Module 4: Biodiversity

Question 1

Define biodiversity?

Answer 1

Biodiversity is: the range of habitats, the number of different species and their relative abundance, and the genetic diversity within a species within an area.

Question 2

What is habitat?

Answer 2

Where an organism lives.

Question 3

What is species?

Answer 3

A group of organisms similar in appearance, physiology and genetics whose members are able to interbreed to produce fertile offspring.

Question 4

What is habitat biodiversity?

Answer 4

The range of habitats in which different species live

within an area

Question 5

What is species biodiversity?

Answer 5

The number of different species living in a habitat (species richness) and their relative abundance (species evenness)

Question 6

What is genetic biodiversity?

Answer 6

Genetic Biodiversity ‐ variation between individuals of the same species e.g. breeds of dog.

Question 7

Explain the importance of sampling in measuring the biodiversity of a habitat

Answer 7

To assess biodiversity in a habitat, we ideally need identify each species present and count them ‐ this is impossible. Instead, we sample ‐ study a small area and then multiply the numbers of individuals of each species to estimate numbers in the entire habitat.

Sampling should be representative of the habitat and so needs to sample the range of species in the habitat.

Question 8

Describe how random samples of plants and animals can be taken when measuring biodiversity?

Answer 8

Use random numbers generated by a computer to create coordinates (on a map or within a grid you set)

How many sites should you sample?
It depends on the size of the habitat ‐ the number of samples should be representative of the number and relative abundance of all species in the habitat.

Question 9

How is opportunistic sampling carried out?

Advantages and disadvantages?

Answer 9

Prior knowledge of a site determines the sample site.
You may deliberately sample an area where you know an organism is present.

Advantages:
Quicker than random sampling

Disadvantages:
This may introduce bias to the data ‐ if you sample an area where you know an organism is present this could lead to an overestimation of its abundance or biodiversity generally.

Question 10

How is stratified sampling carried out?

Advantages and disadvantages?

Answer 10

Sampling areas in a habitat which seem very different, separately.

Advantages:
Ensures all different areas in the habitat are sampled ‐ ensures no under representation (random sampling may miss areas)

Disadvantages:
If too many samples are taken in proportionally smaller areas, it could lead to over representation of some areas.

Question 11

How is systematic sampling carried out?

Advantages and disadvantages?

Answer 11

Samples are taken at regular, predetermined intervals across a habitat e.g. belt or line transects.

Advantages:
If there is a clear gradual change in an environmental factor across an environment, a transect can show how species abundance changes with it and therefore the effect of the factor on the different plant species.

Disadvantages:
Species which do not fall on the line or in the belt may be missed and therefore the sample would not be representative and there would be an underestimation in the biodiversity.

Question 12

Method for sampling abundance of plants

Answer 12

• set grid/area to be sampled
• use belt transect to sample
• use 50cmx50cm quadrats
• at regular 5m intervals ‐ systematic sampling
• identify plant species using keys
• record the presence/absence of sp. in each quadrat
• estimate the % cover of each species in your quadrat
• Repeat this using several different transects to show repeatability and identify anomalies
• Extrapolate the data to estimate biodiversity in the entire habitat

Question 13

Describe 7 methods of sampling animals and what kinds of animal each is suitable for

Answer 13

INSERT

Question 14

Describe the mark and capture technique

Answer 14

Allows you to estimate population size of a species.

1. Capture sample of animals
2. mark them ‐ the total number captured = C1
3. Release animals
4. (re)trap/(re)capture another sample using the same method for
   validity
   Number captured = C2 Number recaptured = C3
5. Calculate total population = C1 x C2/C3

Question 15

Suggest 3 species populations which could be estimated with mark, release, recapture

Answer 15

Mice, butterflies, birds

Question 16

Suggest 2 considerations that are needed before carrying out mark, release, recapture

Answer 16

Where and how the individuals will be marked ‐ this must not cause harm e.g. butterflies ‐ not on wings (flight), not on top of body (predation)

Question 17

Suggest 1 limitation of mark, release, recapture

Answer 17

Some animals being trapped with Longworth traps may become ‘trap happy’ and learn that the trap gives them food and safety from predation and become more
likely to return to traps ‐ gives overestimation of population size (data is not representative)

Question 18

Method for sampling animals

Answer 18

• set grid/area to be sampled
• use random numbers generated by a computer to locate the areas you will randomly sample
• pick appropriate capture method CHOSE ONE e.g. sweep nets, pooters, pitfalls etc
• identify each sp. using a key and count the numbers of each sp.
• Repeat this several times in each habitat, using the same technique each time to show repeatability and identify anomalies
• Extrapolate the data to estimate biodiversity in the entire habitat

Question 19

What is species richness?

Answer 19

Number of different species in the habitat.

More species rich + even spread of numbers = more biodiverse.

Question 20

What is species evenness?

Answer 20

Relative numbers of how many individuals in each
species.

More species rich + even spread of numbers = more biodiverse.

Question 21

What is Simpson’s index of diversity?

Answer 21

A measure of biodiversity as it takes into account sp.
richness and sp. evenness.

D = 1 ‐ [Ʃ(n/N)2]

Ʃ = sum of
n = number of individuals in a species
N = total number of individuals of all species

A number closer to 1 for D means the area is more biodiverse.

A number closer to 0 for D means the area is less biodiverse.