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Evidence for condition mediated trade-offs between the HPA- and HPG-axes in the wild zebra finch
journal contribution
posted on 2018-04-01, 00:00 authored by Andrea Crino, S M Jensen, Kate BuchananKate Buchanan, S C GriffithOpportunistic breeding is a strategy used to maximize reproductive success in unpredictable environments. Birds that breed opportunistically are thought to maintain partial activation of the reproductive axis in order to rapidly initiate breeding when environmental conditions become suitable. The physiological mechanisms that modulate reproduction in seasonally breeding birds have been well explored. In contrast, the physiological mechanisms that allow opportunistic breeding birds to maintain a continued state of reproductive readiness has not been well established. Here, we tested the hypothesis that reproductive readiness is modulated through condition-mediated effects on the hypothalamic-pituitaryadrenal (HPA) axis and its downstream effects on corticosterone (CORT) secretion in wild zebra finches (Taeniopygia guttata). We examined the variation in body condition, HPA-axis activity (endogenous and adrenocorticotropic hormone (ACTH)-induced responses), and hypothalamic-pituitary-gonadal (HPG) axis activity activity (baseline and gonadotropin-releasing hormone (GnRH) induced testosterone and estradiol levels) in zebra finches across five sites in the Northern Territory in Australia. We found that birds at the sites in the lowest condition had the highest level of baseline and peak CORT. Additionally, males at the sites in the lowest condition had the highest fold increase in testosterone following a GnRH challenge. Across sites, birds with low body condition had high baseline, peak, and ACTH-induced levels of CORT. Our data suggest that reproductive readiness in opportunistically breeding birds is modulated by condition-mediated trade-offs between the HPA- and the HPG-axes. Further work is needed to understand the environmental conditions that influence reproductive activation in opportunistically breeding birds.
History
Journal
General and Comparative EndocrinologyVolume
259Pagination
189 - 198Publisher
Academic PressLocation
Maryland Heights, Mo.Publisher DOI
ISSN
0016-6480eISSN
1095-6840Language
engPublication classification
C Journal article; C1 Refereed article in a scholarly journalCopyright notice
2017, ElsevierUsage metrics
Categories
Keywords
ACTH challengeAustraliaBirdCorticosteroneEstradiolGnRH challengeOpportunistic breedingTestosteroneUnpredictable environmentsScience & TechnologyLife Sciences & BiomedicineEndocrinology & MetabolismZoologyBODY CONDITIONSTRESS-RESPONSEREPRODUCTIONBEHAVIOROPPORTUNISMPHYSIOLOGYFOODGLUCOCORTICOIDSPREDICTABILITYPhysiologyZoology
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