The sex chromosomes genetically define the developmental fate of an embryo to become a male or a female individual, and usually appear as one pair of morphologically different chromosomes between sexes. For example, women have one pair of XX chromosomes, while men have one pair of XY chromosomes. Now three studies led or co-led by Qi Zhou’s group at the University of Vienna and Zhejiang University of China uncovered the unusual sex chromosomes of Australian iconic animals platypus and emu, as well as Pekin duck. Platypus have five pairs of sex chromosomes forming an unusual chain shape, while the sex chromosomes of emu and duck are not as different between sexes as those of human. These works are the results of international collaboration between scientists from Austria, Australia, China and Denmark, and are published as research papers together on Jan. 6th in the journals Nature, Genome Research and GigaScience.

Publication in Nature: 
Zhou, Y., Shearwin-Whyatt, L., Li, J. et al. Platypus and echidna genomes reveal mammalian biology and evolution. Nature (2021). https://doi.org/10.1038/s41586-020-03039-0

Publication in Genome Research: 
Liu J., Wang Z., Li, J. et al. A new emu genome illuminates the evolution of genome configuration and nuclear architecture of avian chromosomes. Genome Research (2021).
DOI: 10.1101/gr.271569.120

Publication in GigaSciece: 
Li, J., Zhang J., Liu, J. et al. A new duck genome reveals conserved and convergently evolved chromosome architectures of birds and mammals, GigaScience (2021). https://doi.org/10.1093/gigascience/giaa142