Lack of response to pond desiccation by eggs and tadpoles of the Yungas Red-belly Toad (Melanophryniscus rubriventris) in an unpredictable environment

Abstract

Anuran amphibians that breed in ephemeral ponds of unpredictable environments have mechanisms to tolerate or to avoid associated risks of egg and tadpole mortality, such as selection of oviposition sites, plasticity in larval development, and resistance of eggs to desiccation. The Yungas Red-belly Toad (Melanophryniscus rubriventris (Vellard, 1947)) breeds in temporary ponds in the Andean Yungas under unpredictable events of flooding and droughts of reproductive sites. To determine whether this species possesses any developmental mechanisms to deal with the environmental conditions, we experimentally evaluated the resistance of eggs subjected to different times of exposure to air and the tadpoles to different levels of pond desiccation. The species has not developed mechanisms of resistance of its eggs or phenotypic plasticity to the recurrent risks of pond desiccation, and mass mortality is a common event. In such a context, explosive breeding highly synchronized with rainfall, together with fast larval development, seems to be vitally important at these places where the duration of ponds is short and unpredictable.