Genetic architecture and evolution of color variation in American black bears

Current Biology
By: , and 

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Abstract

Color variation is a frequent evolutionary substrate for camouflage in small mammals, but the underlying genetics and evolutionary forces that drive color variation in natural populations of large mammals are mostly unexplained. The American black bear, Ursus americanus (U. americanus), exhibits a range of colors including the cinnamon morph, which has a similar color to the brown bear, U. arctos, and is found at high frequency in the American southwest. Reflectance and chemical melanin measurements showed little distinction between U. arctos and cinnamon U. americanus individuals. We used a genome-wide association for hair color as a quantitative trait in 151 U. americanus individuals and identified a single major locus (p < 10−13). Additional genomic and functional studies identified a missense alteration (R153C) in Tyrosinase-related protein 1 (TYRP1) that likely affects binding of the zinc cofactor, impairs protein localization, and results in decreased pigment production. Population genetic analyses and demographic modeling indicated that the R153C variant arose 9.36 kya in a southwestern population where it likely provided a selective advantage, spreading both northwards and eastwards by gene flow. A different TYRP1 allele, R114C, contributes to the characteristic brown color of U. arctos but is not fixed across the range.

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Publication type Article
Publication Subtype Journal Article
Title Genetic architecture and evolution of color variation in American black bears
Series title Current Biology
DOI 10.1016/j.cub.2022.11.042
Volume 33
Issue 1
Year Published 2023
Language English
Publisher Elsevier
Contributing office(s) Northern Rocky Mountain Science Center
Description 12 p.
First page 86
Last page 97
Country Canada, Mexico, United States
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