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Gonjigz t1_j5214z5 wrote

Reply to comment by Bax_Cadarn 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

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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