In Nature Communications, a group of Australian investigators presents an analysis of ancient cave art and bison DNA to shed light on the rise of the modern European bison. The animals are distinct from their American counterparts, but their origins were unclear due to a gap in the fossil record. The researchers analyzed the genomes of 64 ancient European bison and found that they resulted from a hybridization between the long-extinct Steppe bison and aurochs more than 120,000 years ago. Notably, these findings match up with ancient cave art that portrays the emergence of the European bison. GenomeWeb has more on this study, here.
Over in this week's Nature, a multi-institute team reports new details about the origins and consequences of tetraploidy in the African clawed frog Xenopus laevis. By sequencing the animal's genome and comparing it to the related diploid species X. tropicalis, and characterizing its allotetraploid origin by partitioning its genome into two homoeologous subgenomes, the researchers estimate that the diploid progenitor species of the two frogs diverged around 34 million years ago then converged to form an allotetraploid about 17 million years later. They also found that the X. laevis subgenomes evolved asymmetrically, with one chromosome set undergoing more gene loss, deletion, rearrangement, and reduced gene expression than the other.
Meanwhile, in Nature Methods, collaborators from Pacific Biosciences and Johns Hopkins University describe new open-source algorithms for phased diploid genome assembly using single-molecule real-time sequencing. Sequencing data assemblies generated using the algorithms are substantially more contiguous and complete than other short- or long-read approaches, the researchers report, and the method allowed them to study haplotype structure and heterozygosities between homologous chromosomes, including the identification of widespread heterozygous structural variation within coding sequences. GenomeWeb has more on this, too, here.