1. Population Genetics Studies the genetic variations within a population
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2. Variations
When different species members have differences in characteristics
Ex. Dogs – one species but many varieties

3. Gene pool
All of the genes in a population

4. Why does the dominant trait take over?
Hardy and Weinberg stated the genes in a population will remain stable if under certain conditions

5. Assumptions of Hardy Weinberg
There are no mutations.
No genes transferred (No immigration or emigration)
Mating is random.
The population should be large.
No selection is occurring

6. Hardy-Weinberg theorem
An equation used to identify a
non-evolving population.
Looks at the frequency of each allele
HARDY WEINBERG EQUILIBRIUM = There is no change in gene frequency in a population
p pq + q2= 1

7. Mendel genetics – Apply to alleles in one gametes of one pair
Mate two individuals heterozygous (Bb) for a trait.
25% offspring are homozygous for the dominant allele (BB)
50% are heterozygous like their parents (Bb) and
25% are homozygous for the recessive allele (bb) and express the recessive phenotype

8. populations have random alleles
The frequency of two alleles in an entire population of organisms is unlikely to be exactly the same. Ex. population of hamsters:
A) 80% of all the gametes in the population carry a dominant allele for black coat (B) and
B) 20% carry the recessive allele for gray coat (b).

9. hamsters MENDEL monohybrid cross
Results of random union of the two gametes produced by two individuals, each heterozygous for a given trait. As a result of meiosis, half the gametes produced by each parent with carry allele B; the other half allele b.
RANDOM POP
Results of random union of the gametes produced by an entire population with a gene pool containing 80% B and 20% b.
0.5 B
0.5 b
0.8 B
0.2 b
0.25 BB
0.25 Bb
0.64 BB
0.16 Bb
0.25 bb
0.04 bb

10. Allele frequency P = frequency of dominant allele
q = frequency of recessive allele
Brown eyes vs blue eyes
Brown (B) = P
Blue (b) = q

11. Total frequency of alleles in population = 1 THEREFORE
p + q = (dom + res = 1)
q =1 – p (res = 1 – dom)
p = 1 – q (dom = 1 – res)
Ex. R = red r = white there are 20% white flowers in a field
q freq =.2 (20%) white
then p freq = = .8 (80%) red

12. Allele frequency of a dominant and recessive trait
Similar to punnett square

13. Ex. Frequency alleles of Red (R) and white (r) flowers
p pq q = 1
Frequency freq freq
of RR of Rr rr
genotype genotype genotype

14. p2 + 2 pq + q2 = 1 Given: 4% of the population = white flowers (rr)
What is the frequency of r? (q)
What is the frequency of R? (p)
What % of pop. = Rr?
q2 = so q = so p = .8
4% rr
2(.8)(.2) = .32 Rr = 32% Rr
64% RR

15. NOT Hardy Weinberg equilibrium
Change of allele frequency in 3 generations

16. 5 agents of evolutionary change
Things that CHANGE equilibrium of gene pool

17. 1) Mutation
Change in DNA code
Mutagen

18. Mutations
The origin of new alleles

19. 2) Gene Flow Migration – Individuals move from one population to next
Bring genes into new population

20. 3) Non-Random Mating
Self fertilization
Inter breeding

21. 4) Genetic drift
A change in frequency due to chance

22. Bottleneck effect Genetic drift due to a reduction in population size
Ex skittles

23. Tsunami bottle neck

24. Founder effect
Genetic drift due to formation of a new colony with organisms with distinctly different phenotypes

25. 5) Natural selection Darwin’s idea Survival of the fittest
The environment influences who passes on their DNA

26. Fitness - ability to pass on traits to offspring
The individuals in a population that are most fit are the ones that survive
Attract mates better
Catch prey better
Hide better from predators

27. Polymorphism – When there are two or more forms of one character
aids natural selection by increasing possible phenotypes

28. Geographic Variation Differences in gene pools between populations
Can aid natural selection