11 - Biodiversity Flashcards
What is species richness?
The number of different species living in an ecosystem
What is species evenness?
A comparison of the numbers of individuals of each species living in a community
What is a community?
All the populations of living organisms in a particular habitat
What is a keystone species?
One which has a large effect on its environment compared to its abundance
What would happen if a keystone species were removed from a habitat?
The habitat would be very different, and biodiversity reduced
What are 3 reasons for maintaining biodiversity?
- Ecological- protecting keystone species and maintaining genetic resource 2. Economic- e.g. reducing soil depletion from monoculture will increase further yields 3. Aesthetic- protecting landscapes for the benefit of human enjoyment
What are the two components of species biodiversity?
Species evenness and species richness
What is the general rule linking habitat biodiversity and species biodiversity?
Generally, as habitat biodiversity increases, so does species biodiversity
What is habitat biodiversity?
The number of different habitats found within an area
What is genetic biodiversity?
The variety of genes which make up a species
What are some advantages of greater genetic biodiversity?
Allows for better adaptation to a changing environment and is more likely to result in individuals who are resistant to disease
What is sampling?
Taking measurements of a limited number of individual organisms in a given area
What is the abundance of an organism?
The number of individuals of a species present in an area
What are the two forms of sampling?
Random and non-random
How would you decide which organisms to study in a random sample?
By using a random number generator or computer tables
What are the 3 main techniques used in non-random sampling?
- Opportunistic 2. Stratified 3. Systematic
What is opportunistic sampling and what is its major limitation?
Simply selecting whichever organisms are available; limited as it may not provide a representative sample
What is stratified sampling?
Dividing a population into a number of sub-groups based on a certain characteristic, then taking a random sample from each strata representative to its size
How are systematic samples often carried out?
Using a belt or line transect
What is the difference between belt and line transects?
Line transect involves sampling all organisms found on a line, whereas belt transect samples all organisms found in the area between two parallel lines, making it more accurate
What are two factors which affect the reliability of a sample?
Chance and sampling bias
How can the effects of sampling bias be reduced?
By using random sampling
What is sampling bias?
Where the selection process of a sample is biased, whether accidentally or deliberately
How can the effects of chance on sampling reliability be reduced?
By using a larger sample size