Adaptive genetic variation distinguishes Chilean blue mussels (Mytilus chilensis) from different marine environments

Abstract

Chilean mussel populations have been thought to be panmictic with limited genetic structure. Genotyping‐by‐sequencing approaches have enabled investigation of genomewide variation that may better distinguish populations that have evolved in different environments. We investigated neutral and adaptive genetic variation in Mytilus from six locations in southern Chile with 1240 SNPs obtained with RAD‐seq. Differentiation among locations with 891 neutral SNPs was low (FST = 0.005). Higher differentiation was obtained with a panel of 58 putative outlier SNPs (FST = 0.114) indicating the potential for local adaptation. This panel identified clusters of genetically related individuals and demonstrated that much of the differentiation (~92%) could be attributed to the three major regions and environments: extreme conditions in Patagonia, inner bay influenced by aquaculture (Reloncaví), and outer bay (Chiloé Island). Patagonia samples were most distinct, but additional analysis carried out excluding this collection also revealed adaptive divergence between inner and outer bay samples. The four locations within Reloncaví area were most similar with all panels of markers, likely due to similar environments, high gene flow by aquaculture practices, and low geographical distance. Our results and the SNP markers developed will be a powerful tool supporting management and programs of this harvested species.

Lineage divergence, local adaptation across a biogeographic break, and artificial transport, shape the genetic structure in the ascidian Pyura chilensis

“…The use of putative selected markers (outlier loci) in marine benthic invertebrates has usually increased the strength of detected phylogeographic structure with respect to neutral loci, as is expected, albeit the general patterns remain the same19212223. In contrast to this generalization, in the present study neutral and outlier loci showed contrasting spatial genetic structure patterns in the ascidian Pyura chilensis along 18° degrees of latitude in the Southeast Pacific coast.…”

“…Studies focused on the assessment of phylogeographic signals of outlier and neutral loci in marine systems have been mostly developed for marine mammals and fishes161718. These studies have generally shown that outlier loci possess a stronger signal of the genetic structure, as is expected by definition1920. However, the main signal is mostly congruent between outlier and neutral loci.…”

Native and invasive taxa on the Pacific coast of South America: Impacts on aquaculture, traceability and biodiversity of blue mussels (Mytilus spp.)

“…Single nucleotide polymorphisms (SNPs) are powerful markers to monitor organisms at the individual, population and species levels. They have been developed recently for mussels of the genus Mytilus to study hybrid zones, introgression and adaptive genetic variation with traceability purposes (Araneda et al., ; Saarman & Pogson, ; Zbawicka, Sanko et al., . The availability of a SNP panel now allows for a multi−locus scan of the genome, adding more confidence to Mytilus species identification.…”

“…On the other hand, loci for identification of geographic origin must be more variable amongst populations within species, because they can reflect adaptation to local conditions, as demonstrated recently by Araneda et al. ().…”

Population substructure and signals of divergent adaptive selection despite admixture in the sponge Dendrilla antarctica from shallow waters surrounding the Antarctic Peninsula

“…Although RADseq data can potentially be used for discovering genomic regions under selective pressure (Catchen et al, ; McKinney, Larson, Seeb, & Seeb, ), none of the above‐mentioned studies has used this approach to delve into the footprints that natural selection and local adaptation left in the genome of the three Antarctic species listed above. In contrast, in other latitudes, RADseq has been successfully used to detectloci under selection, providing the grounds to understand processes of adaptive ecological divergence in a range of nonmodel marine organisms (e.g., Araneda, Larraín, Hecht, & Narum, ; Combosch, Lemer, Lemer, Ward, Landman, & Giribet, ; Ferchaud & Hansen, ; Gleason & Burton, ).…”