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Cline coupling and uncoupling in a stickleback hybrid zone
Author(s) -
Vines Timothy H.,
Dalziel Anne C.,
Albert Arianne Y. K.,
Veen Thor,
Schulte Patricia M.,
Schluter Dolph
Publication year - 2016
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12917
Subject(s) - cline (biology) , biology , hybrid zone , gene flow , linkage disequilibrium , evolutionary biology , natural selection , ecology , locus (genetics) , stickleback , selection (genetic algorithm) , allele , genetics , genetic variation , population , gene , fishery , haplotype , demography , artificial intelligence , sociology , computer science , fish <actinopterygii>
Strong ecological selection on a genetic locus can maintain allele frequency differences between populations in different environments, even in the face of hybridization. When alleles at divergent loci come into tight linkage disequilibrium, selection acts on them as a unit and can significantly reduce gene flow. For populations interbreeding across a hybrid zone, linkage disequilibria between loci can force clines to share the same slopes and centers. However, strong ecological selection on a locus can also pull its cline away from the others, reducing linkage disequilibrium and weakening the barrier to gene flow. We looked for this “cline uncoupling” effect in a hybrid zone between stream resident and anadromous sticklebacks at two genes known to be under divergent natural selection ( Eda and ATP1a1 ) and five morphological traits that repeatedly evolve in freshwater stickleback. These clines were all steep and located together at the top of the estuary, such that we found no evidence for cline uncoupling. However, we did not observe the stepped shape normally associated with steep concordant clines. It thus remains possible that these clines cluster together because their individual selection regimes are identical, but this would be very surprising given their diverse roles in osmoregulation, body armor, and swimming performance.