Deep phylogeographic divergence among populations of limpet Siphonaria lessoni on the east and west coasts of South America (aceptado)

NUÑEZ, J.; FERNÁNDEZ IRIARTE P.; OCAMPO E.; IUDICA C.; CLEDÓN M.

MARINE BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2014

0025-3162

The historical processes that could have mainly influenced the genetic structure of species are associated to environmental changes of the Pleistocene glacial cycles. These climate changes, such as temperature, marine currents and loss of coastal habitats may have affected the abundance and geographic distribution of marine species of temperate coastal habitats. In the present work, 552 bp of the COI of 92 individuals were sequenced to analyse the genetic structure of limpet Siphonaria lessoni. The individuals were collected at the intertidal coast of the Southern Atlantic (Mar del Plata, San Antonio, Puerto Madryn and Ushuaia in Argentina) and Southern Pacific (Valdivia and Valparaíso in Chile). The haplotypes of S. lessoni were assigned to the Pacific and Atlantic basins. The AMOVA between clades explained the highest proportion of genetic divergence. The Pacific clade yielded more haplotypes and polymorphic sites as well as higher haplotypic and nucleotide diversity than the Atlantic clade did. Both Tajima?s D and Fu?s Fs were significant and negative, thereby suggesting that both clades are in population expansion. Accordingly, the haplotype network for each clade showed a star-like phylogeographic pattern. The Bayesian Skyline analysis, using 3.5 % of substitution rate revealed an older coalescence in the Pacific clade (80 000 ybp) if compared to that in the Atlantic clade (10 000 ybp). This work reports unequivocal evidence of Pacific-Atlantic geographic isolation for a coastal species, which is probably related to changes in sea level and temperature due to the extended glaciation periods that occurred in the region throughout the Pleistocene.