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MtDNA and nuclear data reveal patterns of low genetic differentiation for the isopods Stenosoma lancifer and Stenosoma acuminatum, with low dispersal ability along the northeast Atlantic coast
Raquel Xavier, Antonio Murias Santos and Madalena Branco

Evidence for a general lack of genetic differentiation of intertidal invertebrate assemblages in the North Atlantic, based on mtDNA sequence variation, has been interpreted as resulting from recent colonization following the Last Glacial Maximum. In the present study, the phylogeographic patterns of one nuclear and one mtDNA gene fragments of two isopods, Stenosoma lancifer (Miers, 1881) and Stenosoma acuminatum Leach, 1814, from the northeast Atlantic were investigated. These organisms have direct development, which makes them poor dispersers, and are therefore expected to maintain signatures of past historical events in their genomes. Lack of genetic structure, significant deviations from neutrality and star-like haplotype networks have been observed for both mtDNA and nuclear markers of S. lancifer, as well as for the mtDNA of S. acuminatum. No sequence variation was observed for the nuclear gene fragment of S. acuminatum. These results suggest a scenario of recent colonization and demographic expansion and/or high population connectivity driven by ocean currents and sporadic long-distance dispersal through rafting.

Keywords: phylogeography, Stenosoma, direct development, glacial refugia, Pleistocene Glaciations, demographic expansion, connectivity
Contents of this volume Sci. Mar. 76(1) : 133-140 Back PDF
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