• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 39
  • 24
  • 1
  • 1
  • 1
  • Tagged with
  • 80
  • 20
  • 18
  • 15
  • 15
  • 14
  • 13
  • 10
  • 10
  • 10
  • 10
  • 10
  • 9
  • 9
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Survey of a Neotropical anuran assemblage (Pacaya-Samiria Reserve, Peru)

Woebbe, Eric 09 May 2017 (has links)
No description available.
52

Multiple paternity and the breeding biology of the red-eyed treefrog, Agalychnis callidryas

d'Orgeix, Christian A. 06 June 2008 (has links)
External fertilization makes male anurans susceptible to direct intrasexual competition for fertilization opportunities at the egg mass. The red-eyed treefrog, Agalychnis callidryas, is one species in which pairs of males appear to simultaneously fertilize the clutch of a Single female. DNA fingerprinting revealed the presence of multiple paternity in two egg clutches examined from two matings involving a female with two males. The breeding biology of females and the potential costs and benefits of mating with multiple males were examined. Females were found to decrease the number of eggs in matings with multiple males. In addition, amplexed females moving toward Oviposition sites avoided secondary males by moving when approached by secondary males. Mortality to the eggs as a result of multiple males attempting to amplex females is suggested as the reason females avoid multiple males. Males were found to exhibit calling site defense from other males. Males used a combination of auditory and a visual behavior in defending calling sites. The call types are described and the contexts within which calls occur is discussed. Density of frogs was found to be a better indicator of the occurrence of matings involving multiple males than the operational sex ratio (number of males/number of females). / Ph. D.
53

Influência dos efeitos da borda sobre a comunidade de anfíbios anuros de serapilheira da Mata Atlântica da Estação Biológica de Boracéia, SP / Influence of edge effects on the leaf-litter anuran community of the Atlantic rain Forest of the Estação Biológica de Boracéia, SP

