PT  - JOURNAL ARTICLE
AU  - Nathan J Kenny
AU  - Warren R. Francis
AU  - Ramón E. Rivera-Vicéns
AU  - Ksenia Juravel
AU  - Alex de Mendoza
AU  - Cristina Díez-Vives
AU  - Ryan Lister
AU  - Luis Bezares-Calderon
AU  - Lauren Grombacher
AU  - Maša Roller
AU  - Lael D. Barlow
AU  - Sara Camilli
AU  - Joseph F. Ryan
AU  - Gert Wörheide
AU  - April L Hill
AU  - Ana Riesgo
AU  - Sally P. Leys
TI  - Tracing animal genomic evolution with the chromosomal-level assembly of the freshwater sponge <em>Ephydatia muelleri</em>
AID  - 10.1101/2020.02.18.954784
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.02.18.954784
4099  - http://biorxiv.org/content/early/2020/05/12/2020.02.18.954784.short
4100  - http://biorxiv.org/content/early/2020/05/12/2020.02.18.954784.full
AB  - The genomes of non-bilaterian metazoans are key to understanding the molecular basis of early animal evolution. However, a full comprehension of how animal-specific traits such as nervous systems arose is hindered by the scarcity and fragmented nature of genomes from key taxa, such as Porifera. Ephydatia muelleri is a freshwater sponge found across the northern hemisphere. Here we present its 326 Mb genome, assembled to high contiguity (N50: 9.88 Mb) with 23 chromosomes on 24 scaffolds. Our analyses reveal a metazoan-typical genome architecture, with highly shared synteny across metazoa, and show that adaptation to the extreme temperatures and conditions found in freshwater largely involves gene duplication. The pancontinental distribution and ready laboratory culture of E. muelleri make this a highly practical model system, which with RNAseq, DNA methylation and bacterial amplicon data spanning its development and range allows exploration of genomic changes both within sponges and in early animal evolution.Competing Interest StatementThe authors have declared no competing interest.