Examining sources of variation in HPG axis function among individuals and populations of the dark-eyed junco.

ABSTRACT: Gonadal steroids are important mediators of traits relevant to fitness, and thus may be targets of selection. However, more knowledge is needed about sources of variation along the endocrine axes that may contribute to functional variation in steroid levels. In a controlled captive environment, we studied males of two closely related subspecies of the dark-eyed junco (Junco hyemalis) that differ in testosterone-related phenotype, asking whether they also differ in testosterone (T), and assessing the contribution of the sequential links of the hypothalamic-pituitary-gonadal axis. When males of both subspecies were challenged with gonadotropin-releasing hormone (GnRH), they were similar in circulating luteinizing hormone (LH) and T responses. When challenged with exogenous LH, they again pro

SUBMITTER: Bergeon Burns CM 

PROVIDER: S-EPMC3944345 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature