Q: If the selection gradient $\beta$ for a trait is less than zero ($\beta < 0$), what does this indicate?

Selection favors smaller values of the trait.

Q: Stabilizing selection is most likely to result in which of the following outcomes?

A reduction in phenotypic variance and maintenance of the mean trait value.

Question 1

Which of the following best describes the process of natural selection as defined by biologists?

Accepted Answer

Any consistent difference in fitness among different classes of biological entities.

Question 2

A population of annual plants produces 3,000 seeds per individual, but only 1 in 1,000 seeds survives to reproduce. What is the average fitness of an individual in this population?

Accepted Answer

$3$

Question 3

Which of the following is NOT a requirement for evolution by natural selection to occur?

Accepted Answer

All individuals in the population must have identical fitness.

Question 4

In a population of asexual plants, genotype A has a fitness of 3 and genotype B has a fitness of 4. If both start with 10 individuals, which genotype will dominate after several generations and why?

Accepted Answer

Genotype B, because it has higher fitness and will increase faster.

Question 5

Which process causes random fluctuations in allele frequencies and is not driven by differences in fitness?

Accepted Answer

Genetic drift

Question 6

Which of the following is an example of genic selection?

Accepted Answer

Transposable elements ('jumping genes') that replicate within the genome regardless of their effect on the organism.

Question 7

The T locus in house mice is an example of a selfish genetic element. What is the main consequence of this locus?

Accepted Answer

It causes homozygous t embryos to die or become sterile, but persists because it spreads efficiently in heterozygotes.

Question 8

Which of the following best illustrates kin selection?

Accepted Answer

Worker bees sacrificing their own reproduction to help the queen produce more offspring.

Question 9

Which statement about group selection is most accurate according to modern evolutionary biology?

Accepted Answer

Individual selection is usually faster and more efficient than group selection.

Question 10

Species selection differs from individual selection in that species selection:

Accepted Answer

Changes the proportion of species with certain traits over time, affecting the diversity of life.

Question 11

Which mode of selection increases the variance of a trait in a population by favoring individuals at both extremes?

Accepted Answer

Disruptive selection

Question 12

A population of birds has small and large beak sizes favored due to different food sources, while intermediate beak sizes have lower survival. This is an example of:

Accepted Answer

Disruptive selection

Question 13

Which of the following equations describes the evolutionary change in mean trait value due to directional selection?

Accepted Answer

$\Delta \bar{Z} = h^2 S$

Question 14

If the selection gradient $\beta$ for a trait is less than zero ($\beta < 0$), what does this indicate?

Accepted Answer

Selection favors smaller values of the trait.

Question 15

Stabilizing selection is most likely to result in which of the following outcomes?

Accepted Answer

A reduction in phenotypic variance and maintenance of the mean trait value.

Question 16

Which of the following is a real-world example of overdominance (heterozygote advantage)?

Accepted Answer

Sickle cell trait conferring malaria resistance in heterozygotes.

Question 17

Negative frequency-dependent selection can maintain genetic diversity because:

Accepted Answer

Rare phenotypes have a fitness advantage, preventing any one type from becoming fixed.

Question 18

Artificial selection differs from natural selection in that artificial selection:

Accepted Answer

Is the selective breeding by humans to increase the frequency of desirable traits.

Question 19

Which of the following scenarios best illustrates multiple niche polymorphism?

Accepted Answer

A population of aphids where different genotypes are adapted to different host plants, and both host plants are present in the environment.

Question 20

Which of the following is a likely consequence of strong artificial selection during domestication?

Accepted Answer

Reduced genetic diversity due to selection for specific alleles.

Types and Modes of Natural Selection: Genetics Study Guide

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