title: Mitochondrial DNA hyperdiversity and its potential causes in the marine periwinkleMelarhaphe neritoides(Mollusca: Gastropoda).
abstract: We report the presence of mitochondrial DNA (mtDNA) hyperdiversity in the marine periwinkleMelarhaphe neritoides(Linnaeus, 1758), the first such case among marine gastropods. Our dataset consisted of concatenated 16S-COI-Cytbgene fragments. We used Bayesian analyses to investigate three putative causes underlying genetic variation, and estimated the mtDNA mutation rate, possible signatures of selection and the effective population size of the species in the Azores archipelago. The mtDNA hyperdiversity inM. neritoidesis characterized by extremely high haplotype diversity (Hd= 0.999 ± 0.001), high nucleotide diversity (π= 0.013 ± 0.001), and neutral nucleotide diversity above the threshold of 5% (πsyn= 0.0677). Haplotype richness is very high even at spatial scales as small as 100m2. Yet, mtDNA hyperdiversity does not affect the ability of DNA barcoding to identifyM. neritoides. The mtDNA hyperdiversity inM. neritoidesis best explained by the remarkably high mutation rate at the COI locus (μ= 5.82 × 10-5per site per year orμ= 1.99 × 10-4mutations per nucleotide site per generation), whereas the effective population size of this planktonic-dispersing species is surprisingly small (Ne= 5, 256; CI = 1,312-3,7495) probably due to the putative influence of selection. Comparison with COI nucleotide diversity values in other organisms suggests that mtDNA hyperdiversity may be more frequently linked to highμvalues and that mtDNA hyperdiversity may be more common across other phyla than currently appreciated.
authors.affiliation: Directorate Taxonomy and Phylogeny & JEMU, Royal Belgian Institute of Natural Sciences , Brussels , Belgium.
authors.forename: Séverine
authors.initials: S
authors.lastname: Fourdrilis
authors.affiliation: Evolutionary Biology and Ecology, Université Libre de Bruxelles , Brussels , Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mardulyn
authors.affiliation: Evolutionary Biology and Ecology, Université Libre de Bruxelles , Brussels , Belgium.
authors.forename: Olivier J
authors.initials: OJ
authors.lastname: Hardy
authors.affiliation: Department of Biology, Invertebrate Section, Royal Museum for Central Africa , Tervuren , Belgium.
authors.forename: Kurt
authors.initials: K
authors.lastname: Jordaens
authors.affiliation: CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Departamento de Biologia da Universidade dos Açores, University of the Azores , Ponta Delgada , Portugal.
authors.forename: António Manuel
authors.initials: AM
authors.lastname: de Frias Martins
authors.affiliation: Directorate Taxonomy and Phylogeny & JEMU, Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Evolutionary Ecology Group, University of Antwerp, Antwerp, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Backeljau
keywords: Effective population size; Haplotype diversity; Mutation rate; Nucleotide diversity; Planktonic dispersal; Selection; mtDNA hyperdiversity