1. Speciation & Patterns of Evolution* *

2. Objectives
Explain how the isolation (physical or genetic) of populations can lead to speciation. * *

3. Vocabualry Species Speciation Geographic isolation
Allopatric Speciation
Reproductive Isolation
Sympatric Speciation
Gradualism
Punctuated equilibrium
Adaptive Radiation/Divergent Evolution
Convergent Evolution * *

4. What is speciation?
Species: a group of organisms that look alike and can interbreed to produce fertile offspring in nature.
SPECIATION: when members of Similar populations can no longer interbreed to produce fertile offspring. *

5. What can cause speciation?
1. GEOGRAPHIC ISOLATION
Physical barrier separates a population
Allopatric Speciation:
New species arise as a result of geographic isolation *

6. What can cause speciation?
2. REPRODUCTIVE ISOLATION
Organisms can no longer mate to produce offspring
Timing
Behavior
Habitat
Infertile Hybrid offspring
Sympatric Speciation
New species arise as a result of reproductive isolation *

7. How fast does speciation occur?
Gradualism
species originate through a gradual change of adaptations
Punctuated equilibrium
speciation occurs relatively quickly, in rapid bursts, with long periods of genetic equilibrium in between. *

8. Comparing Gradualism vs. Punctuated Equilibrium

9. How does environment affect speciation?
Divergent evolution/Adaptive Radiation:
when populations change as they adapt to different environmental conditions, eventually resulting in new species.
Convergent evolution:
distantly related organisms evolve similar traits
occurs when unrelated species occupy similar environments in different parts of the world *

10. ADAPTIVE RADIATION – AN EXAMPLE OF DIVERGENT EVOLUTION*

11. CONVERGENT EVOLUTION EXAMPLE
Psst: this is an example of Analogous Structures *

12. Question #1
Natural processes such as speciation and gradualism provide the genetic basis for _____.
evolution
biogenesis
spontaneous generation
sexual reproduction *

13. Question #1
Natural processes such as speciation and gradualism provide the genetic basis for _____.
evolution
biogenesis
spontaneous generation
sexual reproduction *

14. Question #2
A pattern of evolution that results when two unrelated species begin to appear similar because of environmental conditions is _____.
disruptive selection
directional selection
convergent evolution
divergent evolution *

15. Question #2
A pattern of evolution that results when two unrelated species begin to appear similar because of environmental conditions is _____.
disruptive selection
directional selection
convergent evolution
divergent evolution *