Yolk corticosterone and progesterone levels in Greater Rhea (Rhea americana) eggs vary in a changing social environment

• Autores: Della Costa, Natalia; Martella, Mónica; Bernad, Lucía; Marin, Raúl; Navarro, Joaquín
• Año de publicación: 2022
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Journal of Experimental Zoology Part A: Ecological and Integrative Physiology 337 (6) : 594-599 (July 2022)
• Materia: Ñandú; Yema de Huevo; Corticosterona; Progesterona; Hormonas; Efectos Martenos; Rheas; Egg Yolk; Corticosterone; Progesterone; Hormones; Maternal Effects
• Institución: Instituto Nacional de Tecnología Agropecuaria

Maternal hormones in avian egg yolks may signal and prepare offspring for the prevailing conditions. However, this adjustment requires some degree of flexibility in regulating yolk hormone deposition. The Greater Rhea (Rhea americana) has a particular mating system that combines mixed polygyny and polyandry, communal nesting, and exclusive paternal care of chicks. In this species, we previously found that yolk hormone deposition varies among eggs of different captive populations and could influence chicks' physiology and behavior. However, it is still unknown whether females can modify yolk hormone deposition in a changing social environment. Using a captive population of Greater Rheas, in this study, we quantified yolk hormone levels before and after a reduction in the number of females present in the population. We found that females deposited on average higher yolk corticosterone and lower yolk progesterone after the change in their social environment. Since corticosterone deposited into the yolk comes exclusively from the female's plasma, our results suggest that females had, on average, higher plasma corticosterone levels. The change in the number of females may increase the events of male–male competitions, courtships, and matings, leading to an increase of corticosterone in the females' plasma and then into their eggs. Since we previously found that higher yolk corticosterone and lower yolk progesterone were associated with the production of chicks that have an attenuated stress response, the present study results suggest that yolk hormone deposition is mediated by flexible mechanisms that could adjust development to the prevailing conditions.
EEA Balcarce
Fil: Della Costa, Natalia. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Zoología Aplicada; Argentina.
Fil: Della Costa, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba; Argentina. Instituto de Diversidad y Ecología Animal; Argentina.
Fil: Martella, Mónica. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Zoología Aplicada; Argentina.
Fil: Martella, Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba; Argentina. Instituto de Diversidad y Ecología Animal; Argentina.
Fil: Bernad, Lucía. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.
Fil: Marin, Raúl. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. El Instituto de Ciencia y Tecnología de los alimentos; Argentina.
Fil: Marin, Raúl. Consejo Nacional de Investigaciones Científicas y Técnica. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.
Fil: Navarro, Joaquín. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Zoología Aplicada; Argentina.
Fil: Navarro, Joaquín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba; Argentina. Instituto de Diversidad y Ecología Animal; Argentina.
Fil: Navarro, Joaquín. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecología; Argentina.