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Anurofauna em uma área de ecótono entre Cerrado e Floresta Estacional: diversidade, distribuição e a influência de características ambientaisOliveira, Thiago Alves Lopes de [UNESP] 27 August 2012 (has links) (PDF)
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000698175.pdf: 421291 bytes, checksum: e63db4fb8c10673ad3f1ee9c9b5797d2 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Dois dos maiores desafios da ecologia de comunidades são encontrar padrões a respeito dos grupos de espécies que vivem em seus ambientes e entender os processos que produzem os padrões atuais. Nesse sentido, estudos que descrevam as comunidades biológicas, explorando os padrões de distribuição das espécies em diferentes escalas espaciais e temporais e que analisem o que poderia influenciar essa distribuição, são de grande interesse geral e nos fornecem importantes informações das espécies e habitats que conhecemos. Dessa forma, esse trabalho visa compreender a estrutura de uma comunidade de anfíbios anuros em uma área de ecótono entre cerrado e floresta estacional no nordeste do Estado de São Paulo (Estação Ecológica de Jataí – EEJ). Essas fisionomias no Estado de São Paulo sofreram intensamente a ação de fragmentação e perda de habitat, devido principalmente à urbanização, pecuária e cultivo de monoculturas como a cana-de-açúcar. A área de estudo é a maior unidade de conservação do bioma Cerrado no Estado de São Paulo e apresenta uma interessante área de estudo devido à configuração espacial da área, uma transição entre mosaico de fisionomias de Cerrado e Floresta Estacional. O objetivo do trabalho foi descrever a diversidade da anurofauna terrícola e entender os padrões de distribuição de abundâncias das espécies e de coocorrência. Além desses objetivos, e devido ao viés encontrado na maioria dos trabalhos de ecologia de comunidades que avaliam a influência de descritores dos habitats aquáticos sobre a riqueza e abundância de anfíbios anuros, nosso trabalho também visa compreender os efeitos das características dos habitats terrestres sobre a abundância da anurofauna avaliando quais características do meio físico, como cobertura do dossel, porcentagem... / Two of the biggest challenges in community ecology are the capacity to find patterns in groups of species that live in their environment and to understand the processes that produce these patterns. Accordingly, studies describing the biological communities, exploring their species distribution patterns at different spatial and temporal scales and analyzing what factors influence the distribution of species, are of great interest and provide important information of the species and habitats that we know. Thus, this study aims to understand the structure of a community of frogs and toads in an area of ecotone between savanna and semideciduous forest in the northeastern of São Paulo state (Jataí Ecological Station - JEE). These physiognomies in the state of Sao Paulo suffered intense fragmentation and habitat loss, primarily due to urbanization, livestock and cultivation of monocultures as sugarcane. The study area are the largest protected area of Cerrado in São Paulo state, and presents an interesting area of study due to the spatial configuration of transition between a mosaic of Cerrado and a Floresta Estacional. The aim of this study was to describe the diversity of terrestrial frogs and toads and to understand the patterns of species abundance distributions and co-occurrence. Besides these goals, and due to the bias found in most studies of community ecology to assess the influence of descriptors of aquatic habitats on the richness and abundance of amphibians, our work also aims to understand the effects of the features of terrestrial habitats on the frog’s abundance examining which features of the physical environment, such as canopy cover, percent cover soil, distance from the nearest body of water, could better predict the abundance of anurans. For this purpose, we installed pitfall traps with drift fences... (Complete abstract click electronic access below)
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Diversidade e distribuição de anfíbios no Cerrado: o papel dos fatores históricos e dos gradientes ambientais / Diversity and distribution of anurans in Brazilian Cerrado: the role of historical factors and environmental gradientsPaula Hanna Valdujo 01 March 2011 (has links)
