Maintenance of genetic differentiation across a transition zone in the sea: discordance between nuclear and cytoplasmic markers

Type Article
Date 2005
Language English
Author(s) Lemaire Christophe1, 3, Versini J1, Bonhomme Francois1, 2
Affiliation(s) 1 : Univ Montpellier 2, CNRS IFREMER UMR 5171, Lab Genome Populat Interact Adaptat, Stn Mediterraneenne Environm Littoral, F-34200 Sete, France.
Source Journal of Evolutionary Biology (1010-061X) (Blackwell science), 2005 , Vol. 18 , N. 1 , P. 70-80
DOI 10.1111/j.1420-9101.2004.00828.x
WOS© Times Cited 75
Keyword(s) Reproductive isolation, Phylogeography, MtDNA, Microsatellites, Genetic transitions
Abstract To investigate the origin and maintenance of the genetic discontinuity between Atlantic and Mediterranean populations of the common sea bass (Dicentrarchus labrax) we analysed the genetic variation at a fragment of mitochondrial cytochrome b sequence for 18 population samples. The result were also compared with new or previously published microsatellite data. Seven mitochondrial haplotypes and an average nucleotidic divergence of 0.02 between Atlantic and Mediterranean populations that matches a Pleistocene allopatric isolation were found. The frequency variation at the cytochrome b locus was many times greater between Atlantic and Mediterranean populations ((θ) over cap (C) = 0.67) than at microsatellite loci ((θ) over cap (N) = 0.02). The examination of the different evolutionary forces at play suggests that a sex-biased hybrid breakdown is a likely explanation for part of the observed discrepancy between mitochondrial and nuclear loci. In addition, an analysis is made of the correlation between microsatellite loci points towards the possible existence of a hybrid zone in samples from the Alboran Sea.
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