Week 4

All the alleles present in all individuals in a species are referred to as the _____ of that species. allele frequency gene pool genotype genotype frequency phenotype

Genetic variation has two sources-mutation and: non-random mating. recombination. natural selection. cell division. genetic drift.

What is the result of a mutation that occurs in somatic cells? The mutation will prevent all reproduction. The mutation may be expressed in the individual, but will not be passed along to its offspring. There will never be any visible effect. The mutation will be passed along to the organism's offspring. The mutation will be deleterious.

As a population geneticist, you find a species of snails with more genetic diversity than humans. What does this mean? There is not enough information provided to answer this question. The snails have more DNA than humans. The snails have more mutations occurring than humans. There is more variety in the gene pool of snails than humans. The snails have more genes on their chromosomes than humans.

Consider a population of killer whales. The gene pool of this population would only contain alleles harboring beneficial or neutral mutations, as deleterious mutations are efficiently eliminated from the gene pool of a species. False True

If a gene has two alleles, and allele A has a frequency of 83%, then allele a has a frequency of: 7%. 117%. 166%. 41.5%. 17%.

In a given population, all humans have the same blood type O. If no other alleles for blood type exist in this population, this population is "fixed" for the O allele. False True

Why can't we measure genetic variation in a population using observable traits (phenotypes)? (Select all that apply.) The environment can also affect the phenotype. Many traits are encoded by multiple genes. All traits are encoded by a single gene. Phenotypes are not determined by genes.

Traits favored by sexual selection are the same traits favored by natural selection. True False

The goldenrod gall fly lays its eggs on the terminal buds of goldenrod plants. Larvae chew through the buds and into the stems, where their saliva induces the plant to generate a gall, or outgrowth of tissue that then provides food and shelter for the developing larva. The larvae are prey to both parasitoid wasps and to birds; wasps selectively prey on larvae inside the smallest galls while birds selectively prey on larvae inside the largest galls. Goldenrod gall flies are therefore subject to _____ selection. stabilizing balancing disruptional heterozygote directional

Which of the following is an example of stabilizing selection? decrease in the number of birds with intermediate-sized beaks who are unable to eat large or small seeds breeding dogs from wolves antibiotic resistance in bacteria selection for average birth weight in humans

Prior to the publication of Darwin's On the Origin of Species, people thought what about species? Species changed over time because they were not adapted to their environment. Species evolved at one point, but no longer changed because they were not adapted to their environment. Species were designed already perfectly adapted to their environment. Species changed over time as guided by a divine creator.

Why is it thought that the majority of natural selection is stabilizing selection? Directional selection is more common because it increases adaptations to the environment. Most mutations are beneficial and produce intermediate phenotypes. Artificial selection is the most common, which is a type of stabilizing selection. Most mutations are deleterious and produce an extreme phenotype that is selected against. Mutations produce extreme phenotypes, which are selected for.

Malthus pointed out that populations have the potential to increase geometrically. What did this observation suggest that contributed to the idea of natural selection? Populations may grow faster than their resources. Populations may grow quickly, and then will evolve more quickly. Populations grow quickly, but predators grow more quickly. Populations may grow quickly and spread out over the planet. Populations may grow faster than other competing populations.

The intricate plumage of male birds of paradise has become increasingly elaborate throughout their evolution due to females mating preferentially with males that display the most impressive feathers. This is an example of _____ selection. stabilizing disruptive sexual artificial

Meerkats are small desert mammals that live in groups of 20-50 individuals. You observe one meerkat standing upright on a stump, looking around, while other meerkats forage for food. You hypothesize that this is an example of kin selection. What additional information would you need to know to evaluate your hypothesis? the degree of genetic relatedness of this meerkat to all members of the group the body size of this meerkat relative to other members of the group all other activities of this meerkat as well as those of all other members of the group the gender of this meerkat as well as that of all other members of the group the foraging success of this meerkat as well as that of all other members of the group

Group selection is not typically seen as an evolutionarily stable strategy because: it cannot explain behaviors for species with solitary individuals. None of the answer options is correct. selfish behaviors are more likely to increase individual fitness. average relatedness is very low between individuals in a population, therefore individual fitness cannot increase.