A integração de fatores contemporâneos locais e procesos biogeográficos fornece uma visão ampla e promissora a respeito da diversidade de espécies e seus padrões de diversidade. Utilizando ferramentas recentes para análises espaciais, eu integro fatores históricos e contemporâneos para analisar a distribuição e beta diversidade espécies de anuros do Cerrado. Forneço informações atualizadas a respeito da composição e distribuição das espécies de anuros no Cerrado, com base em um extensivo levantamento em coleções zoológicas e estudos de campo. Analiso a distribuição e beta diversidade em um contexto histórico, enfocando as relações do Cerrado com seus domínios vizinhos, e suas condições ambientais. Registrei 204 espécies de anuros no Cerrado, das quais 50% são endêmicas. Espécies que ocorrem no Cerrado e mais um domínio apresentam alta estruturação espacial, na qual espécies amazônicas estão restritas à porção noroeste e as espécies atlânticas estão restritas à porção sudeste do Cerrado. Registrei espécies endêmicas em quase todas as localidades e em todas as regiões, enquanto espécies de distribuição restrita ocorrem apenas em regiões montanhosas no centro, sudeste e sudoeste do Cerrado. Gêneros originado na Mata Atlântica e Amazonia estão distribuídos em um padrão de \"tabuleiro de xadrez\" dentro do Cerrado, e co-ocorrem menos do que seria esperado ao acaso. Essa estruturação espacial no Cerrado é influenciada pela ação combinada das condições ambientais e restrições históricas: gêneros atlânticos estão predominantemente distribuídos em áreas de montanha, com baixa precipitação e próximas ao limite com a Mata Atlântica, enquanto gêneros amazônicos estão distribuídos em vales mais próximos ao limite com a amazônia. Da mesma forma, os padrões de beta diversidade no Cerrado parece estar fortemente influenciados pelos gradientes ambientais, uma vez que metade da dissimilaridade na composição de espécies entre taxocenoses foi explicada por estes preditores. Espécies endêmica responderam às condições ambientais regionais de forma mais intensa que todas as espécies em conjunto. A resposta das espécies endêmicas parece estar relacionada na similaridade do ambiente em que ocorrem em relação aos domínios vizinhos, uma vez que suas espécies-irmãs estão principalmente distribuídas por estas regiões. Meus resultados reforçam a importância de se considerar a história biogeográfica das linhagens nas análises dos padrões regionais de disversidade. Demonstro também que a heterogeneidade na distribuição das espécies de anuros pode ter uma base histórica, que interage com restrições atuais, como o clima, disponibilidade de habitat e interações ecológicas na montagem de comunidades. / Integrating local contemporary factors and biogeographic processes allows a promising and broad view on species diversity and distribution patterns. Building on the development of new tools for spatial analysis, I integrate historical and contemporary factors that may explain species distribution and beta diversity patterns of anuran amphibians in Brazilian Cerrado. Especifically, I update information about species composition and distribution of anurans in the Cerrado, based on an extensive search in zoological collections and fieldwork. I analyze distribution and beta diversity in a historical framework, focusing on the relationship of the Cerrado with its adjoining domains, and its environmental conditions. I found 204 anuran species occurring within the Cerrado, from which 50% are endemics. Species occurring in the Cerrado and one more domain present a highly structured spatial pattern, in which Amazonian species are restricted to the northwestern part of the Cerrado and Atlantic species are restricted to the southeastern part. I found Cerrado endemics in most of the localities, in all regions, whereas narrow endemics are restricted to mountain ranges in central, southeastern, and southwestern Cerrado. Cerrado anuran genera originated in Atlantic Forest and Amazon are distributed in a checkerboard pattern, and co-occur less than it would be expected by chance. This spatial structure within the Cerrado is influenced by the interplay of environmental conditions and historical constrains: Atlantic genera are mostly distributed in mountainous and upland areas, with low precipitation and closer to the boundaries of Atlantic Forest, whereas Amazonian genera are distributed in valleys closer to the boundaries of the Amazon. Similarly, patterns of beta diversity in the Brazilian Cerrado appear to be strongly influenced by the environmental gradients, since half of the dissimilarity in species composition was explained by these predictors. Endemic species responded to regional environmental conditions stronger than all species. Endemics may be responding to environment based on how similar they are to the conditions of adjoining phytogeographical domains, since their sister-species are mostly distributed in these regions. My results reinforce the importance of taking biogeographical history into account when analyzing spatial patterns of species diversity at a regional scale. I also show that the heterogeneity in anuran distribution in the Cerrado may have a historical basis, which interacts with present-day constraints, such as climate, habitat availability and ecological interactions, to shape local and regional assemblages.
