title: Molecular systematics of the order anaspidea based on mitochondrial DNA sequence (12S, 16S, and COI).
abstract: Fragments from three mitochondrial genes (12S, 16S, and COI) were sequenced to reconstruct a molecular phylogeny of the opisthobranch order Anaspidea. The molecular phylogeny supports the placement of the genus Akera, a taxon previously regarded by some authors as a cephalaspidean, within the Anaspidea. Incongruence between the molecular data and the classifications based on morphology suggests that some of the taxonomic characters (i.e., shell, parapodia fusion) traditionally used for the classification of sea hares must be reevaluated, since they may be homoplastic. The ancestral nature of Notarchus based on the molecular evidence suggests that homoplasy may be an explanation for the morphological resemblance of this species to the more derived sea hares with highly fused parapodia and concentrated nerve ganglia. Finally, examples are given of how comparative studies of the evolution of learning mechanisms in the anaspidean clade will benefit from the phylogenetic hypothesis presented in this paper.
authors.affiliation: Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA. medina@evol5.mbl.edu
authors.forename: M
authors.initials: M
authors.lastname: Medina
authors.forename: P J
authors.initials: PJ
authors.lastname: Walsh
mesh_terms: D000818:Animals; D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D008974:Mollusca / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics
chemical_list: D004272:DNA, Mitochondrial; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; C075526:RNA, ribosomal, 12S; D003576:Electron Transport Complex IV