title: Testosterone production ability predicts breeding success and tracks breeding stage in male finches.
abstract: Testosterone (T) is an important mediator of reproductive behaviours and potential target for selection. However, there are few data relating natural variation in T to fitness estimates. Here, we used the GnRH challenge (an injection of gonadotropin-releasing hormone which stimulates maximal T release), to examine how individual differences in T relate to reproductive success and how T changes across date and breeding stage. We measured pre- and post-challenge T, in captive male Gouldian finches (Erythrura gouldiae), before and after introducing females, and across breeding stage. Post-challenge T before introducing females positively predicted breeding success. Post-challenge T levels were unrelated to date, but strongly related to stage; T production ability was strongly attenuated in incubating males. Prechallenge T levels related only to date. Our results suggest that T production ability is an important target for selection and that when males invest heavily in parental care they reduce their sensitivity to GnRH.
authors: Research School of Biology, Australian National University, Canberra, ACT, Australia.|School of Biological Sciences, University of Auckland, Auckland, New Zealand.
authors: K E
authors: 0000-0002-6908-7015
authors: KE
authors: Cain
authors: Research School of Biology, Australian National University, Canberra, ACT, Australia.
authors: S R
authors: SR
authors: Pryke
mesh_terms: D000818:Animals; D005260:Female; D046369:Finches; D007987:Gonadotropin-Releasing Hormone; D008297:Male; D012098:Reproduction; D013739:Testosterone / Q000378:metabolism*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone
keywords: birds; competition; fitness; gonadotropin-releasing hormone (GnRH challenge); individual variation; testosterone