Artificial selection and domestication | Natural selection | AP Biology | Khan Academy

Dogs, known as man's best friend, are a single species despite variations in breed appearance.
Male and female dogs can reproduce to produce viable offspring, highlighting their classification as one species.

Interesting questions arise regarding the origins of dogs and the reason for the specialized breeds we see today:
- Rottweilers for protection.
- Terriers for hunting rodents.
- Border collies for herding.

Artificial selection: Humans selectively breed animals instead of allowing natural selection to take its course.
- Rapid changes in dog characteristics occur through human intervention in breeding.
- Breeding reflects artificial selection.
Ancestral lineage: Today's dogs descended from wolves.
- Early natural selection involved wolves that scavenged near human settlements; friendly variants benefited from this behavior.
- Over time, wolves became domesticated, leading humans to recognize and breed particularly useful ones.

Continuous selective breeding led to specialized breeds:
- Border collies, selected by sheep herders for herding abilities.
- Terriers, bred to hunt rodents.
- Rottweilers, bred for protection and defense.
The transformation from wolves to specialized dogs took place over tens of thousands of years through natural and artificial selection.

Not limited to dogs, many farm animals (e.g., pigs) result from artificial selection.
- Farm pigs are bred for docility and ease of care compared to their wild ancestors.

Domesticated crops: Similar to animals, most produce in supermarkets comes from artificial selection.
- Wild variants of vegetables and fruits have been selectively bred over 10,000 to 15,000 years for desirable traits.
- Selection leads to crops that are more robust, tastier, and adaptable to various climates.