Individual variation in testosterone and parental care in a female songbird; the dark-eyed junco (Junco hyemalis)

摘要: When competition for sex-specific resources overlaps in time with offspring production and care, trade-offs can occur. Steroid hormones, particularly testosterone (T), play a crucial role mediating such males, often increasing competitive behaviors while decreasing paternal behavior. Recent research has shown that females also face trade-offs; however, we know little about the of T female phenotypes general, particular. Here examine relationship between individual variation maternal effort endogenous dark-eyed junco, common songbird. Specifically, measure circulating before after physiological challenge (injection gonadotropin releasing hormone, GnRH), determine whether either is related to provisioning, brooding, or amount sequestered egg yolk. We found producing more response spent less brooding nestlings, but provisioned nestlings frequently, deposited their eggs. These findings suggest that, likely important life history tradeoffs, direction relationships phenotype may differ from what generally observed high levels are not necessarily as costly previous work might suggest.