Question 23What is the MOST LIKELY explanation for why there is variation in aging across different species?O The strength of selection is determined by agingO Trade-offs only apply to some speciesO Mutation accumulation theory applies to some species while antagonistic pleiotropy applies to othersO Different species suffer different levels of background (i.e., extrinsic) mortality

Aging is a continuous and an inavitable process it occurs in all the species throughout the world…

What is the MOST LIKELY explanation for why there is variation in aging across different species? The strength of selection is determined by aging O Trade-offs only apply to some species Mutation accumulation theory applies to some species while antagonistic pleiotropy applies to others Different species suffer different levels of background (i.e., extrinsic) mortality

What is the MOST LIKELY explanation for why there is variation in aging across different species? The strength of selection is determined by aging O Trade-offs only apply to some species Mutation accumulation theory applies to some species while antagonistic pleiotropy applies to others Different species suffer different levels of background (i.e., extrinsic) mortality

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter21: Microevolution: Genetic Changes Within Populations

Section: Chapter Questions

Problem 1TYK: The reason spontaneous mutations do not have an immediate effect on allele frequencies in a large...

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The original source of new alleles, upon which selection operates,is mutation, a random event that occurs without regard to selectionalvalue in the organism. Although many model organismshave been used to study mutational events in populations, someinvestigators have developed abiotic molecular models. Soll et al.(2006. Genetics 175:267–275) examined one such model to studythe relationship between both deleterious and advantageousmutations and population size in a ligase molecule composed ofRNA (a ribozyme). Soll found that the smaller the population ofmolecules, the more likely it was that not only deleterious mutationsbut also advantageous mutations would disappear. Whywould population size influence the survival of both types ofmutations (deleterious and advantageous) in populations?
n class we investigated the reason cystic fibrosis is maintained in the human population in higher frequency than we expected given the deleterious effects of being homozygous at the CFTR gene. We calculated the actual mutation rate of the CFTR gene to be 6.7 x 10-7. The mutation rate expected under mutation-selection balance was 4 x 10-4. What is the most plausible explanation as to why cystic fibrosis is maintained in the human population at a higher frequency than we expect? a. Negative selection against the CFTR deleterious alleles is too weak to eliminate the alleles from the human population. b. Positive selection for the CFTR deleterious alleles is likely occurring in response to some other selective pressure in the human population, possibly resistance to typhoid fever. c. The CFTR gene has an exceedingly low mutation rate causing humans to have no genetic variation at that gene. d. The CFTR gene has an exceedingly high mutation rate and that is…
The reason spontaneous mutations do not have an immediate effect on allele frequencies in a large population is that: a. mutations are random events, and mutations may be eitherbeneficial or harmful. b. mutations usually occur in males and have little effect oneggs. c. many mutations exert their effects after an organism hasstopped reproducing. d. mutations are so rare that mutated alleles are greatlyoutnumbered by nonmutated alleles. e. most mutations do not change the amino acid sequence of aprotein.
Three basic predictions underlie genetic drift in populations: (1) As long as the population size is finite,some level of genetic drift will occur; thus, withoutnew mutations, all variation will drift either to fixationor to loss. (2) Drift happens faster in small populationsthan in large populations. (3) The probability that anallele is fixed (goes to a frequency of 1.0) is equal toits initial frequency (p) in the population, while itsprobability of loss from the population due to drift isequal to 1 − p. Given these three predictions:a. What is the allele frequency of a new autosomalmutation immediately after it occurs in a diploidpopulation of size N = 100,000?b. What is the allele frequency of a new autosomalmutation immediately after it occurs in a diploidpopulation of size N = 10?c. In which population does the new mutation have ahigher probability of going to fixation by chancewith genetic drift?
Color blindness in humans is caused by an X-linked recessive allele. Ten percent of the males of a large andrandomly mating population are color-blind. A representative group of 1000 people from this population migrates to a South Pacific island, where there are already1000 inhabitants and where 30 percent of the males arecolor-blind. Assuming that Hardy–Weinberg equilibrium applies throughout (in the two original populationsbefore the migration and in the mixed population immediately after the migration), what fraction of malesand females can be expected to be color-blind in the generation immediately after the arrival of the migrants?
Most new mutations are detrimental, yet rare beneficial mutations canbe adaptive. With regard to the fate of new mutations, discuss whetheryou think it is more important for natural selection to select againstdetrimental alleles or to select in favor of beneficial ones. Which doyou think is more significant in human populations?
QUESTION 11 Which type of selection pressure is most likely to lead to the evolution of distinct species? O directional selection O disruptive selection O sensational selection O stabilizing selection Click Save and Submit to save and submit. Click Save All Answers to save all answers.
O Mutation-selection balance Suppose that one allele A₁ mutates to another allele A2 at some rate, μ. Suppose as well that A₁ is dominant over A2 such that A₁A1 and A₁A2 both have the same fitness, but that individuals that are homozygous recessive (A2A2) for the mutant allele A2 are less fit than the dominant genotype by some amount s, the selection coefficient. In this case, A2 mutant alleles come into the population at rate µ, and are removed from the population only when the show up in homozygous genotypes. The gory mathematical proof can be found in Box 7.8, which tells us that: O ■ Example: Suppose A₁ mutates to A2 at rate 0.005, but A₂A2 homozygous recessives are 50% less fit (s = 0.5) than either A₁A1 or A₁A2. What are the expected equilibrial abundances of A₁ and A2? μ = 0.005 S = 0.5 p* = 1-sqrt(µ/s) = 1-sqrt(0.005/0.5) = 0.9 = sqrt(µ/s) = sqrt(0.005/0.5) = 0.1 ● * p = = 1-sqrt(µ/s) q* = sqrt(μ/s) ● Question: Suppose A₁ mutates to A2 at rate 0.01, but A₂A2 homozygous…
Assuming that the mutation rate is µ/gamete/generation andthe population size is N diploid individuals, what is the numberof new mutations introduced into the population each generation?
QUESTION 3 Darwin's theory of natural selection explains: O The way life began. O The way evolution works at the genetic level. The way dinosaurs became extinct. O That traits within a breeding population that are adaptive to specific environmental circumstances become more numerous in that population over time.
When considering synonymous and nonsynonymous mutations within a population, which of the following is TRUE? O Nonsynonymous mutations will more often be removed by purifying selection The two types of mutations are not distinguished by purifying selection O Synonymous mutations will more often be removed by purifying selection Only synonymous mutations are retained by natural selection O Only nonsynonymous mutations are retained over the course of evolution
In a small group of people living in a remote area, there is a high incidence of "blue skin", a condition that results from a variation in the structure of hemoglobin. All of the "blue-skinned" residents can trace their ancestry to one couple, who were among the original settlers of this region. The unusually high frequency of "blue skin" in the area is an example of [ Select ] [Select] mutation natural selection sexual selection « Previous Next heterozygote advantage founder effect checkedat 9:39pm Subm