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- #21
Wow. I'll be reading for a while. Thankyou!You did read the post about poultry genetics? It is not the same as humans. The hens ovum determines gender and not the rooster.
D.W. Burt, in Encyclopedia of Genetics, 2001
Avian and mammalian sex chromosomes evolved independently (Fridolfsson et al., 1998;Nanda et al., 1999, 2000) and should therefore have fundamentally different sex-determining genes. The sex chromosomes in birds are designated Z and W. The female is the heteromorphic (ZW) sex and the male homomorphic (ZZ). The average avian Z chromosome is a medium-sized macrochromosome. The W chromosome of most modern birds is a microchromosome, considerably smaller than the Z and largely heterochromatic. The Z and W chromosomes are derived from a common ancestral chromosome (Fridolfsson et al., 1998;Shetty et al., 1999). Heterochromatinization, deletion, and rearrangement of the W chromosome have contributed to the evolution of highly differentiated sex chromosomes in modern birds. In primitive birds, such as ratites, the W chromosome resembles the Z in size and morphology, and most likely in gene content (Fridolfsson et al., 1998;Ogawa et al., 1998). It is not clear in birds, whether the Z or W chromosome determines sex.