T3.3 - Biodiversity Flashcards
State what is meant by the term biodiversity
The variety of organisms living in an area
Biodiversity can be assessed at what three levels?
Habitat
Species
Genetic
State what is meant by the term habitat.
The place where an organism lives
State what is meant by habitat biodiversity
The number of habitats in an area.
The UK has large habitat biodiversity e.g. deciduous forest, fen, heathland, sand dunes, moorland, marshland, peat bog, grassland etc.
The Antarctic has has very low habitat biodiversity
Explain the importance of habitat biodiversity to maintaining species biodiversity
Specific habitats are occupied by different organisms.
-The greater the number of habitats, the greater the species diversity.
- So habitat protection is important to maintain species biodiversity.
- Habitat loss is one of the biggest threats to biodiversity and the most common cause of extinction.
Give examples of habitat destruction
Deforestation
Ploughing natural meadows for agriculture
Draining wetlands and peat lands
creating dams
What two factors determine species biodiversity?
Species richness and evenness
What data is required to compare biodiversity of two sites?
Species richness and evenness of both areas
State what is meant by the term species richness
The number of different species found in the habitat
Why is species richness limited as a measure of biodiversity?
Species richness is the number of different species found in the habitat
It does not take into account relative abundance of each species
State what is meant by the term species eveness
The relative abundance of individuals of each species in a habitat
Name the formula used to measure biodiversity
Index of diversity
Simpson’s index - What is N, n, and Σ?
N = total number of organisms
n = number of individuals of a single species
Σ = sum of
What sampling method would you use to estimate the population of each species found in a habitat?
Random sampling using quadrants
What is the significance of a high value of D?
High values of D signify:
high biodiversity
Many different species + many organisms
Environment is not stressed, with more ecological niches
Complex food webs
Habitat is stable - able to withstand change
What is the significance of a low value of D?
low values of D signify
Low biodiversity
Few different species
Environment is stressed, with fewer ecological niches
Simple food webs
Habitat is unstable - small changes cause more damage
Explain why extinction will reduce biodiversity
Biodiversity depends on the number of species.
Extinction will reduce the number of species as well as ones that depend on them
What are keystone species?
A species which has a disproportionately large effect on ecosystem stability relative to its abundance due to their role in the ecosystem e.g an apex predator
Explain what is meant by the term endemic
The ecological state of a species being unique to a defined geographic location (having evolved there)
State what is meant by the term invasive species
A species that has been introduced (non-indigenous) into an environment and typically causes ecological or economic harm
Explain what effect invasive species have on biodiversity
Causes either competition or predation so reduces biodiversity
Explain why higher genetic diversity results in lower chance of extinction
Species that contain greater biodiversity are more likely to be able to adapt to changes in the environment, because there is more likely to be some individuals that carry an advantageous allele, which enables them to survive the altered condition
Explain how genetic diversity can be increased
● Mutations in DNA create new alleles
● Gene flow/migration transfers of alleles between populations due to interbreeding between individuals of different populations.
Explain how genetic diversity can be decreased
● Selective breeding increases the frequency of the allele coding for the desired traits, decreasing frequency of allele coding for undesirable traits
● Natural selection selects against alleles coding for less
advantageous characteristics, which are lost from population
● Gene bottlenecks – few individuals survive an event or change (disease, natural disaster etc), thus reducing the gene pool. Only alleles in surviving population can be passed on.
● Founder effect– small no of individuals create new colony, geographically isolated from rest, so gene pool of new population is low.
Explain the effects of low genetic diversity
Species is less able to respond to environmental change, as it is less likely an individual has an advantageous allele, this is results in a higher risk of extinction.
There is an increase in genetic disorders and infertility due to inbreeding.
How is genetic biodiversity measured?
Measure the proportion of polymorphic genes.
What are polymorphic genes?
Genes that have more than one allele
How is the proportion of polymorphic genes calculated?
Number of polymorphic gene loci / total number of gene loci.
Explain the economic reasons for maintaining biodiversity
Ecosystem services are provided by bio diverse ecosystems e.g. regulation of atmosphere and climate, formation and fertilisation of soil so we can grow food, recycling of nutrients, growth of timber, food and fuel, safe and stable water supplies.
There would be additional costs to humanity if we had to provide these services without the help of natural, healthy ecosystems.
Explain the ethical reasons for maintaining biodiversity
Species become extinct as a result of human action.
Humans have a responsibility to maintain species, ecosystems and habitats for future generations.
All organisms have a right to survive and live in the way to which they have become adapted.
List some human activities that reduce biodiversity
Hunting
Agriculture (monoculture, farming)
Diverting water
Mining resources
Over-harvesting
Agriculture
Pesticides
Habitat destruction e.g. deforestation
Introducing invasive species
Combustion of fossil fuels as causing global warming
Explain how different agricultural practices (farming methods) reduce biodiversity
Woodland clearance - done to increase area of farmland - it directly reduces the number of trees and different tree species, which also destroys habitats, shelter and food sources for other species.
Hedgerow removal - done to increase area of farmland (by turning lots of small fields into fewer large fields) - it directly reduces the number of trees and different tree species, which also destroys habitats, shelter and food sources for other species.
Pesticides - used to kill pests that feed on crops - this directly kills the pests and reduces a food source for consumers that feed on them, reducing their number too.
Herbicides - used to kill unwanted plants (weeds) - this
reduces plant diversity and could reduce numbers of herbivores that feed on them.
