1. The Origin of Species Chapter 24 Biology – Campbell Reece

2. What is a species? Biological species concept: Biological species concept: Reproductive isolation Reproductive isolation

3. What is a species?

4. Prezygotic Barriers What are prezygotic barriers? What are prezygotic barriers? Habitat isolation Habitat isolation Behavioral isolation Behavioral isolation

5. Habitat and Behavioral Isolation

6. Prezygotic Barriers Temporal isolation Temporal isolation Mechanical isolation Mechanical isolation Gametic isolation Gametic isolation

7. Temporal, Mechanical & Gametic Isolation

8. Postzygotic Barriers What are postzygotic barriers? What are postzygotic barriers? Reduced hybrid viability Reduced hybrid viability Hybrid breakdown Hybrid breakdown

9. Reduced Hybrid Viability & Hybrid Breakdwon

10. Postzygotic Barriers Reduced Hybrid Fertility Reduced Hybrid Fertility

11. Reproductive Barriers

12. Modes of Speciation Allopatric speciation Allopatric speciation Sympatric speciation Sympatric speciation

13. Conditions for Allopatric Speciation More likely if the population is both small and isolated More likely if the population is both small and isolated Barrier has to be significant enough to not be crossable Barrier has to be significant enough to not be crossable They must become different enough that they can no longer interbreed They must become different enough that they can no longer interbreed

14. Adaptive Radiation What is it? What is it? Especially common on island chains such as the Galapagos and the Hawaiian Islands Especially common on island chains such as the Galapagos and the Hawaiian Islands

15. Sympatric Speciation in Plants When meiosis goes wrong… When meiosis goes wrong…

16. Sympatric Speciation in Animals Polyploid speciation in animals? Polyploid speciation in animals? Dependent on different resources Dependent on different resources Nonrandom mating Nonrandom mating

17. Punctuated Equilibrium vs. Gradualism

18. Microevolution vs. Macroevolution Microevolution Microevolution Macroevolution Macroevolution