Question 1

Why do some animals live alone while others form groups?

Accepted Answer

Animals adopt different social strategies based on resource availability and survival benefits. Syrian hamsters are territorial and solitary because they cannot tolerate sharing resources, whereas Russian hamsters live in small groups and form lasting bonds. These behavioral differences reflect evolutionary adaptations to different environmental pressures and mating opportunities.

Question 2

What is an evolutionarily stable strategy in animal behavior?

Accepted Answer

An evolutionarily stable strategy (ESS) is a behavioral strategy that provides greater payoff than alternative strategies, causing it to dominate a population over time. In sea lions, dominant males defending harems achieve higher reproductive success than non-dominant males using alternative mating tactics. Once an ESS arises through mutation or migration, natural selection favors its spread through the population.

Question 3

How does game theory explain animal conflict and cooperation?

Accepted Answer

Game theory uses mathematical models to analyze how different behavioral strategies affect individual fitness by assigning benefits and costs to each interaction. The hawk-dove game demonstrates this by comparing aggressive hawks, which always fight for resources, against peaceful doves, which never fight. By calculating net gains across different interaction types, biologists can predict which strategies persist in populations.

Question 4

What are polymorphic mating systems and how do they work?

Accepted Answer

Polymorphic mating systems occur when one sex, typically males, develops multiple distinct phenotypes and mating strategies within the same population. Sea lion males exhibit this by either defending harems on beaches or remaining in water to intercept females. These alternative strategies coexist because each provides fitness benefits under different circumstances, such as age or physical condition.

Question 5

How do cooperative populations prevent cheaters from invading?

Accepted Answer

Cooperative populations have evolved mechanisms to prevent invasion by non-cooperators, including the ability to switch strategies when necessary or identify and punish cheaters through expulsion. These defenses are critical because in a population of 100% cooperators, uncooperative individuals can out-compete residents by gaining benefits without incurring costs. Cheater detection and punishment maintain cooperation's evolutionary stability.

Question 6

What is the net gain calculation in the hawk-dove game?

Accepted Answer

Net gain equals the benefit obtained from a resource minus the cost incurred during interaction. When two doves meet, each receives half the benefit with no aggression costs. When a hawk meets a dove, the hawk gains all benefits while the dove gains nothing. When two hawks fight, they split the benefit but both incur fighting costs, reducing their net gain.

Question 7

How does reciprocal altruism evolve in animal populations?

Accepted Answer

Reciprocal altruism evolves when individuals can identify each other and expect future interactions, making apparent self-sacrifice adaptive over time. Vampire bats regurgitate food to hungry individuals, expecting the favor returned later. Similarly, birds sound alarm calls when spotting predators, making themselves vulnerable but benefiting when others reciprocate. Game theory shows these behaviors maximize long-term fitness despite immediate costs.

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