Investigating population and succession

Question 1

What is ecology?

Answer 1

The study of how organisms interact with each other and their environment.

Question 2

What is a species?

Answer 2

A group of closely related individuals, which are capable of interbreeding and producing fertile offspring

Question 3

What is a population?

Answer 3

All the individuals of a given species living together in the same area at the same time

Question 4

What is carrying capacity?

Answer 4

Maximum, equilibrium number of organisms of a particular species that can be supported indefinitely in each stable environment.
Birth rates and death rates are in equilibrium

Question 5

What is a community?

Answer 5

All the individuals of all the species living together in the same area at the same time

Question 6

What is a habitat?

Answer 6

The place where an organism lives within an ecosystem

Question 7

What is a niche?

Answer 7

Describes where an organism lives and what it does (its role). This includes what it feeds on and how it interacts with other organisms and the environment

Question 8

What is the abundance of a species?

Answer 8

Population size of each species

Question 9

When estimating, to ensure that the data is not biased what must we do?

Answer 9

Samples must be selected at random

Question 10

When estimating, to ensure that the data collected is reliable, representative and suitable for statistical analysis, what must we do?

Answer 10

Large number of sample must be taken (more than 20)

Question 11

How can we check that a large enough sample is used?

Answer 11

If you calculate a new mean value after each sample is taken (this is called a running mean), enough samples have been taken when this running mean shows no change

Question 12

What is a quadrat?

Answer 12

A frame of known area, which is placed on the ground and an estimation of the population size within the quadrat is made

Question 13

In what ways can we determine the abundance of species within a quadrat?

Answer 13

Density
Percentage cover
Frequency

Question 14

How is density used to measure abundance of species within a quadrat?

Answer 14

Actual count of all individuals present

Question 15

What are the advantages of using a quadrat?

Answer 15

Most accurate

Question 16

What are the disadvantages of using a quadrat?

Answer 16

Often time consuming
Some species can be difficult to count

Question 17

How is percentage cover used to measure abundance of species within a quadrat?

Answer 17

The area of the quadrat covered by one species is recorded as a percentage of the total area
Used when there are too many individuals to count

Question 18

What is a disadvantage of using percentage cover?

Answer 18

In some situations, over layering of species may occur (stratification), therefore, the total percentage cover may be more than 100%

Question 19

How is frequency used to measure abundance of species within a quadrat?

Answer 19

The proportion of quadrats that contain a particular species

Question 20

What is a disadvantage of using frequency?

Answer 20

Least accurate

Question 21

Why is random quadrating done?

Answer 21

To find out what species are present and their relative abundance in a specified area
Compare the species abundance in two different areas
Compare the species abundance at one site (one area) at different seasons/years

Question 22

When is random quadrating used?

Answer 22

To study stationary or very slow moving populations with fairly uniformed distribution across area

Question 23

What is the method of random quadrating?

Answer 23

Map the area using two measuring tapes arranged at right angles to each other to form the axes of a grid
Use a random number generator to obtain a serious of random coordinated
Place a quadrat at the intersection of these coordinates
Abundance can then be estimated using a quadrat by:
- frequency, % cover or density

Question 24

How many quadrats should you use in the sample?

Answer 24

Calculate a running mean
Stop sampling when there is little change
Enough to carry out a statistical test
A large number to make sure mean is reliable (20 or more)
Need to make sure work can be carried out in the time available

Question 25

Describe how you would determine the mean percentage cover for beach grass on a sand dune (3 marks)

Answer 25

Use a random generator to obtain a series of coordinates
Use a large number/sample of quadrats
Divide total percentage by number of quadrats/samples

Question 26

What can systematic sampling consist of?

Answer 26

Transect
Belt transect
Interrupted belt transects

Question 27

How is a transect used in systematic sampling?

Answer 27

Recording what species are touching the line at each sampling point

Question 28

How is a belt transect used in systematic sampling?

Answer 28

Placing two parallel lines across, a meter apart and recording what species are found between the two lines

Question 29

How is an interrupted belt transect used in systematic sampling?

Answer 29

Using one line and placing a quadrat down at equally spaced sampling points and recording abundance of species within the quadrat

Question 30

When carrying out systematic sampling, what must we ensure?

Answer 30

The position of the transect across the area should be random
Enough transects should be performed to ensure data collected is reliable

Question 31

Describe how you would investigate the distribution of marram grass from one side of the dune to the other

Answer 31

Transect/lay tape measure from one side of the dune to the other
Place quadrat at regular intervals along the line
Count plants/percentage cover OR count plants and record where they touch the transect

Question 32

What technique is used to estimate the population size of moving/mobile species (animals)?

Answer 32

Mark-release-recapture

Question 33

What is the method of mark-release-recapture?

Answer 33

animals of a particular species are ethically collected and counted
- the animals are then marked in some way that does not affect ability to feed or increase chance of predation
- the animals are then released and left to redistribute into their population
- after a reasonable time, a second capture is carried out and the total number caught is recorded, as well as how many of those released and recaptured which were previously marked

Question 34

How is the population size calculated using mark-release-recapture?

Answer 34

(number caught first time x number caught second time) / number caught second time which were marked

Question 35

What things must be considered when mark-release-recapture is done?

Answer 35

The population size does not change between the two capture times (very few or no increase in birth/death rate or migration)
The marking should not make the marked animals more susceptible to predators or harm them
The marking should not rub off or be lost
Sufficient time should be left for the released

Question 36

Species should be studied in situ and not removed from the position. Why?

Answer 36

If moved, behaviour will be altered

Question 37

If removal or disturbance is necessary, the individuals should be returned to the same spot if possible. Why?

Answer 37

More likely to integrate back into their population

Question 38

As few individuals as possible should be removed. Why?

Answer 38

Don’t want to effect the natural population

Question 39

There should be minimal damage to organisms or the habitat. Why?

Answer 39

Don’t want to effect the natural population

Question 40

Sites should not be overused and be given time to recover. Why?

Answer 40

Don’t want to effect the natural population