Analysis of a secondary contact between divergent lineages of brown trout Salmo trutta L. from Duero basin using microsatellites and mtDNA RFLPs |
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Authors: | P. Martí nez,&dagger ,C. Bouza,&dagger ,J. Castro,&dagger ,M. Hermida,&dagger ,B. G. Pardo,&dagger L. Sá nchez,&dagger |
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Affiliation: | Departamento de Genética, Universidad de Santiago de Compostela, Facultad de Veterinaria, 27002 Lugo, Spain |
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Abstract: | The analysis of 12 microsatellite loci in 16 native populations of Salmo trutta from Duero basin evidenced a strong genetic differentiation in accordance with the existence of two divergent Atlantic mtDNA lineages, Atlantic (AT) and Duero (DU). These lineages were observed spatially segregated mainly in the Lower-course and in the inner part of the basin. Unlike previous isozyme information, microsatellite data suggested a more downstream location of the sharpest genetic divergence in Duero basin and a more complex structure in the inward area. Putative hybrid populations evidenced higher Hardy–Weinberg and gametic disequilibria than pure ones (Pisuerga, Lower-course), not explained by mixture due to differential immigration pattern across the basin. Hybridization indexes suggested a bimodal pattern of hybridization and a higher weight of Pisuerga region in the genetic composition of hybrid samples in accordance with mtDNA data. The results suggested a limited introgression between AT and DU lineages. Taking into account the time of divergence between both lineages, selection and/or genetic incompatibility appeared necessary to explain the genetic structure observed and the ancient location of DU lineage restricted to this area. |
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Keywords: | hybrid zone microsatellites mtDNA RFLPs phylogeography Salmo trutta secondary contact |
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