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USE OF ADULT ANURAN COMMUNITIES AND DIETS TO ASSESS THE EFFECTS OF STREAM RESTORATION ON AQUATIC TO TERRESTRIAL FOOD WEB SUBSIDIESBowe, Kelsey Lyn 01 December 2019 (has links)
The boundaries between freshwater and terrestrial ecosystems can be areas of important subsidy transfers. These subsidies, such as leaf litter inputs to streams or aquatic emerging insects into riparian zones, link food webs and provide benefits to consumers in the form of nutrients and energy. Subsidies from aquatic systems tend to have high levels of essential long chain polyunsaturated fatty acids (LC-PUFAs), such as eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) that are only produced by certain forms of aquatic algae. These LC-PUFAs are highly important in growth, development, and other metabolic functions across animal groups (Brett and Muller-Navarra 1997, Gladyshev et al. 2009).
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The nose glows: investigating amphibian neuroendocrine pathways with quantum dotsJulien, Allison Rebecca 06 August 2021 (has links)
Today, amphibian extinction rates are rising at an alarming rate. Captive assurance colonies have become a hedge against extinction, and often must employ assisted reproductive technologies (ART) in species that do not readily breed in captivity. One technique that can be utilized in assisted breeding is hormone therapy, which involves the treatment of individuals with exogenous reproductive hormones. The primary delivery method used in most breeding programs is intraperitoneal injection, but many institutions either lack the training necessary to conduct this invasive procedure, or require veterinary staff to perform them, thus delaying breeding events. Therefore, there is interest in alternate means of hormone delivery. In particular, the use of intranasaladministration. The following studies were conducted to determine the efficacy of hormones administered via alternate delivery routes, and to investigate the pathways taken by both intraperitoneal and intranasal delivery methods. Through these studies, wefound that intranasal administration gonadotropin releasing hormone (GnRH), is effective at eliciting sperm production in male anurans. In order to investigate the paths taken by intraperitoneal and intranasal GnRH, I used a treatment of hormone-conjugated quantum dot nanoparticles and employed both in-vivo fluorescence imaging techniques and histological imaging. The evidence presented here suggests that the route traveled by nasally-delivered GnRH is largely swallowed and accumulates in the GI tract, buteventually diffuses into the bloodstream in large enough concentrations to exact a reproductive response. The other hormone investigated here was arginine vasotocin (AVT), a hormone known to elicit calling and amplexus behaviors in amphibians. Though limited reproductive behaviors were observed in these studies, I found that both intranasal and intraperitoneal delivery of AVT resulted in water uptake and retention in males. Fluorescence imaging revealed that AVT, when administered nasally, is largely swallowed, similarly to GnRH. Intraperitoneally-injected AVT, however, was found to accumulate in large concentrations within the interrenal gland and kidney, where it likely stimulated the observed osmoregulatory effects. This study therefore offers insight into an effective alternate hormone delivery method (nasal) and provides compelling evidence into the organs wherein GnRH and AVT act following two different delivery routes.
