Methods of Evolution Page 8 ON YOUR OWN PAPER

Genetics Genes hold the blueprint for all the different adaptations that animals have. All the genes in one population are called the GENE POOL. Each gene (such as eye color) has multiple alleles or options (blue, green, brown, etc.) ALLELE FREQUENCY is a measure of how common an allele is in a population. Blue Eyes Green Eyes Brown Eyes Other

How does the gene pool change? The gene pool can change from DNA MUTATIONS (introduce a new trait), MIGRATION, ENVIRONMENTAL CHANGE, or ISOLATION. The movement of alleles from one population to another is called GENE FLOW.

MIGRATION The FOUNDER EFFECT – a small number of individuals move to a new area

ENVIRONMENTAL CHANGE The BOTTLENECK EFFECT – once a population has been greatly reduced in size, the few survivors have less genetic diversity

ISOLATION Geographic isolation – when a river, mountain or other feature separates a population into two or more groups

ISOLATION Temporal isolation – reproductive periods differ when the population (some mate in spring, others mate in fall)

ISOLATION Behavioral isolation – isolation created by differences in courtship and mating behaviors. Sexual selection – a trait increases mating success

ISOLATION Reproductive isolation – isolation created by differences mating structures or ability to produce viable offspring

How organisms evolve Convergent evolution – two unrelated species evolve similar characteristics (wings in birds and bats)

How organisms evolve Divergent evolution – two related species evolve in different directions (like arm bones in mammals)

How organisms evolve Coevolution – two or more species evolve in response to changes in each other (bird beak and flowers)