Genetic connectivity in the Florida reef system: comparative phylogeography of commensal invertebrates with contrasting reproductive strategies

Authors

  • VINCENT P. RICHARDS,

    1. National Coral Reef Institute, Oceanographic Center, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL 33004 USA,
    Search for more papers by this author
  • JAMES D. THOMAS,

    1. National Coral Reef Institute, Oceanographic Center, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL 33004 USA,
    Search for more papers by this author
  • MICHAEL J. STANHOPE,

    1. Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853 USA,
    Search for more papers by this author
  • MAHMOOD S. SHIVJI

    1. National Coral Reef Institute, Oceanographic Center, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL 33004 USA,
    2. Guy Harvey Research Institute, Oceanographic Center, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL 33004 USA
    Search for more papers by this author

Mahmood S. Shivji, Fax: 954-262-4098; E-mail: mahmood@nova.edu

Abstract

Effective spatial management of coral reefs including design of marine protected areas requires an understanding of interpopulation genetic connectivity. We assessed gene flow along 355 km of the Florida reef system and between Florida and Belize in three commensal invertebrates occupying the same host sponge (Callyspongia vaginalis) but displaying contrasting reproductive dispersal strategies: the broadcast-spawning brittle star Ophiothrix lineata and two brooding amphipods Leucothoe kensleyi and Leucothoe ashleyae. Multiple analytical approaches to sequence variation in the mitochondrial COI gene demonstrated a high degree of overall connectivity for all three species along the Florida reef system. Ophiothrix lineata showed significant genetic structuring between Florida and Belize, and a pattern of isolation by distance but no significant genetic structuring along the Florida coastline. Bayesian estimates of migration detected a strong southerly dispersal bias for O. lineata along the Florida reef system, contrary to the general assumption of northerly gene flow in this region based on the direction of the Florida Current. Both amphipods, despite direct development, also showed high gene flow along the Florida reef system. Multiple inferences of long-distance dispersal from a nested clade analysis support the hypothesis that amphipod transport, possibly in detached sponge fragments, could generate the high levels of overall gene flow observed. However, this transport mechanism appears much less effective across deep water as connectivity between Florida and Belize (1072 km) is highly restricted.

Ancillary