Data from: At least some meiofauna species are not everywhere. Indication of ecological and geological barriers affecting the dispersion of species of Ototyphlonemertes (Nemertea, Hoplonemertea)

Most meiofauna species are known to have a broad distribution with no apparent barriers to their dispersion. However, different morphological and/or molecular methods supported patterns of diversity and distribution that may be different among taxa while also conflicting within the same group. We accurately assessed the patterns of geographic distribution in actual genetic species of a marine meiofauna animal model: Ototyphlonemertes. Specimens were collected from several sites around Europe, Northern and Central America, Southern America, Pacific Islands and Asia. We sequenced regions of two mitochondrial and two nuclear genes. By using single-gene, concatenated dataset, and multi-locus approaches and different DNA-taxonomy methods we disentangled the actual diversity and the spatial structures of haplotypes tested the possible correlation between the genetic diversity and geographic distance, and the spatial structures of haplotypes. Results show (i) the importance of using several genes to uncover both diversity and highlight phylogeographic relationships among species, and that (ii) independent genetic evolutionary entities have a narrower distribution than morphological species. Moreover, (iii) the Mantel test supported a positive correlation between genetic and geographical distance. We also determined the divergence time between some of our entities sampled from the two sides of Panama Isthmus. Results suggest such entities have been separated for a period of time that coincides with the geological closure of the seaway across the Isthmus. We, therefore, propose that in addition to distance other geological and ecological conditions also are barriers to the dispersion and gene flow in marine meiofauna organisms.