Mono culture - when farmers only grow one type of plant species - this reduces biodiversity directly and will support fewer organisms (e.g. as a habitat or food source).
State what is meant by the term endangered species
Species that have such small numbers that they are at risk of extinction
Little genetic variability leaves them susceptible to genetic and infectious diseases
State what is meant by the term conservation
The protection and management of a species and habitats in order to maintain biodiversity
State what is meant by in situ conservation
Protection of species within their native habitat by conservation of natural habitats and ecosystems; involves active management of nature reserves or national parks.
Describe the advantages of in situ conservation
● Species left in the protected area have access to their natural resources and breeding sites
● Species will continue to develop and evolve in their natural habitat thus conserving their natural behaviours
● Allows conservation of a greater number of species at once.
● Animals have more space than in captivity.
● Preserves unrecognised (undiscovered) species
● Protects larger breeding populations
● Active management controls invasive species
● Can control human exploitation
● legal protection for endangered species
● Opportunities for research
● restoration of degraded areas
● less expensive and requires fewer specialised facilities than captive breeding.
Give some examples of active management strategies
● Culling alien or damaging species
● Fire-clearing areas to kill invasive species
● Legal measures against human impacts
● Legal protection for endangered species
● Replanting or reintroducing endangered species
Describe the disadvantages of in-situ conservation
● Controlling human exploitation is difficult
● Habitats that shelter in-situ populations may need extensive restoration, including pest eradication and ongoing control.
● Populations may continue to decline during restoration.
● There may not be enough suitable habitat to maintain wild populations e.g. due to habitat destruction by humans, or large territory requirements (e.g. tigers).
● Human-wildlife conflict, especially in rural Africa; animals may still be hunted in-situ (poaching) even in national parks and reserves, as human populations grow they come into conflict as farms border
natinal parks and animals destroy crops / use same water sources, putting animals and humans in danger.
State what is meant by ex situ conservation
Protection of species outside their natural habitat;
Animals are cared for in zoos
Plants are cared for in botanical gardens/seed banks
When is ex-situ conservation used?
When a species has become critically low in numbers (critially endangered) or when in-situ methods have been unsuccessful.
Describe the role of botanical gardens like Kew Gardens in London in conserving plants species
They collect seeds from the wild, store the seeds and germinate them in protected conditions, increasing the number of individuals of a species very quickly.
State the role of seed banks in conserving plant species.
Store seeds from an endangered plants in dormant state
Explain why seeds instead of whole plants are stored
● Less space is required so more species can be held in the available space
● Most plants produce large numbers of seeds so collecting small samples is unlikely to damage the wild population
● They are easier to store because they are dormant
● It is more cost effective
Explain how seed banks are operated
1) Seeds are collected from a number of individual plants - to ensure high genetic diversity
2) Seeds are x-rayed to check for fully formed embryos - to ensure only viable seeds are stored.
3) Seeds are dried to remove water - to increase storage time.
4) Seeds are stored in the cold e.g. -20°C - to increase storage time.
5) Some seeds are periodically germinated to check for viability - to check systems are working and take action if not.
Explain the advantage of selecting differently sized seeds
Different sized seeds are likely to have more chance of having different alleles
Genetic diversity means there is less chance of all being susceptible to the same diseases as there is a higher chance of an advantageous allele being present
Describe the roles that zoos play in conserving animals.
1) Protection - protect animals from poachers / hunting / predators, they are protected from disease as have access to vet care including vaccinations and medicines, they have a safe habitat, food and water.
2) Re population - increase numbers of species using breeding and reintroduction programmes.
3) Education - they increase public awareness of endangered species and conservation.
4) Research - increase knowledge of breeding & life cycles, better nutrition and health, and develop genetic databases.
Describe the disadvantages of zoos
● Animals suffer stress and boredom due to confinement
● Change behaviour as habitat differs
● Certain species favoured e.g. lions but not rodents!
● Captive breeding programs may not successfully release animals back into the wild
● Removing individuals from the wild will further endanger the wild population
● People can observe wildlife in the wild or visit a sanctuary
● Conservation more successful in situ / in a reserve
Describe how zoos use captive breeding programmes to help conserve rare species.
● They increase the number of individuals of endangered species
● Studbooks are used to monitor births, deaths, select individuals for mating, keep a record of breeding events and any transfer of individuals
● Animals are selected to prevent breeding between closely related individuals to prevent inbreeding depression
● Animals / gametes are exchanged between zoos to maintain heterozygosity in offspring
Explain how breeding programmes in zoos maintain the genetic diversity of captive populations.
● Studbooks are used to monitor births, deaths, select individuals for mating, keep a record of breeding events and any transfer of individuals
● Animals are selected to prevent breeding between closely related individuals to prevent inbreeding depression
● Animals / gametes are exchanged between zoos to maintain heterozygosity in offspring
What are the issues with reintroduction programmes?
● Need to release into protected natural habitat e.g. National Parks otherwise dangers still exist e.g. habitat destruction, lack of resources, poaching
● Captive bred animals show behaviour that may make them unable to compete in the wild e.g. unable to hunt / find food
● Low numbers in wild lead to inbreeding depression
(E.g. Borneo - habitat destruction continues, only 2% forest protected. Will only support limited no. of orangutans. Increased competition for food. Dangers of poaching and hunting remain)
