Responses to dehydration in tadpoles of Physalaemus nattereri (Anura: Leptodactylidae).

In species with complex life cycles, such as anuran amphibians, several traits are influenced by ecological factors during ontogeny. The anuran Physalaemus nattereri shows an aquatic spawning behavior, placing foam nests at the edges of a pond where the water contacts land, exposing tadpoles to dehydration once the pond dries. P. nattereri tadpoles are known to present an intermediate ability to survive out of water when compared to other species reproducing in permanent or temporary ponds. A decrease in size of tadpole tails has been suggested to represent a response to cope with dehydration stress, but might impair swimming performance. We investigated the effect of dehydration on morphological traits, focusing especially on tail proportions, as well as burst swimming speed. P. nattereri tadpoles were exposed to hydric stress on moist paper substrates and morphology and locomotor performance was compared within the same individuals before and after hydric stress. Our experiment showed that morphological changes induced by hydric stress were directly related to swimming performance. Individuals having smaller tails, due primarily to contractions of the medial to distal tail portions, exhibited reduced times to reach burst speed and reduced burst speeds. [ABSTRACT FROM AUTHOR]