Analyses of the genome and transcriptomes of endemic Baikal sponges (Lubomirskiidae)

Abstract

The fauna of endemic Baikal sponges is very diverse, however, the systematics of Lubomirskiidae is contradictory when morphological and molecular data. The development of a taxonomy for Baikal sponges is very important for their conservation. The recently recorded massive disease outbreak and death of Baikal sponges has raised monitoring issues. In order to study the evolution of endemic Baikalian sponges on genomic level we analyzed a draft genome of the Baikal sponge Lubomirskia baikalensis and transcriptomes of three Lubomirskiidae species, obtained using Illumina sequencing. The genome size of Lubomirskia baikalensis (approximately 560 million base pairs) is almost twice that of the closest sequenced outgroup species, Ephydatia muelleri. Given the age of Baikal sponge radiation, these differences have occurred over a relatively short period of time. As Ephydatia is also a freshwater sponge, it is likely that this increase is not due to adaptation to freshwater habitats, but is the result of evolutionary processes related to the sympatric speciation of sponges in Lake Baikal.