Yolk corticosterone in the Gouldian Finch (Erythrura gouldiae)

• Main Authors: A Miltiadous, SR Pryke, Mylene Mariette, Kate Buchanan
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2019
• Subjects: Ecology not elsewhere classified; Zoology not elsewhere classified; Environmental management not elsewhere classified; Maternal effects; maternal investment; eggs; yolk hormones; solid-phase extraction; School of Life and Environmental Sciences; 3103 Ecology; 3109 Zoology; 3104 Evolutionary biology; Finch; Avian Studies
• Online Access: http://hdl.handle.net/10536/DRO/DU:30117906; https://figshare.com/articles/journal_contribution/Yolk_corticosterone_in_the_Gouldian_Finch_Erythrura_gouldiae_/20779681

Maternal hormones are thought to play an important role in determining the rate of evolutionary adaptation. Previous avian studies have shown that the transfer of maternally derived hormones, such as progesterone and testosterone, to the egg, affects many aspects of offspring development. In contrast, the impact of maternal corticosterone (CORT) is much less studied. CORT, the principal avian glucocorticoid hormone, is thought to be passively transferred to the egg yolk from the maternal plasma. Maternal CORT may play a role in determining the development of young birds by adaptively programming offspring for their environment. We developed a protocol which effectively quantifies yolk CORT concentrations both within and across clutches, using solid-phase extraction and radioimmunoassay. We hypothesised that Gouldian Finch (Erythrura gouldiae) mothers would differ in their yolk CORT concentrations and that maternal condition would relate to absolute yolk CORT deposition. We found variation in yolk CORT concentrations between clutches, increasing with egg number in the earlier breeding season, and negatively correlated with yolk mass. Yet, contrary to our predictions, neither maternal mass nor clutch size showed any relationship to yolk CORT concentrations or to egg or yolk mass. Our data suggest that yolk CORT varies with maternal identity for reasons which do not appear to be linked to maternal condition. Further research is needed to determine the link between maternal and egg yolk concentrations at the individual level. Such tests would be valuable for understanding the role of CORT in the reproductive effects previously observed in this threatened species.