1. Outcomes of Evolution

2. Outcomes of Natural Selection
Most quantitative traits resemble bell curve for phenotypes
Natural Selection can alter variation in a population in 3 ways:

3. 1) Stabilizing Selection
Favors individuals with the average phenotype of the trait (average form have the highest fitness)

4. Example of Stabilizing Selection

5. 2) Directional Selection
Environmental conditions favor individuals of one extreme phenotype

6. Example of Directional Selection
D left off here
Example of Directional Selection

7. 3) Disruptive Selection
Environmental conditions favor individuals of both extremes of the phenotype.
Can lead to creation of a new species

8. Example of Disruptive Selection

9. Patterns of Evolution Ways species change to adapt to their habitats:
Coevolution
Convergent Evolution
Divergent Evolution

10. Patterns of Evolution
Coevolution: Two or more species change together!
Examples:
Predator/Prey
Plant and pollinator

11. Patterns of Evolution
Convergent: Two dissimilar species becoming structurally similar Environment selects for similar phenotype (but ancestors were different)
Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups

12. Patterns of Evolution
Divergent: Two similar species become dissimilar in response to environment

13. Evolution Speciation and Reproductive Isolation
Creating a New Species
Evolution
Speciation and Reproductive Isolation

14. Species:
A group of similar organisms that can breed to produce fertile offspring
Liger - not fertile

15. Speciation: Creating a new species
1 species evolves into 2 different species

16. How Speciation Occurs
When a group in a population are separated and can no longer reproduce a new species is formed

17. Ways to create a new species: how are species separated?
Isolation
Geographical Isolation
Reproductive Isolation
Temporal Isolation
Behavioral Isolation
Populations separated by geographical barriers like water, canyons, and mountains
Populations separated by behaviors like mating calls, physical traits, mating dances
Populations separated by time like nocturnal, diurnal, months, years

18. Geographic Isolation Habitat becomes divided
No mating because one species gets separated by a barrier (earthquake, river, etc)
Over time, can lead to two different species.

19. Behavioral Isolation No mating
One does not desire the courtship behavior of the other one
Over time, can lead to two different species

20. Temporal Isolation No mating
One reproduces at different times of day, month, year
Over time, can lead to two different species.

21. Rates of Speciation Gradual - stable rate of change
2 ways in which evolution of species can occur
Scientists think that species with a shorter evolution evolved mostly by punctuated equilibrium, and those with a longer evolution evolved mostly by gradualism.
Gradual - stable rate of change
Punctuated- instant change

22. Critical Questions: How does reproductive isolation affect speciation?
How does geographic isolation affect speciation?