please take both sheets (yellow and white) by the door

Please take both sheets (yellow and white) by the door.

Hardy-Weinberg Lab Notebook

-Due Wednesday, September 9th

1)Title/Date

2)Prelab (key concepts, materials, expected outcomes) Key concepts: equations, 5 requirements for equilibrium, etc.

3) Purpose

4) Procedure, Hypotheses x3 (for each “case” that we complete,)

Data (initial allele frequency, final genotypic COUNT, final allele frequency) for each case

5) ALL answers (#’d) for each case, all 6 H-W Problems (#’d)

You must write these answers in your lab notebook…do NOT staple lab packet into lab notebook!

6) Conclusion…brief but complete! Compare your hypothesis for each case to your results.

Chapter 23: The Evolution of Populations

1. What is a population?- Localized group of individuals of the same species

2. What is a species?- Organisms that can mate & produce fertile offspring in nature

3. What is a gene pool?- All of the genes (both alleles) in a population at any time

4. What is a fixed allele?- An allele that is the same for all members of the population (rare)

5. How can we determine if a population is evolving?- Hardy-Weinberg Theorem--describes non-evolving

populations (a.k.a. population is in equilibrium)- Alleles & genotypes in a gene pool will remain constant unless acted on

by “outside agents”- p + q = 1

- p = dominant allele- q = recessive allele- 1 = ALL alleles in the gene pool


1. What is a population?2. What is a species?3. What is a gene pool?4. What is a fixed allele?5. How can we determine if a population is evolving?

- Hardy-Weinberg Theorem--which actually describes non-evolving populations--population is in equilibrium

- Alleles & genotypes in a gene pool will remain constant unless acted on by agents other than sexual recombination

- p + q = 1- p = dominant allele- q = recessive allele- 1 = ALL alleles in the gene pool

6. What if we want to know specific genotypes of individual in the population?- (p + q)(p + q) = 1

- p2 + 2pq + q2 = 1- p2 = AA – homozygous dominant genotype- q2 = aa – homozygous recessive genotype- 2pq = Aa – heterozygous genotype

Example p + q = 1 p2 + 2pq + q2 = 1500 plants in a population

A – pink flowersa – white flowers20 white flowers (genotype = _____)

How many pink flowers are there? _______

Given: 320 AA160 Aa 20 aa

How many flower color alleles in the population? ______How many dominant (A) alleles? _____How many recessive (a) alleles? _____

What is the frequency of the A allele (p)? ________ a allele (q)? ________

What is the genotypic frequency of AA flowers? ______ Aa flowers? ______ aa flowers? ______

aa

480

1000 = 500 x 2800 = (320 x 2) + (160 x 1)200 = (20 x 2) + (160 x 1)

0.8 = 800/10000.2 = 200/1000

0.64 = p2 = (0.8)2

0.32 = 2pq = 2(0.8)(0.2)0.04 = q2 = (0.2)2


1. What is a population?2. What is a species?3. What is a gene pool?4. What is a fixed allele?5. How can we determine if a population is evolving?6. What if we want to know specific genotypes of individual in the population?7. What are the 5 requirements for a population to be in H-W equilibrium?

- Large population- Isolated population- No mutations- Random mating- No natural selection

8. What happens if any one of these criteria is not met?- No more equilibrium & microevolution occurs

9. What are the causes of microevolution?- Genetic drift – gene pool changes of a small population due to chance

Figure 23.7 Genetic drift

CRCR

CRCW

CRCR

CWCW CRCR

CRCW

CRCW

CRCWCRCR

CRCR

Only 5 of10 plantsleaveoffspring

CWCW CRCR

CRCW

CRCR CWCW

CRCW

CWCW CRCR

CRCW CRCW

Only 2 of10 plantsleaveoffspring

CRCR

CRCR CRCR

CRCRCRCR

CRCR

CRCR

CRCR

CRCRCRCR

Generation 2p = 0.5q = 0.5

Generation 3p = 1.0q = 0.0

Generation 1p (frequency of CR) = 0.7q (frequency of CW) = 0.3


1. What is a population?2. What is a species?3. What is a gene pool?4. What is a fixed allele?5. How can we determine if a population is evolving?6. What if we want to know specific genotypes of individual in the population?7. What are the 5 requirements for a population to be in H-W equilibrium?8. What happens if any one of these criteria is not met?9. What are the causes of microevolution?

