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Evolution Exam 2
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Questions in this quiz (30)
1Which statement about natural selection is true?
- AIt is the same as evolution
- BIt always results in reduced genetic variation
- CIt can have an evolutionary effect only if phenotypic differences are heritable
- DIt acts directly on genotypes
- EChanges in allele frequencies can occur only because of natural selection
2Why did industrial melanism in the peppered moth, Biston betularia, help convince researchers that the intensity of natural selection can be very strong?
- AThe dark-colored morph drove the light-colored morph to extinction
- BBirds were unable to prey on moths once they acquired their color adaionsptat
- CThe moth population exploded, covering England with moths during the Industrial Revolution
- DThe dark-colored allele increased in frequency very rapidly in multiple populations and later decreased rapidly after the environment changed
- ENatural selection maintained constant proportions of the color alleles in the population, despite rapid environmental change brought about by the industrial revolution
3Which conditions are required for natural selection to occur?
- ATraits are heritable; offspring resemble parents
- BTraits are coded for by dominant genes
- CTraits are correlated with fitness
- DPopulations reproduce sexually
4Which of the following is the definition of fitness, according to evolutionary biology?
- AThe quality of being able to fulfill a particular role or task
- BThe fecundity of a genotype
- CThe condition of being physically fit and healthy
- DThe viability of a genotype
- EThe average, lifetime contribution of individuals with a particular genotype to a population
5A change in which variable would not necessarily change an organism's fitness?
- AMating success
- BFertilization success
- CFecundity
- DMutation rate
- EViability
6A population carries two alleles at a locus. One allele has a minuscule fitness advantage. What is the long-term fate of the locus if natural selection is the only important evolutionary force?
- AEventually the beneficial allele will be fixed by natural selection
- BBoth aleles will remain in the population at a ratio proportional to the fitness difference
- CThe population size will increase
- DThe population size will decrease
- EThe allele at a disadvantageous will mutate to improve to the fitness level of the ot
7In a scenario where a population is evolving only in response to natural selection, allele frequencies will change at a rate proportional to the selection coefficient and the...
- Asize of the population
- Bpopulation's growth rate
- Clevel of genetic variation at the locus
- Dmean fitness of the population
- Edegree of the allele's penetrance
8A new mutation in a population of birds appears. It gives individuals a slight advantage in spotting predators and a fitness advantage. If those that have the mutation have 0.5% greater fitness than those without, what is the probability that the mutation will spread and eventually become fixed?
- A0.5%
- B1%
- C2%
- D100%
9What will happen to DNA sequence variation in the regions of the genome immediately adjacent to an allele undergoing a selective sweep, or strong positive selection?
- ADecreased variation and high levels of linkage disequilibrium at nearby sites
- BIncreased variation and high levels of linkage disequilibrium at nearby sites
- CIncreased variation and the absence of linkage disequilibrium at nearby sites
- DDecreased variation and the absence of linkage disequilibrium at nearby sites
- ENo change in local genetic variation
10The colors of individuals in a snail population are determined by a single autosomal locus. A1A1 homozygotes are red, A1A2 heterozygotes are pink, and A2A2 homozygotes are white. Genotypic fitnesses are as follows: wA1A1 = 0.5; wA1A2 = 1.0; wA2A2 = 0.75. At equilibrium,
- Aboth alleles are equally frequent
- Bboth alleles are maintained in the population, and allele A1 is more common than allele A2
- Cthe population is fixed for allele A2 heterozygotes
- Dboth alleles are maintained in the population, and allele A2 is more common than allele A1
- EThe population contains only A1A2 heterozygotes
11If one genotype in a genetically variable population is favored in dry years and a different genotype is favored in wet years...
- Agenetic variation is not necessarily maintained
- Bgenetic drift will be a stronger force than selection
- Cgenetic variation is always maintained
- Drates of fixation are likely to speed up
- Ehard selection is likely to occur
12Human sex ratios are close to equal because if one sex becomes rare, it will be at a fitness advantage and an increase in frequency in the population until equilibrium at 50:50 is regained. This is an example of ...
- Aoverdominance, or heterozygote advantage
- Bnegative frequency-dependent selection
- Cpositive selection on sex ratio
- Dunderdominance, or heterozygote disadvantage
- Epositive frequency-dependent selection
13Populations of the grasshopper Vandiemenella viatica possess different chromosomal fusions and inversions. Grasshoppers that are heterozygous for different chromosomal rearrangements have reduced fitness. What would you expect to observe if you investigated the genotypes of grasshoppers in a recently merged population?
- ANew combinations of genes yielding genotypes of greater fitness
- BFew heterozygotes because of underdominance
- CFrequency-dependent selection, leading to fluctuations in fitness
- DHeterozygotes with greater fitness, owing to overdominance
- EA random assortment of genotypes because of genetic drift
14The end result of positive frequency-dependent selection for a population depends strongly on
- Athe sex ratio of the population
- Bthe initial frequencies of alleles in the population
- Cthe level of background selection
- Dunderdominance by heterozygotes
- Ethe height of the adaptive peak
15Sewall Wright's metaphor of an "adaptie landscape" that includes "peaks" and "valleys" is used widely in evolutionary biology. Natural selection will always move populations' mean fitness up the peaks. Which influence is most likely to cause a popultion to move away from a fitness peak towards a valley?
