Question 1

Changing environmental conditions would most likely cause an existing species to undergo ____.
A) disruptive selection
B) deleterious mutation
C) directional selection
D) stabilizing selection
E) lethal mutation

Accepted Answer

Changing environmental conditions often lead to directional selection, where one extreme of a trait becomes more advantageous, causing the species to evolve in that direction.

Question 2

The success of camouflage from predatory birds drives the predominant phenotypes in snail color. This is an example of ____.
A) predation as an agent of natural selection
B) sexual selection
C) predation as an agent of artificial selection
D) the founder effect
E) a selectively neutral phenotype

Accepted Answer

Predation acts as a selective pressure in natural environments, influencing the survival and reproduction of prey species based on their traits, such as coloration in snails. This process exemplifies natural selection, where predators (birds) indirectly "select" for snail phenotypes that are better camouflaged and thus have higher survival rates.

Question 3

Individuals with one sickle cell allele and one normal hemoglobin allele are not affected by the malaria parasite because of ____.
A) neutral mutations
B) heterozygote advantage
C) frequency-dependent selection
D) disruptive selection
E) stabilizing selection

Accepted Answer

Heterozygote advantage explains why individuals with one sickle cell allele and one normal hemoglobin allele have a resistance to malaria. This genetic makeup provides a survival advantage in regions where malaria is prevalent, as these individuals are less likely to suffer from the severe effects of either sickle cell disease or malaria.

Question 4

Genetic drift is most likely to lead to ____.
A) artificial selection
B) mutation
C) the founder effect
D) gene flow
E) adaptation

Accepted Answer

Genetic drift is a mechanism of evolution that refers to random changes in the frequency of alleles (variants of a gene) within a population. The founder effect is a specific type of genetic drift that occurs when a new population is established by a very small number of individuals from a larger population. This small group may not have the same genetic diversity as the original population, leading to a significant shift in allele frequencies purely by chance.

Question 5

Inbreeding is primarily due to ____.
A) gene flow
B) nonrandom mating
C) neutral mutations
D) natural selection
E) adaptive radiation

Accepted Answer

Inbreeding is primarily due to nonrandom mating, where individuals mate with relatives more often than would occur by chance, leading to an increase in homozygosity and potential expression of deleterious alleles.

Question 6

Genetic drift will have a progressively larger impact on allele frequencies in a population as ____.
A) gene flow increases
B) population size decreases
C) mutation rate decreases
D) population size increases
E) random mating increases

Accepted Answer

Genetic drift has a larger impact on smaller populations because random changes in allele frequencies are more likely to have a significant effect when the number of individuals is limited. In larger populations, these random changes are less likely to significantly alter allele frequencies due to the law of large numbers.

Question 7

Research by Malte Andersson suggests the long tail feathers of male African widowbirds are a product of ____ selection because females are more strongly attracted to males with long tails than to males with short tails.
A) disruptive
B) intersexual
C) intrasexual
D) artificial
E) stabilizing

Accepted Answer

Intersexual selection occurs when members of one sex (usually females) choose mates based on certain traits, such as long tail feathers in male African widowbirds, which are considered attractive.

Question 8

Sometimes the most abundant color form of an animal is preyed upon more extensively than less common forms. This illustrates the phenomenon of ____ selection.
A) stabilizing
B) directional
C) disruptive
D) frequency-dependent
E) artificial

Accepted Answer

This phenomenon is known as frequency-dependent selection, where the fitness of a phenotype depends on its frequency relative to other phenotypes in a given population. In this case, the more common a color form is, the more likely it is to be preyed upon, illustrating negative frequency-dependent selection.

Question 9

When a few individuals colonize a distant locality and start a new population, the allele frequencies of the gene pool may be different than those in the original population. This is known as ____.
A) the founder effect
B) a population bottleneck
C) genetic equilibrium
D) the Hardy-Weinberg principle
E) natural selection

Accepted Answer

The founder effect occurs when a new population is established by a very small number of individuals from a larger population. This can lead to significant differences in the allele frequencies between the new population and the original population, due to the random nature of which alleles the founding individuals carry.

Question 10

When male moose engage in their annual battles, butting heads with their oversized antlers, they are exhibiting ____ selection.
A) stabilizing
B) disruptive
C) directional
D) intrasexual
E) intersexual

Accepted Answer

Intrasexual selection refers to competition among members of the same sex (in this case, males) for mating opportunities. The battles between male moose are a form of this competition, where physical contests determine access to females.

Question 11

Natural selection exerts little or no effect on traits that appear during an individual's ____.
A) preadolescent years
B) embryonic development
C) juvenile phase
D) postreproductive life
E) reproductive life

Accepted Answer

Natural selection has little or no effect on traits that appear during an individual's postreproductive life because these traits do not affect the individual's ability to reproduce and pass on genes to the next generation.

Question 12

Natural selection results most directly in ____.
A) adaptation
B) mutations
C) new species
D) genetic drift
E) gene flow

Accepted Answer

Natural selection leads to adaptation by favoring individuals with traits that are advantageous in a given environment, thereby increasing the frequency of those traits in the population over time.

