BIOB51H3 Lecture Notes - Lecture 9: Genotype Frequency, Allele Frequency, Sickle-Cell Disease

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1 Mar 2016

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Biob51 lec 09 mutation and selection: mutation and evolution. Modern definition of evolution: changes in allele frequencies for a given trait in a population over time so, mutation is also a mechanism of evolution. Does mutation alone cause significant change in allele frequencies: mutation alone is not a potent evolutionary force because it is random and rare. Random because mutation is equally likely at every locus. Rare because mutation rate per locus is low: likelihood that many individuals produce gametes with the same mutation in any one generation = low, population genetics. Is there a way to monitor alleles in populations to predict whether evolution might occur: population: interbreeding group of organisms and their offspring. Population genetics: theory that allows us to track the fate of alleles and genotypes across generations. Mechanisms of evolution: processes that can lead to changes in allele frequency across generations.

Related Questions

Need help with evolution questions:

1.) A haplotype is best defined as the ________________.

	haploid genotypes of all the gametes produced by a diploid individual

ABO blood type conferred by an individual gamete

genotype of either the paternal or maternal chromosomal complement

multilocus genotype of a chromosome or gamete

2.) Which of the following statements regarding linkage disequilibrium is true?

Exists when D is less than zero, but not when it is greater than zero.

Is reduced by sexual reproduction.

Is increased by crossing-over during meiosis.

Is increased by any random sampling error that happens to create or destroy certain chromosome genotypes but not others.

Is reduced by selection that favors certain combinations of genotypes.

3.) Selection on multilocus genotypes in random-mating populations leads to linkage disequilibrium when _______________.

it reduces mutation rates

it eliminates all haplotypes from the population

it prevents crossing-over during meiosis

some allele combinations confer greater fitness than do others

4.) When two loci are in linkage equilibrium, the allele carried on a chromosome at one locus is independent of the allele carried on the chromosome at another locus. When this is the case, _________________.

allele frequencies will not change over time

the two loci (or, more specifically, their protein products) do not interact

the frequency of each haplotype can be calculated by multiplying the frequency of its two alleles

all possible haplotypes occur at equal frequency

5.) Which of the following accurately characterize(s) Muller's ratchet model for the selective advantage of sexual reproduction?

Drift establishes linkage disequilibrium because multilocus genotypes with few mutations are eliminated by chance events.

In populations without sexual reproduction, deleterious mutations accumulate, eventually imposing such a burden that the population goes extinct.

Sex is favored selectively because it recreates the zero-mutation genotypes lost due to drift.

All of the above correctly characterize Muller's ratchet model for the evolution of sexual reproduction.

6.) The genetic signature of recent positive selection on a locus is _______________.

high frequency and low linkage disequilibrium

low frequency and low linkage disequilibrium

low frequency and high linkage disequilibrium

high frequency and high linkage disequilibrium

7.) Sexual reproduction is advantageous both in changing environments and in constant environments, compared to asexual reproduction.

True

False

8.) Sexual reproduction causes genetic recombination via crossing-over, which combines genotypes from different parents.

True

False

9.) One reason sex may be maintained in natural populations is proposed by the "Red Queen Hypothesis", which states that.....

genotypes created by sex are created by natural selection over and over

recombination creating novel genotypes that can resist infection by parasites

mutation load is reduced by novel adaptive mutations

the ability of sex to fix multiple

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.

True

False

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Question 111 pts

As a species, cheetahs seem to have a high risk of extinctionbecause:

A. Gene flow has caused a proliferation of unnecessarygenes.

B. The species' genetic diversity is very low due to a previouspopulation bottleneck event.

C. The species has undergone extreme sexual selection in orderfor males to achieve faster running speeds.

D. Gene flow has been stifled due to an increase in demand forcaptive cheetahs.

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Question 121 pts

A strand of DNA undergoes mutation. Which mutation occurred?

Original DNA- GGA CTC TTA CCC CAC GGA

Mutated DNA- GGG CTC TTA CCC CAC GGA

A. point mutation

B. insertion mutation

C. deletion mutation

D. inversion mutation

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Question 131 pts

A change from one nucleotide to another nucleotide is known as awhat?

