1. Natural Selection vs. Selective Breeding
Environmental and Human Influences
Natural selection and selective breeding can both produce changes in animals and plants. The difference between the two is that natural selection occurs in nature, but selective breeding only occurs when humans intervene.

2. Natural Selection vs. Selective Breeding
Process by which organisms that are best suited to their environment survive and reproduce most successfully.
Method of breeding that allows only those organisms with desired characteristics to produce the next generation.
Natural Selection vs. Selective Breeding

3. Natural Selection Selective Breeding Selected by nature
Selected by humans

4. Natural Selection Example: White Colored vs Dark Colored Peppered Moths during the Industrial Revolution
Manchester, England from to 1890.
Before the industrial revolution, the trunks of the trees in the forest around Manchester were light grayish-green due to the presence of lichens.

5. Natural Darwin’s Finches Selection
Individuals have high genetic diversity
Best fit genes get passed down
Poor genes = less likely to survive

6. Galapagos Finches

7. Natural Selection and Horses

8. Early Horse (Eohippus)
• lived 55-60 million years ago
• lived in forests and ate leaves
• about the size of a fox
• 4 toes to walk on soft forest floor
Modern Horses (Equus)
• began to develop 2 million years ago
• as a result of changes in the global climate, lived in grasslands and ate grass
• developed long legs and one toe (hoof) to help the horse run faster from predators and longer teeth to eat the grass

9. Selective breeding Domestic Animals Plants:
Human Influence on characteristics and behavior.
Domestic Animals
Ex: Chickens, Dogs, Cows, Horses
Plants:
Ex: Corn, Wheat, Fruit hybrids

10. These are the steps in selective breeding:
Identify desirable characteristics
Choose parents w/ these characteristics
Select the best offspring from parents to breed the next generation
Repeat 1-3 continuously

11. Domestic Animals

12. Selective Breeding of Horses
Horses were first domesticated for transportation, agricultural work and warfare
Today they are also bred for racing and companionship

14. Different varieties of dog have been produced over many generations by selective breeding.
For example, pedigree dogs come in lots of different varieties, called breeds of dog. They may be different colors and sizes, but they are all still dogs. They are all still the same species.
Different breeds of dogs
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(click on the link and read about selective breeding of cows and other examples of selective breeding)

16. Cows-bred for meat or milk
The picture above shows a dairy cow. She has been bred for milk.
She has been selectively bred to produce enough milk for ten calves, but her calf is removed from her shortly after birth. Most cows are only milked twice a day. It may have to carry over 20 liters of milk. Many cows go lame through carrying all this milk.
The cow above has been selectively bred for meat. She produces enough milk to feed one calf. Her calf will milk her six times per day. She only needs a small udder.

17. Aberdeen Angus bull - bred for beef
Friesan cow - dairy breed