4.6 Biodiversity within a community Flashcards
What is species diversity?
The number of different species and the number of individuals of each species in a community.
What is species richness?
The number of different species in a particular area at a particular time.
What is genetic diversity?
The variety of genes amongst all the individuals in a population of one species.
What is ecosystem diversity?
The range of different habitats.
What are 5 ways that farming reduces biodiversity?
- Destruction of hedgerows
- Selective breeding
- Monocultures
- Overgrazing
- Filling in ponds & draining wetlands.
How can destruction of hedgerows reduce biodiversity?
- Hedgerows can obstruct farmers from cutting down their fields.
- Hedgerows provide habitats for many animals.
- Meaning these habitats are destroyed when the hedgerows are cut down.
How does selective breeding reduce biodiversity?
- Plants and animals with desired characteristics are constantly selected to reproduce, to continue these desired characteristics in future generations.
- Narrows the gene pool, reducing biodiversity.
How does monoculture reduce biodiversity?
- When only 1 species is grown in the entire field.
- Only 1 species = low biodiversity.
- Only attracts the same type of insects to feed = lower biodiversity.
How does overgrazing reduce biodiversity?
- If animals are left to overgraze, plants are reduced too much.
- Which has a knock-on effect on the food web.
How does filling in ponds & draining wetlands reduce biodiversity?
- Filled in/drained to provide space for farming.
- Destroys habitats.
What are some ways to compromise between the need for farming + maintaining biodiversity?
- Have crop rotations/grow different crops each year.
What is index diversity?
Describes the relationship between the number of species in a community and the number of individuals in each species.
What is the equation for index diversity?
D = N(N-1)/ ∑n(n-1).
What does N stand for in the index of diversity equation?
Total number of species.
What does n stand for in the index of diversity equation?
Number of individuals in each species.
What is one advantage and one disadvantage to a farmer of replanting hedges on her farmland?
Advantage: Greater biodiversity so increase in predators of pests.
Disadvantage: Reduced land area for crop income/growth.
What is meant by ‘species richness’?
A measure of the number of different species in a community.
What is one consideration the scientists had taken into account to make sure their method was ethical?
Must not harm the bees.
What is one consideration the scientists had taken into account to allow them to identify accurately the species to which each belonged?
Must allow close examination/use a key to identify the species.
What is the difference between species richness and an index of diversity?
Species richness measures only the number of different species and does not measure the number of individuals.
