Studies in seascape genomics have detected levels of adaptive divergence in marine species with high gene flow and homogeneous populations. This has highlighted the relevance of geographic and environmental factors as drivers for local adaptations in fishery resources. The pink abalone (Haliotis corrugata) is distributed from California, USA to Baja California Sur, Mexico; exposed to an environmental latitudinal gradient, influenced mainly by the California Current System (CC). The CC carries warm waters from California to the south, while the California Countercurrent carries warm waters, seasonally supplied by the North Equatorial Current to the north. The management of the pink abalone transcends the international border, while Mexico has an active fishery, organized in four administrative areas, the United States keeps the fishery in permanent closure. Both contrasting management strategies lack genetic information that supports such spatial arrangement. Recently, evidence of genomic-population structure was obtained in Mexico; however, the effect of the environment on genetic variation along the species distribution range remains unknown. The objective of the study is to define the biocomplexity of Haliotis corrugata, in terms of neutral and adaptive genomic structure and its underlying causal effects.
A total of 203 samples from 13 locations (Fig. 1a) were processed, covering the species’ distribution, using ddRADseq. Overall, 2,242 SNP’s were obtained, 2,231 neutral and 9 potentially adaptive. The neutral structure identified two groups: 1) California locations (PV, SCnaI, SCteI), and 2) Baja California Peninsula locations (GI, SJI, PCS, FS, CI, NI, PE, PuE, BA, SJ) (Fig 1b). In contrast, the adaptive structure separated a north group, from PV to CI, and a south group, from NI to SJ (Fig. 1c). The adaptive structure matches the grouping of localities based on PCA of environmental variables, where temperature and dissolved oxygen concentration distinguished a north group from PV to FSJ, and a south group from CI to SJ.