Q: In a population of lizards, the frequency of allele G is 0.6 and the frequency of allele g is 0.4. According to the Hardy–Weinberg equation, what is the expected frequency of heterozygotes (Gg)? $$2pq$$

$$2 \times 0.6 \times 0.4 = 0.48$$

Q: A population of beetles has the following genotype counts: 40 AA, 40 Aa, and 20 aa. What is the frequency of allele A? $$\text{Frequency of A} = \frac{2 \times \text{AA} + \text{Aa}}{2 \times \text{Total individuals}}$$

$$\frac{2 \times 40 + 40}{2 \times 100} = 0.6$$

Question 1

Which of the following is NOT an assumption of the Hardy–Weinberg principle?

Accepted Answer

Gene flow occurs freely between populations.

Question 2

In a population of lizards, the frequency of allele G is 0.6 and the frequency of allele g is 0.4. According to the Hardy–Weinberg equation, what is the expected frequency of heterozygotes (Gg)?

$$2pq$$

Accepted Answer

$$2 	imes 0.6 	imes 0.4 = 0.48$$

Question 3

A scientist observes the following genotype frequencies in a rabbit population: GG = 0.25, Gg = 0.50, gg = 0.25. What are the allele frequencies of G and g?

Accepted Answer

G: 0.5, g: 0.5

Question 4

Which scenario best illustrates allopatric speciation?

Accepted Answer

A river forms and splits a population of mice into two groups, which then evolve independently.

Question 5

Which of the following is a postzygotic reproductive barrier according to the biological species concept?

Accepted Answer

Hybrid offspring are sterile and cannot reproduce.

Question 6

A population of 1000 frogs has genotype frequencies: AA = 0.36, Aa = 0.48, aa = 0.16. Is this population in Hardy–Weinberg equilibrium?

Accepted Answer

Yes, because $$p^2 + 2pq$$ + $$q^2 = 1$ and the observed frequencies match the expected.

Question 7

Which of the following best describes a monophyletic group on a phylogenetic tree?

Accepted Answer

A group consisting of an ancestral population and all its descendants.

Question 8

Which event is an example of sympatric speciation caused by an intrinsic factor?

Accepted Answer

A chromosomal doubling event in wheat leading to a new fertile species.

Question 9

Which of the following is a disadvantage of the morphological species concept?

Accepted Answer

It cannot identify cryptic species that differ in non-morphological traits.

Question 10

A population of beetles has the following genotype counts: 40 AA, 40 Aa, and 20 aa. What is the frequency of allele A?

$$	ext{Frequency of A} = \frac{2 	imes 	ext{AA} + 	ext{Aa}}{2 	imes 	ext{Total individuals}}$$

Accepted Answer

$$\frac{2 	imes 40 + 40}{2 	imes 100} = 0.6$$

Question 11

Which of the following best describes a synapomorphy?

Accepted Answer

A shared derived trait found in two or more taxa and their most recent common ancestor.

Question 12

Why do biologists use an outgroup when constructing phylogenetic trees?

Accepted Answer

To help root the tree and distinguish ancestral from derived traits.

Question 13

Which of the following is an example of homoplasy?

Accepted Answer

Wings in bats and wings in birds, which evolved independently.

Question 14

A population of 1600 lizards has genotype frequencies: GG = 0.15, Gg = 0.75, gg = 0.10. Calculate the frequency of allele G.

Accepted Answer

0.15 + 0.5 	imes 0.75 = 0.525

Question 15

Which of the following best describes the parsimony principle in phylogenetic analysis?

Accepted Answer

The hypothesis that requires the smallest number of evolutionary changes is most likely correct.

Question 16

Which of the following is an example of an extrinsic event leading to sympatric speciation?

Accepted Answer

Disruptive selection based on different ecological niches within the same area.

Question 17

Which species concept is most useful for identifying fossil species?

Accepted Answer

Morphological species concept

Question 18

If a population is not in Hardy–Weinberg equilibrium, what can you conclude?

Accepted Answer

At least one of the Hardy–Weinberg assumptions is being violated.

Question 19

Which of the following is a real-world example of vicariance?

Accepted Answer

A glacier forms, splitting a population of plants into two isolated groups.

Question 20

Which of the following statements about phylogenetic trees is TRUE?

Accepted Answer

Branches can rotate at nodes without changing the relationships among taxa.

Speciation, Hardy–Weinberg Principle, and Phylogenetic Trees: Study Notes

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