Scalesia atractyloides genome assembly

Oceanic archipelagos comprise multiple disparate environments over small geographic areas and are isolated from other biotas. These conditions have led to some of the most rapid and spectacular phenotypic changes, which are often repeated, thus offering a unique chance to characterise its genomic basis. These repeated patterns of evolutionary change in plants on oceanic archipelagos, or the ‘plant island syndrome’, include changes in leaf phenotypes, acquisition of perennial life-style, flowering period and self-compatibility, and ancestral ploidy. Here, we describe the genome of the critically endangered and Scalesia atractyloides Arnot., type species for this Galápagos-endemic genus, obtaining a chromosome-resolved 3.2-Gbp assembly with 43,093 candidate gene models. Using a combination of fossil transposable elements, k-mer spectra analyses and orthologue assignment, we identify the two ancestral subgenomes and date their divergence, and the polyploidization event, concluding that th...