RESUMO
Temperature impacts ectotherm performance by influencing many biochemical and physiological processes. When well adapted to their environment, ectotherms should perform most efficiently at the temperatures they most commonly encounter. In the present study, we tested how differences in temperature affects the feeding kinematics of tadpoles of two anuran species: the benthic tadpole of Rhinella schneideri and the nektonic tadpole of Trachycephalus typhonius. Benthic and nektonic tadpoles have segregated distributions within ponds and thus tend to face different environmental conditions, such as temperature. Muscle contractile dynamics, and thus whole organism performance, is primarily temperature dependent for ectotherms. We hypothesized that changes in mean temperatures would have differential effects on the feeding kinematics of these two species. We conducted a laboratory experiment in which we used high-speed videography to record tadpoles foraging at cold and warm temperatures. In general, tadpoles filmed at warm temperatures opened their jaws faster, attained maximum gape earlier, and exhibited shorter gape cycles than tadpoles in cold temperatures, irrespective of species. We also found species x temperature interactions regarding the closing phase velocity, and the percentage of time it takes tadpoles to achieve maximum gape and to start closing their jaws. These interactions could indicate that these two co-occurring species differ in their sensitivity to differences in water temperature and have temperature-dependent feeding strategies that maximize feeding performance in their preferred environment.
Assuntos
Anuros/fisiologia , Comportamento Alimentar/fisiologia , Temperatura , Animais , Fenômenos Biomecânicos , Ecossistema , Larva/fisiologia , Boca , Especificidade da Espécie , Gravação em VídeoRESUMO
The northwestern region of São Paulo was extensively deforested during the agricultural expansion in the last century and only small fragments of the original vegetation cover remained. In this study, we investigated how habitat features influence the composition, richness, and diversity of anurans in environments homogenized by agricultural activities. We sampled monthly six breeding ponds located in pasture areas during twelve months. We recorded ten environmental descriptors for each breeding pond. We found 18 anuran species. The breeding ponds were structurally similar, but species composition differed among them. The environmental descriptors influence varies for each species, as demonstrated by the different associations between species and environmental descriptors shown in the Canonical Correspondence Analysis (CCA). Seven of the ten environmental descriptors explained 67% of the species richness, showing that environmental characteristics influenced the occurrence of the different species. There is no such data set for the region and also for most Brazilian regions, despite its importance in guiding species-oriented conservation actions.
RESUMO
The northwestern region of São Paulo was extensively deforested during the agricultural expansion in the last century and only small fragments of the original vegetation cover remained. In this study, we investigated how habitat features influence the composition, richness, and diversity of anurans in environments homogenized by agricultural activities. We sampled monthly six breeding ponds located in pasture areas during twelve months. We recorded ten environmental descriptors for each breeding pond. We found 18 anuran species. The breeding ponds were structurally similar, but species composition differed among them. The environmental descriptors influence varies for each species, as demonstrated by the different associations between species and environmental descriptors shown in the Canonical Correspondence Analysis (CCA). Seven of the ten environmental descriptors explained 67% of the species richness, showing that environmental characteristics influenced the occurrence of the different species. There is no such data set for the region and also for most Brazilian regions, despite its importance in guiding species-oriented conservation actions.
RESUMO
The northwestern region of São Paulo was extensively deforested during the agricultural expansion in the last century and only small fragments of the original vegetation cover remained. In this study, we investigated how habitat features influence the composition, richness, and diversity of anurans in environments homogenized by agricultural activities. We sampled monthly six breeding ponds located in pasture areas during twelve months. We recorded ten environmental descriptors for each breeding pond. We found 18 anuran species. The breeding ponds were structurally similar, but species composition differed among them. The environmental descriptors influence varies for each species, as demonstrated by the different associations between species and environmental descriptors shown in the Canonical Correspondence Analysis (CCA). Seven of the ten environmental descriptors explained 67% of the species richness, showing that environmental characteristics influenced the occurrence of the different species. There is no such data set for the region and also for most Brazilian regions, despite its importance in guiding species-oriented conservation actions.
