Show simple item record McGlothlin, Joel W. Whittaker, Danielle J. Schrock, Sara E. Gerlach, Nicole M. Jawor, Jodie M. Snajdr, Eric A. Ketterson, Ellen D. 2013-10-01T16:12:26Z 2013-10-01T16:12:26Z 2010-04-15
dc.identifier.citation Natural Selection on Testosterone Production in a Wild Songbird Population Joel W. McGlothlin, Danielle J. Whittaker, Sara E. Schrock, Nicole M. Gerlach, Jodie M. Jawor, Eric A. Snajdr, and Ellen D. Ketterson The American Naturalist Vol. 175, No. 6 (June 2010) (pp. 687-701) en
dc.description.abstract Because of their role in mediating life‐history trade‐offs, hormones are expected to be strongly associated with components of fitness; however, few studies have examined how natural selection acts on hormonal variation in the wild. In a songbird, the dark‐eyed junco (Junco hyemalis), field experiments have shown that exogenous testosterone alters individuals’ resolution of the survival‐reproduction trade‐off, enhancing reproduction at the expense of survival. Here we used standardized injections of gonadotropin‐releasing hormone (GnRH) to assay variation in the testosterone production of males. Using measurements of annual survival and reproduction, we found evidence of strong natural selection acting on GnRH‐induced increases in testosterone. Opposite to what would be predicted from the survival‐reproduction trade‐off, patterns of selection via survival and reproduction were remarkably similar. Males with GnRH‐induced testosterone production levels that were slightly above the population mean were more likely to survive and also produced more offspring, leading to strong stabilizing selection. Partitioning reproduction into separate components revealed positive directional selection via within‐pair siring success and stabilizing selection via extrapair mating success. Our data represent the most complete demonstration of natural selection on hormones via multiple fitness components, and they complement previous experiments to illuminate testosterone’s role in the evolution of life‐history trade‐offs. en
dc.language.iso en_US en
dc.publisher The American Naturalist en
dc.relation.isversionof en
dc.rights CC-BY-NC-SA en
dc.rights By downloading this document or using any information contained therein, you agree to the Creative Commons Attribution-NonCommercial-ShareAlike (CC BY-NC-SA) license terms, which explain terms governing use, creation of derivative research, and requirements for citing the document.
dc.rights.uri en
dc.subject natural selection, sexual selection, testosterone, life‐history trade‐offs, GnRH challenge en
dc.title Natural Selection on Testosterone Production in a Wild Songbird Population en
dc.type Article en
dc.identifier.doi 10.1086/652469

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