Costa, Carolina Ortiz Rocha da 27 June 2014 (has links)
O objetivo deste estudo foi determinar a natureza e a extensão dos efeitos de borda sobre a estrutura da comunidade de anuros de serapilheira da Estação Biológica de Boracéia (EBB). A EBB é uma unidade de conservação com 16.450 ha pertencente à Universidade de São Paulo (USP) e situa-se na Serra do Mar, domínio da Mata Atlântica, a uma altitude de 900m, em uma das regiões mais úmidas do Brasil. A comunidade de anuros de serapilheira foi amostrada entre maio de 2012 a outubro de 2013 nos limites da floresta nativa com cultivo de eucaliptos. Foram amostradas 63 parcelas de 5×5 m dispostas em sete transectos com nove faixas de distância da borda (-50, -25, 0, 25, 50, 75, 100, 125 e 150 m); além de sete parcelas na área-controle, totalizando 1.750 m2 amostrados.Para caracterizar o ambiente em cada faixa de distância, foram medidas as seguintes variáveis: temperatura e umidade relativa da serapilheira, profundidade da serapilheira, cobertura do dossel, diâmetro à altura do peito (DAP) e altura das árvores. Foram capturados 312 indivíduos de 23 espécies de anuros, sendo 19 endêmicas da Mata Atlântica. A comunidade apresentou alta diversidade de espécies (H` = 2,17).A riqueza e a diversidade de anuros aumentaram com a distância da borda florestal. A alta diversidade ß registrada (0,819) para a comunidade de anuros de serapilheira indicou uma alta taxa de substituição de espécies nas diferentes distâncias da borda.Houve maior variação da temperatura e umidade próxima à borda florestal e na área externa à floresta nativa.A riqueza e abundância de anuros foram negativamente correlacionadas com a temperatura e positivamente com a umidade da serapilheira, a densidade do dossel e o diâmetro das árvores.O cultivo de eucalipto pode ter minimizado os efeitos da borda sobre a comunidade de anuros. Os fatores de maior influência sobre a estrutura da comunidade de anuros de serapilheira foram as variações microclimáticas (até a faixa 75 m da borda) e estruturais (densidade do dossel e DAP). Diferentes respostas das espécies aos efeitos de borda indicaram duas faixas de transição para a comunidade de anuros de serapilheria ao longo do gradiente de distância. O primeiro ocorreu entre a borda e os primeiros 25 m no interior da floresta devido à drástica redução da riqueza e da abundância de espécies. O segundo ocorreu entre 50 e 75 m para o interior da floresta, alterando a composição de espécies. Em uma avaliação geral, a extensão dos efeitos de borda na EBB limitou-se a 50 m no interior da floresta. As espécies apresentaram respostas distintas aos efeitos da borda, porém, todas estas estão de acordo com o modelo transacional negativo, pois houve perda da qualidade do hábitat a partir da borda, o que afetou a riqueza e a abundância. / This study aimed at determine nature and extension of edge effects on the structure of a leaf-litter anuran community at the Ecological Station of Boracéia (EEB). EEB is a reserve with 16,450 ha belonging to University of São Paulo (USP) and lies at Serra do Mar, domain of Atlantic Forest, 900 m altitude, in one of the wettest regions of Brazil. The leaf-litter anuran community was sampled between May 2012 and October 2013, on the edge of a native forest with eucalypts cultivation. Sixty-three 5×5 m plots displayed in seven transects along nine distance strips of the edge (-50, -25, 0, 25, 50, 75, 100, 125 e 150 m) were sampled. To characterize the environment in each distance strip, the following measurements were taken: leaf-litter temperature and relative humidity, leaf-litter deepness, canopy cover, diameter at breast height (DBH) and height of trees. Three hundred and twelve individuals of 23 species were captured, being 19 endemic from Atlantic forests. The community presented high species diversity (H` = 2,17). Anuran richness and diversity increased with the distance from the forest edge. High ß diversity found for the leaf-litter anuran community (0.819) indicated a high species turn over along different distances from the edge. There were higher temperature and humidity variation near the edge and outside native forest. Anuran richness and abundance were negatively correlated to temperature and positively with leaf-litter humidity, canopy cover and DBH. Eucalypts cultivation could have minimized the edge effects on the anuran community. Factors most influencing the structure of the leaf-litter anuran community were microclimatic (until 75 m from the edge) and structural (canopy cover and DBH) variations. Different species responses to the edge effects indicated two transition strips for the leaf-litter anuran community along the distance gradient. The first occurred between the edge and the first 25 m inside the forest due to drastic reduction of species richness and abundance. The second occurred between 50 and 75 m inside the forest, changing species composition. In a general, the extension of the edge effects at EEB was limited at 50 m inside the forest. Species presented distinct responses to the edge effects, however, all of them agree with the negative transational model, because there were loss of habitat quality from the edge, which affected richness and abundance.
54