If B = the benefit of a behavior to a recipient, C = the cost of the behavior of the donor, and r = the degree of relatedness between the recipient and donor, then if rB > C, altruism can evolve. True False

What does the term 2pq represent in the Hardy-Weinberg relation? the frequency of homozygous dominant individuals the frequency of deleterious mutations the frequency of homozygous recessive individuals the frequency of heterozygotes

You are given the following information about a population: • There are two alleles: C and c. • C codes for green hair and c codes for white hair. • C is dominant over c. • The frequency of the c allele is 0.3. • The population is comprised of 100 individuals. Assuming the population is in Hardy-Weinberg equilibrium, how many individuals have green hair? 9% of the population will have green hair. 91% of the population will have green hair. 51% of the population will have green hair. 49% of the population will have green hair.

Which of the following is NOT a condition of the Hardy-Weinberg equilibrium? Mutations cannot occur in a population. Mating within a population must be random. Individuals of any genotype must have the same reproductive success as individuals of any other genotype. Individuals can migrate in and out of a population, as long as the population size remains constant. The size of a population must be large.

What term CORRECTLY describes change in allele frequency due to random effect of a small population? nonrandom mating mutation selection genetic drift immigration

If a population is not in Hardy-Weinberg equilibrium, we can conclude that: All of these choices are correct. evolution has occurred because one or more of the assumptions of the Hardy-Weinberg equilibrium has been violated. natural selection has occurred. one of the assumptions of the Hardy-Weinberg equilibrium has been violated. nonrandom mating has occurred.

You are researching a population of moles. In the course of your research, you identify a nearby population that occasionally comes into contact with your study population. What BEST describes the evolutionary process at work? genetic drift natural selection artificial selection gene flow mutation

Endangered species with very small populations are especially at risk of loss of genetic diversity due to: immigration. mutation. natural selection. genetic drift.

Migration reduces genetic differences between populations by allowing gene _____ between the two. repression drift flow augmentation deletion

Mutation increases genetic variation. False True

Why does genetic drift have more of an impact on the evolution of small populations than large ones? Sampling from generation to generation is more variable in small populations than large. Small populations are less affected by mutations. Small populations are more prone to migration. Small populations are affected more by stabilizing selection. Small populations have greater rates of mutation.

Imagine the following genotype frequencies in a population: p2 = 0.49, 2pq = 0.42, q2 = 0.09. Now assume that there is nonrandom mating where individuals with one genotype will only mate with individuals that also have their genotype. Assume this pattern of mating goes on until the frequency of heterozygotes is effectively zero. What will the frequency of allele p be in the population? 0.49 0.91 1.0 0.7 0.3

If two populations are thought to be diverging from one another, what would you expect to observe? an increase in similarity of alleles coding for proteins the same genotypes, but different phenotypes an accumulation of different mutations in different populations more shared mutations in different populations

A gene that no longer retains function is called: a pseudogene. a terminal gene. negatively selected. a gene with a stopped molecular clock. broken.

Two populations that have been separated from each other for a long period of time will have: small differences in phenotype but identical genotypes. limited differences between their genetic sequences. substantial differences between their genetic sequences. no similar genetic sequences. no differences between their genetic sequences.

The correlation between the time two species have been evolutionarily separated and the amount of genetic divergence between them is known as the: molecular clock. Modern Synthesis. natural selection. artificial selection. Hardy-Weinberg equilibrium.

