1. Evidence of Evolution Chapter 8

2. Historical Jean-Baptiste Lamarck

3. Alfred Wallace

4. Voyage of the Beagle

5. Darwin and Natural Selection

6. A Key Insight – Variation in Traits  Darwin’s observations: Populations can produce more individuals than their environment can support Some versions of a trait might enhance an individual’s ability to survive and reproduce in its environment

7. Finches in the Galapagos Islands

8. Terms  Alleles Heterozygote homozygote  Genotype  Phenotype  Frequency  equilibrium genotype phenotype

9. At What Level Does Evolution Occur?  Individuals don’t evolve, populations do!

12. Fig. 18-3b, p. 280 420 Aa butterflies medium-blue wings 490 AA butterflies dark-blue wings 420 Aa butterflies medium-blue wings 90 aa butterflies white wings Starting PopulationNext Generation

14. How can a gene pool change? Mutation Genetic drift Gene flow (migration) Natural selection Sexual selection Will the above have more of an effect on a large population or a small population? Why?

15. Genetic Drift— The Chance Changes  Genetic drift A random change in allele frequencies over time Founder effect Bottleneck Effect

16. Genetic drift is pronounced when a few individuals start a new population

18. Gene Flow (Migration)

19. Natural Selection  Differential survival and reproduction among individuals of a population that vary in the details of their shared traits  In other words….. Some organisms have a better chance of surviving and reproducing than other organisms depending on their traits

20. Natural Selection Natural selection  Differential survival and reproduction among individuals of a population that vary in details of shared, inherited traits Adaptive trait  Any trait that enhances an individual’s fitness- ability to survive and reproduce in a particular environment) Not this kind of fitness!

23. Sexual Selection  With sexual selection, some version of a trait gives an individual an advantage over others in attracting mates

24. Sexual Selection