Phylogeography of the temperate marine bivalveCerastoderma edule(Linnaeus, 1758) (Bivalvia: Cardiidae) in the Subarctic: Unique diversity and strong population structuring at different spatial scales

Abstract

Using mitochondrial COI sequencing, we explored the genetic diversity and population structuring of the common cockle Cerastoderma edule (Linnaeus, 1758) in the Norwegian and Barents Seas. Phylogeographic diversity and hence the evolutionary history of C. edule on the Scandinavian and Russian coastlines were found to be richer than expected for populations of temperate species in postglacially colonized seas. A major phylogeographic break at Lofoten Islands separated a group of subarctic populations dominated by a distinct star‐shaped clade of haplotypes from those to the south, extending to the North Sea and having highest gene diversities (h). At the northeastern edge of the range of C. edule, the Russian Murman coast, populations show a mosaic structure with considerable admixture of haplotypes from the south and high local‐scale variation in haplotype diversity (ranging between 0 and 0.8). To explain this mosaic we refer to the core‐satellite metapopulation model, with Norwegian populations as core, and Murman populations as satellites. Our results contradict the conventional biogeographic paradigm implying lack of metapopulation structuring in marine broadcast spawning invertebrates. Hypotheses considered to explain the origin of the unique variation in cockles from Northern Norway involve an early postglacial colonization and establishment of these populations (10–12 ka ago), a persistent oceanographic break at Lofoten, and a mitochondrial selective sweep associated with the postglacial recolonization of the subarctic seas by the boreal C. edule.

Phylogeography of the Brittle Star Ophiura sarsii Lütken, 1855 (Echinodermata: Ophiuroidea) from the Barents Sea and East Atlantic

“…High mtDNA diversity has recently been recorded in Svalbard populations of intertidal North Atlantic amphipods Gammarus [42] and in the Barents and White Sea populations of amphi-boreal pacific herring Clupea pallasii [43]. On the contrary, typical boreal Atlantic intertidal species demonstrate a gradual northward decline of abundance and genetic diversity with the Barents Sea populations being largely dependent on long-distance larval dispersal from source populations of the Norwegian Sea [8].…”

“…A number of taxa migrated from the Pacific to the Atlantic by trans-Arctic migrations after the first opening of the Bering Strait in the Pliocene [2]. The recent glacial cycle culminating in the last glacial maximum 21 kyr BP (thousands of years before present) lead to the southward retreat of boreal species, yet many populations survived in the northern unglaciated areas known as periglacial refugia [3][4][5][6][7][8][9][10][11][12]. Demographic expansions between the glacial cycles and after the retreat of the LGM ice sheets resulted in secondary contacts between previously isolated populations [6].…”

A case study of local ecological knowledge of shellfishers about edible cockle (Cerastoderma edule) in the Ria de Aveiro lagoon, Western Iberia

“…It prefers sites with a higher salinity gradient located near downstream [ 5 ]. This euryhaline bivalve species have external fertilization, with high fecundity rates and dispersal potential due to the pelagic larval stage [ 6 ]. It is engineer species, as it physically disturbs the water column and the sediments, allowing the presence of microphytobenthos in the ecosystem [ 7 ].…”

Phylogeography of the Brittle Star <em>Ophiura sarsii</em> Lütken, 1855 (Echinodermata: Ophiuroidea) from the Barents Sea and East Atlantic

“…Also, several taxa migrated from the Pacific by transarctic migrations (Laakonen et al, 2020 etc.). While historical ecology of nearhore and intertidal ecosystems are being extensively studied (Colson, & Huges, 2006;Rock et al, 2007;Maggs et al, 2008;Krebes et al, 2011;Genelt-Yanovskiy et al, 2019), our understanding of phylogeography and population structure in deep-sea benthic organisms remains understudied. Subtidal species in the North Atlantic demonstrated different genetic patterns.…”

“…). On the contrary, typical boreal Atlantic intertidal species demonstrate a gradual northward decline of abundance and genetic diversity with Barents Sea populations being largely dependent on long-distance larval dispersal from source populations of the Norwegian Sea(Genelt-Yanovskiy et al, 2019). Bayesian Skyline Plots demographic analysis for two major Atlantic clades of Ophiura sarsii.…”