Molecular phylogeny endorses the relationship between carnivorous and filter-feeding tunicates (Tunicata, Ascidiacea)

TATIÁN, M.; LAGGER, C.; DEMARCHI, M.; MATTONI, C.I.

ZOOLOGICA SCRIPTA

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011 vol. 40 p. 603 - 612

0300-3256

The phylogeny of the tunicates (animals considered the closest relatives to the vertebrates)is not yet completely defined, especially the evolutionary relationships within the class.Molecular studies do not include particular benthic deep-sea species that show morphologicalchanges in the evolution from filter feeding into a carnivorous-feeding habit. Accordingonly to morphological features, these animals are considered as a part of the ClassAscidiacea (Family Hexacrobylidae), but also as a different class, Sorberacea, belonging tothe Phylum Tunicata. In this study, we present a phylogenetic analysis based on 18SrDNA sequences, which clearly included these animals in Ascidiacea but in the FamilyMolgulidae, faster-evolving ascidians with a high evolution rate. This finding supports theidea that carnivory in Molgulidae represents a more recent adaptation to life in the oceandeep bottoms, where organisms have to adapt themselves to a less plentiful particulateorganic carbon supply. Based on molecular and morphological evidence, we propose thefollowing new synonymy: Hexacrobylidae Seeliger 1906 = Molgulidae Lacaze-Duthiers,1877.