Ecology Population Growth and Regulation 3 — Questions and Answers
Question 1: Which of the following best describes a metapopulation?
- A network of local populations connected by dispersal (Correct answer)
- A single large population in a continuous habitat
- A population that has reached carrying capacity
- A population with overlapping generations
Correct answer: A network of local populations connected by dispersal
A metapopulation consists of spatially separated local populations (patches) that interact through immigration and emigration, following the Levins model.
Question 2: What is the primary mechanism by which density-dependent factors regulate population size?
- Feedback loops where increasing density increases mortality or reduces birth rates (Correct answer)
- Random environmental fluctuations independent of population size
- Genetic drift eliminating unfit individuals
- Seasonal changes in resource availability
Correct answer: Feedback loops where increasing density increases mortality or reduces birth rates
Density-dependent regulation creates negative feedback: as population grows, per capita birth rates decline or death rates rise, slowing growth.
Question 3: A population with a stable age distribution growing at λ = 1.2 means:
- The population grows by 20% per time unit (Correct answer)
- The population is at equilibrium
- The population declines by 20% per time unit
- Birth rate equals death rate
Correct answer: The population grows by 20% per time unit
λ (finite rate of increase) > 1 means population growth; λ = 1.2 indicates a 20% increase per generation or time step.
Question 4: Which predator-prey interaction is most likely to produce cyclical population oscillations similar to the Lotka-Volterra model?
- A specialist predator with time-lagged numerical responses to prey (Correct answer)
- A generalist predator that switches between many prey species
- A predator limited by its own intraspecific competition
- A prey species with a refuge population unavailable to predators
Correct answer: A specialist predator with time-lagged numerical responses to prey
Specialist predators with delayed numerical responses create time lags that produce the classic oscillating cycles described by Lotka-Volterra equations.
Question 5: Rmax (maximum intrinsic rate of natural increase) is best described as:
- The growth rate under ideal, unlimited conditions with no competition (Correct answer)
- The growth rate at carrying capacity
- The average growth rate over a population's history
- The growth rate when predation is absent
Correct answer: The growth rate under ideal, unlimited conditions with no competition
Rmax represents the theoretical maximum per capita growth rate achieved when resources are unlimited and environmental conditions are optimal.
Question 6: A population has age structure heavily skewed toward young individuals. What does this predict about future growth?
- Continued population increase as young individuals mature and reproduce (Correct answer)
- Immediate population decline due to low current reproduction
- Stable population because reproductive adults are few
- Rapid decline because juveniles have high mortality
Correct answer: Continued population increase as young individuals mature and reproduce
A young-skewed age structure creates population momentum — as juveniles reach reproductive age, birth rates will increase and the population will grow.
Question 7: Which of the following is a density-independent factor that can cause population crashes?
- A severe drought that kills vegetation regardless of herbivore density (Correct answer)
- Food competition intensifying as herbivore numbers rise
- Pathogen transmission increasing with host density
- Territorial exclusion reducing reproductive success
Correct answer: A severe drought that kills vegetation regardless of herbivore density
Density-independent factors like droughts, floods, or fires affect populations regardless of their size — their impact does not scale with population density.
Ecology Population Growth and Regulation 3
Which of the following best describes a metapopulation?