QOTD With a partner, explain each term and give an example from nature! Natural Selection Artificial Selection Variation Adaptation Mutation Fitness Selective Mating Bottleneck Effect / Founder Effect

TYPES OF NATURAL SELCTION  How Evolution Happens

RECALL: Result of the environment selecting for individuals with certain traits that make them better suited to survive and reproduce Over many generations, frequency of alleles of many different genes may change, resulting in significant changes NATURAL SELECTION:

1. Stabilizing Selection Natural selection that favours intermediate phenotypes and acts against extreme variants Reduces variation and improves adaptation when enviro conditions are stable Eg. Human birth wt.

2. Directional Selection Natural selection that favours the phenotypes at one extreme over the other Distribution curve of phenotypes shifts in the direction of the extreme Eg. Peppered moths (shift to dark) or 3U Bio marks

3. Disruptive Selection Natural selection that favours the extremes of a range of phenotypes rather than intermeds. Can result in elimination of intermediate phenotypes Creates bi-modal dist. Curve Could eventually cause speciation

4. Sexual Selection Favours trait selection that influences mating success Includes sexual dimorphism (males and females of same species look different) Eg. Many animals look for specific traits in a mate (especially humans)