Plasticity of Animal Genome Architecture Unmasked by Rapid Evolution of a Pelagic Tunicate

TLDR

Animal genomes, from sponges to humans, generally conserve global architecture, yet ancestral structures can be deeply modified and may be largely nonadaptive, making rapidly evolving lineages like tunicates valuable for studying genome plasticity. The study seeks to illuminate fundamental mechanisms of intron gain. The authors find that in the tunicate Oikopleura, transposon diversity, developmental gene repertoire, gene order, and intron‑exon organization are all disrupted, revealing extensive genome plasticity.

Abstract

Genomes of animals as different as sponges and humans show conservation of global architecture. Here we show that multiple genomic features including transposon diversity, developmental gene repertoire, physical gene order, and intron-exon organization are shattered in the tunicate Oikopleura, belonging to the sister group of vertebrates and retaining chordate morphology. Ancestral architecture of animal genomes can be deeply modified and may therefore be largely nonadaptive. This rapidly evolving animal lineage thus offers unique perspectives on the level of genome plasticity. It also illuminates issues as fundamental as the mechanisms of intron gain.