Genetic connectivity of the ecosystem engineer Perumytilus purpuratus north to the 32ºS southeast Pacific ecological discontinuity

Connectivity in benthic marine animals with complex life cycles occurs primarily during the pelagic lar-val stage and depends deterministically on oceanographic dynamics. The scale of such larval dispersal is highly uncertain due the difficulty of direct measurement and poor knowledge of larval dynamics and ocean flow variability. This study characterizes the pattern of genetic connectivity in the ecosystem engineer Perumytilus purpuratus between latitudes 23°S and 33°S, which includes the ecological discontinuity reported for many taxa north to 32°S at the southeast Pacific. The genetic discontinuity observed in P. purpuratus around 26°S is described herein while that detected at 28°S is in line with the ecological discontinuity (in coverage, recruitment and density) previously reported for this mussel between 28°S and 32°S. Both discontinui-ties delimitate two major gene pools upon Bayesian infer-ences on geographical variation of five microsatellite loci. Interestingly, marker Pepu 1 was responsible for most vari-ation between pools and was potentially under selection. In fact, inferences excluding Pepu 1 produced a single gene pool ( k = 1) in central-northern Chile. The IBD connec-tivity pattern observed among P. purpuratus beds distrib-uted in the interval 23°S–33°S is congruent with processes driven by larval dynamics, and the dominant equatorward Humboldt Current along a coast largely unaffected by ice during the last Pleistocene glaciation. However, the selec-tive scenario unveiled by microsatellite Pepu 1 inside the 25°S–28°S ecological discontinuity is consistent with selective processes associated with specific mesoscale properties operating in this area. This study highlights the usefulness of integrating different oceanographic scales, ecological data and population genetics to better under-stand connectivity of benthic marine species.Versión del editor2,011