BIOL 123 Lecture Notes - Lecture 7: Genotype Frequency, Genetic Diversity, Genetic Drift

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harlequinmink794

19 Nov 2020

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Fitness is only related to the concept of passing genes - not about survival or a specific goal being reached. I. e not all will survive -- main key is the. Reproductive success of an individual with a particular phenotype. we are not looking at survival at all - just the passing on of the genes. Phenotypic variation among organisms influences the relative probability of survival and reproduction. Population geneticists sample individuals for their genotype at a locus and compare the fitness of individuals with one genotype (i. e. , the average fitness) with the fitness of individuals with other genotypes. Within larger populations; change occurs over a long period of time - there is less random fixation of the alleles. Alleles are all being fixed at constant rates over large periods of time - change is not random; beneficial allele seems to be fixing over the period of time.

Related Questions

1) Which of these probabilities are NOT independent of eachother?

The probability that a student is a sophomore and has brownhair

The probability that when you roll two dice, you will roll a 6before a 2

The probability that it will rain and the probability ofneeding an umbrella

The probability that there will be heavy traffic on BaltimoreAve and the probability you will lose your cell phone

2) We are defining evolution as a "change in allele frequenciesover time". Ironically, the focus of this lab is the Hardy-Weinbergequilibrium - conditions that, if all met, will result in NOevolution occurring. Which of the following are among theconditions that must be met for the Hardy-Weinberg equilibrium toapply perfectly to a population?

A. The population must be very large

B. Individuals must mate at random

C. The alleles must differ in their effects on survival

D. There must be free migration into and out of thepopulation

A & B

A, B, & C

3)In cats, black fur is dominant over any allele for brown fur.If a homozygous dominant cat makes kittens with a heterozygous cat,what is the probability that the first kitten will have brown fur?Report as a proportion, not percentage, e.g., .1, NOT 10%.

The EGLN1 gene helps regulate body oxygen levels. One allele His dominant over h, and helps increase fitness at high altitude(where oxygen is low). In a study of families in Tibet, researchersfound 422 HH individuals, 377 Hh, and 201 hh individuals. The studyshowed that infant mortality was lower in Hh individuals than hh,and lowest in HH individuals.
Is the Tibetan population in Hardy Weinberg Equilibrium at this H/hgene?

What is the most important factor affecting the strength ofgenetic drift?

The frequency of the rarest genotype

The size of the population

The allele frequencies

The genetic diversity in the population

aquamarinerat250

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

Question:

Question 1: What is NOT a force of evolution?

Mutation of genes

Genetic drift

Equilibrium of populations

Migration of populations

Question 2:

Crossing true breeding dark-coated sheep with true breedinglight-coated sheep always results in 100% dark-coated offspring.You are screening a population of 300 Soay sheep for coat color,and you count 243 dark sheep and 57 light sheep. What is thegenotype frequency of the homozygous recessive sheep forTYRP1 gene if the population is in Hardy-Weinbergequilibrium?

.421

0..176

0.864

0.190

Question 3:

In the same population, if it is under Hardy-Weinbergequilibrium, how many individuals do you expect to be heterozygousat TYRP1?

217

0.492

148

124

Question 4:

Rabbit's ears can be either short (dominant) or floppy(recessive). If a population of rabbits in Hardy-Weinbergequilibrium has 250 short eared rabbits and 100 floppy earedrabbits, what is the allele frequency of the "short" allele?

.465

0.714

0.845

0.535

Question 5:

To calculate degrees of freedom, we use the following formula:Degrees of freedom - the number of constraints imposed on yourcomparison. How many constraints are there when we use theChi-square test for Hardy Weinberg equilibrium?

Question 6:

You perform a Chi-square test for gene X and find thep-value to be greater than 0.05. What can you say with 95%certainty about this population?

This population is in Hardy-Weinberg equilibrium at theX locus: gene X isinfluenced by at least oneforce of evolution.

This population is in Hardy-Weinberg equilibrium at theX locus: gene X is notinfluenced by any forces ofevolution.

This population is not in Hardy-Weinberg equilibrium at theX locus: gene X isinfluenced by at least oneforce of evolution.

This population is not in Hardy-Weinberg equilibrium at theX locus: gene X is notinfluenced by any forces ofevolution.

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BIOL 123 Lecture Notes - Lecture 7: Genotype Frequency, Genetic Diversity, Genetic Drift

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