[js1138]

If chromosome count variations were always a barrier to producing fertile offspring, there would be an impregnable barrier to chromosomal speciation. So to speak.

[USConstitutionBuff]

The problem of mitotic segregation and recombination would not apply directly between one member of a species with a chromosomal abnormality and another member of the same species, the genes on the chromosome would line up just fine for recombination.