Funded by National Science Foundation DEB 0716985, DEB 0716964, and MRI 0923063.
Evolution of a sexually dimorphic trait in a broadly distributed topminnow (Fundulus olivaceus)
Article first published online: 8 JUN 2012
© 2011 The Authors. MicrobiologyOpen published by Blackwell Publishing Ltd.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Ecology and Evolution
Volume 2, Issue 7, pages 1371–1381, July 2012
How to Cite
Schaefer, J. F., Duvernell, D. D., Kreiser, B. R., Champagne, C., Clark, S. R., Gutierrez, M., Stewart, L. K. and Coleman, C. (2012), Evolution of a sexually dimorphic trait in a broadly distributed topminnow (Fundulus olivaceus). Ecology and Evolution, 2: 1371–1381. doi: 10.1002/ece3.242
- Issue published online: 6 JUL 2012
- Article first published online: 8 JUN 2012
- Received: 23 January 2012; Revised: 21 February 2012; Accepted: 24 February 2012
- Geographic variation;
- sexual dimorphism;
- sexual selection;
- natural selection
Understanding the interaction between sexual and natural selection within variable environments is crucial to our understanding of evolutionary processes. The handicap principle predicts females will prefer males with exaggerated traits provided those traits are indicators of male quality to ensure direct or indirect female benefits. Spatial variability in ecological factors is expected to alter the balance between sexual and natural selection that defines the evolution of such traits. Male and female blackspotted topminnows (Fundulidae: Fundulus olivaceus) display prominent black dorsolateral spots that are variable in number across its broad range. We investigated variability in spot phenotypes at 117 sites across 13 river systems and asked if the trait was sexually dimorphic and positively correlated with measures of fitness (condition and gonadosomatic index [GSI]). Laboratory and mesocosm experiments assessed female mate choice and predation pressure on spot phenotypes. Environmental and community data collected at sampling locations were used to assess predictive models of spot density at the individual, site, and river system level. Greater number of spots was positively correlated with measures of fitness in males. Males with more spots were preferred by females and suffered greater mortality due to predation. Water clarity (turbidity) was the best predictor of spot density on the drainage scale, indicating that sexual and natural selection for the trait may be mediated by local light environments.