1. Population Genetics

2. The Gene Pool
Members of a species can interbreed & produce fertile offspring
Species have a shared gene pool
Gene pool – all of the alleles of all individuals in a population

3. The Gene Pool Different species do NOT exchange genes by interbreeding
Different species that interbreed often produce sterile or less viable offspring e.g. Mule

4. Populations A group of the same species living in an area
No two individuals are exactly alike (variations)
More Fit individuals survive & pass on their traits

5. Speciation Formation of new species
One species may split into 2 or more species
A species may evolve into a new species
Requires very long periods of time

6. Modern Synthesis Theory
Today’s theory on evolution
Recognizes that GENES are responsible for the inheritance of characteristics
Recognizes that POPULATIONS, not individuals, evolve due to natural selection & genetic drift
Recognizes that SPECIATION usually is due to the gradual accumulation of small genetic changes

7. Microevolution
Changes occur in gene pools due to mutation, natural selection, genetic drift, etc.
Gene pool changes cause more VARIATION in individuals in the population
This process is called MICROEVOLUTION
Example: Bacteria becoming unaffected by antibiotics (resistant)

8. Species & Populations
Population - a localized group of individuals of the same species. 
Species - a group of populations whose individuals have the ability to breed and produce fertile offspring. 
Individuals near a population center are, on average, more closely related to one another than to members of other populations.

10. Gene Pools
A population’s gene pool is the total of all genes in the population at any one time. 
If all members of a population are homozygous for a particular allele, then the allele is fixed in the gene pool.

11. The Hardy-Weinberg Theorem
Used to describe a non-evolving population.
Shuffling of alleles by meiosis and random fertilization have no effect on the overall gene pool. 
 Natural populations are NOT expected to actually be in Hardy-Weinberg equilibrium.

12. The Hardy-Weinberg Theorem
Deviation from Hardy-Weinberg equilibrium usually results in evolution
Understanding a non-evolving population, helps us to understand how evolution occurs
                        .

13. Assumptions of the H-W Theorem
Large population size - small populations can have chance fluctuations in allele frequencies (e.g., fire, storm). (Genetic Drift)
No migration - immigrants can change the frequency of an allele by bringing in new alleles to a population.
No net mutations - if alleles change from one to another, this will change the frequency of those alleles

14. Assumptions of the H-W Theorem
Random mating - if certain traits are more desirable, then individuals with those traits will be selected and this will not allow for random mixing of alleles.
No natural selection - if some individuals survive and reproduce at a higher rate than others, then their offspring will carry those genes and the frequency will change for the next generation.

15. Hardy-Weinberg Equilibrium
                                   
The gene pool of a non-evolving population remains constant over multiple generations; i.e., the allele frequency does not change over generations of time.
The Hardy-Weinberg Equation:
                                    1.0 = p2 + 2pq + q2
                                               
p2 = frequency of AA genotype or homozygous 1 st allelle
2pq = frequency of Aa plus aA genotype or heterozygous
q2 = frequency of aa genotype

16. Hardy-Weinberg Equilibrium
Population of cats
n=100
16 white and 84 black
bb = white
B_ = black
Can we figure out the allelic frequencies of individuals BB and Bb?

17. Hardy-Weinberg Principle
p2 + 2pq + q2
and
p+q = 1 (always two alleles)
16 cats white = 16bb then (q2 = 0.16)
This we know we can see and count!!!!!
If p + q = 1 then we can calculate p from q2
Q = square root of q2 = q √ q=0.4
p + q = 1 then p = .6 ( = 1)
P2 = .36
All we need now are those that are heterozygous (2pq) (2 x .6 x .4)=0.48

18. Hardy-Weinberg Equilibrium

21. *Yes, I realize that this is not really a cheetah.

22. 2) Natural selection
                                   
As previously stated, differential success in reproduction based on heritable traits results in selected alleles being passed to relatively more offspring (Darwinian inheritance).
The only agent that results in adaptation to environment.
3) Gene flow
-is genetic exchange due to the migration of fertile individuals or gametes between populations.

24. 4) Mutation
                                   
Mutation is a change in an organism’s DNA and is represented by changing alleles. 
Mutations can be transmitted in gametes to offspring, and immediately affect the composition of the gene pool.
The original source of variation.

25. Genetic Variation, the Substrate for Natural Selection
           
Genetic (heritable) variation within and between populations: exists both as what we can see (e.g., eye color) and what we cannot see (e.g., blood type).
Not all variation is heritable.
Environment also can alter an individual’s phenotype [e.g., the hydrangea we saw before, and…
…Map butterflies (color changes are due to seasonal difference in hormones)].