Collaborative Research: The Chemical Basis of Ethological Isolation

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9615473 Arnold Understanding the genetic mechanisms underlying the process of speciation is a long-sought goal in evolutionary biology. For example, it has long been thought that genetic mutations resulting in slight differences in chemicals used in communication during the reproductive process (pheromones) might promote isolation of populations, and ultimately the emergence of new species. This research project addresses this question using a well-studied group of amphibians. Terrestrial "lungless" salamanders have evolved a biochemical communication system in which courting males administer a pheromone to females during courtship which increases female receptivity. The pheromone is produced by a gland on the male's chin, and extracts from this gland contain proteins, which have been partially purified and characterized, and used in behavioral experiments. These proteins contain multiple isoforms, the amounts and types of which vary between species and among populations within a single species. Whether the prevalence of any single isoform offers reproductive advantages or promotes isolation between evolving populations is unknown. In the present study, the biochemical characteristics of these proteins and their role in promoting behavioral isolation among salamander populations will be investigated. The research is a collaboration between scientists at two institutions and has two directions: 1) biochemical characterization of the major protein components of gland extracts (relative concentrations, molecular mass, amino acid composition, and N-terminal sequence); and 2) behavioral bioassays to determine the biological activity of the various isoforms in eliciting receptivity in female salamanders from different populations, and/or fostering isolation. Taken together, these studies will allow insights into the biochemical basis of the process of speciation.