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Spatial patterns of neutral and functional genetic variations reveal patterns of local adaptation in raccoon ( P rocyon lotor ) populations exposed to raccoon rabies
Author(s) -
Kyle Christopher J.,
Rico Yessica,
Castillo Sarrah,
Srithayakumar Vythegi,
Cullingham Catherine I.,
White Bradley N.,
Pond Bruce A.
Publication year - 2014
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.12726
Subject(s) - biology , local adaptation , population , adaptation (eye) , genetic diversity , genetic variation , epizootic , genetic variability , evolutionary biology , zoology , genetics , genotype , virus , demography , neuroscience , sociology , gene
Local adaptation is necessary for population survival and depends on the interplay between responses to selective forces and demographic processes that introduce or retain adaptive and maladaptive attributes. Host–parasite systems are dynamic, varying in space and time, where both host and parasites must adapt to their ever‐changing environment in order to survive. We investigated patterns of local adaptation in raccoon populations with varying temporal exposure to the raccoon rabies virus ( RRV ). RRV infects approximately 85% of the population when epizootic and has been presumed to be completely lethal once contracted; however, disease challenge experiments and varying spatial patterns of RRV spread suggest some level of immunity may exist. We first assessed patterns of local adaptation in raccoon populations along the eastern seaboard of N orth A merica by contrasting spatial patterns of neutral (microsatellite loci) and functional, major histocompatibility complex ( MHC ) genetic diversity and structure. We explored variation of MHC allele frequencies in the light of temporal population exposure to RRV (0–60 years) and specific RRV strains in infected raccoons. Our results revealed high levels of MHC variation (66 DRB exon 2 alleles) and pronounced genetic structure relative to neutral microsatellite loci, indicative of local adaptation. We found a positive association linking MHC genetic diversity and temporal RRV exposure, but no association with susceptibility and resistance to RRV strains. These results have implications for landscape epidemiology studies seeking to predict the spread of RRV and present an example of how population demographics influence the degree to which populations adapt to local selective pressures.