Thomas D. Lewin, Isabel Jiah-Yih Liao, Yi-Jyun Luo

bioRxiv 2024.05.15.594353 doi:10.1101/2024.05.15.594353

Annelid comparative genomics and the evolution of massive lineage-specific genome rearrangement in bilaterians

“the last annelid common ancestor retained the ancestral lophotrochozoan karyotype with 20 chromosomes“ “The genomes of all sampled species have at least three ALG fusions compared to the ancestral annelid genome.” “almost all the chromosome fusion events in annelids can be categorized as fusion-with-mixing” “we found no correlation between the ALG fusion rate and the length of chromosomes” “In contrast to fusions, the splitting of ALGs is relatively rare, with only three cases in this dataset of 16 annelid species.” “in both leeches and earthworms, there is complete shuffling of the ancient bilaterian genome [...] there has also been massive genome shuffling between these two groups.“ “within the Clitellata, M. vulgaris has a lineage-specific tetraploidization that is not shared by other earthworms or leeches” “we developed a macrosynteny rearrangement index [...] to quantify both ALG fusion and fission into a single value between 0 (no rearrangement) and 1 (maximum rearrangement).” “dramatic genome rearrangement in clitellates correlates with the evolution of a new ecological niche, alongside divergent genomic location and altered expression of key developmental genes”