Biodiversity Flashcards
(34 cards)
What is biodiversity?
The variety of organisms/species/habitat/genetics in an area
Why is biodiversity important?
Essential for a balanced ecosystem, all species are interconnected and interdependent.
What are the three types of biodiversity?
Species, habitat, genetic
What is species biodiversity?
The varying levels of species evenness and species richness.
What is species richness?
The number of different species living in a given area.
What is species evenness?
The comparison of a the numbers of individuals of each species living in a community.
How is species biodiversity measured?
Using the Simpsons index, D=1-E(n/N) squared.
What does each part of the Simpson’s index stand for?
E=Total
N=Total number of organisms of all species
n=total number of a particular species
What is genetic biodiversity?
The variety of genes that make up a species. Greater genetic biodiversity=better adaptation=result in disease resistant individuals.
What is habitat biodiversity?
Number of different habitats found in a given area. They all interact.
What are the 2 types of sampling?
Random, Non-random
What is random sampling and how do you do it?
When you select individuals by chance. Each organism in the area has an equal chance of selection.
- Mark out grid using tape measures laid at right angles.
- Use random numbers to decide x+y coords on grid
- Take samples from each coord pair generated.
What are the 3 main methods of non-random sampling?
- Opportunistic
- Stratified
- Systematic
What is opportunistic sampling?
Weakest form of sampling as it may not be representative of population size, samples using organisms that are conveniently available.
What is stratified sampling?
Some populations can be divided into strata(sub-groups) based on a characteristic. Eg males vs females.
A random sample is taken from each strata, proportional to its pop size.
What is systematic sampling?
Different areas of habitat are sampled separately. Either done using a belt or line transect.
What is a line transect?
Make line on ground between 2 poles using a tape measure and take samples at specific points.
What is a belt transect?
2 parallel lines are made using tape measures, samples are taken from area in-between 2 lines.
What factors make the samples less reliable and how do you improve their reliability?
- Bias, use random sampling.
- Chance, increase sample size.
How do you sample animals?
Pooter- suctions catches small insects
Pitfall traps- Catches small crawling invertebrates
Sweep nets- catches insects in long grass
Capture-mark-release-recapture- large mammals
Tree beating- invertebrates in trees/bush
Kick sampling- organisms living in a river.
How do you sample plants?
Point quadrat- at set intervals along the bar, pins are pushed through, each species that touches pin is recorded.
Frame quadrat- Type and number of species in each section is recorded
What can frame quadrats measure?
Species density- Count number of visible individual plant species in 1m by 1m quadrat, gives density per square meter measure, ABSOLOUTE
Frequency- Used when individuals of a species are hard to count eg grass. Count number of squares species is in to calculate % frequency
% Cover- estimate by eye of the area a species covers in a quadrat
What is genetic biodiversity?
The variation between the DNA of individuals of a species.
Why is genetic biodiversity important?
More likely to be able to adapt to changes, less likely to go extinct.
This is because some organisms in the species carry advantageous alleles which enable them to survive a change. This gene is passed on.
