The Genetic Basis of Pigmentation Variation in Domesticated Zebra Finches

Abstract

The zebra finch is the most common estrildid finch native to Australia and Southeast Asia. The zebra finch has also been domesticated and is now a common pet and experimental model system for research. As part of the domestication process, multiple color variants have been generated, providing an opportunity to examine the genetic basis of these traits. For this study I focused on two genes whose single nucleotide polymorphisims have been associated with natural variation in pigmentation traits within both human and animal populations. Thus, I set out to examine the SLC45A2 and TYRP1 gene patterns between several morphs of the domesticated zebra finch. To examine pigmentation variations, both TYRP1 and SLC45A2 genes were sequenced from three different color morphs of the domesticated zebra finch. Sequencing the two genes was limited to the first seven exons of each individual DNA sample to approximate the number of substitutions observed between the morphs. Results from this study gave the first characterization of the two pigmentation genes between the different morphs of the domesticated zebra finch. Through genomic analysis of the candidate genes, we were able to locate non-synonymous mutations in SLC45A2 that differentiate the Chestnut Flanked White Continental (CFW-C), lightback and timor morphs from each other. Though our samples were limited, Exons 1, 2 and 7 showed prominent nucleotide substitutions that could potentially be of functional significance. In contrast, Exons 2, 7 and 6 of the TYRP1 gene showed no significant variations among morphs. Changes in SLC45A2 therefore may contribute to the observed phenotypic differences.