1. The study of allele frequencies within a population
Population Genetics
The study of allele frequencies within a population

2. Gene Pool All of the genes of a population of organisms
Organisms that are the most successful at reproducing contribute most to the gene pool

3. Evolution Any change in the frequency of any allele within a gene pool
Populations undergo evolution
Individuals do not undergo evolution

4. Factors Affecting the Allele Frequency
Mutation
Especially important for organisms with short generation times

5. Factors Affecting the Allele Frequency
Migration
Movement of organisms into or out of the population

6. Factors Affecting the Allele Frequency
Genetic Drift
Random change in allele frequencies
Occurs mostly in small, isolated populations

7. Factors Affecting the Allele Frequency
Selection
Environmental pressures
Competition
Climate change

8. Factors Affecting the Allele Frequency
Nonrandom mating
Preferences in selection of a mating partner

9. SPECIES
Species: A group of organisms so similar to one another that they can interbreed and produce fertile offspring
Kingdom
Phylum
Class
Order
Family
Genus
Species

10. Speciation Speciation is the evolution of new species through time
Speciation occurs most rapidly in a small population

11. Mechanisms of Speciation
Artificial Speciation
New species have been developed by man
Intentional mutations
Cross breeding
Genetic engineering

12. Mechanisms of Speciation
Natural Speciation by Isolation of Small Populations
Geographical Isolation
Geographical barriers separate two populations
Mountain ranges
Deep canyons
Bodies of water
Ecological Isolation
Organisms of two populations require different habitats

13. Mechanisms of Speciation
Behavioral Isolation
Changes in habits that identify one population with another
Mating rituals
Methods of communication

14. Mechanisms of Speciation
Seasonal Isolation
Reproductive cycles do not coincide
Plants that flower at different times
Animals that mate or nest build at different times

15. Mechanisms of Speciation
Mechanical Isolation
Physical characteristics that keep organisms from interbreeding
Difference in size
Difference in reproductive anatomy
Inability of sperm to penetrate the egg

16. Observations From the Fossil Record
Species often remain stable for millions of years with little or no noticeable change
Species may disappear rapidly and new species may appear just as fast

17. Population Evolution

18. Punctuated Equilibrium
Long periods of stability followed by short periods of rapid change