Integrative Studies of Amphibians: From Molecules to Mating

Abstract

SYNOPSIS. Studies of reproductive behavior in amphibians have been especially successful in synthesizing data produced from molecular and physiological research with evolutionary parameters, such as measures of reproductive success. In particular, two relatively new areas of amphibian research are highly amenable to synthetic studies. One area is the nature of chemical communication by pheromone delivery in terrestrial salamanders. Male courtship pheromones, for example, are delivered to the female during mating. These pheromones typically are received by the accessory olfactory system and act (presumably via the hypothalamus) to increase female receptivity. At an evolutionary level, pheromone delivery can increase male courtship success and thus the likelihood that a given male will sire offspring. Variation in pheromone composition and effectiveness will permit us to trace the evolution of the male pheromone on a phylogeny of related populations and species. At a proximal level, salamander courtship pheromones are being chemically analyzed in order to identify specific protein components that affect female receptivity. It also will be possible to determine whether chemical variation among males is related to behavioral effectiveness. Thus, courtship pheromone delivery is a behavior that has invited scrutiny from a combination of evolutionary and mechanistic perspectives. The second research area that is gaining from a synthetic approach is the investigation of relationships between hormonal mechanisms and reproductive behavior in field populations of anurans and salamanders. Amphibians are an understudied group, and the area of hormone-behavior relationships is inspired by testable hypotheses based on studies of other terrestrial vertebrates. The ability to correlate physiological measures with estimates of reproductive success identifies areas of amphibian research that will profit from continued attention.