Diversidade de anuros (Amphibia) do Parque Estadual Morro do Diabo, SP /

Santos, Tiago Gomes dos. January 2009 (has links)
Orientador: Célio Fernando Baptista Haddad / Banca: Cynthia Peralta de Almeida Prado / Banca: Cinthia Aguirre Brasileiro / Banca: Luis Felipe de Toledo Ramos Pereira / Banca: Marianna Botelho de Oliveira Dixo / Resumo: Estudamos a riqueza, composição taxonômica e os padrões de distribuição espaciais e temporais de taxocenoses de anuros do Parque Estadual Morro do Diabo (PEMD), o maior remanescente de Floresta Estacional Semidecídua no estado de São Paulo, Brasil. Registramos 28 espécies de anuros (Apêndice I) de setembro de 2005 a março de 2007, que compreenderam um misto de espécies de Mata Atlântica, do Cerrado e de formas amplamente distribuídas na América do Sul, geralmente consideradas tolerantes a modificações antropogênicas. A baixa riqueza de espécies e de modos reprodutivos, a predominância de espécies habitatgeneralistas e a alta similaridade de espécies de anuros com áreas de Cerrado podem ser explicadas pela sazonalidade climática da área estudada (estação seca pronunciada), além da grande distância em relação a centros de diversificação de anuros, como as montanhas costeiras da Floresta Atlântica úmida. Chuva e fotoperíodo explicaram aproximadamente 77% da atividade de vocalização de toda a taxocenose, enquanto somente a chuva e o fotoperíodo explicaram a temporada de vocalização em ambientes temporários e permanentes, respectivamente. Registramos alta sobreposição na temporada de vocalização dos machos, mas segregação na fase larval. A distribuição das espécies de anuros entre sítios de reprodução (Apêndice II) diferiu da esperada pelo acaso e compreendeu três taxocenoses distintas de anuros que foram explicadas pelo conjunto de variáveis ambientais de riachos permanentes, represas permanentes e poças temporárias. Registramos que 19 espécies de anuros (aproximadamente 83% da riqueza total de espécies registradas nos corpos d'água monitorados) foram indicadoras da heterogeneidade ambiental: três espécies indicaram riachos permanentes, quatro indicaram represas permanentes e 12 espécies indicaram poças temporárias... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: We studied richness, composition, and patterns of temporal and spatial distributions of anuran assemblages of Morro do Diabo State Park (MDSP), the major remnant of Mesophytic Semideciduous Forest (MSF) in the state of São Paulo, Brazil. From September 2005 to March 2007 we recorded 28 anuran species (Appendix I), comprising a mix of Atlantic, Cerrado, and South American widespread species, usually considered tolerant to anthropic modifications. The low richness of species and reproductive modes, the predominance of habitat generalist species, and the high similarity with Cerrado areas can be explained by climatic seasonality of the studied area (pronounced dry season), besides its large distance in relation to centers of anuran diversification, such as coastal mountains of the wet Atlantic Forest. Rainfall and photoperiod explained about 77% of calling activity of the whole assemblage, while rainfall alone in temporary habitats and photoperiod in permanent ones explained the calling season. We recorded high temporal overlap for calling males, but segregation for tadpoles. Spatial distribution of anuran species among breeding sites of the MDSP (Appendix II) differed of expected by chance and comprised three distinct anuran assemblages that were explained by the suite environmental variables of permanent streams, permanent dams, and temporary ponds. We recorded that 19 species (about 83% of total anuran species recorded in monitored sites) were indicators of environmental heterogeneity: three anuran species indicated permanent streams, four indicated permanents dams, and 12 anuran species indicated temporary ponds. Regarding to micro-spatial distribution of anuran species at two temporary ponds of MDSP, we recorded that males of most pairs of species (96%) used distinct sites for calling activities. The best combination of variables discriminating anuran species regarding male... (Complete abstract click electronic access below) / Doutor
55

Terrestrial habitat requirements of a suite of anuran species inhabiting a semi-arid region of South East Queensland

