1. Learning Target: Evolution of Populations Ch. 11. 1 – 11. 2, pp
Learning Target: Evolution of Populations Ch – 11.2, pp. 329 – 333, & Ch. 11.6, pp
I Can…Describe how genetic variation within a population increases the chance that some individuals will survive and describe different mechanisms of evolution.

2. Genetic Variation Within Populations
Ch. 11.1, pp
Key Concept:
Populations share a common gene pool
Main Ideas:
Genetic variation within a population increases the chance that some individuals will survive.
Genetic variation comes from
Mutation
Recombination

3. Genetic Variation Within Populations
Ch. 11.1, pp
Gene pool
Store of population’s genetic variation
All alleles within population
Allele frequency
Measure of how common a certain allele is within the population
Each autosomal gene has two alleles
Homozygous
Heterozygous

4. Genetic Variation Within Populations
Ch. 11.1, pp
Phenotype traits:
Monogenic or polygenic
Dominant/Recessive
Incomplete Dominance
Co-Dominance
Permissive/Epistasis

5. Genetic Variation Within Populations
Ch. 11.1, pp
Allele Variation:
Mutations
Change in DNA nucleotide sequence
Recombination
New different combinations of alleles
Crossing over during meiosis

6. Genetic Variation Within Populations
Ch. 11.1, pp
Allele frequency in a population gene pool can be calculated.

7. Natural Selection in Populations
Ch. 11.2, pp
Key Concept:
Populations, not individuals, evolve
Main Ideas:
Natural selection
Acts on distribution of traits
Can change the distribution of traits in one of three ways
Microevolution
Observable change in allele frequency of a population over time

8. Natural Selection in Populations
Ch. 11.2, pp
Normal Distribution
Phenotype frequency highest at mean
Decreases as nears extremes
“Bell” shaped curve
Not undergoing selective pressure

9. Natural Selection in Populations
Ch. 11.2, pp
Directional Selection
Favors one of the extreme phenotypes
Causes shift of highest allele frequency from mean towards one extreme

10. Natural Selection in Populations
Ch. 11.2, pp
Stabilizing Selection
Favors mean phenotype

11. Natural Selection in Populations
Ch. 11.2, pp
Disruptive Selection
Favors both extreme phenotypes
Selects against mean phenotype

12. Direction of Evolution ≠ Purpose or Intent
Natural Selection in Populations
Ch. 11.2, pp
Remember:
Direction of Evolution ≠ Purpose or Intent

13. Patterns in Evolution Key Concept: Evolution occurs in patterns
Ch. 11.6, pp
Key Concept:
Evolution occurs in patterns
Main Ideas:
Evolution is not random
Species can shape each other over time
Species can become extinct
Speciation often occurs in patterns

14. Patterns in Evolution Evolution occurs in patterns
Ch. 11.6, pp
Evolution occurs in patterns
Evolution through natural selection is NOT random.
Mutations cannot be predicted accurately
Termed “Random event”
Source of genetic variation
Natural selection acts upon the variation
Not random
Selective pressure makes one variation more advantageous in survival and/or reproduction than other variation

15. Direction of Evolution ≠ Purpose or Intent
Patterns in Evolution
Ch. 11.6, pp
Selective pressures act upon variations in population:
Adds up over many generations
Advantageous variation becomes more prevalent in population over time.
Population becomes “adapted”
The adaptation (advantage variation) becomes more prevalent and allele frequencies change.
Direction of Evolution ≠ Purpose or Intent

16. Patterns in Evolution Environment drives natural selection
Ch. 11.6, pp
Environment drives natural selection
Environments can change
Convergent Evolution
Different species must adapt to similar environmental pressures.
Evolution toward similar characteristics in unrelated species
Analogous structures
e.g. dolphin and shark tail fin

17. Patterns in Evolution Divergent Evolution
Ch. 11.6, pp
Divergent Evolution
Closely related species evolve in different direction and become increasingly different
Common ancestor
Homologous structures
e.g. Kit fox & Red fox, Galapagos finches, Grey wolf to domestic dogs
Question: Both turtles and snails have shells. Is this an example of convergent or divergent evolution?

18. Patterns in Evolution Coevolution:
Ch. 11.6, pp
Coevolution:
Species react to each other in many different ways
Beneficial e.g. ____________________________
Parasitic e.g. _____________________________
Arms race e.g. ____________________________

19. Patterns in Evolution Extinction: Elimination of a species from Earth
Ch. 11.6, pp
Extinction:
Elimination of a species from Earth
Unable to adapt to changing environments
Background extinction :
Continuous over time
Affects one to small number of species in an area
Mass Extinction:
Rare
Global level
Many species
Five mass extinctions in last 600 million years

20. Patterns in Evolution Patterns in evolution: Punctuated equilibrium
Ch. 11.6, pp
Patterns in evolution:
Punctuated equilibrium
Episodes of speciation followed by long periods of little evolutionary change
Adaptive radiation
Diversification of one ancestral species into many descendant species
Different environmental pressures