Chromosomes differ between the sexes
In several animal species, the chromosomes differ between the sexes. The male contains a Y chromosome. In some animals, however, as an example birds, it's the opposite way around. In birds, the females have their own chromosome, the W chromosome. For the primary, researchers in Uppsala have mapped the genetic structure and evolution of the W chromosome. Every individual of a species has the identical forms of chromosomes, with one exception. In several species, the method the sexes differ is that males have their own chromosome, the Y chromosome. This contains genes that end in the development of male characters and reproductive organs. If there's no Y chromosome, the organism will be a female.
In birds, however, the situation is totally different. It’s the females that have a different sex chromosome-- the W chromosome. A bird's W chromosome doesn't contain genes that result in the development of a female. "Sex determination in birds and different animals with a W chromosome appears instead to rely upon the quantity of their similarity to the X chromosome. Two copies of it produce a male, one copy (plus a W chromosome) produces a female," says Hans Ellegren.
The W chromosome appears instead to operate as some quite buffer for females since it contains genes the same as those within the X chromosome. So as for certain genes to figure, it's essential that an individual has 2 copies of that gene. During this method, the W chromosome will function a complement for females who solely have one copy of the X chromosome. Researchers have discovered that the W chromosome changes at a slower rate than the other a part of the genetic material.
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