Open AccessSignatures of selection in the three‐spined stickleback along a small‐scale brackish water – freshwater transition zone
Author(s) -
Konijnendijk Nellie,
Shikano Takahito,
Daneels Dorien,
Volckaert Filip A.M.,
Raeymaekers Joost A. M.
Publication year - 2015
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/ece3.1671
Subject(s) - stickleback , gasterosteus , biology , three spined stickleback , gene flow , local adaptation , evolutionary biology , adaptation (eye) , ecology , brackish water , natural selection , selection (genetic algorithm) , gene , genetics , genetic variation , salinity , population , fishery , fish <actinopterygii> , neuroscience , demography , artificial intelligence , sociology , computer science
Local adaptation is often obvious when gene flow is impeded, such as observed at large spatial scales and across strong ecological contrasts. However, it becomes less certain at small scales such as between adjacent populations or across weak ecological contrasts, when gene flow is strong. While studies on genomic adaptation tend to focus on the former, less is known about the genomic targets of natural selection in the latter situation. In this study, we investigate genomic adaptation in populations of the three‐spined stickleback Gasterosteus aculeatus L. across a small‐scale ecological transition with salinities ranging from brackish to fresh. Adaptation to salinity has been repeatedly demonstrated in this species. A genome scan based on 87 microsatellite markers revealed only few signatures of selection, likely owing to the constraints that homogenizing gene flow puts on adaptive divergence. However, the detected loci appear repeatedly as targets of selection in similar studies of genomic adaptation in the three‐spined stickleback. We conclude that the signature of genomic selection in the face of strong gene flow is weak, yet detectable. We argue that the range of studies of genomic divergence should be extended to include more systems characterized by limited geographical and ecological isolation, which is often a realistic setting in nature.