Dispersal, habitat differences, and comparative phylogeography of Southeast Asian seahorses (Syngnathidae: Hippocampus)

Authors

  • S. A. LOURIE,

    Corresponding author
    1. Project Seahorse, Department of Biology, 1205 Avenue Dr Penfield, Montréal, Québec, H3A 1B1, Canada,
    2. Redpath Museum, McGill University, 859 Sherbrooke Ouest, Montréal, Québec, H3A 2K6, Canada
      S. A. Lourie, Fax: 1 (514) 398 3185; E-mail: sara.lourie@mail.mcgill.ca
    Search for more papers by this author
  • D. M. GREEN,

    1. Redpath Museum, McGill University, 859 Sherbrooke Ouest, Montréal, Québec, H3A 2K6, Canada
    Search for more papers by this author
  • A. C. J. VINCENT

    1. Project Seahorse, Department of Biology, 1205 Avenue Dr Penfield, Montréal, Québec, H3A 1B1, Canada,
    Search for more papers by this author
    • Current address: Project Seahorse, Fisheries Centre, The University of British Columbia, 2204 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada


S. A. Lourie, Fax: 1 (514) 398 3185; E-mail: sara.lourie@mail.mcgill.ca

Abstract

Four distinct phylogeographical patterns across Southeast Asia were observed for four species of seahorse (genus Hippocampus) with differing ecologies. For all species, genetic differentiation (based on cytochrome b sequence comparisons) was significantly associated with sample site (ΦST = 0.190–0.810, P < 0.0001) and with geographical distance (Mantel's r = 0.37–0.59, P < 0.019). Geographic locations of genetic breaks were inconsistent across species in 7/10 comparisons, although some similarities across species were also observed. The two shallow-water species (Hippocampus barbouri and Hippocampus kuda) have colonized the Sunda Shelf to a lesser degree than the two deeper-water species (Hippocampus spinosissimus and Hippocampus trimaculatus). In all species the presence of geographically restricted haplotypes in the Philippines could indicate past population fragmentation and/or long-distance colonization. A nested clade analysis (NCA) revealed that long-distance colonization and/or fragmentation were likely the dominant forces that structure populations of the two shallow-water species, whereas range expansion and restricted dispersal with isolation by distance were proportionally more important in the history of the two deeper-water species. H. trimaculatus has the most widespread haplotypes [average clade distance (Dc) of nonsingleton haplotypes = 1169 km], indicating potentially high dispersal capabilities, whereas H. barbouri has the least widespread haplotypes (average Dc = 67 km) indicating potentially lower dispersal capabilities. Pleistocene separation of marine basins and postglacial flooding of the Sunda Shelf are extrinsic factors likely to have contributed to the phylogeographical structure observed, whereas differences among the species appear to reflect their individual ecologies.

Ancillary