Cryptic speciation and paraphyly in the cosmopolitan bryozoan Electra pilosa - Impact of the Tethys closing on species evolution

Cosmopolitan nature of the marine bryozoan Electra pilosa was studied to clarify geographic structure and to Outline evolution and phylogeography of the species. Several local populations from the Northeast Atlantic (North Sea and Baltic Sea), Arctic (Barents Sea and White Sea) and Indo-West Pacific (New Zealand) were compared. In addition, we examined the closely related species L posidoniae from the Mediterranean Sea. Phylogenetic analysis based on both 16S and 18S rDNA indicate that the Indo-West Pacific E pilosa is a sister species to the Atlantic-Mediterranean clade, with the latter including the species E posidoniae and the Atlantic population of E pilosa. The topology of the phylogenetic tree leads us to conclude that E pilosa is a paraphyletic species group relative to E posidoniae, and a molecular dating of its divergence is consistent to geologic events associated with the closure of the Tethys Sea. (c) 2007 Elsevier Inc. All rights reserved.