Ecology Of Populations 3 — Questions and Answers
Question 1: In the logistic growth equation dN/dt = rN(1 − N/K), population growth rate is greatest when N equals:
- K
- K/4
- K/2 (Correct answer)
- 2K
Correct answer: K/2
The logistic growth rate is maximized at N = K/2, where the term (1 − N/K) is 0.5 and rN is still large.
Question 2: Mark-recapture studies estimate population size using the Lincoln-Petersen method. If 50 animals are marked, 60 are later captured, and 15 of those are marked, what is the estimated population size?
- 200 (Correct answer)
- 175
- 150
- 100
Correct answer: 200
N = (M × C) / R = (50 × 60) / 15 = 200, where M = marked, C = second capture, R = recaptured marked individuals.
Question 3: Which life history strategy is associated with K-selected species?
- High reproductive rate, small body size, short lifespan
- Few offspring, extensive parental care, late maturity (Correct answer)
- Early maturity, minimal parental care, boom-bust dynamics
- High fecundity in early life with rapid population turnover
Correct answer: Few offspring, extensive parental care, late maturity
K-selected species invest heavily in few offspring and typically live in stable environments near carrying capacity.
Question 4: A metapopulation consists of:
- A single large population in a continuous habitat
- Several subpopulations connected by dispersal across a fragmented landscape (Correct answer)
- All populations of a species on Earth
- A population that has reached carrying capacity
Correct answer: Several subpopulations connected by dispersal across a fragmented landscape
Metapopulations are networks of spatially separated subpopulations that exchange individuals through immigration and emigration.
Question 5: Which of the following best describes scramble competition within a population?
- Dominant individuals monopolize resources, leaving subordinates with little
- All individuals share resources equally, but each may get an insufficient amount (Correct answer)
- Predators regulate prey populations by removing weak individuals
- Individuals leave overcrowded areas to colonize new habitats
Correct answer: All individuals share resources equally, but each may get an insufficient amount
In scramble competition, resources are divided among all competitors, potentially leaving each individual with too little to survive or reproduce.
Question 6: What is the net reproductive rate (R₀) of a population, and what does R₀ = 1 indicate?
- Average number of offspring per female lifetime; population is stable (Correct answer)
- Number of deaths per birth; population is declining
- Ratio of juveniles to adults; population has equal age classes
- Intrinsic growth rate; population doubles each generation
Correct answer: Average number of offspring per female lifetime; population is stable
R₀ is the average number of offspring each female produces over her lifetime; R₀ = 1 means each female replaces herself exactly, indicating a stable population.
Question 7: Inbreeding depression in small populations is primarily caused by:
- Increased genetic drift removing beneficial alleles
- Higher expression of deleterious recessive alleles due to increased homozygosity (Correct answer)
- Competitive exclusion by closely related individuals
- Reduced mutation rate in genetically uniform populations
Correct answer: Higher expression of deleterious recessive alleles due to increased homozygosity
Mating among relatives increases homozygosity, raising the probability that offspring inherit two copies of harmful recessive alleles.
Ecology Of Populations 3
In the logistic growth equation dN/dt = rN(1 − N/K), population growth rate is greatest when N equals: