Speciation patterns in gastropods with long-lived larvae from deep-sea seamounts

Characterizing speciation processes in the sea remains a highly contentious issue because geographic barriers to gene exchange, which are the initial conditions for the allopatric speciation model, are not obvious. Moreover, many benthic marine organisms have long-lived planktonic larvae that allow them to connect distant patches of habitats. We here analyse the pattern of speciation in the gastropod genus Bursa in which all species have long-lived and planktonic-feeding larvae. We use a large taxonomic and ecologic coverage of Bursidae from the Indo-Pacific. We use an integrative approach to taxonomy to give more support to available taxonomic hypotheses. This analysis revealed cryptic lineages and suggest that a taxonomic revision of the family should be performed. A molecular clock calibrated from the fossil record was used to estimate divergence times. We then focus on the three co-existing species living in the deep waters of New Caledonia. Over the wide sampled area, no genetic structure was detected for the three species. We show that among New Caledonia species, Bursa fijiensis and Bursa quirihorai are reciprocally monophyletic. These two species are the two more closely related species in the inferred phylogeny. The present biogeographic ranges of the two species and the estimated time of divergence make the scenario of geographic isolation followed by secondary contact unlikely.