Biodiversity Flashcards
Habitat diversity
Habitat biodiversity refers to the number of different habitats within an area
Species biodiversity
Measured in 2 components
Species evenness- comparison of number the number of individuals of each species living in a community
Species richness- number of species living in an area
Genetic biodiversity
Refers to the variety of genes that make up a species
High levels of genetic diversity will lead to a lot of different characteristics being exhibited
Random sampling
Selecting individuals by chance, each individual in the population has an equal chance of being selected
1) Mark out grids on the grass using 2 tape measures laid at right angels
2) use random numbers to determine x and y co-ordinates
3) take a sample at each coordinate pairs generated
3 types of non random sampling
Opportunistic , stratified, systematic
Opportunistic sampling
Weakest form of sampling as it may not be representative of the population
Uses organisms conveniently available
Stratified sampling
Some populations can be divided into a number of strata based on characteristics
Random sample is then taken from each of these strata proportional to its size
Systematic sampling
Different areas within an overall habitat are identified, which are then sampled separately
E.g a line transect or a belt transect
describing how to distribution of organism changes as you move closer to the coast or across a field
Why may a sample not be reliable
Sampling bias - selection process may be biased
Chance- organisms selected may, by chance, not be representative
Ways to sample animals
Porter is used to catch small insects by sucking though a mouthpiece
Sweep nets are used to catch insects in long areas of grass
Pitfall traps are used to catch small, crawling invertebrates such as beetles, spiders and slugs
Tree beating is used to take samples of the invertebrates living in a tree or bush
Kick sampling is used to study organisms living in a river to disturb the substrate, net is held downstream to catch any organisms released
Point quadrats
Consist of a frame containing a horizontal bar
At set intervals along the bad, long pins can be pushed through the bar to reach the ground
Each species of plant the pin touches is recorded
Factors increasing genetic biodiversity
Mutations in DNA
Interbreeding between different populations, this is known as genetic flow
Factors that reduce genetic biodiversity
Selective breeding- where only a few individuals with the desired characteristics are selected to breed
Captive breeding programs
Natural selection- species evolve to contain primarily alleles which code for the advantages characteristics
Genetic bottlenecks- few individuals within a population survive an event or change in environment
The founder effect- where a small number of individuals create a new colony, geographically isolated from the original
Human influence on biodiversity
Deforestation - permeant removal of large areas of forest
Agriculture- increasing amounts of land has to be farmed in order to feed the growing population, this has resulted in large amounts of land being cleared and planted with one crop, reducing biodiversity
Climate change- there is much evidence that the release of carbon dioxide and other pollutants into the atmosphere from the burning of fossil fuels increasing global temp
Agricultural changes that effect biodiversity
Deforestation- to increase the area of land available
Removal hedgerows - as a result of mechanisation farmers remove hedgerows to give them more space to fertilise
Use of chemicals (pesticides and herbicides)
Pesticides- kill pests that would eat crops
Herbicides- kill weeds
Climate change
Temperature increasing at increasing rate
Increased water vapour in air
Temp of ocean has increased, contributing to sea level rise
Global average sea level rise increasing
Artic temperature increasing
Mountain glaciers melting due to heat increases
Long term upward trends in precipitation