Disruption of Genetic Equilibrium

1. Disruptionof Genetic Equilibrium Chapter 16.2

2. Evolution- the change in a population’s allele or genotype frequencies over generations Evolution is caused by: • Mutations • Gene Flow • Genetic Drift • Nonrandom Mating • Natural Selection

3. Mutations • Mutations occur when an organism is exposed to mutation-causing agents such as radiation and chemicals • Mutations produce completely new alleles for traits • However, mutations can be beneficial

5. Gene Flow • Gene Flow- process of genes moving from one population to another • The constant flow of genes is caused by immigration and emigration

6. African Baboon Troop

7. Genetic Drift • Genetic Drift- phenomenon by which allele frequencies change as a result of random events • In small populations, one change can result in big disruptions • In large populations, a change is less effective • *Thought to be another possible reason for the evolution of new species

8. Nonrandom Mating • Because of geographic location, many organisms end up mating with relatives -This can amplify certain traits, and result in disorders in offspring • Other organisms mate based upon similar traits, called assortativematingtive mating • Sexual selection is when females choose a mate based on certain traits. The better the traits, the higher chance of survival.

10. Natural Selection – Stabilizing Selection • Individuals with the average form of a trait have the highest fitness • The average is ideal • Ex. Lizards

11. Natural Selection- Disruptive Selection • Individuals with either extreme variables of a trait have greater fitness than individuals with the average form of trait • Ex. Sea shells

12. Natural Selection- Directional Selection • Individuals that display a more extreme form of a trait have greater fitness than individuals with an average form of the trait • Ex. Anteaters