Q: A researcher uses the mark-recapture method to estimate a fish population. She marks 40 fish, releases them, and later captures 100 fish, 10 of which are marked. What is the estimated population size using the Lincoln-Petersen estimator?

$$N = \frac{40 \times 100}{10} = 400$$

Question 1

A biologist is studying two forest patches. Patch A has 200 deer in 10 km$$^2$$, while Patch B has 150 deer in 2 km$$^2. $$Which patch has the higher population density, and what is the correct calculation for density?

Accepted Answer

Patch B; density = $$\frac{150}{2} = 75$$ deer/km$$^2$$

Question 2

Which pattern of dispersion is most commonly observed in natural populations, and what is a likely ecological reason for this pattern?

Accepted Answer

Clumped; because resources are often patchy and social behavior promotes grouping

Question 3

A researcher uses the mark-recapture method to estimate a fish population. She marks 40 fish, releases them, and later captures 100 fish, 10 of which are marked. What is the estimated population size using the Lincoln-Petersen estimator?

Accepted Answer

$$N = \frac{40 	imes 100}{10} = 400$$

Question 4

Which of the following best describes a Type I survivorship curve, and which organism is a classic example?

Accepted Answer

Low mortality until old age; humans

Question 5

Given the exponential growth model $$\frac{dN}{dt} = r_{max} N$$, what happens to the population size over time if $$r_{max} \u003e 0$$ and resources are unlimited?

Accepted Answer

Population size increases exponentially, forming a J-shaped curve

Question 6

Which of the following is a key difference between the exponential and logistic growth models?

Accepted Answer

The logistic model includes carrying capacity $$K$$, limiting growth as $$N$$ approaches $$K$$

Question 7

Which of the following is an example of a density-dependent factor regulating population size?

Accepted Answer

A disease spreading more rapidly as population density increases

Question 8

In the classic hare-lynx population cycles, which of the following best explains the observed population dynamics?

Accepted Answer

Predator-prey interactions and food availability interact to cause cycles

Question 9

Which statement best describes a metapopulation?

Accepted Answer

A group of spatially separated populations connected by occasional dispersal

Question 10

Which of the following best describes the competitive exclusion principle?

Accepted Answer

Two species competing for the same limiting resource cannot coexist in the same place

Question 11

A barnacle species can live throughout the intertidal zone in the absence of competitors, but is restricted to the upper zone when another barnacle species is present. What is the term for the area where it actually lives in nature?

Accepted Answer

Realized niche

Question 12

Which of the following is an example of Batesian mimicry?

Accepted Answer

A non-toxic butterfly resembling a toxic butterfly

Question 13

Which of the following best distinguishes mutualism from commensalism?

Accepted Answer

Mutualism benefits both species; commensalism benefits one without affecting the other

Question 14

Which of the following is NOT a major prey defense strategy?

Accepted Answer

Resource partitioning

Question 15

Which of the following best describes the Shannon diversity index and its use?

Accepted Answer

It combines species richness and relative abundance to quantify community diversity

Question 16

Why are food chains typically limited to 3–5 trophic levels?

Accepted Answer

Because energy transfer between trophic levels is inefficient, with only about 10% passed on

Question 17

Which of the following best distinguishes a keystone species from a foundation species?

Accepted Answer

A keystone species has a disproportionately large effect on community structure relative to its abundance

Question 18

Which of the following is an example of a primary succession event?

Accepted Answer

Colonization of bare rock after a volcanic eruption

Question 19

According to the species-area curve, what is the general relationship between island size and species richness?

Accepted Answer

Larger islands tend to have more species due to greater habitat diversity and lower extinction rates

Question 20

Which hypothesis helps explain the latitudinal gradient in species richness?

Accepted Answer

Tropical regions have higher productivity and more stable climates, supporting more species

Population and Community Ecology: Study Guide for Exam #3

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