The ZW sex-determination system is reversed compared to the XY system: females have two different kinds of chromosomes ZWand males have two of the same kind of chromosomes ZZ. The ZW sex-determination system is found in birds, some reptiles, and some insects and other organisms. Current Biology.
March Evolutionary Ecology Research. Ellis, K. Takifugu Amhr2 Receptor for Amh.
Further information: Environmental sex determination. This system is observed in a number of insects, including the grasshoppers and crickets of order Orthoptera and in cockroaches order Blattodea. Female gametes can either contain a Z chromosome or a W chromosome.
Categories : Chromosomes. Monotreme sex chromosomes—implications for the evolution of amniote sex chromosomes. A few species of fish, reptiles, and insects reproduce by parthenogenesis and are female altogether.
The X and Y sex chromosomes are different in shape and size from each other, unlike the rest of the chromosomes autosomes , and are sometimes called allosomes. It is singled out in this review because of its likely key role in sex determination both in birds and in reptiles with TSD.
More research must be conducted in order to determine the exact sex determining gene of the platypus. Genome Res.