Thermal Adaptive Genotypes in the Clam Mactra veneriformis

This study investigates the genetic basis of thermal adaptation in two geographically distinct populations of the clam Mactra veneriformis from the Bohai Sea, China. The research integrates physiological phenotyping (cardiac performance measurement), genotyping-by-sequencing (GBS), and genome-wide association study (GWAS) approaches. Although population genetic structure based on neutral single nucleotide polymorphisms (SNPs) showed low differentiation, significant divergence was observed in heat tolerance between the Dongying (DY) and Panjin (PJ) populations. This phenotypic difference is linked to the differential distribution of specific thermal-adaptive genotypes (e.g., thermotolerant pureA and thermosensitive AmixB). The study identified multiple candidate genes and SNP loci significantly associated with upper thermal limits (FLT). Functional analysis suggests that these genetic variations may influence thermal adaptation by modulating codon usage bias and protein structural stability. The findings provide crucial insights into the microclimate-driven evolutionary mechanisms of thermal tolerance in marine bivalves. This dataset offers valuable genetic resources for understanding climate change impacts and for informing conservation and selective breeding strategies in aquaculture.