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Science Papers Examine Genetic History of East Asian Individuals, Melanoma in Swordtail Fish, More

By analyzing the newly sequenced genomes of 26 individuals from northern and southern East Asia who lived 9,500 to 300 years ago, scientists from the Chinese Academy of Sciences have uncovered details about the poorly understood genetic history of the region. The researchers studied the genomes along with existing data on ancient and present-day individuals, and found evidence of a major episode of admixture involving northern East Asian ancestry spreading across southern East Asia after the Neolithic Era, which transformed the genetic ancestry of southern China. They also find shared ancestry between ancient individuals on the southeast coast of mainland East Asia, islands in the Taiwan Strait, and the southwest Pacific island Vanuatu, pointing to a southern China origin for proto-Austronesians. GenomeWeb has more on this, here.

The discovery of incompatible alleles that cause melanoma in swordtail fish sheds new light on the evolution of new species. In a study appearing in Science, investigators from Stanford University and their collaborators note that the emergence of reproductive barriers between populations is the first step in the process of speciation, but that little is known about how this occurs at the genetic level. It is posited that new mutations arising in diverging species can interact negatively in hybrids, generating lower hybrid viability or causing hybrid sterility. To explore this further, the scientists use genome-wide sequencing and gene mapping approaches to identify the genes responsible for an incompatibility that causes melanoma in swordtail fish hybrids. One of the genes, they write, also causes melanoma in hybrids between distantly related species. Further, the melanoma causes degradation of the tailfin that hinders swimming ability, thereby reducing survival in the wild.