BIO120H1 Lecture Notes - Lecture 5: Neo-Darwinism, Population Genetics, Dna Replication

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Foundations of population genetics: r. a. fisher, j. b. s. What processes influence patterns of genetic diversity: mutation (increases diversity) Caused by random errors during dna replication: random genetic drift (decreases diversity) Drift important when populations become small: natural selection (can decrease or increase diversity) See diagrams on slides: purifying (negative selection): mutations that reduce fitness removed by selection, positive selection (adaptation): mutations that increase fitness become fixed, balancing selection: natural selection maintains diversity; e. g. heterozygote advantage. Less fit types maintained by repeated mutation: selection maintaining variation. Early evidence for the existence of genetic variation: selection experiments on quantitative traits in different groups of organisms, involves controlled breeding and selection of individuals for many generations. Example: breeding for bristle number in fruit flies. Chose ones with highest bristle number, bristle number eventually increased, showed that bristle number had genetic variability. Example 2: selecting maize (corn) for oil, once selection is relaxed, random mating will re- approach a mean.

Related Questions

1/ What is the difference between the different patterns ofselection: directional, stabilizing, anddiversifying?

2/ How do bacteria acquire genetic variation and how does thatdiffer from the mechanism by which humans acquire variation?

3/ What were the key observations made by Darwin to develop thebasic tenants of the theory of evolution? Has thistheory been tested?

4/ What are the most common misconceptionsabout evolution and why are they not valid arguments againstevolution?

5/ The key component of the theory of evolution isnatural selection. Define this process. Why is itcommonly known as âsurvival of the fittestâ? What are examples offactors (selective pressures) that drive evolutionof populations?

6/ What is the indirect evidence of evolution? What arehomologous and analogousstructures? What is convergent evolution?How does similarity of proteins between different species supportthe idea of evolution?

7/ Be able to explain why the following statement is true:Natural Selection works on individuals while evolution works onpopulations over generations. Or to put it another way: Individualsdo not evolve, populations do.

8/ How can evolution explain theformation of complex structures such as the eye or the flagellamotor?

9/ What causes variation in a species? To putthis another way: all humans have the same genes, yet we do notlook alike. What is the reason for the phenotypicdifferences between individuals of the same species? What isgenetic recombination?

10/ What are the dangers of small populations of a species froma genetic and evolutionary standpoint? What is thebottleneck effect?

11. How does speciation occur? What is theimportance of geographic isolation? How is thisillustrated in the Galapagos?

12. What is Darwinian Medicine and how does ithelp us better understand medical conditions?

copperhornet769

1. What is the difference between the different patternsof selection: directional, stabilizing, anddiversifying?

2. How do bacteria acquire genetic variation and how doesthat differ from the mechanism by which humans acquirevariation?

3. What were the key observations made by Darwin todevelop the basic tenants of the theory of evolution? Has thistheory been tested?

4. What are the most common misconceptions about evolutionand why are they not valid arguments against evolution?

5. The key component of the theory of evolution is naturalselection. Define this process. Why is it commonly known asâsurvival of the fittestâ? What are examples of factors (selectivepressures) that drive evolution of populations?

6. What is the indirect evidence of evolution? What arehomologous and analogous structures? What is convergent evolution?How does similarity of proteins between different species supportthe idea of evolution?

7. Be able to explain why the following statement is true:Natural Selection works on individuals while evolution works onpopulations over generations. Or to put it another way: Individualsdo not evolve, populations do.

8. How can evolution explain the formation of complexstructures such as the eye or the flagella motor?

9. What causes variation in a species? To put this anotherway: all humans have the same genes, yet we do not look alike. Whatis the reason fro the phenotypic differences between individuals ofthe same species? What is genetic recombination?

10. What are the dangers of small populations of a speciesfrom a genetic and evolutionary standpoint? What is the bottleneckeffect?

11. How does speciation occur? What is the importance ofgeographic isolation? How is this illustrated in theGalapagos?

12. What is Darwinian Medicine and how does it help usbetter understand medical conditions?

carminegnu677

Random, chance events that change allele frequencies are knownas:

A. Gene flow

B. Genetic drift

C. Natural selection

D. Balancing selection

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Question 21 pts

What type of selection acts to maintain the two extremephenotypic variants in a population?

A. Disruptive selection

B. Directional selection

C. Positive selection

D. Artificial selection

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Question 31 pts

Approximately, how much of our DNA is shared with our closestrelatives, chimpanzees?

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Question 41 pts

The large canines of male baboons are likely the result of________, while the fact that some male baboons are very colorfulis probably the result of _______.

A. Mutation; balancing selection

B. Gene flow; sexual dimorphism

C. Male competition; female choice

D. Mate choice; genetic drift

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Question 51 pts

Negative assortative mating results in an increased frequency ofhomozygous genotypes within a population.

True

False

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Question 61 pts

Genetic evidence suggests that humans and Neandertals neverinterbred.

True

False

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Question 71 pts

The specific variant of the FOXP2 gene associated with languageacquisition in humans is found in both humans and Neandertals.

True

False

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Question 81 pts

Industrial melanism describes the change in moth color from paleto dark after pollution from factories resulted in coating treetrunks with a layer of dark soot. Which statement is trueconcerning industrial melanism?

A. After pollution levels increased, all moths became darkercolored because soot got on their wings

B. The dark moths survived better after pollution levelsincreased because they were not poisoned by the pollutants

C. Individual moths changed their color in response to thepollution

D. Dark moths were present in the population before pollutionlevels increased

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Question 91 pts

Patterns of evolution can be seen above the species level

True

False

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Question 101 pts

Inbreeding is problematic because it increases the probabilitythat offspring inherit two copies of a recessive mutation thatcauses disease.