EVALUATING THE TARGETS OF SELECTION DURING CHARACTER DISPLACEMENT
Article first published online: 16 JUN 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 10, pages 2946–2958, October 2011
How to Cite
Martin, R. A. and Pfennig, D. W. (2011), EVALUATING THE TARGETS OF SELECTION DURING CHARACTER DISPLACEMENT. Evolution, 65: 2946–2958. doi: 10.1111/j.1558-5646.2011.01357.x
- Issue published online: 3 OCT 2011
- Article first published online: 16 JUN 2011
- Accepted manuscript online: 25 MAY 2011 11:50AM EST
- Received November 16, 2010, Accepted May 7, 2011, Data Archived: Dryad doi:10.5061/dryad.q4v08
- divergent selection;
- phenotypic plasticity;
- selection differential;
- selection gradient;
- targets of selection
Ecological character displacement occurs when competition imposes divergent selection on interacting species, causing divergence in traits associated with resource use. Generally, divergence is assumed to occur when selection acts on the same, continuously varying trait in both species. However, selection might target multiple traits, and even closely related heterospecifics involved in character displacement might differ in selective targets. We investigated the targets of selection in a species of spadefoot toad, Spea multiplicata, during experimentally imposed competition with a congener, S. bombifrons. When examining traits separately, we found significant selection acting on multiple resource-acquisition traits. Yet, controlling for the independent effects of these traits in a multiple regression revealed that direct selection on a single trait might have contributed toward indirect selection on other correlated traits. Moreover, although we found evidence for plasticity in most traits, competition with S. bombifrons imposed selection on morphology and not on plasticity. Additional experiments suggest that the selective targets during character displacement might differ between the two species involved in this one instance of character displacement. Identifying the targets of competitively mediated selection is crucial, because whether and how character displacement ultimately unfolds depends on the nature of these targets and correlations among them.