PCB4674 Exam 1: Principles of Evolution 2026 – FSU
1. Which individual is credited with developing the theory of evolution by
natural selection independently of Charles Darwin?
A. Jean-Baptiste Lamarck
B. Alfred Russel Wallace
C. Charles Lyell
D. Gregor Mendel
Answer: B
Rationale: Alfred Russel Wallace co-developed the theory of natural selection and
prompted Darwin to publish ‘On the Origin of Species’.
2. What is the primary mechanism of evolution that results in adaptation?
A. Genetic drift
B. Gene flow
C. Mutation
D. Natural selection
Answer: D
Rationale: Natural selection is the only evolutionary mechanism that consistently leads to
adaptive evolution by favoring traits that increase fitness.
3. In the context of phylogenetics, what is a ‘synapomorphy’?
A. A shared primitive character state
B. A shared derived character state
C. A character state unique to a single taxon
D. An analogous structure due to convergence
Answer: B
,Rationale: Synapomorphies are shared derived traits used to define clades and determine
evolutionary relationships.
4. Which of the following describes the ‘Biological Species Concept’?
A. Species are defined by their physical appearance
B. Species are defined by their ecological niche
C. Species are groups of interbreeding populations reproductively isolated from others
D. Species are the smallest monophyletic groups on a tree
Answer: C
Rationale: Ernst Mayr’s Biological Species Concept emphasizes reproductive isolation as
the key factor in defining species.
5. The bones in the wing of a bird and the arm of a human are examples of:
A. Analogous structures
B. Homologous structures
C. Vestigial structures
D. Homoplastic structures
Answer: B
Rationale: These structures are homologous because they are derived from a common
vertebrate ancestor, despite having different functions.
6. Which evolutionary force is most likely to reduce genetic differences between
two populations?
A. Gene flow
B. Natural selection
C. Genetic drift
D. Mutation
Answer: A
Rationale: Gene flow, the movement of alleles between populations, tends to homogenize
populations and reduce genetic divergence.
, 7. Hardy-Weinberg equilibrium assumes all of the following EXCEPT:
A. No mutation
B. Non-random mating
C. Infinite population size
D. No migration
Answer: B
Rationale: The Hardy-Weinberg principle assumes random mating; non-random mating
changes genotype frequencies.
8. What is the ‘founder effect’?
A. The movement of individuals into a new ecosystem
B. High mutation rates in pioneering species
C. Increased fitness in a new environment
D. Genetic drift that occurs when a small group establishes a new population
Answer: D
Rationale: The founder effect is a form of genetic drift occurring when a small subset of a
population colonizes a new area, often with reduced genetic diversity.
9. Which type of selection favors individuals at both extremes of a phenotypic
range?
A. Stabilizing selection
B. Disruptive selection
C. Directional selection
D. Negative frequency-dependent selection
Answer: B
Rationale: Disruptive selection favors the extremes over the intermediate phenotypes,
potentially leading to speciation.
1. Which individual is credited with developing the theory of evolution by
natural selection independently of Charles Darwin?
A. Jean-Baptiste Lamarck
B. Alfred Russel Wallace
C. Charles Lyell
D. Gregor Mendel
Answer: B
Rationale: Alfred Russel Wallace co-developed the theory of natural selection and
prompted Darwin to publish ‘On the Origin of Species’.
2. What is the primary mechanism of evolution that results in adaptation?
A. Genetic drift
B. Gene flow
C. Mutation
D. Natural selection
Answer: D
Rationale: Natural selection is the only evolutionary mechanism that consistently leads to
adaptive evolution by favoring traits that increase fitness.
3. In the context of phylogenetics, what is a ‘synapomorphy’?
A. A shared primitive character state
B. A shared derived character state
C. A character state unique to a single taxon
D. An analogous structure due to convergence
Answer: B
,Rationale: Synapomorphies are shared derived traits used to define clades and determine
evolutionary relationships.
4. Which of the following describes the ‘Biological Species Concept’?
A. Species are defined by their physical appearance
B. Species are defined by their ecological niche
C. Species are groups of interbreeding populations reproductively isolated from others
D. Species are the smallest monophyletic groups on a tree
Answer: C
Rationale: Ernst Mayr’s Biological Species Concept emphasizes reproductive isolation as
the key factor in defining species.
5. The bones in the wing of a bird and the arm of a human are examples of:
A. Analogous structures
B. Homologous structures
C. Vestigial structures
D. Homoplastic structures
Answer: B
Rationale: These structures are homologous because they are derived from a common
vertebrate ancestor, despite having different functions.
6. Which evolutionary force is most likely to reduce genetic differences between
two populations?
A. Gene flow
B. Natural selection
C. Genetic drift
D. Mutation
Answer: A
Rationale: Gene flow, the movement of alleles between populations, tends to homogenize
populations and reduce genetic divergence.
, 7. Hardy-Weinberg equilibrium assumes all of the following EXCEPT:
A. No mutation
B. Non-random mating
C. Infinite population size
D. No migration
Answer: B
Rationale: The Hardy-Weinberg principle assumes random mating; non-random mating
changes genotype frequencies.
8. What is the ‘founder effect’?
A. The movement of individuals into a new ecosystem
B. High mutation rates in pioneering species
C. Increased fitness in a new environment
D. Genetic drift that occurs when a small group establishes a new population
Answer: D
Rationale: The founder effect is a form of genetic drift occurring when a small subset of a
population colonizes a new area, often with reduced genetic diversity.
9. Which type of selection favors individuals at both extremes of a phenotypic
range?
A. Stabilizing selection
B. Disruptive selection
C. Directional selection
D. Negative frequency-dependent selection
Answer: B
Rationale: Disruptive selection favors the extremes over the intermediate phenotypes,
potentially leading to speciation.
