Consequences of female-biased inheritance to genome evolution.

Paternal genome elimination (PGE) is an unusual reproductive mode where male pass exclusively maternally inherited genes. Males don’t recombine, nor segregate chromosomes. Genetically the systems work the same as haplo-diploids, but as male soma is not haploid but diploid, which does have consequences for selection. I study these systems together with my colleagues in Ross lab at the University of Edinburgh.

Currently, I am focusing on one PGE taxon in particular system - globular springtails. They are interesting mostly for their peculiar double X system of sex determination.

Springtail double X system

The X chromosome evolution is rather special in species with Paternal Genome Elimination. There are only three known PGE clades to still have X chromosomes, although the sex determination was overwritten by other mechanisms - fungus gnats, gall midges and globular springtails. The X chromosomes are likely remains of the ancestral X chromosome from the old times of more conventional reproductive strategy. Interestingly enough, globular springtails don’t just have one X chromosome, they have two different X chromosomes (therefore could be called X1X200 system). Our recent preprint shows that the two X chromosomes represent a very large portion of the genome, we further work to understand the peculiar evolution of the double-X system in globular springtail using comparative genomic and transcriptomic approaches.