DISSERTATION RESEARCH: A Hormonal Mechanism for the Maternal Transduction of Ecological Conditions to the Avian Embryo

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Maternal effects occur when a female modifies her offspring in a manner not attributable solely to the offspring's genes. Often these effects are influenced by the ecological environment of the mother, but how ecological conditions are transmitted through the mother to her offspring are poorly understood. This proposal involves the investigation of the hormonal mechanisms by which mother birds modify the avian embryo's hormonal milieu according to food availability in the maternal environment. Preliminary findings in the American kestrel indicate that food availability influences the laying female's blood-plasma levels of the hormone prolactin, that her plasma prolactin influences how much androgen hormone she deposits in her egg yolks, and that yolk androgens affect offspring survival. However, it is not known if food affects yolk androgen levels. In this proposal, food availability will be manipulated to determine how it affects yolk androgen levels.Maternal effects are ubiquitous in nature, occurring in numerous plant species, insects, and all classes of vertebrates. This study may reveal a mechanism by which ecological conditions such as food availability may be transduced to the avian embryo. A mechanistic link from the environment, through the mother, and to the offspring has been described in few if any organisms.