Question 13

With frequency-dependent selection, highest mortality can be expected in ____.
A) the most abundant genotype
B) the least abundant genotype
C) the least well-adapted genotype
D) heterozygous genotypes
E) homozygous recessive genotypes

Accepted Answer

Frequency-dependent selection often leads to the most abundant genotype experiencing the highest mortality because predators, parasites, or diseases can more easily target or adapt to the most common forms, reducing their advantage over time.

Question 14

Andrew P. Hendry and colleagues discovered that Galápagos ground finches with small bills and ground finches with large bills were more common and had higher fitness than birds with bills of intermediate size, a demonstration of ____ selection.
A) disruptive
B) directional
C) stabilizing
D) sexual
E) artificial

Accepted Answer

Disruptive selection is demonstrated when individuals at the two extremes of a trait distribution have higher fitness than individuals with intermediate traits, as seen in the case of the Galápagos ground finches with either small or large bills.

Question 15

Snow geese usually select mates of their own color, an example of ____.
A) genetic drift
B) founder effects
C) population bottlenecks
D) nonrandom mating
E) random mating

Accepted Answer

Snow geese choosing mates based on color is an example of nonrandom mating, where mate selection is influenced by phenotypic preferences rather than occurring by chance.

Question 16

The stable presence of two or more phenotypes in a population is called a ____.
A) balanced polymorphism
B) mixed gene pool
C) mutation pressure
D) population bottleneck
E) competitive advantage

Accepted Answer

Balanced polymorphism refers to the stable presence of two or more phenotypes within a population, where genetic diversity is maintained through natural selection or other processes.

Question 17

Genetic variations that confer no apparent selective advantage or disadvantage in a particular environment are said to be selectively ____.
A) random
B) deleterious
C) neutral
D) benign
E) stabilizing

Accepted Answer

Genetic variations that confer no apparent selective advantage or disadvantage are described as selectively neutral. These variations do not affect an organism's fitness and therefore are not influenced by natural selection.

Question 18

In many species, sexual selection is the most probable cause of ____, differences in the size or appearance of males and females.
A) adaptive radiation
B) inbreeding
C) mutation
D) polymorphism
E) sexual dimorphism

Accepted Answer

Sexual dimorphism refers to differences in size or appearance between males and females of the same species, often resulting from sexual selection.

Question 19

Very small and very large human newborns are less likely to survive than those born at an intermediate weight due to ____.
A) sexual selection
B) artificial selection
C) disruptive selection
D) directional selection
E) stabilizing selection

Accepted Answer

This is an example of stabilizing selection, where individuals with intermediate traits (in this case, weight) have higher survival and reproductive success compared to those with extreme traits. This selection pressure tends to reduce variation in the population and keeps the trait values around an optimal intermediate range.

Question 20

Disadvantageous recessive alleles are protected from natural selection due to ____.
A) homozygosity
B) diploidy
C) genetic drift
D) haploidy
E) adaptation

Accepted Answer

Diploidy protects disadvantageous recessive alleles from natural selection because these alleles can be carried in a heterozygous state without affecting the phenotype of the organism. This means that individuals can carry and potentially pass on these alleles without them being exposed to selection pressures.

Quiz 21: Microevolution: Genetic Changes Within Populations

Changing environmental conditions would most likely cause an existing species to undergo ____.

The success of camouflage from predatory birds drives the predominant phenotypes in snail color. This is an example of ____.

Individuals with one sickle cell allele and one normal hemoglobin allele are not affected by the malaria parasite because of ____.

Genetic drift is most likely to lead to ____.

Inbreeding is primarily due to ____.

Genetic drift will have a progressively larger impact on allele frequencies in a population as ____.

Research by Malte Andersson suggests the long tail feathers of male African widowbirds are a product of ____ selection because females are more strongly attracted to males with long tails than to males with short tails.

Sometimes the most abundant color form of an animal is preyed upon more extensively than less common forms. This illustrates the phenomenon of ____ selection.

When a few individuals colonize a distant locality and start a new population, the allele frequencies of the gene pool may be different than those in the original population. This is known as ____.

When male moose engage in their annual battles, butting heads with their oversized antlers, they are exhibiting ____ selection.

Natural selection exerts little or no effect on traits that appear during an individual's ____.

Natural selection results most directly in ____.

With frequency-dependent selection, highest mortality can be expected in ____.

Andrew P. Hendry and colleagues discovered that Galápagos ground finches with small bills and ground finches with large bills were more common and had higher fitness than birds with bills of intermediate size, a demonstration of ____ selection.

Snow geese usually select mates of their own color, an example of ____.

The stable presence of two or more phenotypes in a population is called a ____.

Genetic variations that confer no apparent selective advantage or disadvantage in a particular environment are said to be selectively ____.

In many species, sexual selection is the most probable cause of ____, differences in the size or appearance of males and females.

Very small and very large human newborns are less likely to survive than those born at an intermediate weight due to ____.

Disadvantageous recessive alleles are protected from natural selection due to ____.