Poecilia picta female genome assembly files

Sex chromosome dosage compensation is a model to understand the
coordinated evolution of transcription, however, the advanced age of the
sex chromosomes in model systems makes it difficult to study how the
complex regulatory mechanisms underlying chromosome-wide dosage
compensation can evolve. The sex chromosomes of Poecilia picta have
undergone recent and rapid divergence, resulting in widespread gene loss
on the male Y, coupled with complete X Chromosome dosage compensation, the
first case reported in a fish. The recent de novo origin of dosage
compensation presents a unique opportunity to understand the genetic and
evolutionary basis of coordinated chromosomal gene regulation. By
combining a new chromosome-level assembly of P. picta with whole-genome
bisulfite sequencing and RNA-seq data, we determine that the Yin Yang 1
(YY1) DNA-binding motif is associated with male-specific hypomethylated
regions on the X, but not the autosomes. These YY1 motifs are the result
of a recent and rapid repetitive element expansion on the P. picta X
Chromosome, which is absent in closely related species that lack dosage
compensation. Taken together, our results present compelling support that
a disruptive wave of repetitive element insertions carrying YY1 motifs
resulted in the remodeling of the X Chromosome epigenomic landscape and
the rapid de novo origin of a dosage compensation system.