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What is biodiversity?
Variety of living organisms present in an area,. includes plants, animals, fungi and other living things within and between species of ecosystems.
Why is maintaining biodiversity important?
Essential in maintaining a balanced ecosystem for all organisms.
Provide us with food, oxygen, medicines and other materials we need to survive.
All species are interconnected- if one part of the food web changes it will affect other areas.
Why do we need to measure biodiversity?
Plays an important role in conservation, the effects of any changes to the environment can be measured (may include the effects of human activity, disease or climate change).
To research different levels of biodiversity in an area.
What is an Environmental Impact Assessment (EIA)?
Must be undertaken to attempt to predict the positive and negative effects of a future project on biodiversity, biodiversity is studied at different levels:
Habitat
Species
Genetic
What are the three different levels of biodiversity?
Habitat biodiversty
Species biodiversity
Genetic biodiversity
What is habitat biodiversity?
Refers to the number of different habitats found within an area. Each habitat can support a number of different species.
For example, the UK is home to many habitats like meadows, woodlands, streams and sand dunes. In contrast Antarctica is almost entirely an ice sheet and has very low habitat biodiversity.
What is species biodiversity?
There are two different components to species biodiversity:
Species richness- number of different species in an area
Species evenness- Comparison of the number of different species living in a community.
What is a community?
All the populations of living organisms in a particular habitat.
What is genetic biodiversity?
Refers to the variety of genes that make up a species.
For many genes, different versions (alleles) exist, this leads to genetic biodiversity within a species.
This can lead to some different characteristics being exhibited and allows for better adaptation to the environment- individuals are more likely to be resistant to disease.
What is sampling?
Taking measurements of a limited number of individual organisms present in a particular area.
The number of individuals of a species present in an area is known as the abundance of an organism.
Sampling can be random or non-random.
What is random sampling?
Selecting individuals by chance, each has an equal likelihood of being selected. To decide what organisms to study, random number tables or computers can be used, you should have no involvement.
What is non-random sampling?
The sample is not chosen at random, and can be divided into three main categories. These are:
Opportunistic
Stratified
Systematic
What is opportunistic sampling?
The weakest form of non-random sampling, may not be representative of the whole population and only uses organisms that are conveniently available.
What is stratified sampling?
Populations divided into a number of strata (sub-groups), based on a particular characteristic. Random sample is then taken from each of these strata proportional to its size.
What is systematic sampling?
Different areas within an overall habitat are identified, these are then sampled separately. Often carried out using a belt or line transect:
Line transect- Marking a line across the ground between two poles and taking samples at specified points.
Belt transect- Provides more information, two parallel lines are marked, samples are taken of the area between the two lines.
Why might a sample be less reliable?
A sample is never truly representative of the organisms present in a habitat, this may be due to the following:
Sampling bias- the selecting process may be biased, this may occur by accident or deliberately. This can be reduced by using random sampling, where human involvement is removed.
Chance- organisms selected may, by chance, not be representative. Its effects can be reduced by using a large sample size, which is more reliable.
What are the different methods of sampling animals?
Pooter- used to capture small insects by sucking on a mouthpiece, insects are drawn into a holding chamber, there is a filter before the mouthpiece to prevent them from being sucked into the mouth.
Sweep nets- used to catch insects in areas of long grass.
Pitfall traps- used to catch small crawling invertebrate like slugs, spiders and beetles. A hole is dug into the ground, which insects fall into, it is deep enough so they cannot crawl out and is covered by a propped above roof structure. Normally left overnight so nocturnal species can also be sampled.
Tree beating- used to take samples of invertebrates living in trees or bushes, a large white cloth is stretched out under a tree which is then shaken to dislodge the invertebrates.
Kick sampling- used to study organisms living near a river. The bank and bead are ‘kicked’ for a period of time to disturb the substrate. A net is held downstream to capture organisms flowing in the water.
What are the different methods of sampling plants?
Point quadrat- a frame containing a horizontal bar, at set intervals along the bar, long pins can be pushed through it to reach the ground. Each species if plant the pin touches is then recorded.
Frame quadrat- consists of a square frame divided into a grid of equal sections. Type and number of species within each section is then recorded.
To study how the distribution and presence of a species varies, a quadrat is placed systematically along a line or belt transect.
Describe how a frame quadrat can be used to measure the density, frequency and percentage cover of a population.
Density- if individual large plants can be seen clearly, count the number of them in a 1m by 1m square quadrat. This gives the density per square metre which is not an estimate.
Frequency- used where individual members are hard to count, like moss or grass. Using the small grids within a quadrat, count the number of squares a particular species is present in.
