Biology 1201A Lecture Notes - Pleistocene, Multimodal Distribution, Heliconius

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pucemammoth997

24 Dec 2011

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Within individuals: proportion of heterozygous loci within an individual. Within populations: number of polymorphic loci in the gene pool of a population. Between populations: degree of difference in alleles, and/or allele frequencies between two or more populations. Upsetting the equilibrium: mutation spontaneous and heritable change in dna: rare, random errors, usually harmful or neutral slow mechanism of evolution, if alone the ultimate source of genetic variation. The paradox of genetic variation: any allele could be beneficial or detrimental, selection should reduce genetic variation by fixation genetic variation should be temporary, actually lots of genetic variation, including balanced polymorphisms". Differential survival and reproduction of individuals in a population due to current environmental influences. Modes of selection 1: directional y c n e u q e r f time x1 x1 phenotype x2: fitness increases with phenotype value, average phenotype changes over time, variance reduced or unchanged.

Related Questions

1. Humans and chimpanzees share several polymorphic loci. Which is the LEAST plausible explanation for this fact?

A. Balancing selection has maintained polymorphism in both species

B. Incomplete lineage sorting left polymorphic loci and those have persisted since the speciation event.

C. Interbreeding has allowed introgression of alleles at theses loci in both directions.

D. Genetic variation provided by the polymorphic alleles enhances resistance to pathogens.

2. According to the social brain hypothesis, we should expect primates living in larger social groups to have:

A. Larger brains, specifically, a neocortex of relatively larger size

B. Lager incisors and canines, to defend against more social competitors

C. Smaller brains, because many individuals can work together to solve problems

D. Great variation in brain and neocortex size, with the dominant individuals having the largest

3. You extract DNA from human bones in an ancient village buried by volcanic ash. You discover that there is an extremely high frequency of the LCT allele for lactase persistence. What might you reasonably conclude about the population?

A. This population is likely the source of the high frequency of the LCT gene in Northern Europe

B. The village could not be more than 4,500 years old

C. The members of this population likely used domesticated livestock for their milk

D. villagers had a diet rich in wheat or another domesticated crop

4. Why do populations father from Africa have more deleterious mutations in their genome?

A. Repeated bottlenecks and founder effects made drift more intense more often

B. Populations farther from Africa have been exposed to more mutagens in the environment

C. As people migrated over the globe they interbred with Neanderthals and Denisovans

D. The populations are younger, so purifying selection has not had time to purge delirious mutations from the populations.

yelloweel732

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

1. If an individual has a genotype of Bb, what types of gametes (sperm/egg) could they produce?
A) B
B) b
C) B or b
D) Bb, BB, bb
E) Bb

2. Which of the following statements is true about phenotypic plasticity, i.e., phenotype variation that is the result of genotype by environment interactions?
A. Phenotypic plasticity is only favored when the parental environment is a good predictor of the offspring environment
B. Since the trait expression of a genotype varies across environments, it cannot respond to selection
C. A variable environment is required for phenotypic plasticity to be selected for
D. A single trait can only ever be plastic or non-plastic within a species
E. Phenotypic plasticity can only occur within a single generation, never across generations

3. With large numbers of genes contributing to variation for a phenotypic trait (e.g. height in humans), the population approaches what kind of distribution for that trait?
A. Mendelian
B. Exponential
C. Binomial
D. Normal
E. Continuous

4. A classic example of phenotypic plasticity is caste determination in social insects. Whether a female ant becomes a worker, soldier, or queen is determined by the food she is fed. Would you say this this an example of G, E, or GxE?

5. In an infinite population, the frequency of the A allele is 0.3 and the frequency of the a allele is 0.7. What is the frequency of heterozygotes?
A. .10
B. .21
C. .30
D. .42
E. .70

6. Blue eyes are a recessive trait caused by an autosomal allele. If there are 180 people with blue eyes in a population of 500 people, what is the frequency of the brown-eye allele? (Assume HWE)
A. .36
B. .40
C. .50
D. .60
E. .64

7. Imagine flower color in diploid roses is determined by a single gene with two alleles, white and red, which are co-dominant so that heterozygotes are pink. Frank is colorblind and can only discriminate between white and colored roses, and knows that his population has 18 white roses and 182 non-white roses. How many of Frankâs roses are pink? (Assume HWE.)
A. 18
B. 21
C. 42
D. 84
âE. 100

8. Imagine flower color in diploid roses is determined by a single gene with two alleles, white and red, which are co-dominant. If Eva's population has 250 white roses, 500 pink roses, and 250 red roses, what is true about this population?

A. It is not in Hardy-Weinberg equilibrium
B. It is under balancing selection
C. It is connected to another population by migration
D. It is in Hardy-Weinberg equilibrium
ââE. White is a recessive lethal

9. 9% of a population is unable to taste the compound PTC, which is a recessive trait. Assuming HWE, if two carriers of the non-tasting allele had a baby what is the probability that it would be unable to taste PTC?
A. 0.09
B. 0.25
C. 0.30
D. 0.50
E. 0.70

10. (Adapted from: Christensen, A. C. (2000). Cats as an aid to teaching genetics. Genetics, 155(3), 999-1004.) ss cats have no white fur, Ss cats generally have <50% white fur, and SS cats generally have >50% white fur (cats who are 100% white are scored as dominant white and can't be scored for piebald spotting). The S allele is incompletely dominant, but variably expressed, so there is a more-or-less continuous gradient of white pigmentation in populations. You and your friends score all non-white cats up for adoption: http://www.adoptapet.com/cat-adoption/search/50/miles/48824 and find there are 160 with >50% white fur, 350 with <50% white fur, and 490 with no white fur. Which of the following statements is definitely true:

A. The population is in Hardy-Weinberg equilibrium
B. The population is not in Hardy-Weinberg equilibrium
C. There is selection acting on the population
D. It is impossible to know if the population is in Hardy-Weinberg equilibrium
E. Fur color is not a heritable trait and therefore cannot evolve

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Biology 1201A Lecture Notes - Pleistocene, Multimodal Distribution, Heliconius

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