Unique structure and positive selection promote the rapid divergence of Drosophila Y chromosomes

Unique structure and positive selection promote the rapid divergence of Drosophila Y chromosomes

Blog Article

Y chromosomes across diverse species convergently evolve a gene-poor, heterochromatic organization enriched for duplicated genes, LTR retrotransposons, and satellite DNA.Sexual antagonism voyage et cie discount code and a loss of recombination play major roles in the degeneration of young Y chromosomes.However, the processes shaping the evolution of mature, already degenerated Y chromosomes are less well-understood.Because Y chromosomes evolve rapidly, comparisons between closely related species are particularly useful.

We generated de novo long-read assemblies complemented with cytological validation to reveal Y chromosome organization in three closely related species of the Drosophila simulans complex, which diverged only 250,000 years ago and share >98% sequence identity.We find these Y chromosomes are divergent in their organization and repetitive DNA composition and discover new Y-linked gene families whose evolution is driven by both positive selection and gene conversion.These Y chromosomes are also enriched for large deletions, suggesting that the repair of double-strand breaks on Y chromosomes may be biased toward microhomology-mediated end joining over canonical non-homologous end-joining.We propose that this repair mechanism contributes to the convergent custom congratulations banner evolution of Y chromosome organization across organisms.