Ecological divergence exhibits consistently positive associations with reproductive isolation across disparate taxa

doi:10.1073/pnas.0508653103

Ecological divergence exhibits consistently positive associations with reproductive isolation across disparate taxa

*Department of Biological Sciences, Vanderbilt University, Station B, Box 35-1634, Nashville, TN 37235-1634;
^‡Department of Biosciences, Behavioral Ecology Research Group, Simon Fraser University, Burnaby, BC, Canada V5A 1S6; and
^§Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701

Edited by Francisco J. Ayala, University of California, Irvine, CA, and approved January 10, 2006 (received for review October 4, 2005)

Abstract

To what degree is the divergent adaptation responsible for life’s phenotypic variety also responsible for generating the millions of species that manifest this variation? Theory predicts that ecological divergence among populations should promote reproductive isolation, and recent empirical studies provide support for this hypothesis in a limited number of specific taxa. However, the essential question of whether ecology plays a truly general role in speciation has yet to be systematically evaluated. Here we address this integral issue using an approach that adds an ecological dimension to comparative studies investigating the relationship between reproductive isolation and divergence time. Specifically, we quantify ecological divergence for >500 species pairs from eight plant, invertebrate, and vertebrate taxa and statistically isolate its association with reproductive isolation. This approach demonstrates a highly consistent and significant positive association between ecological divergence and reproductive isolation across taxa. This relationship was also observed across different aspects of ecological divergence and components of reproductive isolation. These findings are highly consistent with the hypothesis that ecological adaptation plays a fundamental and taxonomically general role in promoting reproductive isolation and speciation.

Footnotes

^†To whom correspondence should be addressed. E-mail: daniel.j.funk{at}vanderbilt.edu
Author contributions: D.J.F. designed research; D.J.F., P.N., and W.J.E. performed research; D.J.F. and P.N. analyzed data; and D.J.F., P.N., and W.J.E. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

Abbreviations:

RI,

reproductive isolation;

ED,

ecological divergence;

GD,

genetic distance;

C&O,

Coyne and Orr
Freely available online through the PNAS open access option.