Genome size variation in a species of rotifer: is it trasponsons or genome duplication?


This talk was awarded second place in the student presentation awards

The Brachionus plicatilis species complex inhabits important niches in a wide range of freshwater habitats worldwide with at least 15 different species. As well as a range of morphologies and body sizes, B. plicatilis spp. exhibits genome size variations up to 8-fold. This dramatic change in genome size across the species complex is likely the largest observed in such closely related animals. The consequences of such variation, on both the structure and composition of genome, and the biology of the species complex is unknown. One species in this complex, Brachionus asplanchnoidis, has genome sizes ranging from 205Mbp to 271Mbp. Genome sequencing and analysis of different populations from this species are the first step in understanding such large genome size changes on short evolutionary time-scales. These data will then be related to biological and ecological outcomes. Initial analyses of B. asplanchnoidis genomes indicate that repetitive DNA sequences and genome duplication followed by rediploidisation likely both contribute to the observed genome size variation. The identity and distribution of these sequences shed light on the influence of both repetitive sequences and whole genome duplications not only on genome size evolution, but also on rotifer biology.