Biodiversity Flashcards
What is biodiversity?
The variety of species in an area.
The variety of genes in a population.
Define habitat
The environment in which a species usually lives
Define community
All the populations of living organisms in a particular habitat.
Define species richness
Number of species living in a particular area
Define species evenness
Number of individuals of each species living in a community
What does species evenness indicate?
Higher species evenness indicates higher biodiversity.
Low species evenness indicates dominance by only a few species.
Explain the importance of sampling in measuring the biodiversity of a habitat
- It is difficult to count every individual.
- Sample provides an estimate
- Representative of whole area
Outline how to perform unbiased, random sampling with a quadrat
- Mark a grid in the area to be sampled using measuring tapes.
- Use a random number generator to provide coordinates on the grid.
- Place quadrat at coordinates and count species/organisms within a species.
- Determine abundance e.g. percentage frequency or percentage cover
- Repeat many times
- Calculate mean
Determine methods of non-random sampling
Opportunity
- Use organisms that are conveniently available
- May not be representative of the population
Stratified
- Population divided into subgroups
- Random sample taken from each subgroup proportional to its size
Systematic
- Different areas in habitat identified
- Each area sampled e.g. belt transect
Outline how to perform unbiased sampling with a transect
- Set up transect along area to be sampled
- Place quadrat at regular intervals and count species / organisms within a species
- Determine abundance e.g. percentage frequency or percentage cover
- Repeat many times
- Calculate mean
How can representative samples be obtained when sampling?
- Unbiased method of selecting sample area e.g. random number generator
- Sample many times and calculate mean
- Standardised sampling procedure e.g. size of net, only count organisms completely in quadrat
- Use identification key
- Sample at different times/seasons.
Simpson’s diversity index equation
D = 1 - (n/N2)
n = number of individuals of a particular species
N = total number of individuals of all species
Outline the significance of a high value of Simpson’s Index of Diversity
- Many species present (high species richness)
- All species evenly represented (high species evenness)
- High biodiversity - More robust habitat
Outline the significance of a low value of Simpson’s Index of Diveristy
- Habitat dominated by only a few species
- Habitat is unstable
- Less likely to cope with change
Define genetic biodiverity
Differences in alleles within a population of a species
More alleles present = more genetically biodiverse
Explain the importance of genetic biodiversity
- Greater genetic biodiversity = more likely to adapt to changes in environment
- Less likely to become extinct
- Likely to be some organisms with advantageous alleles
- These organisms more likely to survive and reproduce
- Advantageous alleles passed onto next generation
What factors increase genetic biodiverity?
- Mutations in DNA create new alleles
- Interbreeding between populations increases gene flow
What factors decrease genetic biodiversity?
- Genetic bottlenecks - major event leads to only few individuals surviving - leads to small gene pool
- Selective breeding
- Natural selection - less advantageous alleles lost
- Captive breeding e.g. zoos
Define polymorphic gene
A gene with more than one allele e.g. human blood groups
Define monomorphic gene
A gene with only one allele - most genes are monomorphic genes
Define loci
The position of a gene on a chromosome
How is genetic biodiversity measured?
- Using the proportion of polymorphic gene loci in a population
- The greater the proportion, the greater the genetic biodiversity
How is the proportion of polymorphic gene loci in a population calculated?
Proportion of polymorphic gene loci = number of polymorphic gene loci / total number of loci
Why is human impact on biodiversity increasing?
- Population rapidly increasing
- Require more food, housing, resources etc
List human activities that can reduce biodiversity
- Deforestation
- Agriculture
- Pollution (climate change)
Explain how deforestation can reduce biodiversity
- Reduces number of trees
- Reduces species diversity
- Destroys animal habitat
Explain how agriculture can reduce biodiversity
- Removal of hedgerows destroys habitats and reduces prey for birds
- Monocultures reduce species diversity
- Removal of meadows reduces species diversity and habitats
- Pesticides and herbicides reduces species diversity
Explain how climate change could reduce biodiversity
- Global warming is melting polar ice caps - Could lead to extinction of species living in polar regions - Changes migration pattern of Arctic animals
- Rising sea levels could flood low lying land - Reduces terrestrial habitats - Salt water could reduce fresh water habitats in rivers
- Higher temperatures and less rainfall - Reduction in plant species - Xerophytes becoming more dominant - Impact on food chains
- Insect life cycles will change - Key pollinators of many plants - Could lead to extinction of plants - Greater spread of tropical diseases
Suggest how the excessive use of inorganic fertilisers can cause a reduction in biodiversity
- Fertiliser promotes growth of a few plant species
- Other plant species out-competed
- Leads to disruption of food chains
- Reduction in soil quality over time so plants cannot grow
Explain why a reduction in biodiversity may present problems for agriculture in the future
- Loss of genetic diversity in wild population
- Environmental requirements may change in future
- Lost alleles may have been useful to withstand change
Define keystone species
- Species that are essential for maintaining biodiversity
- Has disproportionately large effect on their environment relative to their abundance
Explain why keystone species are often predators
- Predators keep populations of prey at a consistent level
- Allows for balanced coexistence of other species
Why is it important to maintain biodiversity?
