What is the sex determination system for birds?

In birds, the sex determination system operates on a ZZ/ZW basis, which is distinct from the more commonly known XX/XY system found in many mammals. In this system, males possess two of the same sex chromosomes (ZZ), while females have two different sex chromosomes (ZW). This means that male birds develop from the ZZ pair, while female birds develop from the ZW pair.

The ZZ/ZW system is noteworthy for its implications in genetic inheritance and evolutionary biology. Because the female carries the heterogametic sex chromosomes (ZW), she has the potential to pass either type of chromosome to her offspring, thereby influencing the sex ratio of the next generation. This ZW/ZZ system can also affect various traits linked to sex, such as plumage and behavior, which can be understood further through genetics and developmental biology.

This understanding provides insight into the diversity of sex determination mechanisms across the animal kingdom, highlighting the relevance of different chromosomal systems in ecological and evolutionary contexts.