Investigating the origin of mammal sex chromosomes

Platypus image - Image courtesy of Matt Chan

Undertake a research project that investigates the origin of therian sex chromosomes.

Genes from the therian X map predominantly on platypus autosome 6, including the therian gametolog of Sry, Sox3. This showed that the therian sex chromosomes evolved after the divergence of monotremes.

Alternatively the ancestral mammalian sex chromosomes may have been replaced by a different sex chromosome system in the monotreme lineage. In order to investigate these different possibilities we investigated if platypus chromosome 6 shows any signatures of sex chromosome differentiation that may have been maintained in monotremes. 

Surprisingly we discovered sex specific changes in Sox3 and show that platypus chromosome 6 homologs segregate non randomly into sperm. 

Our current work investigates the meiotic pairing and association of chromosome 6 with nucleolus and sex chromosomes at male meiosis, which might provide insights into the mechanisms of this unusual organisation of platypus chromosome 6.

The extent of this differentiation and whether this may predate monotreme divergence is as yet unclear.


Professor Frank Grützner


Professor Frank Grützner

Research area: Genetics, monotreme genomics, evolution and conservation

Recommended honours enrolment: Honours in Molecular and Biomedical Science

Tagged in Honours projects - Molecular and biomedical science, Honours projects - Ecology and environmental science, Honours projects - Evolution and palaeobiology, Honours projects - Animal science, Honours projects - Frank Grutzner, Honours projects - Molecular and biomedical science: Genetics