Biodiversity Flashcards
Define biodiversity
All of the variety in the living world (/another habitat)
Comprised of
• species diversity
• genetic diversity
• ecosystem diversity
Species diversity
Number of different species and the number of individuals of each species within a community
Genetic diversity
The variety of genes possessed by the individuals that make up the population of a species
Ecosystem diversity
The range of different habitats, from small -> plant earth
Measuring species diversity
d = N(N-1) / Σn(n-1)
N = total number of organisms of all species n = total number of organisms of each species
What does calculating species diversity show
Allows us to measure ecosystem stability (high value = stable; less affected by environmental change)
Species diversity in extreme environments
- LOW
- instable ecosystem
- experiences greater change
- fewer organisms have the adaptations to survive
How does agriculture reduce species diversity - the basics
• species and organism selection and rejection reducing species and genetic diversity
How does agriculture reduce species diversity - the specifics does
- pesticides kill competing species
- hedgerows removed, woodland grubbed out
- monocultures
- ponde and wetlands filled in
- land over-grazed, preventing regeneration
- no crop rotation, under-sowing
Why do we select plants/animals
- financial stability
* high food demand
Describe agricultural reduction of species diversity
majority of biomass support used for selected species; lack of space, food, light, minerals for other species found in a natural ecosystem
Aim of conservation
To increase species and habitat diversity without raising food costs or lowering yield
Conservation techniques
- maintaining hedgerows at most beneficial size and shape
- plant hedges instead of fences as field boundaries
- maintain + create ponds
- not draining wetlands
- plant native trees on land with low species diversity
- reduce pesticide, biological control, and pesticide-resistant GMO usage
- use organic fertilisers
- rotate crops with nitrogen fixing crops rather than fertilisers
- use intercropping rather than herbicides (controls weeds and pests)
- create natural meadows; use hay rather than grass for silage
- leave cutting off verges and field edges until after flowering + seed dispersal
- introduce conservation headlands
Hedge shape
A is better than rectangular
Nitrogen fixing crops
Allowing nitrogen enrichment
Conservation headlands
Areas at the edges of fields where pesticides are used restrictively, so that wild flowers and insects can breed
Hedgerows
- remover to allow for increase in large farm machinery
- removed to allow space for crop growth
- increase species diversity
- act are corridors along which species’ move to disperse themselves
- provide food for animals inside + around
Maintaining biodiversity
Allows a stable global ecosystem
Community
The population of all the living organisms of a species present in a particular ecosystem at a particular time, interacting
Population
Total number of individuals of one species (that can potentially interbreed) in a particular habitat at a particular time
Ecosystem
All the biotic and abiotic components of a particular area (dynamic)
Niche
- how an organism responds/fits in to its environment
* governed by biotic + abiotic conditions
Carrying capacity
- the population size an ecosystem can support
* varies due to abiotic and biotic factors
Describe population growth curve
1) lag phase
2) log phase
3) stable phase - population fluctuates due to limiting factors
4) death phase, esp. in sealed environments
Natural factors affecting biodiversity
- natural disasters
- climate change
- interactions between invasive and non-invasive species
Man-made factors affecting biodiversity
- pollution
- deforestation
- climate change
Assessing genetic diversity
Compare:
• DNA
• RNA
• amino acids
Assessing species diversity
- use random/systematic sampling
- don’t forget field guide!
- mean average
Assessing ecosystem diversity
Compare habitats and abiotic characteristics
Species richness
The number of different species present in a habitat
Species evenness
??
Habitat
- the place where an organism typically lives, characterised by the physical conditions and other organisms present
- have microhabitats with microclimates