Chambers, Joanne January 2008 (has links)
Hypothesised causes of the observed world-wide decline of amphibian populations are varied and in some cases contentious. Insufficient information relating to the autecology of many amphibian species can cause erroneous speculations regarding critical habitat requirements and hence management programs designed to enhance population viability are often unsuccessful. Most amphibians display a bi-phasic life history that involves occupation of an aquatic breeding habitat and terrestrial habitats that are used for foraging, and shelter from predation and environmental stress. However, the focus of most amphibian research is centred on the breeding habitat, with limited research being conducted into the terrestrial habitat requirements of most amphibian species. Barakula State Forest is a large continuous area of open woodland situated in the semi-arid region of Queensland. The forest supports 21 species of endemic anurans, many of which use ephemeral waterbodies for breeding. This area is, therefore, an ideal location to test the relative importance of terrestrial habitat on the distribution of a suite of frogs that display different morphological and physiological characteristics. On the landscape scale, the attributes of the terrestrial environment at three survey areas within Barakula were similar. However, at the patch scale, ground truthing showed there were considerable variations in vegetation and ground cover attributes within and between each survey site. Measured properties of the soil also tended to vary within and between sites. Soil texture ranged from sandy to heavy clay, soil pH ranged from 3.9 to 6.4 and soil moisture varied considerably. Agar models, used for testing evaporative moisture loss at different microhabitats, retained significantly higher levels of moisture when positioned in the buried microhabitat during summer, but in winter, models that were placed under leaf litter retained higher levels of moisture. Variations in levels of moisture loss at the five different microhabitats were evident within and between the survey sites. Despite a prolonged drought, 1844 native frogs representing 17 species were pitfall trapped. Members from the family Myobatrachidae comprised 94% of these captures, and burrowing species accounted for 75% of total captures. Species were not randomly distributed within or between the survey sites. Vegetation attributes and soil properties played a significant role in influencing the catch rates and traplines that supported similar vegetation and soil attributes also tended to catch similar species. Capture rates of six of the seven burrowing species were significantly influenced by soil properties. When given a choice of four different microhabitats created in enclosures, individuals from five species showed varying responses to habitat choice during night time activity. During daylight all species tended to avoid bare areas and burrowing species tended to burrow under some form of cover. Pseudophryne bibronii metamorphs showed a significant avoidance to soils with high pH. The number of Limnodynastes ornatus metamorphs was significantly and positively correlated with moisture levels surrounding a breeding area. Limnodynastes ornatus metamorphs tended to avoid areas that did not support some form of cover. Embryos from the terrestrial egg laying P. bibronii translocated to sites with varying levels of soil pH, suffered increased mortality where the soil pH was &gt4.8. In the laboratory, embryonic survival was not significantly different between the four pH treatments. There was a significant influence of fungal infection on survival rates and ranked fungal infection was significantly different between the four pH treatments. The terrestrial environment at the three survey sites has provided sufficient protection from environmental elements to allow a large diversity of anurans to persist for long periods without access to permanent water. Management must consider the importance of the non-breeding habitat when defining buffer zones, restoration programs and conservation strategies to ensure that the complete set of ecological requirements for frog species are provided.
