Patterns of dispersal and larval development of archaeogastropod limpets at hydrothermal vents in the eastern Pacific

Patterns of dispersal and larval development were examined in four species of archaeogastropod limpets from hydrothermal vents along the northern East Pacific Rise and Galapagos Rift. Allozyme analysis revealed that recognized subspecies Lepetodrilus elevatus elevatus (McLean) and L.e. galriftensis (McLean), occurred sympatrically along the East Pacific Rise and should be treated as full species. Larval shell characteristics of L. elevatus (s.s.) and L. galriftensis and two other sympatric species, Lepetodrilus pustulosus (McLean) and Eulepetopsis vitrea (McLean), suggest that all four species possess nonplanktotrophic modes of development which may limit long-distance dispersal capabilities. Theoretical considerations suggest that species with limited long-distance dispersal will migrate among habitat islands in a 'stepping-stone' fashion, and thus, are expected to exhibit genetic evidence of 'isolation-by-distance'. Notwithstanding, E. vitrea and L. pustulosus did not exhibit the expected decline in rates of gene flow with increasing geographic distances between localities, Apparently for these two species, modes and rates of dispersal could not be predicted from a knowledge of larval shell morphology. Although L. elevatus and L. galriftensis exhibited trends that may be consistent with 'isolation-by-distance', the number of population samples available for this study were inadequate to reject the null hypothesis of genetic structure being independent of geographical distance. Copyright (C) 1997 Elsevier Science B.V.