Ch.53 - Population Ecology

Question 1

A _________ describes all organisms of the same species living in the same environment

Answer 1

A population describes all organisms of the same species living in the same environment.

• Share resources, exposed to same environmental factors.
• How do a/biotic factors influence density, distribution, size and age structures of populations?

Question 2

What are the three D’s of population ecology?

Answer 2

Density, Dispersion, Demographics

Question 3

How is density measured?

Answer 3

individuals per unit area (terrestrial) or per unit volume (aquatic)

Question 4

What are three sampling techniques for measuring density?

Answer 4

Randomly selected plots

• Works best in homogeneous areas

Indirectly

• Counting nests, burrows, tracks, fecal droppings

Mark-recapture methods

• Capture, tag, release, wait, recapture

Question 5

Describe the formula for the mark-recapture method.

Answer 5

N = m*n / x

m = number marked in first capture (or s for first sample)

x = number of marked individuals recaptured

n = total number in second capture

N = total population size

Question 6

To measure the population of fish in a lake, 200 individuals were netted and marked with a fin clip, and then returned to the lake. The next week, the lake is netted again and out of the 200 lake trout that are caught, 50 have fin clips. What would be the most accurate estimate of the population size?

Answer 6

N = m*n / x

N = (200)*(200) / (50) = 800

Question 7

What are some assumptions of the mark-recapture method of measuring population density?

Answer 7

Assumptions of M-R

• Marked/unmarked individuals have the same probability of being captured
• Marked organisms completely mix back into the population
• No births/deaths/immigration/emigration during the re-sampling interval

Question 8

What factors contribute to changes in density?

Answer 8

Additions:

• Births: all forms of reproduction
• Immigration: influx of new individuals

Removal:

• Deaths
• Emigration