Biodiversity

• Levels of biodiversity

  Habitat

  Number of different habitats in an area, the greater the habitat diversity the more species you will find there

  An area with a variety of natural habitats will support greater biodiversity than for example a farm field
• Levels of biodiversity

  Species

  Measure of number of species- species richness- and the number of individuals of each species- species evenness

  If an area has high species richness (lots of different species) and high species evenness (lots of individuals of different species) then it would have high species biodiversity
• Levels of biodiversity

  Genetic

  Refers to the variety of genes with a species

  Many of these genes will be identical in all individuals in a population but some will show variation

  A high genetic biodiversity indicates species with many polymorphic genes- many genes with more than one version in the population

  High genetic biodiversity in a species allows the species to adapt to environmental changes
• Random sampling

  -Sample sites within a habitat are selected at random and each area has an equal chance of getting selected

  -Random number generators or computers can be used to select random coordinates within the habitat to see which areas to study in detail

  -The results from this can be used to estimate the biodiversity of the entire habitat

  Advantage- unbiased

  Disadvantage- areas my be unrepresentative of the whole area and may be inaccurate

  -This can be fixed by increasing the sample size
• Non-random sampling

  Opportunistic- organisms are chosen to be sampled as they are conveniently available

  Advantage- easier than random sampling

  Disadvantage- may be bias, an overestimation is likely

  Stratified- if a habitat is not uniform but has several distant areas this ensures that you take samples of each subgroup proportional to its size

  Systematic- this is used when investigating how factors changes over an environmental gradient, you would sample on intervals along a transect
• How to measure species biodiversity

  The species richness can be measured using sampling techniques and a list of all species found can be made and the total number of species counted

  The species evenness can be measured by making a list of species present and how many individuals of each species are found

  If all species present are found in equal numbers the species evenness is high
• Use of Simpson's index

  The biodiversity of a habitat is often measured to asses the health of a habitat

  An area with high biodiversity, one with lots of species all well represented will indicate a stable ecosystem

  Stresses such as pollution can lower the biodiversity as fewer species are able to survive

  One way to measure it is the Simpson's index-

  D= 1-(∑ (n/N)2)

  n= the number of organisms of a particular species

  N= the total number of organisms found in all species together
• How genetic biodiversity may be assessed

  Members of the same species share the same genes but there can be different alleles

  The more alleles the higher the genetic biodiversity

  High genetic biodiversity allows the species to adapt to changes to environment

  Genetic biodiversity increases if there is a mutation creating a new allele or when individuals move round and interbreed with other populations causing gene flow
• How genetic biodiversity can be assessed

  Various mechanisms to bring low genetic biodiversity

  Selective breeding (when humans only allow certain individuals to breed)

  Captive breeding programmes (in zoos when there only small number of individuals are able to breed together)

  Rare breeds (when there are low numbers of a previously fashionable breed)

  Artificial cloning (when a cutting is taken to reproduce a plant asexually as it has good qualities)
• How genetic biodiversity is assessed

  Various mechanisms to bring about low genetic biodiversity

  -Stabilising selection (a form of natural selection where the environment and alleles are not advantageous and lost in the population)

  -Genetic bottlenecks (when an event has catastrophic effect on the population killing of many leaving just a few individuals)

  Genetic drift (random changes in allele frequencies due to small population)
• How genetic biodiversity is assessed

  We can measure genetic biodiversity by measuring polymorphism

  Polymorphic genes are ones where there is more than one allele in a population

  Proportion of polymorphic gene loci=

  Number of polymorphic gene loci/total number of loci (x100)

  The locus (plural loci) of a gene is the position of a gene on a chromosome
• Factors affecting biodiversity

  The term extinction refers to the point where the last individual of a species dies so the species no longer exists

  Diversity naturally increases over time and then some catastrophe reduces it for a while

  Now the world is losing plant and animal species

  It will soon approach previous mass extinction rates but there is a difference between the current and previous extinctions

  Physical events caused them in the past but now its humans
• Factors affecting biodiversity

  Deforestation

  Most is caused deliberately by humans to harvest wood or use the land to make room for housing or agriculture

  This destroys the habitat of many species reducing diversity of plants that are moved and animals that use them for shelter
• Factors affecting biodiversity

  Agriculture

  An increasing amount of land is converted to agricultural use

  Farmers tend to grow a very small number of species

  They will grow as many as they can to maximise yield and income (monoculture)