- APurifying selection
- BLarge population size
- COverdominant selection
- DPositive selection
- EGenetic drift
16Consider a deleterious recessive allele. If the mutation rate at this locus is 10-6, and the selection coefficient is 0.001, the equilibrium allele frequency will be
- A0
- B0.000001
- C0.00001
- D0.001
- E1
17Which scenario would be found in a tension zone of a cline?
- ANatural selection eliminates heterozygotes, preventing introgression dep into the other side of the cline
- BThere are differing selection pressures on either side of the cline
- CThere is strong gene flow, relative to the selection
- DSelection is weak but the cline is maintained by low dispersal rates
- ELocal adaptation has led to a very low FST between either end of the cline
18Imagine a widely distributed mammal species for which body size shows strong heritability and follows Bergmann's rule. Predict the outcome if efficient predators that live in warm regions preferentially attack large individuals.
- AEvolution of smaller body sizes across the entire range
- BEvolution of larger body sizes across the entire range
- CEvolution of a cline, with large-bodied individuals in the south and small bodied individuals in the north
- DEvolution of a cline, with large bodied individuals in the north and small bodied individuals in the south
- EExtinction of the mammal, as too many stresses cannot be handled at once
19What is most likely to increase rates of gene flow for a benthic (bottom dwelling) marine invertebrate?
- AIncreased lifespan of planktonic larvae
- BGreater maximum age reached by adults
- CStronger natural selection for camouflage color patterns
- DExpansion of territory size defended by breeding males
- EAn expansion in the breadth of diet
20A population of finches on an oceanic island varies at a particular gene locus. The current allele freuency is A1 = 40%, A2 = 60%, and there are 12,000 birds on the island. On the nearest continental mainland, the same species is monomorphic for allele A1. If 3,000 birds migrate from the mainland to the island, by how muc will the frequency of allele A1 change on the island?
- A0.08
- B0.12
- C0.15
- D0.45
- E0.48
21Which condition would result in the least evolution as a result of gene flow?
- AUnusually high migration variance
- BA great dispersal distance between birth and mating
- CIndividuals that are very successful at migrating to new populations, but cannot mate in the new locations
- DMigration rates that vary greatly from year to year
- EVery different allele frequencies in different subpopulations
22Which is the best explanation for what FST represents?
- AThe fraction of genetic variance in a group of populations that results from differences between them
- BA direct estimation of isolation-by-distance
- CThe variance of gene frequencies within a population compared to the variance of gene frequencies in another population
- DThe fraction of individuals in a population that arrives from another population that arrives from another population in each generation
- EThe average distance between the birthplaces of a parent and its offspring
23You observe a very narrow cline in the middle of a broadly distributed species' range. From this you could conclude that...
- Aselection is strong
- Bmigration variance is high
- Cmigration variance is low
24In which situation will gene swamping prevent local adaptation?
- ASelection is strong and migration is low
- BGene flow is high and the patch favoring the alternative allele is small
- CSelection and migration are both very high in magnitude
- DSelection and migration are both very low in magnitude
- EThe adaptive trait varies quantitatively and is controlled by several gene loci
25Populations of the Florida panther were reduced to very low levels in the second half of the twentieth century. In 1968 Alligator Alley, and extension of a major highway, divided the population into a northern and southern population), estimate the Ne of the population to be 75 individuals on either side of the highway, and measure an FST of 0.30, what can we conclude about the effect of the highway?
- AThe highway completely isolates the southern population, allowing no gene flow
- BThe highway is not a barrier to the cats at all, and the regions north and south of the highway act as a single, well-mixed population
- CThe highway only hinders migration a little bit and gene flow is maintained at a relatively high rate
- DThe highway severely blocks the southern population, allowing only a tiny amount of gene flow
- EThe environment has been divided into subregions too small to support large numbers of territorial cats
26Predict the FST of a population that has been split in two by a vicariance event that evely divided it into two populations of 2,500 individuals if the migration rate is 0.01%
- A0.00025
- B0.2
- C0.235
- D0.9615
- E4
27The product Ne m is equal to the
- Amigration variance
- Baverage distance between the birthplace of parent and offspring
- Cnumber of migrants that arrive in a population in a generation
- Dwidth of a cline when selection and gene flow work agains each other
- Echange in allele frequency in a population as a result of gene flow
28Which organism depends most on high rates of dispersal and migration for the survival of its population?
- AAn annual wildflower that colonizes disturbed patches
- BAn insect that depends on a very specific flower for nectar meals
- CA freshwater fish that lives in an ancient lake
- DAn island population of bats
- EA domesticated animal, like a cow or a sheep
29Which factor is least likely to limit dispersal to a new range of an organism whose environment is changing?
- AThe rea of suitable habitat has decreased outside of original range
- BImpassable barriers to movement exist
- COrgansim is physiologically incapable of surviving elsewhere
- DOrganism is a relatively poor disperser
- EOrganism has a generalist diet and can find food in many habitats
30Many North American animal species migrated to the south during Pleistocene ice ages and returned to the north during interglacial periods. These observations are consistent with
- Aexpanded physiological tolerance
- Bdistribution shift and habitat tracking
- Cmigration barriers
- Drange expansion by adaptation
- Edeclining habitat size
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- Quiz on Evolution Exam 2, created by Jo O'Bar on 21/10/2019.
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- Jo O'Bar
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