4.2.1 - Biodiversity Flashcards
What is biodiversity?
the variety of living organisms in an area
What is the relationship between biodiversity and the stability of an ecosystem?
proportional to eachother
-more biodiversity there is, the more stable the ecosystem is
What different levels can biodiversity be considered on?
- habitat biodiversity (e.g. sand dunes, woodland, meadows, streams)
- species biodiversity (species richness and species evenness)
- genetic biodiversity (e.g. different breeds within a species)
What is habitat biodiversity?
the number of different organisms in an area
What is species biodiversity?
species richness (number of different species living in an area) species evenness (abundance of each species -comparison between the number of each different species)
What is sampling?
taking measurements of individual organisms present in a particular area
What is random sampling?
selecting individuals by chance
-each individual in the population has an equal likelihood of being selected
What is non-random sampling?
sample is not chosen by random
- opportunistic: uses organisms that are available conveniently at the time
- stratified: population is divided into sub groups and then a random sample is taken from each sub group proportional to its size
- systematic: different areas within an overall habitat are sampled separately
What is opportunistic sampling?
a type of non-random sampling where organisms that are conveniently available at the time are used
What is stratified sampling?
a type of non-random sampling where populations are divided into strata (sub groups) based on a characteristic and then a random sample is take from each strata proportional to its size
What is systematic sampling?
a type of non-random sampling where different areas within an overall habitat are identified and then sampled separately
-usually carried out by using a line or belt transect (quadrat moved along line
Name some sampling techniques for animals
- pooter (insects)
- sweep nets (insects in areas of long grass)
- pitfall traps (small, crawling invertebrates)
- tree beating (invertebrates in trees/bushes)
- kick sampling (organisms living in water)
- tullgren funnel (organisms in soil)
Name some sampling techniques for plants
- point quadrats
- frame quadrats
How do you increase the reliability of sampling?
- taking a large number of samples at a number of different points
- use random sampling (to reduce bias)
What is Simpsons index of biodiversity?
a better measure of biodiversity that takes species richness and evenness into account
What does a low/high value from Simpsons index of biodiversity mean?
0 = no diversity
1 = infinite diversity
(closer to 0 = lower biodiversity, closer to 1 = higher biodiversity)
How does genetic biodiversity occur within a species?
- there is little variation of DNA within a species
- all members have the same gene but different alleles
- differences in alleles creates genetic biodiversity
- more alleles present, the more genetically biodiverse a population
proportion of polymorphic gene loci (%) =
number of polymorphic gene loci
__________________________
total number of loci
What factors decrease genetic biodiversity?
- artificial cloning
- selective breeding
- captive breeding programmes
- rare breeds
- natural selection
- genetic bottlenecks
- the founder effect
- genetic drift
What factors increase genetic biodiversity?
- interbreeding
- mutations
What are polymorphic genes?
genes that have more than one allele
-the more polymorphic genes a species has, the more genetically biodiverse the species is
What factors affect biodiversity?
- human population growth
- agriculture (monoculture, chemicals, etc)
- climate change
What is monoculture?
when a large amount of biodiverse land is cleared and a single crop is plants
- only one species present
- less animal species can be supported (less food sources)
What reasons are there for biodiversity to be maintained?
- ecological (eg. protecting keystone species, maintaining genetic resources)
- economic (eg. reducing soil depletion from continuous monoculture)
- aesthetic (eg. protecting landscapes)
