Variação sazonal em parâmetros associados à biologia termal e ao balanço hídrico na Perereca Raspa-cuia, Scinax fuscovarius (Anura: Hylidae)

• Autor(a) principal: Maenaka, Beatriz Machado
• Data de Publicação: 2022
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/216095
• topic: Amphibians; Thermal preference; Thermal tolerance; Water balance; Seasonality; Zoologia; Temperatura corporal; Estresse hídrico; Herpetologia; Anuros

Due to ectothermy and the high permeability of their skin, the thermal biology and water balance of anuran amphibians are highly influenced by variations in environmental temperature and water availability. Seasonally, environmental variations are often followed by concurrent adjustments in thermal biology and water balance. In this study, we investigated the seasonal variation in parameters associated to the thermal biology and water balance in the snouted treefrog, Scinax fuscovarius (Anura, Hylidae). This species is a midsize arboreal and nocturnal treefrog with a wide geographical distribution in South America. S. fuscovarius is known by remaining active throughout the year, which makes it particularly adequate to the goal of the present study. Thermal measured parameters included body temperature of field active frogs (TFIELD), thermal preference (TPREF) in laboratory and the minimum and maximum critical temperatures (CTMIN and CTMAX, respectively). In terms of water balance, we measured: rates of evaporative water loss (EWL, at 15, 25 and 35 °C); dehydration tolerance (EWLCRIT) and water uptake (WU) rate (both at 25 °C). Capture and measurements were carried out in the middle of the two seasons typical for the study site: the hot/wet summer and the cold/dry winter. All experiments were carried out with adult individuals captured in Rio Claro, in the state of São Paulo, Brazil. We found that TFIELD, TPREF, EWLCRIT and WU were higher in summer compared to winter. EWL rates did not vary seasonally, but showed a positive relationship with experimental temperatures. There were no seasonal variations in the tolerance to critical temperatures (CTMAX and CTMIN). Our data show that S. fuscovarius presents seasonal adjustments in some parameters of their thermal biology and water balance, but not in others. This should reflect differences in the degree of phenotypic plasticity among the tested parameters, functional compromises, specially between thermoregulation and water balance, and seasonal changes in environmental contingencies.