Parallel adaptations of Japanese whiting, Sillago japonica under
temperature stress
Abstract
Knowledge about the genetic adaptations of various organisms to
heterogeneous environments in the Northwestern Pacific remains poorly
understood. The mechanism by which organisms adapt to temperature in
response to climate change must be determined. We sequenced the whole
genomes of Sillago japonica individuals collected from different
latitudinal locations along the coastal waters of China and Japan to
detect the possible thermal adaptations. A total of 5.48 million single
nucleotide polymorphisms (SNPs) from five populations revealed a
complete genetic break between the China and Japan groups. This genetic
structure was partly attributed to geographic distance and local
adaptation. Although parallel evolution within species is comparatively
rare at the DNA level, the shared natural selection genes between two
isolated populations (Zhoushan and Ise Bay/Tokyo Bay) indicated possible
parallel evolution at the genetic level induced by temperature. Our
result proved that the process of temperature selection on isolated
populations is repeatable. Additionally, the candidate genes were
functionally related to membrane fluidity in cold environments and the
cytoskeleton in high-temperature environments. These results advance our
understanding of the genetic mechanisms underlying the rapid adaptations
of fish species. Projections of species distribution models suggested
that China and Japan groups may have different responses to future
climate changes: the former could expand, whereas the latter may
contract. The results of the present population genomic work expand our
understanding of genetic differentiation and adaptation to changing
environments.