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.