VICARIANCE AND DISPERSAL EFFECTS ON PHYLOGEOGRAPHIC STRUCTURE AND SPECIATION IN A WIDESPREAD ESTUARINE INVERTEBRATE

摘要: Vicariance and dispersal can strongly influence population genetic structure allopatric speciation, but their importance in the origin of marine biodiversity is unresolved. In transitional estuarine environments, habitat discreteness barriers could enhance divergence provide insight to evolutionary mechanisms underlying freshwater biodiversity. We examined this by assessing phylogeographic widespread amphipod Gammarus tigrinus across 13 estuaries spanning its northwest Atlantic range from Quebec Florida. Mitochondrial cytochrome c oxidase I nuclear internal transcribed spacer 1 phylogenies supported deep consistent with Pliocene separation cryptic northern southern species. This break occurred Virginian-Carolinian coastal biogeographic zone, where an oceanographic discontinuity may restrict gene flow. Ten populations species four distinct clades, supportive Pleistocene separation. Glaciation effects on are largely unknown, analysis molecular variance (AMOVA) a among clades formerly glaciated versus nonglaciated areas Cape Cod, Massachusetts. finding was concordant patterns other species, though there no significant relationship between latitude diversity. supports vicariance events different glacial refugia. AMOVA results private haplotypes most support distribution estuaries. Clade mixture zones historical colonization human-mediated transfer. An isolation-by-distance model detected after we excluded suspected invasive haplotype St. Lawrence estuary. The occurrence divergent limited dispersal, dispersed distribution, factors as important determinants speciation diversification.