3.4.6-Biodiversity Within A Community Flashcards
(13 cards)
What is biodiversity?
Variety of organisms in an ecosystem
Define species and species richness
Species-Organisms that are able to produce fertile offspring
Species richness-The number of different species in a community
What does the index of diversity describe?
The relationship between the number of species in a community and the number of individuals in each species
How can farming impact biodiversity?
1.Monocultures-Decrease plant diversity and also species that depend on them for food/habitat
2.Pesticides-Can harm other species or those depending on the target species
3.Removal of hedgerows-loss of habitats/shelter
4.Deforestation-loss of habitats/food sources
Why is it more useful to calculate an index of diversity than to record species richness?
Index of diversity also measures the number of each species which is useful because there may be many of some species but few of others
Give two ways a student can ensure the index of diversity was representative of each habitat
Random samples and a large number of samples
Farmers are now being encouraged to replant hedges on their land
Suggest an explain one advantage and one disadvantage to a farmer of replanting hedges on the farmland
Advantage-greater bio diversity so increase in predators of pests
Disadvantage-reduced land area for crop growth
Describe how you would investigate the effect of an invasion by a non-native species of plant over many years on the abundance of a native species of plant in a community
Set up grid system with coordinates
Place large number of quadrats coordinates randomly selected
Count number of native plant in quadrants
Repeat at the same time each year
What is inter-specific variation?
Variation between different species
Due to different genes causing differences in physical traits and environmental factors like lifestyle and diet
What is intra specific variation?
Variation between individuals within a species
Due to different alleles and environmental factors
Genetic diversity can be made by comparing…
1.Comparing the frequency of measurable or observable characteristics-Because these are based on genes and greater variety of alleles means more diversity. However, environmental factors can alter traits for example diet has affect on height.
2. Comparison of DNA base sequences-Computers can sequence the DNA and produce data to be analysed and patterns to be compared by tagging each base with different coloured dye the more similar the sequence the more related the organism
3. Comparison of mRNA base sequences-base sequences of mRNA are complimentary to DNA so can assess genetic diversity
4. The amino acid sequence in proteins.-Populations that are more genetically diverse will have more differences in amino acid sequence because they are determined by mRNA and DNA
How has method of investigating genetic diversity changed?
Gene technology now allows investigation of DNA sequences to be used rather than inferring DNA differences from observable characteristics
Measuring variation
1.Random sampling-generating random co-ordinates across an area to prevent bias and collect samples from these random coordinates repeating several times as the larger the sample size the less the effects of chance
2.Calculating a mean value of the data and standard deviation
3. The smaller the standard deviation the closer the values are to the mean suggesting little variation
