FOSS Genetic Technology Resources UNNATURAL SELECTION If you rounded up all the in your neighborhood, you would see amazing differences in them. There could be bossy little terriers, low-slung dachshunds, fast long-legged greyhounds, huge Great Danes, and powerful pit . Where did they all come from? Why do they look so different?

A Long Partnership The domestic , in all its sizes, shapes, and temperaments, evolved from the wolf. Bones of wolves and early humans were deposited together as long as 400,000 years ago. DNA analysis suggests that wolves became dogs about 130,000 years ago. That was long before humans settled down and started to farm. As some humans settled down, they selected the qualities that they wanted in a dog. Dogs played various roles in human culture, including hunting, defending livestock, and carrying loads. Each of these roles required different qualities. Suppose you wanted a dog to chase badgers out of their burrows. The dog would need short legs and an attitude. If a dog in the community had particularly short legs, you would make sure it produced offspring. You would the offspring with the shortest legs, and then breed the short-legged offspring again. In a few generations, you might have a bunch of short-legged dogs.

FOSS Heredity and Course version date 6/2016 © The Regents of the University of California Can be duplicated for classroom use. FOSS Genetic Technology Resources

Among them, you would look for the ones that were eager to take on a mean badger. You would breed those with the right shape and attitude about badgers. They would be likely to produce offspring with those characteristics. This process might have produced the dachshund. Choosing Traits Humans decide what traits they want in a dog and find individuals that have those traits. Then they breed them to reinforce those traits. This selection is not a natural process. It is known as artificial selection. Artificial selection has been used to produce 400 of dogs, as well as many types of , , , hogs, dairy cows, , , tomatoes, corn, and so on. The desirable trait can vary widely. Does it produce a more beautiful ? Does the produce more tomatoes? Humans are very good at changing the of organisms. By selective breeding, they produce that satisfy some need. Have you ever tasted a pluot? It is a combination of a plum and an apricot. The sweet fruit was developed when a California farmer used a tiny brush to transfer a bit of pollen from an apricot to a plum. Look around your neighborhood and in the grocery store. Artificial selection has produced a wide of fruits and vegetables for us to enjoy. Sometimes artificial selection has negative outcomes. Careless selective breeding of dogs can lead to bad hips or a nasty temper. who belong to national dog clubs have strict breeding requirements that are meant to avoid genetic problems. They try to breed out unhealthy conditions.

FOSS Heredity and Adaptation Course version date 6/2016 © The Regents of the University of California Can be duplicated for classroom use.