Life-History Traits of Three Syntopic Species of the South American Redbelly Toads (Anura: Bufonidae: Melanophryniscus) from the Atlantic Forest of Argentina

Abstract

Amphibians from Atlantic Forests of South America are one of the most threatened vertebrates of the world, mainly due to the habitat loss and infectious diseases. With the goal to improve the knowledge of the lifehistory traits of the amphibian that inhabit these regions, and thus, to aid conservation and management-decision making, our main goals were to describe the reproductive activity pattern and analyze the interspecific variation in body size and the reproductive traits of three species of redbelly toads (Melanophryniscus) of the Atlantic Forest of Argentina. We also analyzed age structure, whether Sexual Size Dimorphism (SSD) exists, and if this dimorphismcould be explained by proximate mechanisms such as differences in growth patterns. The Melanophryniscus we studied bred during two or three consecutive days, in several explosive events that occurred between April 2009 and October 2012. These events were determined by a trade-off between the air and water temperature, and the level of the water bodies. We observed spatial segregation among the three species we studied when they reproduced synchronously and in sympatry and with the presence of multiple clutches. We found inter-specific differences inbody size. We recorded male-biased sex ratio and SSD in all three species of Melanophryniscus studied. We also found significant interspecific differences in age-related parameters following the differences in body size. Species were not sexually dimorphic by age. We also did not find covariation between body size and reproductive traits. These new insights allow us to predict the responses of Melanphryniscus we studied to the impact of the destruction of their habitat and global warming.