Genome sequencing and assembly of Ellobius lutescens and Ellobius talpinus

The X and Y sex chromosomes of placental mammals show hallmarks of a tumultuous evolutionary past. The X chromosome has a rich and conserved gene content while the Y chromosome has lost most of its genes. In the Transcaucasian mole vole Ellobius lutescens, the Y chromosome including Sry has been lost, and both females and males have a 17,X diploid karyotype. Similarly, the closely related E. talpinus, has a 54,XX karyotype in both females and males. To evaluate genetic consequences related to loss of the Y chromosome, we performed genome sequencing and de novo assembly of E. lutescens and E. talpinus genomes. The genome of these mole vole species presents opportunities to study properties of a new pair of sex chromosomes, comparable to the proto-XY pair in the mammalian ancestor 160 million years ago, and to evaluate the selective mechanisms acting on a univalent and clonally inherited post-X chromosome.