MEPS 219:169-175 (2001)  -  doi:10.3354/meps219169

Large genetic distances within a population of Amphipholis squamata (Echinodermata; Ophiuroidea) do not support colour varieties as sibling species

Renate Sponer1, Dimitri Deheyn2,*, Michael S. Roy1,**

1Evolutionary Genetics Laboratory, Zoology Department, University of Otago, PO Box 56, Dunedin, New Zealand
2Laboratoire de Biologie marine, Université de Mons-Hainaut, Pentagone, 6 av. du Champs de Mars, 7000 Mons, Belgium
*Present address: Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0202, USA **Corresponding author. E-mail:

ABSTRACT: The brittle star Amphipholis squamata is paradoxical in that it lacks an obvious dispersive phase yet has a world-wide distribution. Although individuals from distant populations are morphologically similar, a recent phylogenetic analysis found multiple clades separated by large genetic divergences. These clades were not phylogeographically structured and genetic divergences within populations were typically as high as those amongst populations. The recent suggestion that the sympatric colour varieties Œorange¹, Œdark brown¹, Œbeige¹, Œblack¹ and Œgrey¹ represent sibling species, led us to test whether colour variety and phylogeny were congruent. Genetic distances among sequences of the mitochondrial gene 16S rRNA from the colour varieties were surprisingly high (up to 13% uncorrected distance) and phylogenetic analyses using maximum parsimony, maximum likelihood and neighbour joining gave well supported, congruent phylogenies. However, the clades were not consistent with colour variety. When clades were constrained to make colour varieties monophyletic, tree scores were always significantly worse. We conclude from the results of this study that colour varieties do not represent distinct phylogenetic lineages. We discuss the implications of our results in the light of the possibility of clonality or self-fertilization in this species.

KEY WORDS: Cryptic species · Phylogeny · 16S mtDNA · Bioluminescence · Speciation · Colour morphs

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