Q: A researcher uses the mark-recapture method to estimate a fish population. She marks 50 fish, releases them, and later catches 40 fish, 10 of which are marked. What is the estimated population size ($$N$$)? Use the formula: $$N = \frac{M \times n}{m}$$

$$N = \frac{50 \times 40}{10} = 200$$

Question 1

Which of the following best describes a population in ecological terms?

Accepted Answer

A group of organisms of the same species that live in the same area and can potentially interbreed.

Question 2

Which dispersal pattern is most likely to result from territorial behavior among animals?

Accepted Answer

Uniform

Question 3

A researcher uses the mark-recapture method to estimate a fish population. She marks 50 fish, releases them, and later catches 40 fish, 10 of which are marked. What is the estimated population size ($$N$$)?

Use the formula: $$N = \frac{M 	imes n}{m}$$

Accepted Answer

$$N = \frac{50 	imes 40}{10} = 200$$

Question 4

Which of the following is NOT an assumption of the mark-recapture method?

Accepted Answer

The population size decreases between samplings.

Question 5

Which of the following factors would most likely cause a clumped dispersion pattern in a population?

Accepted Answer

Patchy distribution of resources

Question 6

Given the following data from quadrat sampling: mean number of individuals per quadrat = 5, variance = 2. What is the dispersion index ($$D$$), and what does it indicate?

$$D = \frac{	ext{variance}}{	ext{mean}}$$

Accepted Answer

$$D = \frac{2}{5} = 0.4$$, indicating a uniform distribution

Question 7

Which of the following best describes an r-selected species?

Accepted Answer

Produces many offspring with little parental care

Question 8

A population of rabbits grows from 100 to 160 in one year. What is the per capita growth rate ($$r_{\Delta t}$$)?

$$r_{\Delta t} = \frac{\Delta N}{N}$$

Accepted Answer

$$r_{\Delta t} = \frac{60}{100} = 0.6$$

Question 9

Which of the following is a density-dependent factor that can regulate population size?

Accepted Answer

Competition for resources

Question 10

In the logistic growth model, what happens to the population growth rate as the population size ($$N) $$approaches the carrying capacity ($$K$$)?

$$\frac{\Delta N}{\Delta t} = r_{\Delta t} N \left(1 - \frac{N}{K}\right)$$

Accepted Answer

It decreases and approaches zero

Question 11

Which survivorship curve (Type I, II, or III) is typical for species that produce many offspring but provide little parental care?

Accepted Answer

Type III

Question 12

A population of 500 individuals has a per capita growth rate ($$r_{\Delta t}) of 0.1. $$How many individuals are added to the population in one year?

$$R = r_{\Delta t} N$$

Accepted Answer

$$R = 0.1 	imes 500 = 50$$

Question 13

Which of the following is an example of a trade-off in life history strategies?

Accepted Answer

Producing many small seeds versus few large seeds

Question 14

Which of the following best explains why exponential growth cannot continue indefinitely in natural populations?

Accepted Answer

Resources become limiting as population size increases

Question 15

Which population distribution pattern is most likely to be observed in a field of dandelions where seeds are dispersed by wind?

Accepted Answer

Random

Question 16

If a population's birth rate and immigration rate are equal to its death rate and emigration rate, what will happen to the population size?

Accepted Answer

It will remain stable

Question 17

Which of the following is a characteristic of K-selected species?

Accepted Answer

Stable population size near carrying capacity

Question 18

A population of insects has a carrying capacity ($$K) of 1000. If $$the current population size ($$N) is 900 $$and $$r_{\Delta t} = 0.2$$, what is the expected change in population size ($$\Delta N) in $$one time interval?

$$\frac{\Delta N}{\Delta t} = r_{\Delta t} N \left(1 - \frac{N}{K}\right)$$

Accepted Answer

$$\frac{\Delta N}{\Delta t} = 0.2 	imes 900 	imes (1 - \frac{900}{1000}) = 0.2 	imes 900 	imes 0.1 = 18$$

Question 19

Which of the following is an abiotic factor that can influence population size?

Accepted Answer

Rainfall

Population Ecology: Structure, Dynamics, and Growth

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