  Many practices in agriculture have knock on effects like deforestation and removal of hedgerows to make it easier for machinery to access the land

  Herbicides and pesticides are also used
• Factors affecting biodiversity

  Climate change

  Global warming is the mean surface temperature and related to human activity

  Carbon dioxide levels in the atmosphere have increased trapping thermal energy in the atmosphere, this effects biodiversity

  -Arctic species adapted to live in conditions are having to move further north to survive

  -Low lying lands are flooded due to rising sea levels removing some habitats
• Factors affecting biodiversity 


  Other human activities affect biodiversity-

  -Pollution- alters the environment and therefore reducing available habitats for species

  -Preditiation of species- we preditate species for food (overfishing) or other resources

  -Killing for protection- we kill species that pose a threat to human health

  -Invasive species- we introduce into a new area where they are not native which outcompete native species
• Reasons for maintaining biodiversity

  Ecological

  Organisms show interdependence, they cannot live in isolation they depend on other species for existence

  Some species in a community are known as keystone species

  These are species that has a disproportionately large effect on the ecosystem compared to their abundance

  If they are removed then the whole system can change
• Reasons for maintaining biodiversity

  Economic

  Humans rely on a biodiverse ecosystems

  When biodiversity falls due to deforestation and soil erosion and denitrification can occur which decreases the ability of a country to grow crops

  Monoculture can also lead to soil erosion and depletion of nutrients, the plant doesn't die and give nutrients back to the soil, it is framed so farmers are dependent on fertilisers

  High biodiversity can also protect against changing environments e.g., irish potato famine
• Reasons to maintain biodiversity

  Economic

  We also rely on many species to provide us with resources.

  Unsustainable harvesting of trees will lead to the eventual collapse of the timber industry and negative effect on economy

  Many medicinal drugs originate from wild species which may give lage economic benefits in the future

  Ecotourism can be big business and large economic gains
• Reasons to maintain biodiversity

  Aesthetic

  Presence of plants and animals leads to enriched life

  Many people take pleasure in walking in natural environments

  Natural environments can be inspiration to artists

  People recover better in nature
• Conservation

  In situ

  This takes place in the natural habitat of an organism

  Often focus on species that are endangered or vulnerable to extinction

  Aims to protect the habitat of these species enabling them to continue to exist in the wild interacting with other species

  Includes nature reserves, the active management includes

  -Controlling grazing and poaching

  -Restricting human access

  -Feeding animals

  -Reintroducing species

  -Culling of invasive species

  -Halting succession
• Conservation

  Ex situ

  This involves removing species from its habitat carrying out conservation activities in order to maintain or increase the numbers in the wild

  Botanical gardens give plants ideal conditions for growth

  Seed banks- seeds can be made to enter dromany when they are neither growing nor dying

  Seeds need to be kept cold and dry then they can survive for hundreds of years
• Conservation

  Ex situ

  Zoos- captive breeding programmes of rare and endangered species and conduction of research that is beneficial

  Provide animals with shelter food medicines and absence of predators and mates

  If a mate is not available they can be imported from other zoos or seamen sent for artificial insemination

  Often populations in zoos are small and problems of interbreeding can occur

  To try counter this international records of breeding animals and relationships in zoos are kept
• Conservation

  Zoos- reintroduction to the wild can face difficulties

  -They may be endangered because of their habitat, poaching if the habitat has not been re-established then its pointless

  -Animals born in captivity may-

  Not know how to find food or hunt

  May no longer be fearful of humans potentially putting then at risk of poaching or not know how to be fearful of predators

  -Animals may not breed in their natural environment as they may not have learnt mating behaviours

  -Bred away from natural environment my have not been exposed to natural pathogens
• Conservation agreements

  International

  International union for the conservation of nature (IUCN) secures agreements between countries

  It publishes a Red List annually that documents all the species that are endangered or at risk

  This enables countries to work together on more at risk species

  They also established CITES which regulates the trade and safeguards the most vulnerable species from exploitation
• Conservation agreements

  International

  Nations met at the Earth Summit, Convention on Biological Diversity (CBD) was agreed which ensures nations develop strategies on sustainable development to ensure maintenance of biodiversity
• Conservation agreements

  Local

  Countryside Stewardship Scheme

  Payments were made to farmers and landowners in order to enhance and conserve English landscapes. Aims-

  -Improve natural beauty and diversity of the countryside

  -Enhance, restore and re-create targeted landscapes their wildlife habitats and historical features

  -Improve opportunities for public access