56

Estudo comparativo da taxocenose de anuros de quatro municípios do Lagamar Paulista

Ramos, Juliana Zina Pereira [UNESP] 18 January 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:35:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-18Bitstream added on 2014-06-13T19:25:16Z : No. of bitstreams: 1 ramos_jzp_dr_rcla.pdf: 1486958 bytes, checksum: 1deaf8b552b3e70b44e3724804558867 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Durante o período de fevereiro de 2007 a janeiro de 2009, foram estudadas as taxocenoses de anuros de quatro Municípios do Lagamar Paulista, litoral sul do Estado de São Paulo, um complexo estuarino-lagunar caracterizado por três ilhas continentais e porções continentais adjacentes a esta ilhas. Com o objetivo de inventariar as comunidades de anuros da costa (Iguape e Pariquera-Açu) e das ilhas (Ilha de Cananéia, Ilha do Cardoso e Ilha Comprida) e revelar padrões de diversidade e similaridade faunística, foram realizadas campanhas mensais com duração de três a quatro dias consecutivos nos quais as espécies de anuros foram registradas através do uso de duas metodologias complementares (armadilhas de interceptação e queda e procura ativa). Os resultados obtidos através da análise dos dados de composição comparada de espécies revelaram que as comunidades estudadas estão estruturadas. As comunidades das ilhas de Cananéia e Comprida apresentaram um alto grau de similaridade em diversidade de espécies. O mesmo pode ser dito para Pariquera-Açu em relação à Iguape. A análise molecular da estrutura de populações de cinco espécies de anuros ocorrentes nos cinco locais estudados [Rhinella ornata, Dendrophryniscus leucomystax, Hypsiboas albomarginatus, Scinax sp. 1 (aff. alter) e Haddadus binotatus] revelou padrões diferenciados de estrutura e diferentes cenários de formação destas populações. Mecanismos pretéritos relacionados à colonização das ilhas por espécies de anuros, bem como características intrínsecas das espécies colonizadoras podem ter sido os maiores responsáveis pelos padrões de estrutrura de comunidades e estruturas populacionais observados para os locais estudados. O presente estudo evidencia a importância de estudos multidisciplinares para a compreensão da estrutura e evolução de populações e comunidades de anuros. / From February 2007 to January 2009 we studied the anuran taxocenosis of four municipalities of an estuary-lagoon complex in the south coast of São Paulo State (Lagamar) composed by three continental Islands and continental areas adjacent to these Islands. In order to survey the anuran communities from the continental areas (Iguape Pariquera-Acu) and Islands (Cananéia, Cardoso, and Comprida), and to determine patterns of diversity and faunal similarity we conducted monthly surveys lasting three to four days each in which anuran species were registered through two complementary methods (pitfall traps with drift fences and active search). The species composition analysis revealed that the anuran communities of the Lagamar are structured. Anuran communities from Cananéia and Comprida Island, as well as Pariquera-Açu and Iguape, were more similar regarding species composition. The analysis of molecular diversity patterns of five species shared among the studied areas [Rhinella ornata, Dendrophryniscus leucomystax, Hypsiboas albomarginatus, Scinax sp. 1 (aff. alter), and Haddadus binotatus] revealed different structural patterns and historical scenarios of populations arrangements. Historical mechanisms related to island colonization by some anuran species as well as intrinsic characteristics of these species may account for contemporary patterns of community and population structure. The present study reinforces the importance of interdisciplinary studies for the comprehension of population and community structure and evolution.
57

