Strategies and reproductive modes of anurans (Amphibia) in a permanent pond in Serra de Paranapiacaba, southeastern Brazil

Abstract

Strategies and reproductive modes of anurans (Amphibia) in a permanent pond in Serra de Paranapiacaba, southeastern Brazil. This study describes the temporal patterns, behavioral strategies, reproductive modes, and fecundity of an anuran assemblage in a permanent pond in Serra de Paranapiacaba, municipality of Ribeirão Branco, south of São Paulo State (approximately 24º13'S; 48º46'W; ca. 800m above sea level). Field work was carried out between January and December 1993, totaling 40 nights of observation. Seven preliminary visits were made before this period and seven additional ones after December 1993. Naturalistic observations usually began before sunset and were concluded around 24:0001:00h. On three occasions the observations lasted the entire night. The commonest reproductive strategy among males of different species was that performed by calling male, but the satellite behavior was observed in some species. The calling temporal pattern was prolonged for the species of the assemblage; however, some species called only occasionally. Six different reproductive modes were observed in the pond or on its margins. The SVL of females of different species was positively correlated with egg clutch volume, irrespective of the reproductive mode. The SVL of females was also positively correlated with the number of eggs per clutch, although the correlation is stronger for species with a generalized reproductive mode. However, for species with specialized reproductive mode the number of eggs per clutch was not correlated with the SVL of females. A significant and positive correlation between female SVL and egg diameter was also detected for species with generalized reproductive mode. On the other hand, for species with specialized reproductive mode, female's SVL and egg diameter were negatively correlated. Terrestrial reproductive modes are possibly restricted to small-sized species. Large eggs may face problems of gas exchange due to their longer development period and lower surface/volume ratio.