Some proteins have a slower molecular clock due to _____ selection, which eliminates harmful alleles. disruptive negative positive beneficial neutral

Suppose that kin selection is acting upon a group of rodents. The average female typically has four offspring in her lifetime. If, instead of raising her own offspring, a female helps her sister raise her offspring (i.e. her own nieces and nephews). How many offspring would her sister have to have in order for her to experience no net loss in fitness? 8 10 4 12

Inbreeding depression is a serious concern in small populations of endangered organisms. Why is inbreeding depression a concern for such populations? Related individuals are more likely to mate with one another and this will increase the frequency of heterozyous genotypes. Related individuals will not mate with one another, and this increases the probability that two deleterious alleles will be present when unrelated individuals mate. Related individuals are more likely to mate with one another and this increases the probability that two deleterious alleles will be present in the offspring. Related individuals will not mate with one another, therefore population number will decline.

Imagine the following genotype frequencies in a population: p2 = 0.49, 2pq = 0.42, q2 = 0.09. Now assume that there is nonrandom mating where individuals with one genotype will only mate with individuals that also have their genotype. Assume this pattern of mating goes on until the frequency of heterozygotes is effectively zero. What will the frequency of allele p be in the population? 0.7 0.91 0.49 0.3 1.0

For reciprocal altruism to work, individuals must be able to: calculate the fitness value of individual interactions. recognize one another. remember previous interactions. recognize one another, remember previous interactions, and calculate the fitness value of individual interactions. recognize one another and remember previous interactions.

If a population is not in Hardy-Weinberg equilibrium, we can conclude that: nonrandom mating has occurred. All of these choices are correct. natural selection has occurred. evolution has occurred because one or more of the assumptions of the Hardy-Weinberg equilibrium has been violated.

In a population of Mendel's garden peas, the frequency of green-flowered plants (genotype aa) is 49%. The population is in Hardy-Weinberg equilibrium. What are the frequencies of the AA and Aa genotypes? 49% AA, 2% Aa 33% AA, 18% Aa 42% AA, 9% Aa 9% AA, 42% Aa The frequencies cannot be determined from the information provided.

In a population of Mendel's garden peas, the frequency of the dominant A (yellow flower) allele is 80%. Let p represent the frequency of the A allele and q represent the frequency of the a allele. Assuming that the population is in Hardy-Weinberg equilibrium, what are the genotype frequencies? 80% AA, 10% Aa, 10% aa 75% AA, 15% Aa, 10% aa 50% AA, 25% Aa, 25% aa 16% AA, 40% Aa, 44% aa 64% AA, 32% Aa, 4% aa

Imagine the following genotype frequencies in a population: p2 = 0.49, 2pq = 0.42, q2 = 0.09. Now assume that there is nonrandom mating where individuals with one genotype will only mate with individuals that also have their genotype. Assume this pattern of mating goes on until the frequency of heterozygotes is effectively zero. In addition, there is also inbreeding depression such that individuals with the genotype represented by p2 die before they can reproduce. What will be the frequency of allele q? 0.3 0.91 0.7 1.0 0.49

Imagine the following genotype frequencies in a population: p2 = 0.49, 2pq = 0.42, q2 = 0.09. Now assume that there is nonrandom mating where individuals with one genotype will only mate with individuals that also have their genotype. Assume this pattern of mating goes on until the frequency of heterozygotes is effectively zero. Is this population in Hardy-Weinberg equilibrium? Yes, because allele frequencies did not change. No, because there is nonrandom mating. No, because allele frequencies changed. Yes, because there is not inbreeding depression.

Evolution is both random and non-random

selective agent

Darwin's theory

3 modes of selection

Which mode(s) of selection will not necessarily change the mean trait value in a population?

Directional selection does not continue in the same direction indefinitely for two primary reasons:

Sexual dimorphism

sexual selection

Kin selection

fitness

sources of genetic variation

Balancing Selection

how do we know if a population is evolving?

Hardy Weinberg principle shows that evolution is not happening

Assortative Mating

genetic drift Drift tends to reduce genetic variation - the extent to which it does this is dependent upon population size (drift has a stronger effect on smaller populations), not on the existing amount of variation.

Hardy Weinberg Equilibrium

There are other mechanisms that can cause allele and genotype frequencies to change. These are :