1. Chapter 4 Evolution and Biodiversity:

2. Origins of Life Early Earths information comes from chemical & radioactivity analysis of rocks and fossils Earth developed in 2 phases –See fig 4-3 on pg 66 –Chemical evolution – 4.7-4.8 billion years Biological evolution – 3.7-3.8 billion years Prokaryotic bacteria Single cell eukaryotic creatures Multi-cellular organisms

3. Evolution All species descended from earlier, ancestral species –Micoevolution – small genetic changes that occur in a population –Macroevolution – large-scale evolutionary changes through which new species are formed while other species are lost through extinction

4. Microevolution Alleles – genes that may have 2 or more molecular forms –Sexual reproduction allows random shuffling or recombination of alleles Mutations – random changes in the structure or number of DNA molecules –Exposure to chemicals or radiation –Random mistakes that sometimes occur in coded genetic instructions during replication

6. Microevolution (continued) Natural selection – genetically based traits that increase their chances to survive Natural variability –Heritable so they can pass on the trait –Produce more offspring (differential reproduction) Adaptation – hereditary traits that help an organism to survive in new conditions –Natural selection –Migration –Become extinct

7. Artificial Selection Genetic engineering and all that is! www.answers.com/topic/artificial- selection http://evolution.berkeley.edu/evolibrary/im ages/evo/mustardselection.jpg

8. Coevolution Species adapts because of another species adaptation

9. Ecological Niche Niche is defined as the role in which a species plays within its ecosystem –An understanding of a species niche allows us to be more aware of : The affects we have on the success of that’s species survival The competition for resources that species have within a community (realized niche) General classifications of species

10. Natural Factors Relating to Extinction Extinction occurs when environmental conditions change, and adaptation or migration can not occur in time for a species to exist. –Large scale movement of the continents (continental drift) –Gradual climate changes –Rapid climate changes

11. Unnatural Factors Relating to Extinction Humans have played a major role in the unnatural process of extinction. –Clear cutting or burning of forests, woods and grasslands –Over hunting of animals for food, by-products and sport –Population of humans have increased exponentially and have taken over the habitat of other species

12. Summary See slide show on specific species See film CNN: Costa Rica – Science in the Rainforest