Influência dos efeitos da borda sobre a comunidade de anfíbios anuros de serapilheira da Mata Atlântica da Estação Biológica de Boracéia, SP / Influence of edge effects on the leaf-litter anuran community of the Atlantic rain Forest of the Estação Biológica de Boracéia, SP

Carolina Ortiz Rocha da Costa 27 June 2014 (has links)
O objetivo deste estudo foi determinar a natureza e a extensão dos efeitos de borda sobre a estrutura da comunidade de anuros de serapilheira da Estação Biológica de Boracéia (EBB). A EBB é uma unidade de conservação com 16.450 ha pertencente à Universidade de São Paulo (USP) e situa-se na Serra do Mar, domínio da Mata Atlântica, a uma altitude de 900m, em uma das regiões mais úmidas do Brasil. A comunidade de anuros de serapilheira foi amostrada entre maio de 2012 a outubro de 2013 nos limites da floresta nativa com cultivo de eucaliptos. Foram amostradas 63 parcelas de 5×5 m dispostas em sete transectos com nove faixas de distância da borda (-50, -25, 0, 25, 50, 75, 100, 125 e 150 m); além de sete parcelas na área-controle, totalizando 1.750 m2 amostrados.Para caracterizar o ambiente em cada faixa de distância, foram medidas as seguintes variáveis: temperatura e umidade relativa da serapilheira, profundidade da serapilheira, cobertura do dossel, diâmetro à altura do peito (DAP) e altura das árvores. Foram capturados 312 indivíduos de 23 espécies de anuros, sendo 19 endêmicas da Mata Atlântica. A comunidade apresentou alta diversidade de espécies (H` = 2,17).A riqueza e a diversidade de anuros aumentaram com a distância da borda florestal. A alta diversidade ß registrada (0,819) para a comunidade de anuros de serapilheira indicou uma alta taxa de substituição de espécies nas diferentes distâncias da borda.Houve maior variação da temperatura e umidade próxima à borda florestal e na área externa à floresta nativa.A riqueza e abundância de anuros foram negativamente correlacionadas com a temperatura e positivamente com a umidade da serapilheira, a densidade do dossel e o diâmetro das árvores.O cultivo de eucalipto pode ter minimizado os efeitos da borda sobre a comunidade de anuros. Os fatores de maior influência sobre a estrutura da comunidade de anuros de serapilheira foram as variações microclimáticas (até a faixa 75 m da borda) e estruturais (densidade do dossel e DAP). Diferentes respostas das espécies aos efeitos de borda indicaram duas faixas de transição para a comunidade de anuros de serapilheria ao longo do gradiente de distância. O primeiro ocorreu entre a borda e os primeiros 25 m no interior da floresta devido à drástica redução da riqueza e da abundância de espécies. O segundo ocorreu entre 50 e 75 m para o interior da floresta, alterando a composição de espécies. Em uma avaliação geral, a extensão dos efeitos de borda na EBB limitou-se a 50 m no interior da floresta. As espécies apresentaram respostas distintas aos efeitos da borda, porém, todas estas estão de acordo com o modelo transacional negativo, pois houve perda da qualidade do hábitat a partir da borda, o que afetou a riqueza e a abundância. / This study aimed at determine nature and extension of edge effects on the structure of a leaf-litter anuran community at the Ecological Station of Boracéia (EEB). EEB is a reserve with 16,450 ha belonging to University of São Paulo (USP) and lies at Serra do Mar, domain of Atlantic Forest, 900 m altitude, in one of the wettest regions of Brazil. The leaf-litter anuran community was sampled between May 2012 and October 2013, on the edge of a native forest with eucalypts cultivation. Sixty-three 5×5 m plots displayed in seven transects along nine distance strips of the edge (-50, -25, 0, 25, 50, 75, 100, 125 e 150 m) were sampled. To characterize the environment in each distance strip, the following measurements were taken: leaf-litter temperature and relative humidity, leaf-litter deepness, canopy cover, diameter at breast height (DBH) and height of trees. Three hundred and twelve individuals of 23 species were captured, being 19 endemic from Atlantic forests. The community presented high species diversity (H` = 2,17). Anuran richness and diversity increased with the distance from the forest edge. High ß diversity found for the leaf-litter anuran community (0.819) indicated a high species turn over along different distances from the edge. There were higher temperature and humidity variation near the edge and outside native forest. Anuran richness and abundance were negatively correlated to temperature and positively with leaf-litter humidity, canopy cover and DBH. Eucalypts cultivation could have minimized the edge effects on the anuran community. Factors most influencing the structure of the leaf-litter anuran community were microclimatic (until 75 m from the edge) and structural (canopy cover and DBH) variations. Different species responses to the edge effects indicated two transition strips for the leaf-litter anuran community along the distance gradient. The first occurred between the edge and the first 25 m inside the forest due to drastic reduction of species richness and abundance. The second occurred between 50 and 75 m inside the forest, changing species composition. In a general, the extension of the edge effects at EEB was limited at 50 m inside the forest. Species presented distinct responses to the edge effects, however, all of them agree with the negative transational model, because there were loss of habitat quality from the edge, which affected richness and abundance.
58

DIVERSIDADE E PADRÕES DE USO DO ESPAÇO DE ANFÍBIOS ANUROS DA ÁREA DE PROTEÇÃO AMBIENTAL DO IBIRAPUITÃ / DIVERSITY AND PATTERNS IN SPACE USAGE OF ANURAN AMPHIBIANS AT THE ÁREA DE PROTEÇÃO AMBIENTAL DO IBIRAPUITÃ

