Each new population evolves independently 5. Inversions - the change in orientation of segments of a chromosome. A loop structure must be formed during meiosis or a heterozygote to allow proper pairing of the chromosomes. When the chromosomes divide at metaphase, there will be chromosome breakage, duplications of chromosome regions, and in general a loss of fertility. The results after metaphase would again result in many gametes with major deletion or duplications.
Polyploidy is the duplication of chromosomes in an organism.
Primarily in plants. Aneuploidy - the gain or loss of a single chromosome. Plants can often tolerate the gain or loss of a single chromosome very well, especially if they are already polyploid for the whole set of chromosomes. A triploid would have 18 chromosomes, a tetraploid would have 24, and so on Autopolyploid - where an individuals chromosomes chromosomes are doubled resulting in four essentially identical chromosomes. Resulting gametes often have unequal chromosome numbers and are fertile.