Black coats in an admixed wolf × dog pack is melanism an indicator of hybridization in wolves?
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The use of functional mutations, in addition to standard noncoding molecular markers, can help to detect hybridization and gene introgression in wild canid populations. We analyzed ancestry of a canid pack breeding in Central Italy that showed black coats and other unusual morphological traits suggesting wolf × dog hybrid origins. Individuals were identified by genotyping excremental DNA at 13 autosomal microsatellites, mtDNA control region sequences, a male-specific restriction site on the ZFX/Y gene to determine the gender of the individuals, four Y-linked microsatellites to determine male haplotypes, and two melanistic mutations: a SNP at exon 4 of the Agouti locus and a 3-bp deletion at a β-Defensin gene, the K locus. Results showed that: (1) the pack was founded by a single breeding pair of related individuals, probably brother and sister, and no immigrant was detected; (2) parents and offspring showed signals of admixture at autosomal microsatellites; and (3) the melanistic K locus deletion was present in the black-coated female parent and in 8/14 offspring, but it was absent in the wild type male parent. This deletion was found also in 17/40 village dogs randomly sampled from nearby areas, but it was absent in a random sample of 40 Italian wolves. These findings suggest that the pack received the K locus deletion from dogs. Admixture analyses of empirical and simulated genotypes indicate the parents of the pack originated through a single hybridization event at least two generations back. Genetic and phenotypic assessments of coat color mutations can contribute to investigation of the origin and dynamics of functional polymorphisms in hybridizing wolf populations and to develop appropriate guidelines to contrast hybridization with their domesticated relatives.
KeywordsCanis lupus Wolf × dog hybridization β-Defensin gene Coat color polymorphism Admixture analysis Gene introgression Conservation genetics
We warmly thank everybody who made it possible to realize this research project and who contributed to obtain samples used in this study, in particular: G. P. Sammuri (President of the Maremma Regional Park), M. Aloisi that kindly helped in collecting most of the dog blood samples, and L. Rigacci for the pictures. P. Ciucci kindly commented on an early version of the manuscript. The project was supported by the Italian Ministry of Environment, Direction of Nature Protection, and by the Tuscany Region through the Maremma Regional Park. We are particularly grateful to the EJWR Associated Editor and two anonymous referees for their constructive comments and insightful ideas that helped to deeply improve an early version of this manuscript.
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