A. Point mutation

B. Insertion mutation

C. Deletion mutation

D. Inversion mutation

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Question 141 pts

A change from one nucleotide to another nucleotide is known as awhat?

A. point mutation

B. insertion mutation

C. deletion mutation

D. inversion mutation

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Question 151 pts

According to the Typological Species Concept, species are:

A. An interbreeding group of organisms

B. Static entities endowed with fixed properties

C. A local population of organisms that have similargenes, interbreed, and produce offspring

D. An exclusive community of gene exchange

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Question 161 pts

Recognizing reproductive isolation is key to defining speciesunder the Biological Species Concept.

True

False

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Question 171 pts

The binomial system of classification was developed by:

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Question 181 pts

A derived trait, unique to a particular taxon within a givencladogram is called:

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Question 191 pts

Analogy, and not homology, is useful for reconstructingevolutionary history.

True

False

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Question 201 pts

A phylogeny is which of the following:

A. A depiction of an organism's complete genome

B. A depiction of evolutionary relationships betweenorganisms

C. The gradual evolution of one species intoanother

D. The Latin name of an organism including its genus andspecies designation

coffeegoat763

Q1. What is the founder effect?

Sampling error that occurs during the establishment of a newpopulation by a small number of migrants.

Strong natural selection acting on the founders of a newpopulation because the environment they are now living in is sodifferent from the environment they came from.

A phenomenon named after William Founder, who observed that toppredators generally have low genetic diversity.

Rapid population growth following a bottleneck.

Q2. The effects of genetic drift are more pronounced in largerpopulations.

True

False

Q3. Inbreeding tends to increase the proportion of homozygousindividuals in a population (i.e. individuals that have two copiesof the same allele).

True

False

Q4. The effective size of a population is:

The size of an idealized randomly-mating population that is notunder selection and has the same heterozygosity as the actualpopulation.

The size of an idealized randomly-mating population that has thesame heterozygosity as the actual population, but does not loseheterozygosity over time.

The size of an idealized randomly-mating population losinghomozygosity at the same rate as the actual population.

The size of an idealized randomly-mating population losingheterozygosity at the same rate as the actual population.

Q5. Which of the following tends to reduce the effective size ofa population?

Check all that apply:

Increasing the population size.

A biased sex ratio.

Non-random mating.

Q6. If gametes from a gene pool combine randomly to make only asmall number of zygotes, the allele frequencies among the zygotesmay be different than they were in the gene pool because:

The effects of natural selection are more pronounced in smallpopulations.

The effects of genetic drift over several generations are morepronounced with small numbers of gametes.

The effects of differences in frequencies for different allelesare more pronounced with small numbers of zygotes.

The effects of sampling error are more pronounced with smallsamples.

Q7. Genetic drift is different from natural selectionbecause:

In natural selection allele frequencies change because somealleles confer higher fitness, whereas in genetic drift allelefrequencies change because of chance sampling error.

Natural selection acts primarily in large populations, whereasgenetic drift acts primarily in small ones.

Natural selection is a mechanism of evolution, whereas geneticdrift is an outcome of evolution.

Natural selection tends to cause rapid evolution, whereasgenetic drift tends to cause slow evolution.

Q8. Imagine a population evolving by genetic drift in which thefrequency of allele K is 0.65. What is the probability that at somepoint in the future allele K will drift to a frequency of 1?

Q9. A dwindling population of 1000 frogs occupies an isolatedwatershed in Costa Rica. To help preserve the species, scientistscaught 20 frogs to start a new population in a nearby watershed.This species has a gene that affects eye shape. The 1000-memberwild population has two alleles for this gene: R and r, withfrequencies 0.7 and 0.3, respectively. What will be the allelefrequencies of R and r in the 20-member founder population?

The frequencies will be 0.7 for R and 0.3 for r.

The frequencies will be 1.0 for R and 0 for r.

The expected frequencies are 0.7 for R and 0.3 for r. The actualfrequencies could be different.

The founder populations's allele frequencies will necessarily bedifferent than the source population's frequencies.

Q10. For a population containing 90 females and 10 males, whatis the effective population size, N_e ?

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BIOB51H3 Lecture Notes - Lecture 9: Genotype Frequency, Allele Frequency, Sickle-Cell Disease

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