Yolk immunoreactive corticosterone does not relate with maternal fecal glucocorticoids in a captive population of Greater Rheas (Rhea americana)

DELLA COSTA, NATALIA S.; NAVARRO, JOAQUIN L.; MARIN, RAÚL H.; MARTELLA, MÓNICA B.

Journal of Ornithology

Springer

Año: 2020

2193-7192

Maternalcorticosterone in avian egg yolks may signal and prepare offspring for the prevailingconditions. However, this adjustment requires flexible mechanisms of regulationthat lead to the absence of a correlation between hormone levels in the motherand the yolk. In this study, we examined whether yolk immunoreactivecorticosterone and maternal glucocorticoid levels are related in the greaterrhea (Rhea americana), a ratitespecies with a communal nesting system. During the intermediate laying periodof the season, we carried out daily nest-observations to collect those eggs inwhich the laying female was identified. We also collected fresh fecal samplesfrom the identified laying females toquantify their fecal glucocorticoid metabolite (FGM) levels during the yolkformation period (7 days before egg-laying). Yolk immunoreactive corticosteroneand FGM levels were measured using a corticosterone125 radio-immunoassaykit, previously validated for the species. No significant relationships werefound between female FGM and yolk immunoreactive corticosterone. Althoughfutures studies are needed to elucidate the underlying mechanisms, our results suggestthat greater rhea female maybe able to control the distribution of corticosterone into their yolks,supporting the idea that this hormone may be mediating an adaptive maternaleffect.