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Relação sazonal entre reprodução, imunidade e ocorrência de endoparasitas em anfíbios anuros da Caatinga / Seasonal relationship between reproduction, immunity and occurence of endoparasites of anuran amphibians of CaatingaMadelaire, Carla Bonetti 19 October 2012 (has links)
A grande maioria das espécies de anfíbios anuros apresenta um padrão de reprodução sazonal, caracterizado nos machos por um pico de andrógenos que desencadeia maturação testicular, bem como manutenção do comportamento sexual. No entanto, os altos níveis de andrógenos podem apresentar um efeito imunossupressor, podendo também aumentar a probabilidade de infecções parasitárias. A Caatinga brasileira é caracterizada por altas temperaturas e chuvas sazonais e imprevisíveis que determinam o padrão reprodutivo e de atividade dos anuros dessa região, algumas espécies como P. diplolister apresentam comportamento de estivação durante a seca, já Rhinella Jimi e R. granulosa permanecem ativos quanto ao forrageamento durante este período. As drásticas variações deste ambiente poderiam acentuar os ajustes fisiológicos apresentados por essas espécies, principalmente para a espécie estivadora. Foram estudadas as inter-relações entre caracteres morfológicos, fisiológicos e parasitológicos dessas três espécies de anuros, em três períodos distintos, (A) durante a temporada reprodutiva, em um período entre dois surtos reprodutivos (período entre chuvas); (B) durante um surto reprodutivo que acompanhou um evento de chuvas e (C) no período da seca. As duas espécies de Rhinella apresentaram evidências de modulações imunológicas de acordo com período, e correlações entre caracteres imunológicos, fisiológicos e número de parasitas. Pleurodema diplolister apresentou padrões imunológicos coerentes com o processo de economia energética durante a estivação, como redução do número de leucócitos totais, com concomitante aumento na contagem de eosinófilos e relação positiva entre intensidade parasitária e contagem total de leucócitos. As três espécies estudadas apresentaram depleção das reservas energéticas durante o período reprodutivo, possivelmente associada à alta demanda energética do comportamento vocal. Também apresentaram padrões similares de maturação testicular, evidenciando que as espécies estudadas possuem um padrão de reprodução oportunista, típico de espécies que ocupam ambientes áridos. As três espécies também apresentaram relação entre parâmetros imunológicos e carga parasitária, no entanto, para esclarecer as relações causais entre esses fatores, são necessários testes adicionais de desafio imunológico, bem como infecção experimental por parasitas / Most part of anurans show a seasonal pattern of reproduction, when males display high levels of androgens associated with testicular development and sexual behavior maintenance. However, high androgens levels also can shows an immunosuppressive effect resulting in increased parasitological disease. The semi-arid Caatinga is an environment characterized by high temperatures and unpredictable seasonal rains that determine the breeding season of anurans. During the dry season, Pleurodema diplolister aestivate borrowed, Rhinella granulose and R. jimi remain foraging. Drastic variation in this environment could increase the physiological adjustments displayed by these species, mainly by P. diplolister. The inter-relation between morphological, physiological and parasitological characters was studied in these three anuran species, in three different periods: (A) dry season, (B) during the rainfall, when males are calling, and (C) in the interval between rainfalls, when males are foraging within the reproductive season. The Rhinella species presented evidences of immunological modulations according to the period and correlations between immunological, physiological parameters and number of parasites. Pleurodema diplolister presented immunological patters consistent with the process of energy economy during aestivation, including total leukocyte reduction, along with eosinophil increase and positive relation between total leukocyte and parasite intensity. The three species presented depletion in energy reserves during the breeding season, possibly associated with the high energy demand of vocal behavior. They also presented a similar pattern of testicular development, indicating that these species present opportunistic reproduction pattern, typical of species that occupy arid environments. The studied species also showed correlations between immunological parameters and parasite load, however, to clarify the causal relation between these parameters, additional immunological challenges and experimental parasite infection are necessary
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Influência antrópica sobre a riqueza e abundância de anfíbios anuros em alagados de um remanescente de Mata Atlântica, Paraíba, BrasilAlves, Brygida Carolyne Freire 24 July 2014 (has links)
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Previous issue date: 2014-07-24 / The Neotropical Region has the highest rates of endemism and species richness of amphibians
in the world, but there are many gaps in the evaluation of the structure of assemblages in
neotropical environments, mainly in the Atlantic Forest. These environments suffer a gradual
process of fragmentation resulting from anthropogenic activity, being characterized as a
mosaic of forest patches with different disturbances regimes. In this context, the present study
aimed to evaluate the anuran assemblages associated with puddles and flooded areas used as
breeding sites in the Biological Reserve Guaribas, assessing the existence of patterns of
resource use in along the anthropogenic disturbance and the influence of habitat and
environmental variables. The samplings were made during the rainy season and wet season
form 2013 and twelve environmental variables corresponding to physicochemical aspects of
water and soil, as well as characteristics of the vegetation stratification. The environmental
variables that contributed most to the dissimilarity between areas was described by PCA, the
patterns in structuring the assemblage of anurans between areas was verified by nMDS, the
environment/species matrices were related through analysis for CCA check the influence of
these environmental factors on anuran assemblage. The hypotheses to be tested were: (1)
there is a strong relationship between habitat structure with the anuran assemblages and (2)
the environmental factors the puddles and flooded areas influence the patterns of the
assemblages structure in a gradient of anthropic disturbance. Twenty species totaling 289
individuals were recorded. The results corroborate the patterns of distribution and richness of
frogs in puddles and flooded areas and showed a strong influence of environmental factors.
