Biodiversity - Chapter 17 AQA AS Biology
Chapter 17 - AQA AS Biology
- Created by: H.N
- Created on: 30-12-12 19:47
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- Biodiversity
- Genetic diversity = variety of genes possessed by the individuals that make up any 1 species
- Biodiversity = general term to describe variety in the living world
- Ecosystem diversity = range of different habitats within a particular area
- Species Diversity
- Species diversity = the no. of different species + the no. of individuals within a community
- measuring species diversity
- no. of different species in a given area
- proportion of the community made up of an individual species
- d = N(N-1) / {n(n-1)
- Key:
- d= species diversity index
- N= total no. of organisms of all species
- n= total no. of organisms of each species
- { = the sum of
- n= total no. of organisms of each species
- N= total no. of organisms of all species
- d= species diversity index
- the higher the value of 'd', the greater the species diversity
- Key:
- higher the species diversity index - the more stable an ecosystem + the less its affected by climate
- Impact of agriculture
- farmers select species for particular qualities that make them more productive
- no. of species + variety of alleles possessed is reduced to the few with the desired features
- any area can only support a certain amount of biomass
- if large amount taken up by 1 species then less space for other species
- competition for space + resources - many won't survive
- if large amount taken up by 1 species then less space for other species
- pesticides used to exclude other species
- reduction in species diversity = low species diversity index in agricultural ecosystems
- farmers select species for particular qualities that make them more productive
- Impact of deforestation
- tropical rain forests - highest species diversity
- some due to accidental fires, but vast majority due to human actions
- sometimes due to man- made pollutants producing acid rain
- Deforestation = the permanent clearing of forests and the conversion of land to other uses e.g. agriculture, grazing, housing + reservoirs
- loss of biodiversity, reduced species diversity
- even new forests grown for commercial purposes have just a few predominant tree types
- { = the sum of
- higher the species diversity index - the more stable an ecosystem + the less its affected by climate
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