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High degree of genetic differentiation in marine three‐spined sticklebacks ( G asterosteus aculeatus )
Author(s) -
DeFaveri Jacquelin,
Shikano Takahito,
Shimada Yukinori,
Merilä Juha
Publication year - 2013
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.12430
Subject(s) - biology , gasterosteus , three spined stickleback , genetics , stickleback , evolutionary biology , population , gene flow , genetic divergence , gene , genetic variation , allele , genetic drift , directional selection , selection (genetic algorithm) , genetic diversity , fish <actinopterygii> , demography , artificial intelligence , fishery , sociology , computer science
Populations of widespread marine organisms are typically characterized by a low degree of genetic differentiation in neutral genetic markers, but much less is known about differentiation in genes whose functional roles are associated with specific selection regimes. To uncover possible adaptive population divergence and heterogeneous genomic differentiation in marine three‐spined sticklebacks ( Gasterosteus aculeatus ), we used a candidate gene‐based genome‐scan approach to analyse variability in 138 microsatellite loci located within/close to (<6 kb) functionally important genes in samples collected from ten geographic locations. The degree of genetic differentiation in markers classified as neutral or under balancing selection—as determined with several outlier detection methods—was low ( F ST = 0.033 or 0.011, respectively), whereas average F ST for directionally selected markers was significantly higher ( F ST = 0.097). Clustering analyses provided support for genomic and geographic heterogeneity in selection: six genetic clusters were identified based on allele frequency differences in the directionally selected loci, whereas four were identified with the neutral loci. Allelic variation in several loci exhibited significant associations with environmental variables, supporting the conjecture that temperature and salinity, but not optic conditions, are important drivers of adaptive divergence among populations. In general, these results suggest that in spite of the high degree of physical connectivity and gene flow as inferred from neutral marker genes, marine stickleback populations are strongly genetically structured in loci associated with functionally relevant genes.