The variables that better explained the structure of the assemblies were related to vertical
stratification of vegetation, litter depth, depth of the water body, pH and water temperature.
there was a record of the use of 11 distinct microhabitats for reproductive activity, herbaceous
vegetation in water and soil and dry soil were the most used. The widespread use of different
microhabitats for several species, distributed in breeding sites, indicate the importance of
these habitats for the conservation of local anurans in the Atlantic Forest. / A região Neotropical apresenta os maiores índices de riqueza de espécies e
endemismos de anfíbios anuros do mundo, porém muitas são as lacunas quanto à avaliação da
estruturação das taxocenoses em ambientes neotropicais, sobretudo na Mata Atlântica. Esses
ambientes sofrem com o gradativo processo de fragmentação decorrentes da ação antrópica,
sendo caracterizadas como um mosaico de manchas de florestas, com diferentes regimes de
distúrbios. Nesse contexto, o presente estudo teve por objetivo avaliar a taxocenose de anuros
associada a poças e zonas alagadas, utilizadas como sítios reprodutivos na Reserva Biológica
Guaribas, verificando a existência de padrões no uso de recursos em um eixo de perturbação
antrópica e a influência das variáveis ambientais e dos habitats estudados. As coletas foram
realizadas durante o período chuvoso e de estiagem de 2013 e doze variáveis ambientais
correspondentes a aspectos fisicoquímicos da água e do solo, bem como características da
estratificação vegetal. As variáveis ambientais que mais contribuíram para a dissimilaridade
entre as áreas foram descritas através da PCA, os padrões na estruturação da taxocenose de
anuros entre as áreas foram verificados através da técnica de ordenação nMDS, as matrizes
ambiente/espécies foram relacionadas através da análise CCA para verificar a influência
desses fatores ambientais na taxocenose de anuros. As hipóteses testadas foram: (1) há uma
forte relação entre a estrutura do hábitat com as assembleias de anuros e (2) os fatores
ambientais das poças e áreas alagadas influenciam nos padrões da estrutura das assembleias
em um gradiente de perturbação antrópica. Foram registradas 20 espécies, totalizando 289
indivíduos. Os resultados corroboram com os padrões de distribuição e riqueza de anuros em
áreas alagadas e poças e evidenciaram uma forte influência dos fatores ambientais. As
variáveis que melhor explicaram a estrutura das assembleias foram estratificação vertical da
vegetação, profundidade da serrapilheira, profundidade do corpo d’água, pH e temperatura da
água. Foi registrado o uso de 11 microhábitats distintos para atividade reprodutiva, vegetação
herbácea na água e no solo e solo seco foram os mais utilizados. O uso generalizado dos
diversos microhábitats por várias espécies, distribuídos nos sítios de reprodução, indicam a
importância desses ambientes para a conservação da anurofauna local no remanescente de
Mata Atlântica.
