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Covariation in life-history traits : differential effects of diet on condition, hormones, behavior, and reproduction in genetic finch morphs

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journal contribution
posted on 2012-03-01, 00:00 authored by S Pryke, Lee AstheimerLee Astheimer, S Griffith, William Buttemer
The relative contribution of genetic and environmental factors in determining variation in life-history traits is of central interest to evolutionary biologists, but the physiological mechanisms underlying these traits are still poorly understood. Here we experimentally demonstrate opposing effects of nutritional stress on immune function, endocrine physiology, parental care, and reproduction between red and black head-color morphs of the Gouldian finch (Erythrura gouldiae). Although the body condition of black morphs was largely unaffected by diet manipulation, red birds were highly sensitive to dietary changes, exhibiting considerable within-individual changes in condition and immune function. Consequently, nutritionally stressed red birds delayed breeding, produced smaller broods, and reared fewer and lower-quality foster offspring than black morphs. Differences in offspring quality were largely due to morph-specific differences in parental effort: red morphs reduced parental provisioning, whereas black morphs adaptively elevated their provisioning effort to meet the increased nutritional demands of their foster brood. Nutritionally stressed genetic morphs also exhibited divergent glucocorticoid responses. Black morphs showed reduced corticosterone-binding globulin (CBG) concentrations and increased levels of free corticosterone, whereas red morphs exhibited reduced free corticosterone levels and elevated CBG concentrations. These opposing glucocorticoid responses highlight intrinsic differences in endocrine sensitivities and plasticity between genetic morphs, which may underlie the morph-specific differences in condition, behavior, and reproduction and thus ultimately contribute to the evolution and maintenance of color polymorphism.

History

Journal

American naturalist

Volume

179

Issue

3

Pagination

375 - 390

Publisher

University of Chicago Press

Location

Chicago, Ill.

ISSN

0003-0147

eISSN

1537-5323

Language

eng

Notes

Reproduced with the kind permission of the copyright owner.

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2012, The University of Chicago