- Genetic drift – gene pool changes of a small population due to chance- Bottleneck effect – a disaster reduces the population size so that the

surviving population is NOT representative of the original population- Founder effect – genetic drift in a new colony such as an island

Figure 23.8 The bottleneck effect

Originalpopulation

Bottleneckingevent

Survivingpopulation

(b) Similarly, bottlenecking a population of organisms tends to reduce genetic variation, as in these northern elephant seals in California that were once hunted nearly to extinction.

(a)Shaking just a few marbles through the narrow neck of a bottle is analogous to a drastic reduction in the size of a population after some environmental disaster. By chance, blue marbles are over-represented in the new population and gold marbles are absent.

• Founder effect: ~80% of the current members of the FLDS sect are descendants of just 2 men. Fumarase deficiency (a.k.a. “polygamist Down’s”) is prevalent.


1. What is a population?2. What is a species?3. What is a gene pool?4. What is a fixed allele?5. How can we determine if a population is evolving?6. What is we want to know specific genotypes of individual in the population?7. What are the 5 requirements for a population to be in H-W equilibrium?8. What happens if any one of these criteria is not met?9. What are the causes of microevolution?

- Genetic drift – gene pool changes of a small population due to chance- Bottleneck effect – a disaster reduces the population size so that the

surviving population is NOT representative of the original population- Founder effect – genetic drift in a new colony such as an island

- Gene flow – gain or loss of alleles due to immigration or emigration- Mutations – changes in an organism’s DNA can create new alleles- Non-random (selective) mating – favored alleles are selected for- Natural selection – variability within a population enables some organisms

to be better suited for survival and reproduction


1. What is a population?2. What is a species?3. What is a gene pool?4. What is a fixed allele?5. How can we determine if a population is evolving?6. What is we want to know specific genotypes of individual in the population?7. What are the 5 requirements for a population to be in H-W equilibrium?8. What happens if any one of these criteria is not met?9. What are the causes of microevolution?10.What is a heterozygote advantage?

- Aa genotype has a selective advantage - Sickle-cell allele & malaria resistance

Figure 23.13 Mapping malaria and the sickle-cell allele


1. What is a population?2. What is a species?3. What is a gene pool?4. What is a fixed allele?5. How can we determine if a population is evolving?6. What is we want to know specific genotypes of individual in the population?7. What are the 5 requirements for a population to be in H-W equilibrium?8. What happens if any one of these criteria is not met?9. What are the causes of microevolution?10. What is a heterozygote advantage?11. How can natural selection change a population?

- Directional selection- Disruptive selection- Stabilizing selection

Figure 23.12 Modes of selection

(a) Directional selection shifts the overallmakeup of the population by favoringvariants at one extreme of thedistribution. In this case, darker mice arefavored because they live among darkrocks and a darker fur color conceals themfrom predators.

(b) Disruptive selection favors variantsat both ends of the distribution. Thesemice have colonized a patchy habitatmade up of light and dark rocks, with theresult that mice of an intermediate color areat a disadvantage.

(c) Stabilizing selection removesextreme variants from the populationand preserves intermediate types. Ifthe environment consists of rocks ofan intermediate color, both light anddark mice will be selected against.

Fre

quen

cy o

f in

divi

dual

s

Phenotypes (fur color)

Original population

Originalpopulation

Evolvedpopulation

please take both sheets (yellow and white) by the door

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