RESUMO
Anthropic activities have deeply changed natural environments and constantly affected the diversity and distribution of anurans. This study aimed to investigate the following questions: (1) What is the frogs composition in a pasture region with a pronounced seasonal climate in extreme northwest of the state of São Paulo? (2) How are adults and tadpoles of the species distributed temporally and spatially? (3) Is species richness correlated to descriptors of reproductive habitats heterogeneity? In the study site 20 anuran species were recorded, distributed in 11 genus of four families: Leptodactylidae (9), Hylidae (8), Microhylidae (2) and Bufonidae (1). From these, Chaunus schneideri (Werner, 1894), Physalaemus centralis Bokermann, 1962 and Physalaemus fuscomaculatus (Steindachner, 1864) were recorded only by tadpoles collection, whereas Dendropsophus minutus (Peters, 1872) and Leptodactylus labyrinthicus (Spix, 1824) occurred only in water bodies next to the studied ones. The recorded species are known by their ample geographic distribution and for colonizing disturbed areas in other localities. There was no correlation between species richness and structural complexity of water bodies. However, the greater richness was recorded in temporary water bodies that kept water more than six months throughout the year. The temporary ponds of unstable hydroperiod were colonized initially by leptodactylids, while the permanent or temporary ponds were colonized by hylids. The vocalization and reproductive activity of most species were restricted to the warm and rainy period of the year, a typical pattern of communities in the tropical seasonal regions. Five species [Chaunus schneideri, Dendropsophus nanus (Boulenger, 1889), Hypsiboas albopunctatus Spix, 1824, Leptodactylus podicipinus (Cope, 1862) and Pseudopaludicola aff. saltica (Cope, 1887)] vocalized during the dry and rainy seasons, but only C. schneideri and H. albopunctatus reproduced during the dry season. The weak spatial and temporal segregation, recorded to adults and tadpoles, is not enough to explain reproductive isolation among species. Other factors, like acoustic segregation and calling site segregation, may have major importance to explain species coexistence. Climatic severity (wide and pronounced dry season, unpredictability and inconstancy of rains in the beginning of the rainy season), along with the high level of natural habitat being converted in cultivated areas are, probably, the factors responsible for the predominance of species typical from disturbed areas.
As atividades antrópicas têm alterado profundamente os ambientes naturais e muitas vezes afetado a diversidade e distribuição dos anuros. O objetivo deste estudo foi investigar as seguintes questões: (1) qual a composição da anurofauna em uma região de pastagem com clima marcadamente sazonal no extremo noroeste paulista? (2) como adultos e girinos das espécies se distribuem temporal e espacialmente? (3) a riqueza de espécies está correlacionada com descritores da heterogeneidade dos hábitats de reprodução? Na área estudada foram registradas 20 espécies de anuros, distribuídas em 11 gêneros de quatro famílias: Leptodactylidae (9), Hylidae (8), Microhylidae (2) e Bufonidae (1). Destas, Chaunus schneideri (Werner, 1894), Physalaemus centralis Bokermann, 1962 e Physalaemus fuscomaculatus (Steindachner, 1864) foram registradas apenas por coleta de girinos, enquanto Dendropsophus minutus (Peters, 1872) e Leptodactylus labyrinthicus (Spix, 1824) ocorreram somente em corpos d'água próximos aos selecionados. As espécies registradas são conhecidas por sua ampla distribuição geográfica e por colonizarem áreas alteradas em outras localidades. Não houve correlação entre a riqueza de espécies e a complexidade estrutural dos corpos d'água. Entretanto, a maior riqueza de espécies foi registrada nos corpos d'água de longa duração. As poças temporárias de hidroperíodo instável foram colonizadas inicialmente por leptodactilídeos, enquanto que as poças permanentes ou temporárias estáveis foram colonizadas por hilídeos. A atividade de vocalização e de reprodução da maioria das espécies foi restrita ao período quente e chuvoso do ano, um padrão típico de ambientes tropicais sazonais. Cinco espécies [Chaunus schneideri, Dendropsophus nanus (Boulenger, 1889), Hypsiboas albopunctatus Spix, 1824, Leptodactylus podicipinus (Cope, 1862) e Pseudopaludicola aff. saltica (Cope, 1887)] vocalizaram durante a estação seca e chuvosa, mas apenas C. schneideri e H. albopunctatus se reproduziram durante o período seco. A fraca partilha espacial e temporal, registrada para adultos e girinos, não foi suficiente para explicar o isolamento reprodutivo entre as espécies. Outros fatores, como a partilha acústica e a segregação dos sítios de vocalização, podem ter maior importância para explicar a coexistência das espécies. A severidade climática (extensa e pronunciada estação seca, imprevisibilidade e inconstância das chuvas no início da estação chuvosa), juntamente com o elevado grau de conversão do hábitat natural em áreas de cultivo são, provavelmente, os fatores responsáveis pelo predomínio de espécies conhecidas por colonizar com sucesso áreas antrópicas em outras regiões do país.
