1. Explain why variations in a population are seen as a bell shaped curve. Agenda for Friday Feb 20 th 1.Patterns and Mechanism notes 2.Go over variation lab

3. Genetic Equilibrium Allele frequency in a gene pool is not changing –Hardy Weinberg Disruption of Equilibrium = Change

4. 1. Natural Selection

5. Types of Natural Selection Directional Selection - extreme phenotype has higher fitness Peppered Moth

6. Stabilizing Selection - intermediate phenotype has a higher fitness

7. Disruptive Selection - intermediate phenotypes are of lower fitness than extreme phenotypes

8. 2. Mutation Neutral mutation – no impact on survival or reproduction Beneficial mutation – increase in survival or reproduction

9. 3. Gene Flow/Migration Individuals enter or leave a population –emigrate = lose alleles –immigrate = gain alleles

10. 4. Genetic Drift Unpredictable changes in allele frequency due to small population size –Population bottleneck –reduction of a population –Founder Effect – individuals leave a population and establish a new one

11. 5. Nonrandom Mating Choosing a mate Sexual Selection – ability to attract a mate

12. Patterns of Evolution

13. Coevolution Change of two or more species in close association with each other Predators and prey Parasites and hosts Plant eating animals and plants

14. Convergent Evolution Environment selects similar phenotypes although ancestral types were different Sharks and dolphins

15. Divergent Evolution Two or more related populations or species become more and more different Response in differing habitats Result in new species

16. Adaptive Radiation Many related species evolve from a single ancestral species

17. Artificial Selection Intentional breeding for specific traits

18. Rates of Evolutionary Change Rapid rates of evolution occur when conditions favor new traits –Otherwise evolution is slow Based on many factors –Mutation rate, lifespan of organism

19. Rate of Speciation

20. Patterns of Evolutionary Change Novel features evolved infrequently –Most changes are modifications Organisms have increased in size and complexity Predations rates increased = evolution of better defenses

22. Describe convergent evolution. Agenda for Thursday May 29 th 1. Bunny Lab