Open AccessBorn blonde: a recessive loss‐of‐function mutation in the melanocortin 1 receptor is associated with cream coat coloration in A ntarctic fur seals
Author(s) -
Peters Lucy,
Humble Emily,
Kröcker Nicole,
Fuchs Birgit,
Forcada Jaume,
Hoffman Joseph I.
Publication year - 2016
Publication title -
ecology and evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.17
H-Index - 63
ISSN - 2045-7758
DOI - 10.1002/ece3.2290
Subject(s) - biology , genetics , melanocortin 1 receptor , allele , population , loss of heterozygosity , genetic variation , coat , microsatellite , evolutionary biology , gene , ecology , demography , sociology
Although the genetic basis of color variation has been extensively studied in humans and domestic animals, the genetic polymorphisms responsible for different color morphs remain to be elucidated in many wild vertebrate species. For example, hypopigmentation has been observed in numerous marine mammal species but the underlying mutations have not been identified. A particularly compelling candidate gene for explaining color polymorphism is the melanocortin 1 receptor ( MC 1 R ), which plays a key role in the regulation of pigment production. We therefore used Antarctic fur seals ( A rctocephalus gazella ) as a highly tractable marine mammal system with which to test for an association between nucleotide variation at the MC 1 R and melanin‐based coat color phenotypes. By sequencing 70 wild‐type individuals with dark‐colored coats and 26 hypopigmented individuals with cream‐colored coats, we identified a nonsynonymous mutation that results in the substitution of serine with phenylalanine at an evolutionarily highly conserved structural domain. All of the hypopigmented individuals were homozygous for the allele coding for phenylalanine, consistent with a recessive loss‐of‐function allele. In order to test for cryptic population structure, which can generate artefactual associations, and to evaluate whether homozygosity at the MC 1 R could be indicative of low genome‐wide heterozygosity, we also genotyped all of the individuals at 50 polymorphic microsatellite loci. We were unable to detect any population structure and also found that wild‐type and hypopigmented individuals did not differ significantly in their standardized multilocus heterozygosity. Such a lack of association implies that hypopigmented individuals are unlikely to suffer disproportionately from inbreeding depression, and hence, we have no reason to believe that they are at a selective disadvantage in the wider population.