Answer: Gaining or losing a chromosome will result in major genetic changes for that horse, as either it will be missing important DNA or will have too much DNA. Either can cause mutations to occur in the animal's genome. Chromosomal changes are caused by an error during either meiotic or mitotic cell division. An error could be that a cell has too much copies of a chromosome, or not enough, which causes the mutations mentioned above. Hope this helps some, I know it's not a super meaty answer.
Explanation:
Cell bio is important so that we can know more about cells and how they function
Disruptive selection or diversifying selection describes the changes in population genetics where extreme values for a trait are favored over intermediate values.
So according to this definition, the conclusion can be derived as :
The most common circumference(s) to be after 10 generations of diversifying selection will be greater than 2 cm and less than 2 cm.