from 404 individuals. We combined tree and frequency- based methods, assuming a scenario of recent divergence and hybridization. Both marker types supported the existence of five genetic units, three being distributed within the core distribution of the group, and two with more isolated distributions. We found evidence of contact zones between two pairs of units... (Complete abstract click electronic access below) / Orientador: João Miguel de Barros Alexandre / Coorientador: Célio Fernando Baptista Haddad / Banca: Fernando Jorge Guimarães Sequeira / Banca: Sergio Furtado dos Reis / Banca: Cinthia Aguirre Brasileiro / Banca: Cristina Y. Myaki / Doutor