Open AccessPopulation genetics, phylogeography and speciation of Cystodytes (Ascidiacea) in the western Mediterranean Sea
Author(s) -
LÓPEZLEGENTIL SUSANNA,
TURON XAVIER
Publication year - 2006
Publication title -
biological journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.906
H-Index - 112
eISSN - 1095-8312
pISSN - 0024-4066
DOI - 10.1111/j.1095-8312.2006.00614.x
Subject(s) - biology , phylogeography , cytochrome c oxidase subunit i , evolutionary biology , population , genetic structure , mediterranean sea , genetic divergence , mediterranean climate , genetic variation , ecology , zoology , analysis of molecular variance , population genetics , range (aeronautics) , clade , species complex , phylogenetic tree , genetic diversity , genetics , gene , demography , sociology , materials science , composite material
Several morphotypes that so far have been attributed to the allegedly cosmopolitan ascidian Cystodytes dellechiajei occur in the Mediterranean Sea. Colour variation is the difference most frequently reported. In this study, we addressed the genetic structure of this ascidian in relation to geographical location and colour morph. Partial sequences of the gene cytochrome c oxidase subunit 1 (COI) were obtained from seven populations of the western Mediterranean, encompassing eight colour varieties. All population genetic analyses (exact test, pairwise F ST , hierarchical analysis of molecular variance, multidimensional scaling, nested clade analysis) indicated clearly that differences between colour morphs are large enough to obscure any geographical differentiation when colours are combined within localities. When variance due to colour divergence was removed, however, a significant geographical variability between localities remained. The genetic divergence between the colour morphs analysed was significant in comparisons of the brown and purple forms with the others, but not among the green, blue, and white morphs. Phylogeographic analyses suggest that population fragmentation and range expansions have shaped the present‐day distribution of the haplotypes. Taken together with existing chemotype information, our results indicate that several species are present in the area, and that a thorough revision of the genus is necessary. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 203–214.