Bolzan, Ana Maria Rigon 19 February 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Studies of biodiversity surveys and habitat requirements are essential in landscapes threatened by anthropogenic conversion, such as those that make up the Pampa biome. In the present study we determined the spatial distribution of richness of anurans at the Área de Proteção Ambiental (APA) do Ibirapuitã, the largest protected federal area within the Pampa biome in Brazil. Thus we: (1) describe the composition of anuran community regarding species richness, abundance, constancy of occurrence and reproductive modes; (2) compare the frogs composition with other localities of grassland southernmost of South America; (3) tested whether local variables of waterbodies, space and landscape are determinants of species richness, and (4) tested whether environmental heterogeneity influences the structure of anuran community. Sampling was carried from October to November 2012 and at November 2013, the searching at breeding sites method, tadpole collecting and examination of specimens housed in herpetological collections. A total of 64 waterbodies (40 ponds and 24 streams) were sampled for the anuran amphibians, as well as were recorded environmental descriptors in three scales: local, space, and landscape. We recorded the occurrence of 33 anuran species at the APA Ibirapuitã. The registered anurans are typical of open areas, and at least 10% of them are restricted of the grassland areas to the subtropical region of South America, including two endangered species at the global and state levels. Pseudopaludicola falcipes was the most abundant species and Hypsiboas pulchellus was the species most frequently recorded. Five reproductive modes were recorded, and the deposition and the development of exotrophic tadpoles in lentic waterbodies was the most common mode (57.5%). Cluster analysis revealed five groups with more than 50% similarity, whose structure was influenced by geographic distance, but can be partially interpreted by regional peculiarities. We used generalized regression models considering the set of descriptors as predictors of anuran species richness. Subsequently, we use a partition of variance to evaluate the independent and shared explicability between different sets of predictors. Finally, we use a Canonical Redundancy Analysis to explore the role of environmental descriptors on the species abundance of frogs in ponds and streams. The richness in ponds was influenced by the local variable representing the area of waterbodies. Already the abundance was correlated with the percentage of vegetation on the shores and the water temperature. In streams, the species richness of anurans was correlated with a local variable (number of strata of emergent vegetation) and a landscape variable (distance in relation to human residences). Species abundance was affected by higher vegetation strata (> 200 cm) on the shores and by water electrical conductivity. The combined contribution of local and landscape variables have important implications for understanding how amphibians are distributed in the grassland environment. Our work shows the importance of conserving grassland biomes which are increasingly threatened by human activities. / Studies of biodiversity surveys and habitat requirements are essential in landscapes threatened by anthropogenic conversion, such as those that make up the Pampa biome. In the present study we determined the spatial distribution of richness of anurans at the Área de Proteção Ambiental (APA) do Ibirapuitã, the largest protected federal area within the Pampa biome in Brazil. Thus we: (1) describe the composition of anuran community regarding species richness, abundance, constancy of occurrence and reproductive modes; (2) compare the frogs composition with other localities of grassland southernmost of South America; (3) tested whether local variables of waterbodies, space and landscape are determinants of species richness, and (4) tested whether environmental heterogeneity influences the structure of anuran community. Sampling was carried from October to November 2012 and at November 2013, the searching at breeding sites method, tadpole collecting and examination of specimens housed in herpetological collections. A total of 64 waterbodies (40 ponds and 24 streams) were sampled for the anuran amphibians, as well as were recorded environmental descriptors in three scales: local, space, and landscape. We recorded the occurrence of 33 anuran species at the APA Ibirapuitã. The registered anurans are typical of open areas, and at least 10% of them are restricted of the grassland areas to the subtropical region of South America, including two endangered species at the global and state levels. Pseudopaludicola falcipes was the most abundant species and Hypsiboas pulchellus was the species most frequently recorded. Five reproductive modes were recorded, and the deposition and the development of exotrophic tadpoles in lentic waterbodies was the most common mode (57.5%). Cluster analysis revealed five groups with more than 50% similarity, whose structure was influenced by geographic distance, but can be partially interpreted by regional peculiarities. We used generalized regression models considering the set of descriptors as predictors of anuran species richness. Subsequently, we use a partition of variance to evaluate the independent and shared explicability between different sets of predictors. Finally, we use a Canonical Redundancy Analysis to explore the role of environmental descriptors on the species abundance of frogs in ponds and streams. The richness in ponds was influenced by the local variable representing the area of waterbodies. Already the abundance was correlated with the percentage of vegetation on the shores and the water temperature. In streams, the species richness of anurans was correlated with a local variable (number of strata of emergent vegetation) and a landscape variable (distance in relation to human residences). Species abundance was affected by higher vegetation strata (> 200 cm) on the shores and by water electrical conductivity. The combined contribution of local and landscape variables have important implications for understanding how amphibians are distributed in the grassland environment. Our work shows the importance of conserving grassland biomes which are increasingly threatened by human activities.
59