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Predation, Palatability and the Distribution of Tadpoles in the Amazon RainforestHero, Jean-Marc, n/a January 1991 (has links)
A variety of aquatic habitats with different levels of potential predators are available to larval amphibians in Central Amazon rainforest. The anuran community at Reserva Florestal Adolfo Ducke, 25 km east of Manaus, Amazonas, Brasil, was studied to determine which species have eggs and/or larvae in water and how those larvae are distributed in time and space. The temporal and spatial distribution of potential predators as well as abiotic characteristics of these waterbodies were determined simultaneously to test for correlations with the distribution of tadpoles. The distribution of tadpoles was strongly related to fish predation pressure. Several tadpole species were found only in waterbodies with high fish abundance and thus have the ability to survive with fish. Most of these tadpoles were found to be unpalatable in controlled experiments. Unpalatability is the major adaptation allowing the coexistence of tadpoles and fish and is thus a major factor affecting tadpole community composition in this system. Controlled experiments showed that fish do not eat anuran eggs while the tadpoles of Leptodacrylus knudseni and Osteocephalus taurinus ate all types of eggs offered. The percentage of anurans with aquatic oviposition was positively related to fish abundance and negatively related to the occurrence of species of tadpole that ate eggs in experiments. These findings suggest that the present patterns of anuran distribution represent an evolutionary response to predation on the eggs and larvae. Contrary to the models of Heyer et al. (1975) and Wilbur (1984), desiccation and predation-pressure were not the major factors affecting species richness within waterbodies of the RFAD rainforest. In support of the model of Heyer et al. (1975), anuran species richness was correlated with the size of the waterbody. This could be because the size of the waterbody is related to increased complexity and availability of microhabitats. The range of volumes of waterbodies was also found to directly affect species richness of the RFAD community. While predation appeared to have a limited effect on species richness of individual ponds, predation-pressure was found to have a major influence on species composition. Anuran eggs and larvae survived with specific predators by possessing particular survival-traits (e.g. unpalatability and oviposition strategies). However, survival-traits were not effective against all predators in all habitats. The distribution of different predators among ponds provides a patchy environment on a local scale (i.e. within ponds). When combined with the variety of survival-traits exhibited by the anuran species, this spatial patchiness in predation contributes towards species richness within the anuran community of the RFAD rainforest.
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Altitudinal Variation in the Life History of Anurans in Southeast QueenslandMorrison, Fiona Clare, n/a January 2002 (has links)
Global declines and disappearances of amphibians from high altitude, pristine habitats have been reported in recent years. To date the cause of many of these declines and/or disappearances has not been identified. Although it is well documented that life history characteristics of temperate amphibians are influenced by altitude (due to systematic variation of temperature with altitude), little work has been carried out on the effects of altitude on Australian anurans. This lack of ecological data is a major impediment to identifying the causal factors responsible for amphibian declines. Due to differences in life history characteristics, high altitude populations may be less resilient than their lowland counterparts and subsequently may be more vulnerable to extinction. Consequently, the main aim of this study was to determine whether altitude influenced life history characteristics and ultimately population resilience of anurans in the southeast Queensland region. Six anuran species; Litoria chloris, L. lesueuri, L. pearsoniana (Anura: Hylidae), Mixophyes fasciolatus, M. fleayi and M. iteratus (Anura: Myobatrachidae) were studied over three field seasons (1997-1999) in 18 sites of varying altitude (100-950m) in the southeast Queensland region. The life history characteristics examined were: activity and breeding season length, fecundity and egg size, number of clutches produced per season, tadpole growth and development rates, longevity, age at maturity, reproductive life span, average lifetime fecundity, survival and recapture rates. The data were collected using a combination of field-based surveys (body sizes, clutch sizes, and survival and recapture rates), museum specimen dissections (clutch and egg sizes), reciprocal transplant field experiments (tadpole growth and development rates) and skeletochronology (longevity, age at maturity, reproductive lifespan and average lifetime fecundity). On average, high altitude populations of all species had shorter breeding and activity seasons than low altitude populations (up to 10 weeks less in some cases). The magnitude of the difference in breeding season length varied among years depending on the average temperature and rainfall for the year; i.e. differences appeared greater in warmer and wetter years. Within a population males had longer breeding and activity seasons than females. Although breeding season length varied with altitude, the number of nights that individuals were active within the breeding season did not vary; i.e. low altitude populations were not active for more nights despite having a longer breeding season. This result was attributed to the absence of a relationship between individual activity and environmental variables (air temperature, rainfall, etc.) in many of the populations. Generally, intraspecific clutch size did not vary significantly with altitude. This result was due to the absence of a significant relationship between female body size and altitude (as clutch size is proportional to female body size). Egg size also did not vary with altitude however, suggesting egg size may be canalized (i.e. fixed) in