Date of Award

2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

The study of genetics is fundamental to understanding the function and evolution of complex phenotypic traits in animals. Nowadays behavioral studies are focusing on genetics as a key to understanding behavioral variability. In this PhDdissertation I study the effect of a genetic system, the melanocortin system, on the behavioral and morphological polymorphism of the white-throated sparrow ( Zonotrichia albicollis ). I examined the behavioral differences in a wintering population in Indiana, and a breeding population in Upstate New York. I studied the genetic differences through protein assays and gene sequencing on the behaviorally tested individuals. Finally, I assessed the gene expression of the main components of the melanocortin system on cultured dermal fibroblasts. Behavioral trials during the winter showed that tan birds acclimated better to captive conditions and appeared to be bolder than white birds when facing novel objects. During the breeding season, the behavioral response was associated with the social and physical environment the birds inhabited. Molecular analyses revealed differences in the melanocortin system between white-throated sparrow morphs. Although there seemed to be no major structural differences in the melanocortin system master gene (pro-opiomelanocortin, POMC ) sequence, the results suggested different evolutionary pressures acting on the POMC gene between morphs. The study of gene expression on white-throated sparrow dermal fibroblasts suggested differences in expression and regulation of key components of the melanocortin system between morphs. Overall, the differences in expression levels and gene sequence imply an important role of this system in morph characterization.

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