Habitat use of the western toad in north-central Alberta and the influence of scale

Browne, Constance 06 1900 (has links)
The western toad (Anaxyrus boreas, formerly Bufo boreas) is one of many amphibian species considered to be at risk of extinction (COSEWIC status is Special Concern). I examined habitat use patterns of the western toad using several methods to gain a better understanding of its habitat requirements. I examined the relationship between relative abundance of the western toad and two sympatric amphibian species (wood frog, Lithobates sylvaticus; and boreal chorus frog, Pseudacris maculata) and habitat features at eight scales of spatial extent at 24 wetlands in the Lake Utikuma region of Alberta, Canada. I radio-tracked adult western toads in three study areas in the Aspen Parkland and Boreal regions of north-central Alberta to examine 1) whether patterns of habitat selection change with different scales of spatial extent, spatial resolution, habitat composition, temporal period, and between males and females during the active period, 2) habitat used for hibernation, and 3) factors influencing the timing and nature of movements to hibernation sites. I found that the abundance of the three amphibian species was best described at different spatial extents and was related to the biology of each species. Resource Selection Function (RSF) models, created using radio-telemetry data, indicated that habitat selection was scale-dependent for western toads; differences in selection were observed among study designs, study areas, time periods, and sexes. Predictive ability did not differ significantly among study designs. However, models that were created using a fine-grained map and home-range spatial extent generally produced models with greater predictive ability than models using a coarse-grained map or population-range extent. During the active season toads selected open habitat types such as wet shrub, disturbed grass, and crop/hay fields. Western toads hibernated terrestrially in pre-existing tunnels and the majority of toads hibernated in forest stands dominated by spruce. Toads used hibernation sites 1461936 m from breeding ponds and 68% of hibernacula were communal. Arrival at and entry into hibernation sites was influenced by temperature and/or day length; larger toads moved to hibernation sites later in the year. My research results can be used to identify and protect habitat for western toads in Canada. / Environmental Biology and Ecology
60

Male Combat, Paternal Care, and the Evolution of Male Biased Sexual Size Dimorphism in the Emei Moustache Toad (Leptobrachium boringii)

Hudson, Cameron 06 September 2012 (has links)
I describe the natural history and reproductive behaviours of the Emei Moustache Toad (Leptobrachium boringii), testing the hypotheses that the species exhibits resource defense polygyny, and that combat, and paternal care lead to the evolution of male-biased sexual size dimorphism. In this study I document combat behaviour and paternal care for the first time in this species. Between February and March of 2011 and 2012, 26 female and 55 male L. boringii from Mount Emei UNESCO World Heritage Site, Sichuan, China, were observed throughout the breeding season. Prior to the breeding season, males grow 10-16 keratinized maxillary spines, which fall off once the season has ended. Throughout this time, males construct and defend aquatic nests where they produce advertisement calls to attract females. In a natural setting, I documented 14 cases involving a total of 22 males where males used their moustaches for aggressive interaction, and nest take over was observed on seven occasions. Despite my predictions, neither male body size nor body condition significantly affects the outcome of an aggressive interaction, though this may be representative of a low sample size. Males were also observed to possess injuries resulting from combat. Combat trials conducted in artificial nests demonstrated heightened aggression from resident males towards intruders. Genetic analysis using microsatellite markers revealed several cases of multiple paternity, both within nest and within clutch, indicating that some alternative male reproductive strategy, such as satellite behaviour is occurring. Larger males were observed to mate more frequently, and in multiple nests, suggesting that females are selecting for larger males, or that larger males are more capable of defending high quality territories. Males showed evidence of paternal care behaviours by remaining with the nests once females had left, moving throughout the nest cleaning, touching the eggs, and blowing bubbles into the centre of the doughnut-shaped egg masses. From this study I conclude that the male biased sexual size dimorphism in L. boringii is likely the result of both combat and paternal care behaviours creating a selection pressure on male body size.

Page generated in 0.0524 seconds