Phylogeography and Taxonomic Revision of the Pen Shell Atrina pectinata Species Complex in the South China Sea

Hai-Yan Wang,Tao Zhang,Dong-Xiu Xue

doi:10.3389/fmars.2021.753553

Abstract

Phylogeographic studies contribute to addressing questions regarding the geographic patterns and evolutionary scenarios within and among species and also shed light on the taxonomic status of widely distributed species complexes. The pen shell Atrina pectinata species complex is a widely distributed and economically important bivalve in the northwestern Pacific. Previous phylogeographic studies have identified four genetically distinct cryptic species within the A. pectinata species complex along the coast of China, of which three cryptic species were distributed in the South China Sea. However, less attention has been given to their identification and delimitation. Herein, we report the phylogeography and taxonomic revision of the A. pectinata species complex in the South China Sea using DNA sequence data from mitochondrial cytochrome oxidase I (COI) and 16S ribosomal RNA (16S rRNA), and nuclear 28S ribosomal RNA (28S rRNA) gene markers. Using a combination of phylogenetic and DNA-based species delimitation analysis methods, we found strong support for four genetically valid species in the A. pectinata species complex and defined them as A. japonica, A. lischkeana, Atrina sp., and A. pectinata based on our results as well as on previous morphological and genetic studies. A demographic historical analysis showed that all three species in the South China Sea had populations that were relatively stable over time and then subjected to sudden expansion during the late Pleistocene (60,000–90,000 years ago). These results provide new insights into the systematics and evolution of the A. pectinata species complex and have important conservation and management implications.

Highlights

Species identification and delimitation are fundamentally important within the fields of biology, biogeography, ecology, and conservation, as species are the fundamental units for biodiversity quantification and management (Agapow et al, 2004; Bickford et al, 2007; Liu et al, 2020)
The automatic barcode gap discovery (ABGD) method clustered the sequences into four groups that were congruent with the four clades inferred in the phylogenetic analyses, representing four putative species: A. japonica, A. lischkeana, Atrina sp., and A. pectinata
Using the generalized mixed Yule coalescent model (GMYC) approach, the null model of a single species was rejected for mitochondrial cytochrome oxidase I (mtCOI) genes (likelihood ratios for single threshold model: 63.09 (P = 1.99 × 10−14), and indicated four clusters (Supplementary Figure 3)

Summary

Introduction

Species identification and delimitation are fundamentally important within the fields of biology, biogeography, ecology, and conservation, as species are the fundamental units for biodiversity quantification and management (Agapow et al, 2004; Bickford et al, 2007; Liu et al, 2020). Taxonomic Revision of Atrina pectinata morphological characteristics; these processes require a high level of expertise and are time consuming. Molecular analytical approaches (e.g., DNA barcoding) have been developed to identify and delimit species and are used to resolve many taxonomic problems associated with different animals and plant species (Wiens and Servedio, 2000; Goldstein and DeSalle, 2011; Previšicet al., 2016; Sun et al, 2016; Liu et al, 2020). The family Pinnidae Leach, 1819, includes approximately 50 species of commercially important subtidal and coastal species that inhabit tropical and temperate coastal oceanic waters worldwide (Huber, 2010; Lemer et al, 2014). Atrina pectinata Linnaeus, 1767, one of the most diverse Pinnidae species, is a large wedge-shaped marine bivalve distributed along the coasts of Indo-Pacific countries. Since the first description of this species in 1767, the nomenclature of A. pectinata has been confusing: Rosewater (1961) assigned 12 distinct Indo-Pacific Atrina species to a single A. pectinata species, Wang (1997) assigned 11 synonymous names to A. pectinata, and Huber (2010) assigned only three synonymous names to A. pectinata

Methods

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Discussion

Conclusion