Deck 3: The Developmental and Molecular Bases of Behavior

Question 1

When someone says that there is a gene for a behavior, they most likely mean that

A) the gene is solely responsible for the development of that behavior.
B) individuals with different forms of that gene exhibit different behaviors.
C) the role of the environment in affecting the development of the behavior is relatively small.
D) the behavior is unlikely to respond to selection, since there is no variation in the species.

Answer 1

B

Question 2

Is an adaptation a "genetically determined" phenotype? Why or why not?

A) No, because the development of every phenotype requires more than genetic information.
B) No, because adaptations are only revealed when individuals interact with the environment.
C) No, because half of every phenotype is composed of genes, while the other half is environmental.
D) Yes, because only hereditary traits can enable an individual to adapt to changing conditions.

Answer 2

A

Question 3

Could social and solitary phenotypes ever occur in the same species strictly because of environmental differences that affected the development of the two phenotypes?

A) No, because both genetic and environmental factors are necessary for development of every phenotype.
B) No, because this is equivalent to saying that the two traits are environmentally determined, which is incorrect.
C) Yes, because as polyphenisms illustrate, some differences in gene-environment interactions are caused only by differences in the environment side of the interaction.
D) Yes, because the environment is absolutely essential for the development of every phenotype, especially behavioral ones.

Answer 3

C

Question 4

Over the course of its lifetime, worker honey bees change behavioral states multiple times, from a young adult that cleans cells to a nurse bee to a forager. What causes a worker honey bee to go through these different behavioral stages?

A) These stages are the result of changes in gene expression that are based entirely on the bee's age.
B) Changes in the interplay between brain gene expression and the bee's social environment produce behavioral variation over the honey bee's life.
C) Honey bees progress from one stage to another based on the current population density of the hive.
D) Each behavioral stage is induced by the different protein and nutritional substrates that honey bees eat throughout their lifetime.

Question 5

Homeobox genes, which are critical for the developmental organization of bodies, are found in species as diverse as humans and fruit flies. This shared set of genes indicates that

A) humans and fruit flies are actually closely related to one another.
B) homeobox genes evolved independently multiple times in many different organisms.
C) humans and fruit flies are under similar selective pressures that have led to the evolution of genes with similar functions.
D) these genes originated in a distant common ancestor and have been retained due to their usefulness.

Question 6

Young and colleagues studied the genetic mechanisms underlying the differences in social behavior in monogamous prairie voles and polygynous montane voles. Which constitutes a hypothesis?

A) They asked whether vasopressin, which stimulates V1a receptors in the brains of prairie voles, is responsible for activating the male reward system, causing them to maintain pair bonds.
B) They suggested that male prairie voles would have more V1a receptors in their brains than male montane voles.
C) They knew that the V1a receptor protein, crucial to the vasopressin-based system of pair bonding, is encoded by the avpr1a gene.
D) They found that differences in vasopressin receptor expression and reproductive behavior was directly related to the length of microsatellite repeats in the promoter of avpr1a.

Question 7

Young and colleagues studied the genetic mechanisms underlying the differences in social behavior in monogamous prairie voles and polygynous montane voles. Which constitutes a prediction?

A) They asked whether vasopressin, which stimulates V1a receptors in the brains of prairie voles, is responsible for activating the male reward system, causing them to maintain pair bonds.
B) They suggested that male prairie voles would have more V1a receptors in their brains than male montane voles.
C) They knew that the V1a receptor protein, crucial to the vasopressin-based system of pair bonding, is encoded by the apr1a gene.
D) They found that differences in vasopressin receptor expression and reproductive behavior was directly related to the length of microsatellite repeats in the promoter of avpr1a.

Question 8

Young and colleagues studied the genetic mechanisms underlying the differences in social behavior in monogamous prairie voles and polygynous montane voles. Which demonstrates the crucial role that genetic regulatory regions play in the evolution of behavior?

A) They asked whether vasopressin, which stimulates V1a receptors in the brains of prairie voles, is responsible for activating the male reward system, causing them to maintain pair bonds.
B) They suggested that male prairie voles would have more V1a receptors in their brains than male montane voles.
C) They knew that the V1a receptor protein, crucial to the vasopressin-based system of pair bonding, is encoded by the apr1a gene.
D) They found that differences in vasopressin receptor expression and reproductive behavior was directly related to the length of microsatellite repeats in the promoter of avpr1a.

Question 9

Immature blackcap warblers that have never migrated exhibit migratory restlessness in the fall. Isolated young birds whose parents orient due west also orient west, while isolated young birds whose parents orient to the south also orient south. This provides evidence that

A) the social environment is critical for determining migratory orientation.
B) birds whose parents orient to the west had higher reproductive success than birds orienting in another direction.
C) evolution acts to separate bird populations during migration so as to minimize competition for resources.
D) genetic differences underly the migratory behavior of different blackcap warbler populations.

Question 10

Refer to the figure.
DNA methylation, an epigenetic modification which alters DNA accessibility and impacts gene expression, influences the morphological and behavioral development of growing honeybee larvae. Explain how the data shown, which compare caste development in honeybees injected with a control (left) versus an enzyme that controls DNA methylation (right), support or refute this hypothesis.

Question 11

Refer to the graph.
Based on the results in the graph, describe an experiment to test for a genetic basis, specifically the role of vasopressin and the avpr1a gene, on the monogamous mating system of prairie voles.

Question 12

In dung beetles, males utilize two distinct mating approaches. Large males produce horns that are used in male-male competition for resources and access to females. Small males, however, lack horns and instead try to sneak by the large males to reach females. Adult body size, horn length, and mating approach are influenced by the nutritional conditions that larvae experience. Is this an example of behavioral polyphenism or behavioral polymorphism? Explain.

Question 13

In dung beetles, males utilize two distinct mating approaches. Large males produce horns that are used in male-male competition for resources and access to females. Small males, however, lack horns and instead try to sneak by the large males to reach females. Adult body size, horn length, and mating approach are influenced by the nutritional conditions that larvae experience.
Statement: Nutritional conditions during development influence expression of the insulin receptor gene, which impacts horn growth and mating approach in males.
What is this statement called? Explain.

Question 14

In dung beetles, males utilize two distinct mating approaches. Large males produce horns that are used in male-male competition for resources and access to females. Small males, however, lack horns and instead try to sneak by the large males to reach females. Adult body size, horn length, and mating approach are influenced by the nutritional conditions that larvae experience.
Statement: Based on what we know about polyphenisms, it is likely that these phenotypes evolved in discrete, nonoverlapping environmental conditions.
Is this an accurate statement? Explain.

Question 15

Explain how regulatory regions are critical for modulating behavioral differences. Provide an example of a study species, describing how variation in a specific gene leads to behavioral differences in that species.