In order to answer this question we studied Drosophila species. Hence the mammalian Y is largely an impoverished "degenerated" version of the X chromosome [ 56 ]. However two lines of evidence found here suggest that the causal link between X-A fusions and Y chromosome incorporations is, at best, weak.
In this Page. Then an incorporation of the Y chromosome into an autosome would have generated an intermediate stage with two genetically redundant copies of each formerly-linked gene middle. Possible mechanism for primary sex determination in mammals. For a complete ovary, a second X chromosome is needed.
Legislation that singles out trans people for humiliation are not good laws and are not good for society. Nice and tidy. Main article: Temperature-dependent sex determination. Current Biology. You just said all non-binary individuals have mental retardation.
An XY individual with androgen insensitivity syndrome. Science — The male, being XY, can generate two types of sperm: half bear the X chromosome, half the Y. If the Y chromosome is present, testes form and secrete two major hormones. So, as shown in Fig 6the current Y of D. BMC Genomics Kirkpatrick M How and why chromosome inversions evolve.
PLoS biology 8: e For the sake of clarity we omitted the Y chromosome incorporation events. The gene content of the Y chromosomes seems to have no correlation with their morphologies, which are quite variable among montium species Table D in S1 File. Genetica — Alternative hypothesis for the re-appearance of Y-linkage in the montium and pseudoobscura lineages The duplicated Y hypothesis Fig 5 is bold, but as far as we can see it is the best explanation for the data.
In order to answer this question we studied Drosophila species.