Biodiversity Flashcards
Biodiversity
measure of variation found in the living world
3 types of biodiversity
Habitat
-range of different habitats in which different species live
Species
-range of organisms found in a habitat
-measured by species richness and evenness
Genetic
-variation between individuals belonging to the same species
Types of sampling to measure biodiversity of a habitat
Random
Non random- opportunistic, stratified, systematic
Random sampling
-done by creating a grid with coordinates and using random number generator
Advantage- ensures data isn’t biased by selective sampling
Disadvantage- may not cover all areas of the habitat equally
Opportunistic sampling
-researcher makes sampling decisions based on prior knowledge eg. choosing an area that contains specific species
Advantage- easier and quicker than random
Disadvantage- may be biased as researcher chooses location
Stratified sampling
-dividing a habitat into areas that appear different and sampling each separately
Advantage- ensures all areas of habitat are sampled, so no species missed
Disadvantage- may lead to over-representation of some areas in the sample
Systematic sampling
-samples taken at fixed intervals across the habitat (line/ belt transect)
Advantage- useful when the habitat shows a clear gradient in environmental factors eg. distance from pond
Disadvantage- species may be missed as only species on the line can be counted
Sampling plants
-quadrats- estimate the percentage cover as quadrats divided into 100 squares
-point frame- frame with needles, count any species touching the needle and calculate percentage cover
Transect
-line- record plants touching the line at regular intervals
-interrupted belt transect- use quadrats at set intervals along the line
-continuous belt transect- place quadrat beside the line and move it along the line
Catching invertebrates
-sweep netting- walk through habitat with a stout net and sweep through areas of vegetation.
-pitfall trap- small container buried in soil so only rim is below surface. Animals moving through leaves will fall into the container
-light trap- trap flying insects at night. Insects are attracted to light and will fall into ethanol
Trapping small mammals
-use a longworth trap and use mark and recapture technique
Mark recapture technique
-capture a sample of animals
-mark each individual, the number captured = C1
-release marked animals and leaves traps for period of time
-number of animals captured on the second occasion= C2
-number of already marked animals captured= C3
total population= C1xC2/ C3
Simpsons index of diversity
D= 1- [sum of (n/N)^2]
n= number of individuals of a particular species
N= total number of all individuals of all species
-high value of simpsons index= high diversity
Measuring genetic diversity
Genetic diversity= found when more than one allele for a particular locus
-look at physical characteristics
Calculating genetic diversity
-calculate the number of loci in heterozygotes
-calculate the percentage of loci that have more than one allele
-polymorphic gene loci- a locus with more than 2 alleles
Factors affecting biodiversity
-Human population growth- exploit environment for food, resources, pollution
-agriculture- uses monoculture and selective breeding. Large areas of land is cleared for agriculture
-climate change- species that aren’t able to adapt to changes are dying, decreasing population and genetic diversity
-extinction
Ecological reasons to maintain biodiversity
Interdependence of organisms
-ecosystems are complex as species have evolved to live with each other and depend on each other
-all animals linked within food chain/ web
-when one species is affected by human activities, other species will also be affected (keystone species)
Genetic resource
-if biodiversity declines, genetic diversity declines
-this means we could lose the natural solutions to our problems eg. medicines, vaccines