Marine Biology

, Volume 139, Issue 2, pp 221–233

Molecular genetic evidence for probable reticulate speciation in the coral genus Madracis from a Caribbean fringing reef slope

  •  O. Diekmann
  •  R. Bak
  •  W. Stam
  •  J. Olsen

DOI: 10.1007/s002270100584

Cite this article as:
Diekmann, O., Bak, R., Stam, W. et al. Marine Biology (2001) 139: 221. doi:10.1007/s002270100584

Abstract.

For many corals, the existence of morphologically distinct yet sympatric populations/species implies reproductive isolation. Conversely, the presence of many intermediate and overlapping morphologies combined with synchronous, mass spawning suggests incomplete reproductive isolation. In Madracis (Scleractinia: Astrocoeniina: Pocilloporidae), high levels of morphological plasticity among the five most commonly recognized species (M. mirabilis, M. senaria, M. decactis, M. formosa and M. pharensis) on Caribbean reefs led us to question species boundaries. Phylogenetic relationships were investigated at the intra-individual, inter-individual and inter-specific levels using the ITS1-5.8S-ITS2 region (ca. 613 bp) of the ribosomal DNA cistron. Inter-specific divergence was ca. 6%, while intra-individual and intra-specific divergences ranged from 0% to 4.9% and 3.3% to 3.5%, respectively. M. senaria and M. mirabilis formed monophyletic groups. M. formosa, M. decactis and M. pharensis formed a paraphyletic complex. High levels of intra-individual and intra-specific ITS polymorphism in the decactis-formosa-pharensis cluster may be the result of very recent speciation within the clade (i.e. maintenance of ancestral polymorphism and incomplete lineage sorting), or the result of repeated introgressive hybridization among the three taxa. Polymorphism parsimony of 89 sites, including nine that showed additivity, revealed a phylogenetic topology more consistent with inter-taxal hybridization. Results are discussed in terms of weak reproductive barriers, and phylogenetic fission and fusion under Veron's model of reticulate speciation in corals. Ecological studies involving Madracis should consider M. decactis, M. formosa and M. pharensis as a complex.

Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  •  O. Diekmann
    • 1
  •  R. Bak
    • 2
  •  W. Stam
    • 1
  •  J. Olsen
    • 1
  1. 1.Department of Marine Biology, Center of Evolutionary and Ecological Studies, University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands
  2. 2.Institute of Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94766, 1090 GT Amsterdam, The Netherlands
  3. 3.Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790 AB Den Burg, The Netherlands