Deep phylogeographic structure may indicate cryptic species within the Sparid genus Spondyliosoma.

Niall J Mckeown,Warren M Potts,Michael P Gwilliam,Warwick H.H Sauer,Ilze Skujina,Paul W Shaw,Amy J.E Healey

doi:10.1111/jfb.14316

Niall J Mckeown, Warren M Potts + Show 5 more

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https://doi.org/10.1111/jfb.14316

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Abstract

Two geographically nonoverlapping species are currently described within the sparid genus Spondyliosoma: Spondyliosoma cantharus (Black Seabream) occurring across Mediterranean and eastern Atlantic waters from NW Europe to Angola and S. emarginatum (Steentjie) considered endemic to southern Africa. To address prominent knowledge gaps this study investigated range-wide phylogeographic structure across both species. Mitochondrial DNA sequences revealed deep phylogeographic structuring with four regionally partitioned reciprocally monophyletic clades, a Mediterranean clade and three more closely related Atlantic clades [NE Atlantic, Angola and South Africa (corresponding to S. emarginatum)]. Divergence and distribution of the lineages reflects survival in, and expansion from, disjunct glacial refuge areas. Cytonuclear differentiation of S. emarginatum supports its validity as a distinct species endemic to South African waters. However, the results also indicate that S. cantharus may be a cryptic species complex wherein the various regional lineages represent established/incipient species. A robust multilocus genetic assessment combining morphological data and detailing interactions among lineages is needed to determine the full diversity within Spondyliosoma and the most adequate biological and taxonomic status.

Highlights

The Sparidae are demersal fishes commonly found at a range of depths in temperate and tropical marine waters with maximum species diversity in the NE Atlantic Ocean and Mediterranean Sea (Bauchot & Hurau, 1986)
Range contraction and expansion events associated with the Quaternary glaciations (2.5 MYA up until the Last Glacial Maximum 26.5–19KY BP) have profoundly shaped the phylogeographic structure of many marine taxa (Maggs et al, 2008)
Chronic isolation in disjunct areas of persistence has contributed to genetic divergence, regionally associated phylogroups and even speciation. Signatures of such processes are strikingly evident in the phylogeography of Spondyliosoma

Summary

| INTRODUCTION

The Sparidae (seabreams) are demersal fishes commonly found at a range of depths in temperate and tropical marine waters with maximum species diversity in the NE Atlantic Ocean and Mediterranean Sea (Bauchot & Hurau, 1986). Within this family the genus Spondyliosoma is currently recognized as comprising two species, Spondyliosoma cantharus (black seabream) and Spondyliosoma emarginatum (Steentjie). As an initial focus was to assess the species status of S. emarginatum, nuclear DNA differentiation was assayed between S. emarginatum from South Africa (southern Benguela subsystem) and S. cantharus from Angola (the putative southern limit of S. cantharus and within the northern Benguela subsystem), i. e., the geographically closest representatives of the two species

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION