Contemporary nuclear and mitochondrial genetic clines in a north temperate estuarine fish reflect Pleistocene vicariance
Date
2011
Authors
Bradbury, I. R.
Coulson, M. W.
Campana, S. E.
Paterson, I. G.
Bentzen, Paul
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Abstract
Contemporary genetic spatial structure in north temperate marine species is likely the
culmination of multiple vicariant and dispersive cycles. Here we evaluate spatial genetic structure
in an estuarine fish, rainbow smelt Osmerus mordax, from coastal Newfoundland, Canada, using data
from both mtDNA (ND5) sequences and nuclear loci (11 microsatellites). Sequence analysis of ND5
identified a previously unrecognized genetic discontinuity between 2 hypo thesized glacial clades in
southeastern Newfoundland. Microsatellite based tests for directional selection identified a locus
(Omo11, p < 0.001) that mirrored mtDNA clades in the geographic distribution of its 2 common
alleles but did not display elevated differentiation following correction for heterozygosity.
Bayesian multilocus clustering of the remaining micro satellite loci supported the presence of 2
predominant groups, for which the spatial distribution was also largely consistent with those of the
mtDNA and Omo11 clades. Taken together, the similarity in microsatellite and mtDNA clines supports
the hypothesis that contemporary spatial structure in smelt reflects historical landscape isolation
maintained by low dispersal and selective processes producing reinforcement between diverging
populations. As genetic structure in northern marine and estuarine species may be largely determined
by historical glacial cycles of vicariance, contemporary estimates of connectivity should be
interpreted in the context of both past and present landscape structure.
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Citation
Bradbury, I. R., M. W. Coulson, S. E. Campana, I. G. Paterson, et al. 2011. "Contemporary nuclear and mitochondrial genetic clines in a north temperate estuarine fish
reflect Pleistocene vicariance." Marine Ecology Progress Series 438: 207-U235. doi:10.3354/meps09286