CONTEXT-DEPENDENT SEX ALLOCATION: CONSTRAINTS ON THE EXPRESSION AND EVOLUTION OF MATERNAL EFFECTS
Article first published online: 18 JUL 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 10, pages 2792–2799, October 2011
How to Cite
Pryke, S. R., Rollins, L. A. and Griffith, S. C. (2011), CONTEXT-DEPENDENT SEX ALLOCATION: CONSTRAINTS ON THE EXPRESSION AND EVOLUTION OF MATERNAL EFFECTS. Evolution, 65: 2792–2799. doi: 10.1111/j.1558-5646.2011.01391.x
- Issue published online: 3 OCT 2011
- Article first published online: 18 JUL 2011
- Accepted manuscript online: 27 JUN 2011 11:40AM EST
- Received April 11, 2011, Accepted June 4, 2011, Data Archived: Dryad doi:10.5061/dryad.70dj6
- Diet quality;
- Gouldian finches;
- maternal effects;
- maternal condition;
- sex allocation
Despite decades of research, whether vertebrates can and do adaptively adjust the sex ratio of their offspring is still highly debated. However, this may have resulted from the failure of empirical tests to identify large and predictable fitness returns to females from strategic adjustment. Here, we test the effect of diet quality and maternal condition on facultative sex ratio adjustment in the color polymorphic Gouldian finch (Erythrura gouldiae), a species that exhibits extreme maternal allocation in response to severe and predictable (genetically-determined) fitness costs. On high-quality diets, females produced a relatively equal sex ratio, but over-produced sons in poor dietary conditions. Despite the lack of sexual size dimorphism, nutritionally stressed foster sons were healthier, grew faster, and were more likely to survive than daughters. Although these findings are in line with predictions from sex allocation theory, the extent of adjustment is considerably lower than previously reported for this species. Females therefore have strong facultative control over sex allocation, but the extent of adjustment is likely determined by the relative magnitude of fitness gains and the ability to reliably predict sex-specific benefits from environmental (vs. genetic) variables. These findings may help explain the often inconsistent, weak, or inconclusive empirical evidence for adaptive sex ratio adjustment in vertebrates.