1	The Evolution of Populations
2	Population Genetics Population genetics is the study of allele behaviour in populations. A population is a group of interbreeding individuals of a single species.
3	"Variation within a population" Variation within a population Discrete characteristics – Purple vs. White flower colours Quantitative characters – (two or more genes) vary along a continuum
4	"Nonheritable variation" Nonheritable variation Nemoria arizonaria moths Fed oak flowers Fed oak leaves
5	Sources of Genetic Variation All new genes arise by mutation (point mutation) creates new codons and therefore new protein sequences Sexual reproduction provides recombination (meiosis and crossing over) which produces endless genotypic variation in the population
6	Sexual Recombination
7	Hardy-Weinberg Theorem This theorem describes a population that is not evolving. That is the populations allelic frequency is not changing
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9	Gene pool and allelic frequencies AA
10	"This population of “circle..." This population of “circle critters” has twenty members, and each member has two alleles, therefore there 40 alleles in the “gene pool” The allelic frequency of A is 36/40=0.9 The allelic frequency of a is 4/40=0.1
11	"Therefore" Therefore 90% of all the sperm will carry A 10% of all the sperm will carry a 90% of all the eggs will carry A 10% of all the eggs will carry a
12	We could set up a Punnett square with these gene frequencies.
13	We could set up a Punnett square with these gene frequencies.
14	We could set up a Punnett square with these gene frequencies.
15	We could set up a Punnett square with these gene frequencies.
16	We could set up a Punnett square with these gene frequencies.
17	We could set up a Punnett square with these gene frequencies.
18	Hardy-Weinberg formula If p = frequency of allele A = 0.9 And q = frequency of allele a = 0.1 Then AA + 2Aa + aa = 1 would be p² + 2pq + q² = 1 From the above example p = 0.9, and q = 0.1 (0.9)² + 2(0.9)(0.1) + (0.1)² = 1 0.81 + 0.18 + 0.01 = 1
19	Therefore: The term p² = frequency of genotype AA = 0.81 The term 2pq = frequency of genotype Aa = 0.18 The term q² = frequency of genotype aa = 0.01
20	What if you know the genotypic frequency but you wish to calculate the frequency of the alleles in a population? Lets say aa represents blond hair, and 4% of a population have blond hair. Therefore aa = 0.04 We know that q² = the frequency of aa Therefore q =
21	What if you know the genotypic frequency but you wish to calculate the frequency of the alleles in a population? Lets say aa represents blond hair, and 4% of a population have blond hair. Therefore aa = 0.04 We know that q² = the frequency of aa Therefore q = 0.04 = 0.2
22	What if you know the genotypic frequency but you wish to calculate the frequency of the alleles in a population? Lets say aa represents blond hair, and 4% of a population have blond hair. Therefore aa = 0.04 We know that q² = the frequency of aa Therefore q = 0.04 = 0.2 Recall that p + q =1
23	What if you know the genotypic frequency but you wish to calculate the frequency of the alleles in a population? Lets say aa represents blond hair, and 4% of a population have blond hair. Therefore aa = 0.04 We know that q² = the frequency of aa Therefore q = 0.04 = 0.2 Recall that p + q =1 If q = 0.2, then 1 - 0.2 = p = 0.8
24	By substituting into the Hardy-Weinberg equation p² + 2pq + q² = 1 (0.8)² + 2(0.8)(0.2) + (0.2)² = 1 AA = 0.64 Aa = 0.32 aa = 0.04
25	What are the conditions of the Hardy-Weinberg Theorem ? The population must be large Mutations must not occur There must be no immigration or emigration Reproduction must be random There must be no natural selection
26	Genetic Drift
27	The Bottleneck Effect
28	Bottleneck of the Cheetah
29	Cheetah Distribution
30	Gene flow: Migration
31	Nonrandom Mating
32	Causes of Microevolution
33	Patterns of Natural Selection
34	"Directional Selection" Directional Selection The British Peppared Moth Biston betularia
35	Directional Selection -The British Peppared Moth Biston betularia
36	Directional Selection -The British Peppared Moth Biston betularia
37	Adaptive Evolution
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39	Sexual Selection Sexual Dimorphism
40	Intrasexual selection Selection “within the same sex”. Male compete with each other for females.
41	Intersexual Selection Also called “mate choice”. Often female choose the males.
42	Why Sex?
43	Reproductive handicap of sex
44	What advantage does sex provide? “Changing the locks” – bacterial pathogens and the antigens they bind to. “Red Queen race” – Co-evolution of host parasite interactions.
45	The Preservation of Genetic Variation Diploidy – genetic variation hidden from selection by recessive alleles.
46	Balancing Selection Heterozygotic Advantage- Sickle Cell Anemia Hemoglobin H^s Hemoglobin H^a
47	Sickle Cell Anemia Hemoglobin H^s Hemoglobin H^a If H^a was 0.8 =p and H^s was 0.2 = q Then from the Hardy-Weinberg equation p² + 2pq + q² = 1 H^aH^aH^aH^sH^sH^s 0.64 + 0.32 + 0.04 = 1
48	"But before the next generation..." But before the next generation H^sH^s would likely die and not be available to reproduce. Therefore 0.64 = H^aH^a 0.32 = H^aH^s Total 0.96 Now 0.64/0.96 = 0.66 = H^aH^a and 0.32/0.96 = 0.33 = H^aH^s
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50	Malaria Plasmodium sp.
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52	Frequency-Dependent Selection The fitness of a phenotype declines if it becomes too common in the population.
53	"Neutral Variation" Neutral Variation Not all traits have an impact on reproductive success