Heterogeneous microgeographic genetic structure of the common cockle (Cerastoderma edule) in the Northeast Atlantic Ocean: biogeographic barriers and environmental factors

Knowledge of genetic structure at the finest level is essential for conservation of genetic resources. Despite no visible barriers limiting gene flow, significant genetic structure has been shown in marine species. The common cockle (Cerastoderma edule) is a bivalve of great commercial and ecological value inhabiting the Northeast Atlantic Ocean. Previous population genomics studies demonstrated significant structure both across the Northeast Atlantic, but also within small geographic areas, highlighting the need to investigate fine-scale structuring. Here, we analysed two geographic areas that could represent opposite models of structure for the species: 1) the SW British Isles region, highly fragmented due to biogeographic barriers, and 2) Galicia (NW Spain), a putative homogeneous region. 9,250 SNPs genotyped by 2b-RAD on 599 individuals from 22 natural beds were used for the analysis. The entire SNP dataset mostly confirmed previous observations related to genetic diversity and diff..., Sample area and oceanography
Two geographic areas along the Northeast Atlantic coast were investigated (Fig. 1). The first was focused on the British Isles and English Channel (hereafter called the SW British Isles region), where previous, though incomplete information, supported significant genetic sub-structuring (e.g. Coscia et al. 2020; Vera et al. 2022). The second area was Galicia (Northwest Spain), which may be genetically homogeneous according to information in other mollusc species (Diz and Presa 2009; Vera et al. 2016).
Over the cockle reproductive season (May to September; Mahony et al. 2020), the coastline of Galicia is characterised by wind-driven upwelling of cold waters resulting in sea surface temperatures (SSTs) that are several degrees colder than off-shore SSTs (Supplementary Fig. 1b). Also driven by the predominantly northerly winds in the summer months, the Portugal coastal current transports waters southwards along the coastline of Iberia (Teles-Machado et al. 201..., All files can be opened with Notepad or similar., # Vera et al. Heterogeneous microgeographic genetic structure of the common cockle (Cerastoderma edule) in the Northeast Atlantic Ocean: biogeographic barriers and environmental factors

Dataset of the manuscript entitled \"Heterogeneous microgeographic genetic structure of the common cockle (Cerastoderma edule) in the Northeast Atlantic Ocean: biogeographic barriers and environmental factors\". SNPs were obtained using 2bRADseq methodology and using the software STACKS 2.0. All files are in \"Genepop\" format commonly and widely used by the population genetics/genomics research community.

## Description of the data and fiel structure:

Description of files deposited in Dryad:

* 8 Genepop input files:
* CEMicTot.gen: Genepop input file including all the beds and markers used in the study (9,250 markers). Bed codes are shown in Table 1 of the manuscript.
* CEMicN.gen: Genepop input file including the beds from SW British Isles region and all markers used in the study (9,250 m...