Percentage cover- used for speed as lots of data can be collected very quickly, useful when a particular species is abundant or difficult to count. A estimate by eye of the area within a quadrat that particular plant species covers.
Samples should be taken at a number of different points, the larger the sample the more reliable the results. The mean of the different quadrat results should also be calculated, to get an average value for a particular organism per m2.
How can we estimate animal population size in an area?
It can be difficult to accurately determine an animals population size so a technique called ‘capture-mark-release-recapture’ is used.
It involves capturing as many individuals as possible, marking them, and then releasing them back into the community. Time is allowed for them the redistribute themselves before another sample is collected.
Comparing the number of marked individuals with the number of unmarked individuals in the second sample gives an estimated population size.
The greater the number of marked individuals recaptured, the smaller the population.
Why do we measure abiotic factors in an area?
Non-living conditions in a habitat have a direct effect on the living organisms.
To understand the conditions needed for a species survival,, these conditions are usually measured at every sample point.
Many abiotic factors can be measured quickly and accurately using a range of sensors, this is an advantage because:
Rapid changes can be detected
Human error is reduced
High degree of precision can often be achieved
Data can be stored an tracked on a computer
What are some examples of abiotic factors?
wind speed
light intensity
relative humidity
pH
temperature
o2 content in the water
What is Simpson’s Index of Diversity (D) used to calculate?
A measure of biodiversity that takes into account both species richness and evenness.
When using SI the population size usually has to be estimated first using a variety of sampling techniques.
It always results in a value between 1 and 0, where 0 represents no diversity and 1 represents infinite diversity. The higher the value the more diverse the habitat.
Why is genetic diversity important?
Within a species individuals have very little variation within their DNA.
All members of a species have the same genes however some individuals may have different versions (alleles) of theses genes.
The differences in alleles creates genetic diversity in the population. The more alleles present, the more genetically diverse the population.
Greater genetic diversity allows species to adapt to changes in their environment and hence are less likely to become extinct.
This is because the individuals in the population carry an advantageous allele which allows them to survive in the altered conditions.
How does genetic diversity in a population increase and how does it occur?
For genetic diversity to increase, the number of possible alleles in a population must also increase, this can occur through:
Mutations in the DNA creating a new allele.
Interbreeding between different populations, transfers the alleles between the two populations- this is known as gene flow.
How does genetic diversity in a population decrease and how does it occur?
For genetic diversity to decrease, the number of alleles in the population must also decrease, this can occur through:
Selective breeding (artificial selection), only a few individuals in a population are selected for their advantageous characteristics and bred.
Captive breeding programmes like zoos or conservation centres where only a small number of captive individuals are available to breed. Often the wild population is endangered or extinct.
Rare breeds where selective breeding has been used to produce a breed of domestic animal or plant with characteristics that then become less popular, so the numbers of this breed will fall quickly.
Artificial cloning (asexual reproduction), like using cuttings to clone a farmed plant.
Natural selection, species will evolve to contain primarily the alleles that code for advantageous characteristics.
Genetic bottlenecks, a few individuals survive an event or change, thus reducing the ‘gene pool’, only the alleles of surviving members are passed onto offspring.
The founder effect where a small number of individuals create a new colony that is geographically isolated from the original, the resulting gene pool is therefore very small.
Genetic drift, due to the random nature of alleles being passed on from parents, the frequency of occurrence of an allele will vary.
How is genetic biodiversity measured?
One way is through measuring polymorphism, polymorphic genes have more than one allele. Therefore genes that only a single allele exists for are monomorphic. The proportion of genes that are polymorphic can be measured using:
proportion of polymorphic gene loci= number of polymorphic gene loci/ total number of loci.
The greater the proportion of polymorphic gene loci, the greater the genetic biodiversity of the population.
What is the loci?
Loci of a gene refers to the position of the gene on a chromosome.
How is increasing human population affecting biodiversity?
The population is growing at a dramatic rate because of improvements in medicine, hygiene, housing and infrastructure. But to create enough space for these improvements, humans are severely disrupting the ecology of many areas as a result of:
Deforestation
Agriculture
Climate change
How is deforestation affecting biodiversity?
Deforestation is the permanent removal of large areas of forest to provide wood for building and fuel (logging). Most occurs deliberately through human action but also through acid rain.
It greatly reduces the number of trees in an area.
If only one species is felled the species diversity is reduced.
Reduces the number of animal species present in an area as it destroys their habitat, including their food source and home.
Animals may be forced to migrate to other areas to ensure their survival which may increase the biodiversity of surrounding areas.
How is agriculture affecting biodiversity?
An increasing amount of land is cleared to feed the increasing population, they often only grow one species of crop (monoculture).
