Latitudinal environmental variations driving local adaptation of the P. argenteus populations along the coast of China

The habitats of Pampus argenteus spans from subtropical to subfrigid zones and thereby exhibit pronounce latitudinal environmental gradients, which might drive local adaptation of its populations. We re-sequenced 117 draft genomes of P. argenteus from six coastal populations in China. Although limited genetic differentiation among the six populations were found in most genome regions, the Mantel test identified 21 100-Kb sliding windows, whose linearized pairwise fixation index showed significant correlation with latitudinal environmental variations. Within these windows, six (crtc1, grm1, paip2, pde4b, plcl1 and pten) and four (dnajc4, hspd1, pten, fas) genes are associated with light-induced circadian clock regulation and thermal stress response, respectively. Their functions hint that the latitude gradient of sea surface temperature and sunlight duration among sites might be important selective forces driving local adaptation of the P. argenteus populations. Furthermore, 17 genes within the windows regulate neuron activity, genetic variations around these genes may influence the nervous system's response to environmental cues, thereby shaping the distinct migratory and spawning behaviors previously observed in different silvery pomfret stocks. 14 transcriptional and translational factors were included in the 21 windows. 1,607 SNPs were found significantly correlated to latitudinal environmental variations in these windows, with 96.02% of them belongs non-coding regions, where regulatory elements for transcription and translation usually situate. These evidences imply that alterations in gene expression might contribute to local adaptation of the P. argenteus populations.