Drivers Of Genetic Divergence Research Articles

Genomic evidence of population genetic differentiation in deep-sea squat lobster Shinkaia crosnieri (crustacea: Decapoda: Anomura) from Northwestern Pacific hydrothermal vent and cold seep

The galatheid squat lobster, Shinkaia crosnieri Baba and Williams, 1998, is one of the few dominant species inhabiting both deep-sea hydrothermal vents and cold seeps. Here, we used mitochondrial cytochrome c oxidase subunit I (mtDNA COI) and nuclear genome-wide single nucleotide polymorphism (SNP) as genetic markers to investigate genetic connectivity of S. crosnieri populations from a hydrothermal vent of Okinawa Through and a cold seep of the South China Sea. MtDNA COI sequence analyses indicated that deep-sea vent population of S. crosnieri was genetically divergent from cold seep population. To obtain deep insights into the evolutionary forces driving this genetic break, we performed restriction-site associated DNA analysis to evaluate the extent of genetic differentiation in S. crosnieri inhabiting both environments on a genome-wide scale, and to assess the role of selective processes in shaping this pattern. Using the assembled survey genome of S. crosnieri as a reference, 12,963 SNPs were identified for 30 S. crosnieri specimens. The structural and principle component analyses based on SNPs supported genetic differentiation between the vent and seep populations. Evidence for local adaptation of S. crosnieri populations was confirmed by identifying increased population divergence using FST-based outlier tests, which resulted in 54 potentially locally selected SNPs, indicative of an important role for natural selection as a driver of genetic divergence in this species. Further studies revealed that candidate genes containing outlier SNPs were involved in diverse biological processes, including immunity, transposon and metabolic processes. Overall, our results demonstrated significant genetic divergence between the vent and seep S. crosnieri populations in the Northwestern Pacific and provided clues to understand potential genetic basis underlying local adaptation in S. crosnieri during colonization into deep-sea chemosynthetic ecosystems.

Insights on the drivers of genetic divergence in the European anchovy

Anchovies represent the largest world’s marine fish catches and the current threats on their populations impose a sustainable exploitment based on sound scientific information. In the European anchovy (Engraulis encrasicolus), the existence of several populations has been proposed but a global view is missing. Using a multidisciplinary approach, here we assessed the divergence among different ecotypes and its possible causes. SNPs have revealed two functionally distinct ecotypes overlapping in the Central Mediterranean, with one ecotype confined near the river estuaries. The same SNPs outliers also segregated two distinct populations in the near Atlantic, despite their large spatial distance. In addition, while most studies suggested that adaptation to low salinity is key to divergence, here we show that the offshore ecotype has higher environmental tolerance and an opportunistic feeding behaviour, as assessed by the study of environmental conditions, anchovy diet and trophic levels, and passive egg dispersal. These results provide insights into the anchovy evolutionary history, stressing the importance of behaviour in shaping ecotypes.