1. Chapter 9 March 18, 2008

2. Evolution – genetically controlled changes in physiology, anatomy, and behavior that occur to a species over time –Microevolution – evolutionary change within an individual species or population –Macroevolution – evolutionary change within larger taxonomic units such as families Speciation – development of two or more generically differentiable species from a single common ancestor

3. Phenotypic variations – differences in physiology, anatomy, and behavior of different species or individuals of the same species Genotypic variations – differences in the genes between different species or members of the same species

4. Genotypic Variation Geographic races - Genetically and phenotypically distinct members of the same species that occur in different regions Figure 9.1

5. Can offspring of an organism inherit phenotypic traits that are acquired due to environmental conditions acting upon the organism? How then do new genes and genetically controlled traits appear in species? –Mutation –Genetic drift –Natural selection –Gene flow –Adaptation

6. Mutation – changes in DNA

7. Genetic drift

8. Natural Selection – traits that provide an advantage in reproduction are selected fore, whereas disadvantageous traits are selected against

9. Gene flow

10. Adaptation

11. How does evolution lead to speciation? Reproductive isolation – must be barrier between newly formed species and original species Polyploidy – plants that are born with twice the chromosome as the parent making them reproductively isolated Allopatric speciation – formation of a new species by geographic isolation

12. Allopatric speciation

13. Sympatric speciation – development of new species within the same geographic area Causes: –Life cycle timing, such as timing of reproduction –Ethological isolation – barriers to breeding caused by behavior, particularly mate choice –Stenophagy

14. Sympatric Speciation Cichlids of Lake Victoria, Africa

15. Parapatric speciation – caused by the evolutionary divergence of populations that occupy different habitat or niches in the same geographic area –Iris fulva (lower left)– grows on drier riverbanks –Iris giganticaerulea (lower right) – grows in damp marshes –Hybrids possible, but cant survive in either parental niche