title: Molecular systematics of the endemic Leptaxini (Gastropoda: Pulmonata) on the Azores islands.
abstract: The Azorean representatives of the Leptaxini (Pulmonata) are single island endemics, where a high-spired shell distinguishes the monotypic genus Helixena from two slightly different low-spired forms within Leptaxis (azorica and caldeirarum type). We studied the evolutionary history of putative taxa and the three shell-types using 12 allozyme loci and sequences of nuclear (ITS-1 and ITS-2) and mitochondrial DNA (COI and 16S rRNA). While little variation was found in both ITS genes, allozyme and mtDNA divergence was among the highest reported for pulmonate land snails. Generally, phylogeographic patterns are indicative of allopatric differentiation via the successive colonization of (younger) islands, while a major role for adaptive evolution is not supported. The azorica shell-type is monophyletic and has no common history with other sympatric shell-types on the same islands. The (ambiguous) position of Helixena sanctaemariae makes Leptaxis paraphyletic on the Azores and possibly also the caldeirarum shell-type. Helixena can therefore not be distinguished as a separate genus on the Azores. Following a lineage-based concept, representatives on all (ancient) islands should be considered distinct species.
authors.affiliation: Royal Belgian Institute of Natural Sciences, Brussels. pvanriel@naturalsciences.be
authors.forename: Patrick
authors.initials: P
authors.lastname: Van Riel
authors.forename: Kurt
authors.initials: K
authors.lastname: Jordaens
authors.forename: Natalie
authors.initials: N
authors.lastname: Van Houtte
authors.forename: Antonio M Frias
authors.initials: AM
authors.lastname: Martins
authors.forename: Ronald
authors.initials: R
authors.lastname: Verhagen
authors.forename: Thierry
authors.initials: T
authors.lastname: Backeljau
mesh_terms: D000818:Animals; D001394:Azores; D001483:Base Sequence; D005075:Biological Evolution; D004272:DNA, Mitochondrial; D005787:Gene Frequency; D014644:Genetic Variation; D007527:Isoenzymes; D010802:Phylogeny; D012335:RNA, Ribosomal; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012908:Snails / Q000145:classification* / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial; D007527:Isoenzymes; D012335:RNA, Ribosomal