BIO 419 EVOLUTIONARY BIOLOGY
FINAL EXAM
Natural Selection Population Genetics Phylogenetics Speciation
Macroevolution and Molecular Evolution Questions and Answers
Verified Solutions 2026 2027
1. Which evolutionary mechanism is the sole source of novel genetic variation upon
which natural selection can act?
A. Genetic drift
B. Mutation
C. Gene flow
D. Non-random mating
Rationale: Mutation is the ultimate source of all original genetic novelty. Recombination reshuffles existing
alleles, but only mutation generates brand-new DNA sequences.
2. What type of natural selection favors individuals at one extreme of a phenotypic
distribution, shifting the population mean over time?
A. Directional selection
B. Stabilizing selection
C. Disruptive selection
D. Balancing selection
Rationale: Directional selection acts against one phenotypic extreme, driving the population mean toward
the favored extreme phenotype (e.g., antibiotic resistance development).
3. What mode of speciation occurs when a physical geographic barrier splits a single
population into isolated sub-populations that diverge over time?
A. Sympatric speciation
B. Allopatric speciation
C. Parapatric speciation
D. Peripatric speciation
, Rationale: Allopatric speciation relies on physical geographic barriers (like mountain ranges or rivers) that
block gene flow, allowing isolated gene pools to diverge through selection and drift.
4. What concept defines a species as a group of actually or potentially interbreeding
natural populations that are reproductively isolated from other such groups?
A. Biological Species Concept (Mayr)
B. Phylogenetic Species Concept
C. Morphological Species Concept
D. Ecological Species Concept
Rationale: Ernst Mayr's Biological Species Concept centers on reproductive isolation; individuals belong
to the same species if they interbreed and produce fertile offspring under natural conditions.
5. What evolutionary term describes independent evolution of similar structural or
functional features in distantly related lineages facing similar environmental pressures?
A. Homology
B. Convergent Evolution (Analogy)
C. Adaptive Radiation
D. Coevolution
Rationale: Convergent evolution produces analogous traits (e.g., wings in birds and bats, streamlined
bodies in sharks and dolphins) in unrelated lineages adapting to similar ecological niches.
6. In a phylogenetic tree, what term describes a grouping that includes an ancestral
species and ALL of its descendants?
A. Monophyletic group (Clade)
B. Paraphyletic group
C. Polyphyletic group
D. Outgroup
Rationale: A monophyletic group (or clade) contains a common ancestor and every descendant lineage
branching from that node. Paraphyletic groups omit some descendants.
7. What evolutionary principle states that the simplest phylogenetic tree requiring the
fewest evolutionary transitions (character changes) should be chosen first?
FINAL EXAM
Natural Selection Population Genetics Phylogenetics Speciation
Macroevolution and Molecular Evolution Questions and Answers
Verified Solutions 2026 2027
1. Which evolutionary mechanism is the sole source of novel genetic variation upon
which natural selection can act?
A. Genetic drift
B. Mutation
C. Gene flow
D. Non-random mating
Rationale: Mutation is the ultimate source of all original genetic novelty. Recombination reshuffles existing
alleles, but only mutation generates brand-new DNA sequences.
2. What type of natural selection favors individuals at one extreme of a phenotypic
distribution, shifting the population mean over time?
A. Directional selection
B. Stabilizing selection
C. Disruptive selection
D. Balancing selection
Rationale: Directional selection acts against one phenotypic extreme, driving the population mean toward
the favored extreme phenotype (e.g., antibiotic resistance development).
3. What mode of speciation occurs when a physical geographic barrier splits a single
population into isolated sub-populations that diverge over time?
A. Sympatric speciation
B. Allopatric speciation
C. Parapatric speciation
D. Peripatric speciation
, Rationale: Allopatric speciation relies on physical geographic barriers (like mountain ranges or rivers) that
block gene flow, allowing isolated gene pools to diverge through selection and drift.
4. What concept defines a species as a group of actually or potentially interbreeding
natural populations that are reproductively isolated from other such groups?
A. Biological Species Concept (Mayr)
B. Phylogenetic Species Concept
C. Morphological Species Concept
D. Ecological Species Concept
Rationale: Ernst Mayr's Biological Species Concept centers on reproductive isolation; individuals belong
to the same species if they interbreed and produce fertile offspring under natural conditions.
5. What evolutionary term describes independent evolution of similar structural or
functional features in distantly related lineages facing similar environmental pressures?
A. Homology
B. Convergent Evolution (Analogy)
C. Adaptive Radiation
D. Coevolution
Rationale: Convergent evolution produces analogous traits (e.g., wings in birds and bats, streamlined
bodies in sharks and dolphins) in unrelated lineages adapting to similar ecological niches.
6. In a phylogenetic tree, what term describes a grouping that includes an ancestral
species and ALL of its descendants?
A. Monophyletic group (Clade)
B. Paraphyletic group
C. Polyphyletic group
D. Outgroup
Rationale: A monophyletic group (or clade) contains a common ancestor and every descendant lineage
branching from that node. Paraphyletic groups omit some descendants.
7. What evolutionary principle states that the simplest phylogenetic tree requiring the
fewest evolutionary transitions (character changes) should be chosen first?
