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Bax_Cadarn t1_j506f30 wrote

Reply to comment by suvlub in Given that reproduction is difficult or impossible when both animals have different numbers of chromosomes, how did so many species evolve to have so many different numbers of them? by MercurioLeCher

I would like to point out many women can have 45 chromosomes and people with 47 or 48 aren't unheard of either - Turner's and Klinefelter's.

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wheatgrass_feetgrass t1_j50kn4u wrote

The sex chromosomes are unique though. The X chromosome is the only chromosome that is almost fully functional whether there's 1 or more copies. The Y chromosome is not necessary for life, though it does serve a function besides "make boy", as missing it or duplicating it is not a side effect free situation as in XO and XYY like you pointed out.

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Gonjigz t1_j50wy3x wrote

This is a very specific phenomenon though. 47 chromosomes are almost always incompatible with survival to adulthood unless the extra chromosome is a sex chromosome or a 21, and I don’t think monosomy of any of the autosomes is compatible with life.

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Bax_Cadarn t1_j50zfyj wrote

Nope, Turner's is the only nonlethal monosomy, but there are 2 more non-sexual trisomies that aren't lethal, 13 and 18 iirc.

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Gonjigz t1_j5214z5 wrote

Edward’s and Patau syndrome, both of which have more than a 90% mortality rate before 1 year of age. There are extremely rare cases of survival beyond childhood which is why I said almost always, but by and large these syndromes do not allow for survival to adulthood.

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