Studying Biodiversity Flashcards
what is biodiversty
The variety of living organisms in an area
what is a species
A group of similar able to reproduce to produce fertile offspring
What is a habitat
Area inhabited by a species
what is habitat diversity
Number of different habitats in an area
Eg could contain sand dunes, woodlands and meadows
what is species diversity
The number of each species ( species richness) and the abundance of each species in an area ( species evenness)
How to carry out a sample to measure biodiversity
1) Choose an area to sample.
2) Count the number of individuals of each species in that area
3) Repeat the process, to give a better indication of the entire habitat.
4) Use the results to estimate a total number of individuals or different species in a habitat.
different sampling techniques that are used for different species
1) for insects- pitfall trap
2) small organisms that live in soil: Use a tunnel Gren funnel ( soil sample is put on a mesh filter at the top of a funnel and a light is shone down into it. Organisms move away from the light being shined and fall ou tof the funnel into a collecting beaker.
3) for aquatic organisms: Use kick sampling, and kick the water and use a net to collect all the organisms disturbed
4) for organisms living in long grass, use a sweep net
to avoid bias, what type of sampling should be used
Random sampling
- EG divide the field into grids using measuring tape and use a random number generator to select coordinates
when should you use a non random sample over a random sample
when there is lots of variety in the distribution of species in the habitat and you want to make sure all the different areas are sampled
3 types of non- random sampling
1) Systematic: When samples are taken at fixed intervals
2) Opportunistic: THis is when samples are chosen by the investigator, simple to carry out but the data wll be BIASED
3) Stratified: When different areas in a habitat are identified and sampled separately in proportion to their part of the habitat as a whole.
what is species richness
The number of different species in an area. The higher the number of species the greater the species richness
What is species Evenness
The relative abundance of species in each area
- the more SIMILAR the population size of species in an area the greater the species evenness.
what does” simpsons index of diversity” take into account
BOTH species richness and species eveness
Simpsons diversity index
D=1 - (sigma(n/N)^2)
D is simpson’s diversity of index
- n is the total number of INDIVDUALS of one species
- N is the total number of organisms of all species
The simpsons diversity index is always a value between “0 and 1 “
- the closer to 1 the index is the more diverse the habitat ( greater species richness and evenness)
