Table of Contents
International Journal of Evolutionary Biology
Volume 2012 (2012), Article ID 148745, 14 pages
http://dx.doi.org/10.1155/2012/148745
Research Article

Divergent Evolution of Male Aggressive Behaviour: Another Reproductive Isolation Barrier in Extremophile Poeciliid Fishes?

1Department of Ecology and Evolution, J.W. Goethe University Frankfurt, Siesmayerstrasse 70-72, 60054 Frankfurt am Main, Germany
2Department of Zoology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
3Department of Biology & W. M. Keck Center for Behavioral Biology, North Carolina State University, 127 David Clark Labs, Raleigh, NC 27695-7617, USA
4Department of Ethology, University of Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany

Received 15 July 2011; Revised 20 September 2011; Accepted 14 October 2011

Academic Editor: Kyoichi Sawamura

Copyright © 2012 David Bierbach et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Reproductive isolation among locally adapted populations may arise when immigrants from foreign habitats are selected against via natural or (inter-)sexual selection (female mate choice). We asked whether also intrasexual selection through male-male competition could promote reproductive isolation among populations of poeciliid fishes that are locally adapted to extreme environmental conditions [i.e., darkness in caves and/or toxic hydrogen sulphide (H2S)]. We found strongly reduced aggressiveness in extremophile Poecilia mexicana, and darkness was the best predictor for the evolutionary reduction of aggressiveness, especially when combined with presence of H2S. We demonstrate that reduced aggression directly translates into migrant males being inferior when paired with males from nonsulphidic surface habitats. By contrast, the phylogenetically old sulphur-endemic P. sulphuraria from another sulphide spring area showed no overall reduced aggressiveness, possibly indicating evolved mechanisms to better cope with H2S.