SELECTION NATURAL

Theory of Natural Selection Explains how a population changes over many generations in response to its environment.

1. OVERPRODUCTION Many species produce more offspring than will survive to maturity.

Overproduction Examples Up to 10,000 Eggs Up to 10,000,000 Eggs!

Overproduction Examples: THE QUEEN! >30,000 Eggs a Day, lives for 10 years= >108,000,000 in their lifetime!

2. Genetic Variation Individuals within a population are slightly different from one another. Individuals have unique combinations of traits, such as size, color and ability to find food. Some traits can increase or decrease an individuals chance for survival.

Genetic Variation Examples

3. Struggle to Survive Resources: In any ecosystem, there is not enough food, water, and other resources available for all organisms to survive Many organisms are killed by other organisms Only some individuals in a population are able to survive to adulthood

The Peppered Moth: The Struggle to Survive Example In less than 50 years (1848-1895) the once rare dark form accounted for 98% of all Peppered moths in London. Why?

4. Successful Reproduction This is the key to Natural Selection! Individuals that are well adapted to their environment are more likely to survive and reproduce These “well adapted” traits are then passed on to the next generation

Speciation: Darwin’s Finches When a portion of a population becomes separated, the two populations can become so different over time they can no longer interbreed. From one come many: Now 13 species of finch on the Galapagos.