- Maintains complex, stable food chains
- Maintains variety of habitats for other organisms
- Ensures keystone species are not removed - avoids drastically changing habitat
- Aesthetic reasons e.g. natural beauty
- Economic reasons e.g. tourism
- Provides natural resources e.g. wood, medicine
Define in situ conservation
In natural habitat
Define ex situ conservation
Not in natural habitat
e.g. zoos, botanical gardens, seed banks
Define preservation
Protection of an area by restricting or banning human use
Give the benefits of in situ conservation in wildlife reserves
- Controlled grazing allows plant species to recover
- Human access restricted e.g. paths to prevent trampling of plants
- Control poaching of animals
- Reintroduction of species
- Removal of invasive species - ensure native species able to access resources
Give the benefits of in situ conservation in marine conservation zones
- Preserves species-rich areas e.g. coral reefs
- Control fishing areas and methods
What are the difficulties of setting up marine conservation zones?
- Large areas of sea required as aquatic species often move large distances
- Economic impact on fishermen
Explain why it is sometimes necessary to conserve a plant species outside of its natural habitat (et situ)
- Natural habitat lost due to climate change/human activity
- Number of plants in natural habitat is very low
- Reproduction is difficult in wild if numbers are low
- Breeding ex situ can maintain the gene pool
- Allows protection from grazers, plant collectors or competing species
- Protection from disease
What is the purpose of a seed bank?
- A store of plant genetic material
- Seeds dried and stored at cold temperatures to maintain viability
- Provides back-up against extinction
Why should the seeds of the same species in a seed bank be collected from several different sites in the wild?
- Maintains genetic variation in gene pool
- Reduces chance of future disease affecting the whole population
- Reduces chance of inbreeding
- Maintains geographical variation
Give advantages of conserving plant species as seeds and not as adult plants
- Can be collected with minimal damage to wild population
- Take up little space
- Can store greater genetic diversity
- Low maintenance costs
- Easier and cheaper to transport
- Remain viable for long periods
- Prevents fertilisation by undesired pollen
Explain why some species are conserved in captivity (ex situ) rather than in the wild (in situ)
- Protection from diseases or poisons
- Health of individuals monitored
- Reduced mortality of young
- Provision of mates
- Protection from hunting and predation
- Competition reduced between individuals and species
Why may organisms born in captivity not be suitable for release into the wild?
- May be loss of resistance to diseases present in wild
- Behaviour vital for survival in wild may not have been learnt
- Natural habitat may no longer be large enough to take more individuals
Discuss the advantages of captive breeding programs
- Maintains or increases endangered populations
- Allows for reintegration of species into its habitat
Discuss disadvantages of captive breeding programs
- Leads to loss of genetic diversity
- Leads to organisms not learning behaviours of their wild counterparts
- Genetic problems can occur in offspring due to inbreeding
- Can decrease the disease resistance of a population
State what CITES stands for
- Convention on International Trade in Endangered Species
What are the aims of CITES?
- Conservation of biodiversity
- Regulate trade of endangered species
- Ensure trade does not endanger wild populations
What are the aims of the Rio Convention on Biological Diversity?
- Sustainable use of organisms and habitats
- Share access to scientific knowledge and technology
- Promote international cooperation on biodiversity issues
- Promote ex situ conservation methods
What are the aims of the Countryside Stewardship Scheme?
- Sustain beauty and diversity of the landscape
- Improve, extend and create wildlife habitats
- Restore neglected land
- Improve opportunities for countryside enjoyment
Explain why local and international agreements can help preserve biodiversity
- Landowners have economic reasons for exploiting natural resources
- Exploitation leads to loss of biodiversity
- Financial incentives needed to replace income from exploiting a resource
- Animals do nor respect nation’s boundaries
- To preserve number of species in natural habitat
Define sustainable development
Economic development that meets the needs of the people today.
Without limiting future generations’ ability to meet their needs.
