Pleistocene separation of mitochondrial lineages of Mytilus spp. mussels from Northern and Southern Hemispheres and strong genetic differentiation among southern populations

• Published in: Molecular Phylogenetics and Evolution
• Main Authors: Gérard, Karin, Bierne, Nicolas, Borsa, Philippe, Chenuil, Anne, Féral, Jean-Pierre
• Other Authors: Station Marine d'Endoume, Université de la Méditerranée - Aix-Marseille 2, Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement IRD : UR226-Centre National de la Recherche Scientifique (CNRS), Écosystémique des communautés récifales et de leurs usages dans le Pacifique insulaire (CoReUS), Diversité, évolution et écologie fonctionnelle marine (DIMAR), Centre National de la Recherche Scientifique (CNRS)-Université de la Méditerranée - Aix-Marseille 2
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Southern Hemisphere; Cyto-nuclear discordance; Mytilus; Kerguelen; connectivity; 16S rDNA; COI; Biological invasions; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Arctic; Kerguelen Island; Kerguelen Islands; New Zealand
• Online Access: https://hal.archives-ouvertes.fr/halsde-00475209; https://hal.archives-ouvertes.fr/halsde-00475209/document; https://hal.archives-ouvertes.fr/halsde-00475209/file/2008_G%C3%A9rard_Mol.Phyl.Evol._pr_Pleistocene%20separation%20of%20mitochondrial%20lineages%20of%20Mytilus%20spp.%20mussels%20from%20Northern%20to%20Southern%20hemispheres%20and%20strong%20genetic%20differentiation%20among%20southern%20populations.pdf; https://doi.org/10.1016/j.ympev.2008.07.006

International audience Smooth-shelled mussels, Mytilus spp., have an antitropical distribution. In the Northern Hemisphere, the M. edulis complex of species is composed of three genetically well delineated taxa: M. edulis, M. galloprovincialis and M. trossulus. In the Southern Hemisphere, morphological characters, allozymes and intron length polymorphisms suggest that Mytilus spp. populations from South America and Kerguelen Islands are related to M. edulis and those from Australasia to M. galloprovincialis. On the other hand, a phylogeny of the 16S rDNA mitochondrial locus demonstrates a clear distinctiveness of southern mussels and suggests that they are related to Mediterranean M. galloprovincialis. Here, we analysed the faster-evolving cytochrome oxidase subunit I locus. The divergence between haplotypes of populations from the two hemispheres was confirmed and was found to predate the divergence between haplotypes of northern M. edulis and M. galloprovincialis. In addition, strong genetic structure was detected among the southern samples, revealing three genetic entities that correspond to (1) South America and Kerguelen Island, (2) Tasmania, (3) New Zealand. Using the trans-Arctic interchange as a molecular clock calibration, we estimated the time since divergence of populations from the two hemispheres to be between 0.5 million years (MY) and 1.3 MY (average 0.84 MY). The contrasting patterns observed for the nuclear and the organelle genomes suggested two alternative, complex scenarios: two trans-equatorial migrations and the existence of differential barriers to mitochondrial and nuclear gene flow, or a single trans-equatorial migration and a view of the composition of the nuclear genome biased by taxonomic preconception.