In Nature Ecology & Evolution this week, an international research team reports the sequenced genomes of two giant tortoises — including Lonesome George, the last member of a now-extinct species of Galapagos Islands tortoises — yielding insights into the genetics of longevity and age-related disease. A comparison of the genomes to those of related species reveals lineage-specific variants affecting DNA repair genes, inflammatory mediators, and genes related to cancer development. "Our study also hints at specific evolutionary strategies linked to increased lifespan, and expands our understanding of the genomic determinants of ageing," the authors write. The Scan has more on this, here.
Also in Nature Ecology & Evolution, a group led by scientists from the University of California, San Diego, presents the genome of the moon jellyfish Aurelia, a cnidarian with a medusa life stage. The data suggest that the increased life cycle complexity in this jellyfish does not correlate with an increased number of genes — suggesting that either medusozoans evolved their complex medusa life stage primarily by re-working genetic pathways already present in the last common ancestor of cnidarians or that the earliest cnidarians had a medusa life stage that was subsequently lost in the anthozoans. "While we favor the earlier hypothesis, the latter is consistent with growing evidence that many of the earliest animals were more physically complex than previously hypothesized," the researchers write.
And in Nature Genetics, scientists from Asia, Europe, and the US publish reference-grade genome assemblies and annotations for two allotetraploid cotton species widely cultivated for their textile fibers: Gossypium hirsutum and Gossypium barbadense. Compared with previous assembled draft genomes, the new genome sequences show considerable improvements in contiguity and completeness for regions with high content of repeats such as centromeres. They are expected to help accelerate evolutionary and functional genomic studies in cotton and inform future breeding programs for fiber improvement, the investigators write.