Journal of Molecular Evolution

, Volume 49, Issue 3, pp 367–375

Speciation Versus Phenotypic Plasticity in Coral Inhabiting Barnacles: Darwin's Observations in an Ecological Context

  • O.  Mokady
  • Y.  Loya
  • Y.  Achituv
  • E.  Geffen
  • D.  Graur
  • S.  Rozenblatt
  • I.  Brickner

DOI: 10.1007/PL00006560

Cite this article as:
Mokady, O., Loya, Y., Achituv, Y. et al. J Mol Evol (1999) 49: 367. doi:10.1007/PL00006560
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Abstract.

Speciation and phenotypic plasticity are two extreme strategic modes enabling a given taxon to populate a broad ecological niche. One of the organismal models which stimulated Darwin's ideas on speciation was the Cirripedia (barnacles), to which he dedicated a large monograph. In several cases, including the coral-inhabiting barnacle genera Savignium and Cantellius (formerly Pyrgoma and Creusia, respectively), Darwin assigned barnacle specimens to morphological ``varieties'' (as opposed to species) within a genus. Despite having been the subject of taxonomic investigations and revisions ever since, the significance of these varieties has never been examined with respect to host-associated speciation processes. Here we provide evidence from molecular (12S mt rDNA sequences) and micromorphological (SEM) studies, suggesting that these closely related barnacle genera utilize opposite strategies for populating a suite of live-coral substrates. Cantellius demonstrates a relatively low genetic variability, despite inhabiting a wide range of corals. The species C. pallidus alone was found on three coral families, belonging to distinct higher-order classification units. In contrast, Savignium barnacles exhibit large between- and within-species variations with respect to both micromorphology and DNA sequences, with S. dentatum ``varieties'' clustering phylogenetically according to their coral host species (all of which are members of a single family). Thus, whereas Savignium seems to have undergone intense host-associated speciation over a relatively narrow taxonomic range of hosts, Cantellius shows phenotypic plasticity over a much larger range. This dichotomy correlates with differences in life-history parameters between these barnacle taxa, including host-infestation characteristics, reproductive strategies, and larval trophic type.

Key words: Phylogenetic reconstruction — Speciation — Phenotypic plasticity — Pyrgomatine barnacles —Cantellius—Savignium— 12S mt rDNA 

Copyright information

© Springer-Verlag New York Inc. 1999

Authors and Affiliations

  • O.  Mokady
    • 1
  • Y.  Loya
    • 2
  • Y.  Achituv
    • 3
  • E.  Geffen
    • 1
  • D.  Graur
    • 2
  • S.  Rozenblatt
    • 4
  • I.  Brickner
    • 2
  1. 1.Institute for Nature Conservation Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, IsraelIL
  2. 2.Department of Zoology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, IsraelIL
  3. 3.Faculty of Life Sciences, Bar Ilan University, Ramat Gan 52900, IsraelIL
  4. 4.Department of Molecular Microbiology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, IsraelIL

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