Chromosomes and Mating

1. Chromosomes and Mating

2. Chromosome number Have you ever wondered why there are not more weird combinations of animals and/or plants on our planet? This is because each species has a unique chromosome set.

3. Chromosome number Even though some species have the same number, they do not contain all of the same genes and the information can be organized differently. For example, gorillas and chimpanzees both have 48 chromosomes. This prevents inbreeding to produce blended offspring.

4. Mismatched Chromosome Sets Sometimes two species are capable of physically mating to combine genetic material but a viable embryo will not develop. For example fruit flies have 4 chromosomes in their sex cells and mosquitoes have 3 chromosomesin their sex cells. Since each chromosome cannot find a homolog, the resulting zygote cell is destroyed.

5. Mismatched Chromosome Sets Sometimes species have similar enough chromosome sets that they can be bred to produce offspring. Organisms that normally do not meet in the wild have been known to produce young in zoos. A few examples involve members of the cat family.

6. Mismatched Chromosome Sets The most familiar example is the liger which results from a female tigermating with a male lion. Both lions and tigers have 38 chromosomes, similar mating rituals and similar reproductive anatomy so reproduction occurs easily. They do not mate naturally because they live on different continents. Ironically, there are more genetic similarities between humans and chimpanzees than between lions and tigers!

7. Human Animal Hybrids An unusual example is seen when humans mate the wild Geoffroys cat with a house cat. Domestic cats have 38 chromosomes while Geoffroys cat has only 36. The chromosomes that do not match up do not contain genes that are vital to the survival of the organism.

8. Human Animal Hybrids The offspring has 37 chromosomes and is called a Safari cat. They have an exotic appearance but an agreeabletemperament. A unique side effect of the odd chromosome combination is the large size – The Safari cat weighs between 25 to 35 pounds!

9. Human Animal Hybrids Humans have been cross breeding some animals for centuries. For example a male donkey and a female horse can be mated to produce a mule. The benefit is an pack animal that is strong but less stubborn.

10. Human Animal Hybrids Horses have 64 chromosomes and donkeys have 62 so the mule has 63 chromosomes. Scientists used to think that all animals with the odd chromosome number would be sterile but in some rare cases two animals like mules or ligers have mated to produce offspring.

11. Human Plant Hybrids Humans have also cross bred plants much more easily than animals. This is because many species of plants have hundreds to thousands of chromosomes with only a few genes on each. There is less likelihood that mismatched chromosomes will have information that is necessary for basic functions.

12. Human Plant Hybrids An example is crossing broccoli with cauliflower to get broccoflower. This plant has the B complex vitamins found in green vegetables but has a less bitter taste. Broccoflower also has twice as much protein than either broccoli or cauliflower contains.