Effects of temperature and volume of water on the growth anddevelopment of tadpoles of Pleurodema diplolister and Rhinella granulosa(Amphibia: Anura)

摘要

The capacity of tadpoles to reduce their metamorphosis time and body size in response to fluctuations in environmental variables of temporary ponds has been recorded in field and laboratory studies. The main alterations in this habitat are related to the decrease of the water level and increase in temperature. However, few studies tried to dissociate the effect of these two variables. The aim of the present study was to analyze simultaneously the effects of water volume reduction and temperature on the development and growth in tadpoles of Pleurodema diplolister (Peters, 1870) and Rhinella granulosa (Spix, 1824) - species that use temporary ponds for reproduction. The tadpoles of these two species were subject to four treatments: (1) constant volume of water of 2000 ml and constant temperature of 26°C; (2) gradually decreasing water volume from 2000 ml to 200 ml or 150 ml and constant temperature of 26 °C; (3) Constant water volume as in (1) and constant temperature of 30 °C or 33 °C and (4) Decreasing water volume (as above) and constant temperature as in the treatment (3). There was no interaction between both tested variables on the growth and development of tadpoles of both species. Tadpoles of P. diplolister and R. granulosa responded to high temperature by decreasing development time. Tadpoles responded to decreasing volume of water by metamorphosing into smaller size. Tadpoles of P. diplolister maintained at 30°C showed growth reduction. Tadpoles of R. granulosa in-creased their body size when subject to the treatment at 30°C.