IRFP: The Function and Evolution of Terrestrial Reproduction

Touchon Justin, Redmond OR

Investigators

Abstract

The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four-month research fellowship by Dr. Justin C. Touchon to work with Drs. Harilaos Lessios and Roberto Ibañez at the Smithsonian Tropical Research Institute in Panama. Understanding the evolution of life-history strategies is a central goal of evolutionary ecology. One of the most important life-history changes to evolve was the shift to living and reproducing on land by vertebrate animals. Frogs are particularly well-suited for studying this evolutionary shift because they were the first vertebrates to successfully invade land and there are numerous independent origins of terrestrial reproduction among frogs. This project uses a treefrog which can flexibly switch between laying aquatic and terrestrial eggs to study how the environment selects for aquatic and terrestrial reproduction. The treefrog Dendropsophus ebraccatus is found from Mexico to Colombia and across that range experiences over 8X variation in rainfall. Rain is particularly important, because it is the most important factor in determining if terrestrial eggs will survive. In addition, this research investigates reproduction in the species most closely related to D. ebraccatus to explore the transition from aquatic to terrestrial egg-laying across species. This project examines how selection has shaped aquatic and terrestrial reproduction throughout Central and South America. This research addresses issues crucial to our understanding of how life on land evolved. The transition to reproducing on land is key to understanding the shift to terrestrial life and is arguably one of the most important in the history of life as a whole. In addition, this research is particularly timely because patterns of rainfall are currently changing, potentially altering selection on terrestrial amphibian eggs. This work will also address broadly general issues about how evolution moves between seemingly alternative strategies, such as laying eggs in water versus laying eggs on land. This research will develop research collaborations in Panama, Costa Rica, Guatemala, Honduras, Nicaragua, Mexico, Belize, Colombia, Ecuador, Brazil and Peru, as well as providing research opportunities for undergraduates in each country. By using a group of especially interesting treefrogs to understand the evolution of terrestrial reproduction, this research will increase awareness of amphibians and their evolutionary and ecological importance.