Could an animal have an odd number of chromosomes?

Answer 1

Think of your body as a loft. In your loft there are storage boxes. In these boxes are a few things which are of use, but the rest is junk. Now, depending on the type of person you are, you may keep this junk for a long time, not bothering to get rid of it - or you may clear out the loft quite quickly.

What does this mean in relation to chromosomes?

Well, the chromosomes are those boxes, and the items within those boxes is DNA. About 5% of our DNA is active, is useful. The rest is, basically, junk. Some animals and plants, we've discovered, get rid of this junk rather quickly, whereas others keep it for a long time. We humans are somewhere in the middle. So the more junk DNA we have, the more chromosomes we have to store it.

Answer 2

Cats and dogs have vastly different evolutionary histories. Since the time they split from their common ancestor, natural selection and gene mutation has slowly changed their Biology. The following is from www.Talkorigins.org:

"Chromosomes can split or join with little effect on the genes themselves. One human chromosome, for example, is very similar to two chimpanzee chromosomes laid end to end; it likely formed from the joining of two chromosomes (Yunis and Prakash 1982). Because the genes can still align, a change in chromosome number does not prevent reproduction. Chromosome counts can also change through polyploidy, where the entire genome is duplicated. Polyploidy, in fact, is a common mechanism of speciation in plants."

Essentially, chromosomes can be copied and modified without changing an organism too much. As a result, when two populations of animals are split, they can undergo tremendous changes in the number of chromosomes in their bodies.

Answer 3

Yes. This creates infertility in some species while others are fertile. Infertile examples are mules (horse/donkey cross) and zebroid (zebra/equine cross). Examples of fertile species are hybid horses (wild horse/domestic horse) and swamp wallabys (females w/11 chromosomes and males w/10). Humans born with an extra chromosome have Downs Syndrome.

Answer 4

Buffalo, cat, cattle, dog, donkey, goat, horse, pig and sheep.