C2 Experimental Design

Question 1

State sampling techniques that can be used to study populations of a species (4).

Answer 1

• capture/recapture
• remote sensing/satellite tracking
• line transects
• quadrats

Question 2

Describe the capture/recapture technique, and what is is useful for.

Answer 2

WHAT
- a number of organisms captured from a pop, marked, and released back to wild
- another group is caught at a later date
- Lincoln’s index used to estimate the population size
(abundance = no. caught in first capture x no. caught in second capture, divided by the no. of marked organisms in second capture)

WHEN
- for mobile populations that cannot be easily counted
Assumptions are made:
- animals have the same probability of being captured both times, regardless whether they were caught 1st time
- pop size did not change significantly in the time between captures
- the marked animals mixed with the rest of the pop before the 2nd recapture

Question 3

Describe remote sensing and satellite tracking, and what they are useful for.

Answer 3

Remote sensing
- uses pulses of radio waves to map ground cover, land changes, and other features like glacier flow
- used when areas are inaccessible or too large to obtain info in another way

Satellite tracking
- organisms with tags send electronic signals to satellites, which shows their exact location
- useful for finding migration patterns/key areas for species under threat, that once identified, can be protected