these species. Results also suggest that females of these species only produce one clutch of eggs per season. Interspecific differences in reproductive characteristics largely reflected differences in reproductive mode, larval habitat and female body size. Altitude negatively influenced growth and development rates in L. chloris and development rates in L. pearsoniana. Tadpoles raised at high altitudes were also generally larger at each Gosner Development Stage in both species. The results of the reciprocal transplant experiments suggested that most of the variation in growth and development rates was due to environmental factors (water temperature) rather than genetic or maternal factors. Altitude or genetic factors did not significantly affect tadpole survival in either species. The results suggest that tadpoles occurring at high altitudes take longer to reach metamorphosis and do so at a larger size than their lowland counterparts. With the exception of L. lesueuri, skeletochronology was suitable for age estimation in the study species. Altitude had a significant effect on the age at maturity or longevity in some of the species, however there were trends toward older individuals and older ages at maturity in high altitude populations for the remaining species. Females were generally older than males for all species and in the case of longer-lived species (i.e. Mixophyes spp.) also tended to be older when breeding for the first time. The large overlap of body sizes of individuals of different ages demonstrates that body size is a poor indicator of age in these species. This is the first study to estimate average lifetime fecundity for more than one amphibian species and/or population. The results suggest that the absence of significant altitudinal variation in the average lifetime fecundity of different populations is due to tradeoffs made by females (current reproduction vs. survival). There was no significant altitudinal variation in annual survival and recapture rates in any of the species, and generally there was no difference in the survival and recapture rates of males and females in each population. Within a year, monthly survival and recapture rates were more variable at low than high altitudes and this was attributed to the longer breeding season of low altitude populations. The results did not support previous studies that suggested there was a size bias in survival and recapture rates. The shorter breeding seasons, slower growth and development rates, older age at maturity and greater longevity found in the high altitude study populations will result in increased generation time in those populations. In turn, increased generation time can cause high altitude populations to be less resilient (i.e. population takes longer to return to equilibrium after a disturbance away from equilibrium) (Pimm et al. 1988, Pimm 1991) and ultimately more vulnerable or prone to extinction or decline. The majority of unexplained global amphibian declines have occurred at high altitudes in tropical and subtropical areas. These latitudinal patterns may be explained by the narrow range of environmental tolerances exhibited by tropical organisms resulting in mountains being effectively higher in the tropics. Consequently, high altitude tropical species are likely to be even more vulnerable than temperate species occurring at similar altitudes. Further work on the effects of geographic variation, especially interactions between altitude and latitude are needed to evaluate the hypotheses for the causes of these declines and disappearances.
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Anuran colonization of newly constructed ponds : The importance of time and distance to source populationsAlmhagen, Jimmy January 2007 (has links)
<p>Dispersal is an important factor in animal ecology. Anurans (frogs and toads) are often philopatric (home loving) but some specimens in a population usually have the capacity to disperse relatively long distances. In this study I investigated the colonization of newly constructed ponds in the southwest of Sweden by three anuran species: The common toad (Bufo bufo), the moor frog (Rana arvalis) and the common frog (Rana temporaria). The ponds were constructed between two and five years ago and were now as frequently occupied as older source ponds in the area. For the common toad and the common frog there was no correlation between distance to source populations and degree of colonization. The moor frog was more common in ponds that were situated in the vicinity of older source ponds with ample populations. The main impression was that these species rapidly colonize newly constructed ponds, at least within moderate distances from source populations. There were some differences between the species though and it seems like the moor frog have more limited dispersal abilities than the other two species.</p>
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Anuran colonization of newly constructed ponds : The importance of time and distance to source populationsAlmhagen, Jimmy January 2007 (has links)
Dispersal is an important factor in animal ecology. Anurans (frogs and toads) are often philopatric (home loving) but some specimens in a population usually have the capacity to disperse relatively long distances. In this study I investigated the colonization of newly constructed ponds in the southwest of Sweden by three anuran species: The common toad (Bufo bufo), the moor frog (Rana arvalis) and the common frog (Rana temporaria). The ponds were constructed between two and five years ago and were now as frequently occupied as older source ponds in the area. For the common toad and the common frog there was no correlation between distance to source populations and degree of colonization. The moor frog was more common in ponds that were situated in the vicinity of older source ponds with ample populations. The main impression was that these species rapidly colonize newly constructed ponds, at least within moderate distances from source populations. There were some differences between the species though and it seems like the moor frog have more limited dispersal abilities than the other two species.
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