RESUMO
Anthropic activities have deeply changed natural environments and constantly affected the diversity and distribution of anurans. This study aimed to investigate the following questions: (1) What is the frogs composition in a pasture region with a pronounced seasonal climate in extreme northwest of the state of São Paulo? (2) How are adults and tadpoles of the species distributed temporally and spatially? (3) Is species richness correlated to descriptors of reproductive habitats heterogeneity? In the study site 20 anuran species were recorded, distributed in 11 genus of four families: Leptodactylidae (9), Hylidae (8), Microhylidae (2) and Bufonidae (1). From these, Chaunus schneideri (Werner, 1894), Physalaemus centralis Bokermann, 1962 and Physalaemus fuscomaculatus (Steindachner, 1864) were recorded only by tadpoles collection, whereas Dendropsophus minutus (Peters, 1872) and Leptodactylus labyrinthicus (Spix, 1824) occurred only in water bodies next to the studied ones. The recorded species are known by their ample geographic distribution and for colonizing disturbed areas in other localities. There was no correlation between species richness and structural complexity of water bodies. However, the greater richness was recorded in temporary water bodies that kept water more than six months throughout the year. The temporary ponds of unstable hydroperiod were colonized initially by leptodactylids, while the permanent or temporary ponds were colonized by hylids. The vocalization and reproductive activity of most species were restricted to the warm and rainy period of the year, a typical pattern of communities in the tropical seasonal regions. Five species [Chaunus schneideri, Dendropsophus nanus (Boulenger, 1889), Hypsiboas albopunctatus Spix, 1824, Leptodactylus podicipinus (Cope, 1862) and Pseudopaludicola aff. saltica (Cope, 1887)] vocalized during the dry and rainy seasons, but only C. schneideri and H. albopunctatus reproduced during the dry season. The weak spatial and temporal segregation, recorded to adults and tadpoles, is not enough to explain reproductive isolation among species. Other factors, like acoustic segregation and calling site segregation, may have major importance to explain species coexistence. Climatic severity (wide and pronounced dry season, unpredictability and inconstancy of rains in the beginning of the rainy season), along with the high level of natural habitat being converted in cultivated areas are, probably, the factors responsible for the predominance of species typical from disturbed areas.
As atividades antrópicas têm alterado profundamente os ambientes naturais e muitas vezes afetado a diversidade e distribuição dos anuros. O objetivo deste estudo foi investigar as seguintes questões: (1) qual a composição da anurofauna em uma região de pastagem com clima marcadamente sazonal no extremo noroeste paulista? (2) como adultos e girinos das espécies se distribuem temporal e espacialmente? (3) a riqueza de espécies está correlacionada com descritores da heterogeneidade dos hábitats de reprodução? Na área estudada foram registradas 20 espécies de anuros, distribuídas em 11 gêneros de quatro famílias: Leptodactylidae (9), Hylidae (8), Microhylidae (2) e Bufonidae (1). Destas, Chaunus schneideri (Werner, 1894), Physalaemus centralis Bokermann, 1962 e Physalaemus fuscomaculatus (Steindachner, 1864) foram registradas apenas por coleta de girinos, enquanto Dendropsophus minutus (Peters, 1872) e Leptodactylus labyrinthicus (Spix, 1824) ocorreram somente em corpos d'água próximos aos selecionados. As espécies registradas são conhecidas por sua ampla distribuição geográfica e por colonizarem áreas alteradas em outras localidades. Não houve correlação entre a riqueza de espécies e a complexidade estrutural dos corpos d'água. Entretanto, a maior riqueza de espécies foi registrada nos corpos d'água de longa duração. As poças temporárias de hidroperíodo instável foram colonizadas inicialmente por leptodactilídeos, enquanto que as poças permanentes ou temporárias estáveis foram colonizadas por hilídeos. A atividade de vocalização e de reprodução da maioria das espécies foi restrita ao período quente e chuvoso do ano, um padrão típico de ambientes tropicais sazonais. Cinco espécies [Chaunus schneideri, Dendropsophus nanus (Boulenger, 1889), Hypsiboas albopunctatus Spix, 1824, Leptodactylus podicipinus (Cope, 1862) e Pseudopaludicola aff. saltica (Cope, 1887)] vocalizaram durante a estação seca e chuvosa, mas apenas C. schneideri e H. albopunctatus se reproduziram durante o período seco. A fraca partilha espacial e temporal, registrada para adultos e girinos, não foi suficiente para explicar o isolamento reprodutivo entre as espécies. Outros fatores, como a partilha acústica e a segregação dos sítios de vocalização, podem ter maior importância para explicar a coexistência das espécies. A severidade climática (extensa e pronunciada estação seca, imprevisibilidade e inconstância das chuvas no início da estação chuvosa), juntamente com o elevado grau de conversão do hábitat natural em áreas de cultivo são, provavelmente, os fatores responsáveis pelo predomínio de espécies conhecidas por colonizar com sucesso áreas antrópicas em outras regiões do país.