With a little help from DNA barcoding: investigating the diversity of Gastropoda from the Portuguese coast.

Luísa M S Borges,Claudia Hollatz,Jorge Lobo,Maria H Costa,Ana C Costa,Filipe O Costa,Ana P Vilela,Maria S G Ferreira,Gonçalo Calado,Rita Coelho,Ana M Cunha

doi:10.1038/srep20226

Abstract

The Gastropoda is one of the best studied classes of marine invertebrates. Yet, most species have been delimited based on morphology only. The application of DNA barcodes has shown to be greatly useful to help delimiting species. Therefore, sequences of the cytochrome c oxidase I gene from 108 specimens of 34 morpho-species were used to investigate the molecular diversity within the gastropods from the Portuguese coast. To the above dataset, we added available COI-5P sequences of taxonomically close species, in a total of 58 morpho-species examined. There was a good match between ours and sequences from independent studies, in public repositories. We found 32 concordant (91.4%) out of the 35 Barcode Index Numbers (BINs) generated from our sequences. The application of a ranking system to the barcodes yield over 70% with top taxonomic congruence, while 14.2% of the species barcodes had insufficient data. In the majority of the cases, there was a good concordance between morphological identification and DNA barcodes. Nonetheless, the discordance between morphological and molecular data is a reminder that even the comparatively well-known European marine gastropods can benefit from being probed using the DNA barcode approach. Discordant cases should be reviewed with more integrative studies.

Highlights

The Gastropoda, the largest class of the Mollusca, is one of the most abundant and diverse groups of marine species[1,2,3]
The inaccuracy of specimens’ identification has posed limitations to research in some areas, such as biodiversity and biogeography, which rely on accurate taxonomy
The number of specimens analysed per species varied from 2 to 10, but six species were represented by a single specimen

Summary

Introduction

The Gastropoda, the largest class of the Mollusca, is one of the most abundant and diverse groups of marine species[1,2,3]. The delimitation of species based solely on morphological characters led, in some cases, to an overestimation of species because some groups exhibit high phenotypic plasticity, e.g. Littorina saxatilis (Olivi, 1792)[8]. The aims of this study were to investigate the molecular diversity of gastropods’ morpho-species that were collected on the Portuguese coast (intertidal and subtidal), initiating a DNA barcode library for this taxon and region. In this process, we investigated the congruence between morphology-based identifications and DNA barcodes, and between the data generated and published sequences from other studies. We gained insights into systematic relationships among species and phylogeographic patterns in some species

Objectives

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Results

Discussion

Conclusion