Biodiversity Flashcards
Define biodiversity
The variety of living organisms in an area.
What 3 levels can biodiversity be considered at?
- Habitat diversity
- Species diversity
- Genetic diversity
Define species
A group of similar organisms able to reproduce to give fertile offspring
Define habitat
The area inhabited by a species. Including physical factors, like soil and temperature range, and living (biotic) factors, like avalibility of food or presence of a predator
Define habitat diversity
The number of different habitats in an area, e.g. a particular area could contain many different habitats- Sand dunes, woodland, meadows, streams etc.
Define species diversity
The number of species (species richness) and the abundance of each species (species evenness) in an area
Define genetic diversity
The variation of alleles within a species (or population of a species) e.g. variation of alleles within dog species would give rise to different breeds.
What is sampling used for?
Measuring biodiversity
Why is sampling used to measure biodiversity?
Because it’s too time consuming to count each individual organism in a habitat/impossible
How might you sample (generally)
- Choose an area to sample (a small area within the habitat being studied)
- Count the no. of individuals of each species (how this is done depends on what you’re counting)
- Repeat process
- Use results to estimate total no. of individuals/different species
Why must you sample as many times as possible?
-To get the best indication of the whole habitat
If comparing habitats, what should the sampling used be?
-The same for both habitats
What are the two types of sampling?
Random and non random
Why is random sampling better than non-random?
Because it helps avoid bias created by the researcher
How might you randomly sample?
- Divide the field up into a grid using measuring tape
- Give each square coordinates
- Use a random number generator to select the coordinates
Why may a non-random sample be necessary?
-When there’s a lot of variety in the distribution of species in a habitat and you want to ensure all differnt areas are sampled
What are the 3 types of non-random sampling?
- Systematic
- Opportunistic
- Stratified
Describe systematic sampling
-When sampling is taken at fixed intervals, often along a line e,g, quadrats could be placed in a line (transect) from an area of shade in the corner to the middle of a field
Describe opportunisitc sampling
- When samples are chosen by the investigator.
- Used because it’s simpe to carry out
- Data will be biased
Describe stratified sampling
-When differnet areas in a habitat are identified and sampled separately in proportion to their part of the habitat as a whole
Describe species richness
- The number of different species in an area.
- The higher the number of species the greater the species richness
- Count the number of differnt species
What sampling is typically used for measuring species richness and evenness?
Random sampling
Describe species evenness
- Is a measure of the relative abundance of each species in an area.
- The more similar the population sizes of each species, the greater the species evenness
- Count the no. of individulas of each species