Genetics, Gene Flow, and Glaciation: The Case of the South American Limpet Nacella mytilina

摘要: Glacial episodes of the Quaternary, and particularly Last Maximum (LGM) drastically altered distribution Southern-Hemisphere biota, principally at higher latitudes. The irregular coastline Patagonia expanding for more than 84.000 km constitutes a remarkable area to evaluate effect Quaternary landscape seascape shifts over demography near-shore marine benthic organisms. Few studies describing biogeographic responses species LGM have been conducted in Patagonia, but existing data from coastal demonstrated marked genetic signatures post-LGM recolonization expansion. kelp-dweller limpet Nacella mytilina is broadly distributed along southern tip South America Falkland/Malvinas Islands. Considering its distribution, abundance, narrow bathymetry, N. represents an appropriate model infer how historical contemporary processes affected intraspecific diversity structure America. At same time, it will be possible determine life history traits ecology are responsible current pattern gene flow connectivity across study area. We phylogeographic demographic inference analyses 12 localities Pacific (PP) one population Islands (FI). Analyses mitochondrial COI 300 individuals revealed low levels polymorphism absence differentiation PP. In contrast, FI showed strong significant Patagonian populations. Higher were also recorded population, together with expanded genealogy supporting hypothesis glacial persistence these islands. Haplotype genealogy, mismatch recognized older complex Demographic reconstructions PP suggest expansion process (7.5 ka), supported by neutrality tests, maximum parsimony haplotype genealogies. Migration rate estimations evidence asymmetrical FI. differentiation, presence single dominant haplotype, high estimated migration rates, signal recent growth, support rapid post-glacial This could sustained larval rafting-mediated dispersal adults northernmost populations following Cape Horn Current System. Marked between explained through differences their respective histories. During LGM, was almost fully covered Ice Sheet, while sheet coverage ice restricted small cirques valleys. As previously sister-species magellanica, rather represent classical refugium mytilina, seems sink and/or secondary contact zone. Accordingly, processes, contrasting histories analyzed sectors, as well constitute main factors explaining biogeographical patterns most shallow