PCB 4674 - Evolutionary Biology Exam 3 Questions &
Answers | Grade A | 100% Correct – Florida State
University
1. According to Hamilton’s Rule, an altruistic behavior is evolutionarily stable if:
A. rB > C
B. rB < C
C. B > C
D. rC > B
Answer: A
Explanation: Hamilton’s Rule states that altruism is favored by natural selection when the
relatedness (r) multiplied by the benefit to the recipient (B) is greater than the cost to the
actor (C).
2. In a haplodiploid system, such as in bees, what is the coefficient of
relatedness (r) between full sisters?
A. 0.25
B. 0.75
C. 0.5
D. 1.0
Answer: B
Explanation: Because sisters share 100% of their father’s genes and 50% of their mother’s
genes, their average relatedness is (1.0 + 0.5) / 2 = 0.75.
,3. The ‘Greenbeard Effect’ refers to a mechanism where:
A. Alleles identify and favor other carriers of the same allele regardless of overall kinship.
B. Organisms favor relatives based solely on physical proximity.
C. Natural selection favors individuals with cryptic coloration.
D. Reciprocal altruism occurs between unrelated individuals.
Answer: A
Explanation: A greenbeard allele causes a phenotype, allows recognition of that phenotype
in others, and triggers preferential treatment toward them.
4. What is the primary difference between intersexual and intrasexual
selection?
A. Intersexual involves male-male competition; Intrasexual involves female choice.
B. Both terms refer to the same process of mate selection.
C. Intersexual occurs between different species; Intrasexual occurs within a species.
D. Intersexual involves female choice; Intrasexual involves male-male competition.
Answer: D
Explanation: Intersexual selection is ‘mate choice’ (usually females choosing males), while
intrasexual selection is ‘mate competition’ (usually males fighting for access to females).
5. Which hypothesis suggests that female preference for a male trait evolves
because the trait is linked to higher survival or fitness genes?
A. Sensory Bias Hypothesis
B. Good Genes Hypothesis
C. Fisherian Runaway Selection
D. Sexual Conflict Theory
Answer: B
Explanation: The Good Genes Hypothesis proposes that ornamental traits are honest
signals of a male’s genetic quality.
, 6. The ‘two-fold cost of sex’ primarily refers to:
A. The lower relatedness to offspring and the production of males who cannot produce offspring.
B. The energy required to find a mate and the risk of predation.
C. The risk of STDs and the energetic cost of meiosis.
D. The requirement of two parents and the loss of beneficial mutations.
Answer: A
Explanation: In sexual reproduction, only females produce offspring, and they only pass
on 50% of their genes, whereas asexuals produce 100% female offspring that carry all the
parent’s genes.
7. Muller’s Ratchet describes the process in asexual populations where:
A. Beneficial mutations accumulate rapidly.
B. Genetic diversity increases due to lack of competition.
C. Deleterious mutations accumulate and cannot be removed by recombination.
D. Population size increases until resources are exhausted.
Answer: C
Explanation: In asexual populations, the lack of recombination means that once a lineage
acquires a deleterious mutation, it cannot easily revert, leading to a ‘ratchet’ of increasing
mutation load.
8. Which life-history strategy is typical of a species living in a highly stable
environment with high competition?
A. Production of many small offspring.
B. Early maturation and high reproductive effort.
C. Short lifespan and rapid development.
D. Production of fewer, high-quality offspring.
Answer: D
Explanation: In stable, competitive (K-selected) environments, investing more resources
into fewer, larger, or better-developed offspring typically yields higher fitness.
Answers | Grade A | 100% Correct – Florida State
University
1. According to Hamilton’s Rule, an altruistic behavior is evolutionarily stable if:
A. rB > C
B. rB < C
C. B > C
D. rC > B
Answer: A
Explanation: Hamilton’s Rule states that altruism is favored by natural selection when the
relatedness (r) multiplied by the benefit to the recipient (B) is greater than the cost to the
actor (C).
2. In a haplodiploid system, such as in bees, what is the coefficient of
relatedness (r) between full sisters?
A. 0.25
B. 0.75
C. 0.5
D. 1.0
Answer: B
Explanation: Because sisters share 100% of their father’s genes and 50% of their mother’s
genes, their average relatedness is (1.0 + 0.5) / 2 = 0.75.
,3. The ‘Greenbeard Effect’ refers to a mechanism where:
A. Alleles identify and favor other carriers of the same allele regardless of overall kinship.
B. Organisms favor relatives based solely on physical proximity.
C. Natural selection favors individuals with cryptic coloration.
D. Reciprocal altruism occurs between unrelated individuals.
Answer: A
Explanation: A greenbeard allele causes a phenotype, allows recognition of that phenotype
in others, and triggers preferential treatment toward them.
4. What is the primary difference between intersexual and intrasexual
selection?
A. Intersexual involves male-male competition; Intrasexual involves female choice.
B. Both terms refer to the same process of mate selection.
C. Intersexual occurs between different species; Intrasexual occurs within a species.
D. Intersexual involves female choice; Intrasexual involves male-male competition.
Answer: D
Explanation: Intersexual selection is ‘mate choice’ (usually females choosing males), while
intrasexual selection is ‘mate competition’ (usually males fighting for access to females).
5. Which hypothesis suggests that female preference for a male trait evolves
because the trait is linked to higher survival or fitness genes?
A. Sensory Bias Hypothesis
B. Good Genes Hypothesis
C. Fisherian Runaway Selection
D. Sexual Conflict Theory
Answer: B
Explanation: The Good Genes Hypothesis proposes that ornamental traits are honest
signals of a male’s genetic quality.
, 6. The ‘two-fold cost of sex’ primarily refers to:
A. The lower relatedness to offspring and the production of males who cannot produce offspring.
B. The energy required to find a mate and the risk of predation.
C. The risk of STDs and the energetic cost of meiosis.
D. The requirement of two parents and the loss of beneficial mutations.
Answer: A
Explanation: In sexual reproduction, only females produce offspring, and they only pass
on 50% of their genes, whereas asexuals produce 100% female offspring that carry all the
parent’s genes.
7. Muller’s Ratchet describes the process in asexual populations where:
A. Beneficial mutations accumulate rapidly.
B. Genetic diversity increases due to lack of competition.
C. Deleterious mutations accumulate and cannot be removed by recombination.
D. Population size increases until resources are exhausted.
Answer: C
Explanation: In asexual populations, the lack of recombination means that once a lineage
acquires a deleterious mutation, it cannot easily revert, leading to a ‘ratchet’ of increasing
mutation load.
8. Which life-history strategy is typical of a species living in a highly stable
environment with high competition?
A. Production of many small offspring.
B. Early maturation and high reproductive effort.
C. Short lifespan and rapid development.
D. Production of fewer, high-quality offspring.
Answer: D
Explanation: In stable, competitive (K-selected) environments, investing more resources
into fewer, larger, or better-developed offspring typically yields higher fitness.