Farmers grow one kind of crop to give a high yield, which is the most economically effective for them.
This causes deforestation as large areas of land are cleared to grow this crop.
Hedgerows are also removed due to mechanisation and to create more space for planting which disturbs the habitat of many animals that live there.
Use of chemicals such as pesticides and herbicides reduces the species diversity of an area as it destroys the pests but also indirectly disturbs the food source of other animals.
herbicides, used to kill weeds reduces plant diversity but also animal diversity as the weeds may be a food source.
Monoculture, the production of only one crop that takes up many acres of land greatly reduces the overall biodiversity levels of an area.
How is climate change affecting biodiversity?
Global warming is a direct effect of climate change and refers to the rise of tech Earth’s mean surface temperature, if global warming continues biodiversity will be affected, for example:
Melting polar ice caps could lead to the extinction of the few plant and animal species living in these regions. The shrinking of the habitat and increasing temperature could allow temperate plant and animal species to live further north.
Rising sea levels from melting ice caps and thermal expansion of ocean could flood low-lying land and could flood habitats and rivers.
Higher temperatures and less rainfall could result in some plant species failing to survive, leading to drought-resistant xerophytes becoming more dominant.
Insect life cycles and populations will change which could cause their range to change which could mean some plants will not be pollenated and may go extinct.
What are the aesthetic reasons for maintaining biodiversity?
The prescence of plants and animals in out environment enriches our lives.
The natural world provides inspiration for people like musicians and writers who provide pleasure for many through music and books.
Studies have shown that patients can recover more rapidly from stress and injury when supported by the natural environment.
What are the economic reasons for maintaining biodiversity?
Continuous monoculture results in soil depletion- a reduction in the diversity of soil nutrients. The crop takes the same nutrients out of the soil year after year and is then harvested. This makes the ecosystem more fragile, so the crops it can support will be weaker, increasing vulnerability to opportunistic insects, plant competitors and microorganisms.
The farmer will therefore become increasingly more dependent on expensive pesticides, herbicides and fertilisers in order to maintain productivity.
What are the ecological reasons for maintaining biodiversity?
Some species play a key role in maintaining the structure of an ecological community, these are known as keystone species.
Keystone species have a disproportionately large effect on their environment relative to their abundance. They affect other organisms and help to determine the species richness and evenness in the community.
When they are removed the habitat is drastically changed, all other species are affected and some may disappear all together, it is therefore essential to protect them.
How does human activity increase biodiversity?
Natural habitats can be created by human intervention and the management of land.
Farming, grazing, planting of hedges, meadows and forest management have changed the landscapes, the habitats and the ecology over thousands of years.
Farmers and landowners contribute to the management of ecosystems.
What is conservation?
The name given to the preservation and careful management of the environment and of natural resources, conserving a natural habitat gives the organisms living in it the best chance at survival.
What are the two different categories of conservation?
In situ conservation- within the natural habitat
Ex situ conservation- out of the natural habitat
What is sustainable development?
Economic development that meets the needs of people today without limiting the ability of future generations.
Explain how wildlife reserves are an example of in situ conservation.
Once an areas has been designated as a wildlife reserves, active management is required, techniques may include:
Controlled grazing- only allowing livestock to graze a particular area of land for a certain period of time to allow species time to recover.
Restricting human access.
Controlling poaching- creating defences to prevent access, issuing fines.
Feeding animals- helps to ensure animals reach reproductive age.
Reintroduction of species- adding species that have become locally extinct, or whose numbers have decreased significantly.
Culling or removal of invasive species- organisms that are not native to the area might have negative effects on the economy, environment or health. They compete with native species for resources.
Halting succession- succession is a natural process in which early colonising species are replaced over time until a stable mature population is reached.
Explain marine conservation zones are an example of in situ conservation.
Marine reserves are vital in maintaining species-rich areas such as coral reefs, which are being devastated by non-sustainable fishing methods.
The purpose is not to prevent fishermen from visiting the entire area, but to create areas of refuge, within which populations can build up and repopulate adjacent areas.
Explain how botanic gardens are an example of ex situ conservation?
Plant species can be grow successfully in botanical gardens.
Here the species is actively managed to provide them with the best resources to grow such as soil nutrients, sufficient watering and the removal or prevention of pests.
Explain how seed banks are an example of ex situ conservation?
Seed banks are an example of gene banks- a store of genetic material. Seeds are carefully stored so that new plants may be grown in the future.
They are dried and stored at temps of -20 degrees centigrade to maintain their viability. This slows down the rate at which they lose their ability to germinate.
This provides a back up against the extinction of plants.
However this does not work for all plants as some seeds die when dried and frozen, like most tropical rainforest trees.
Explain how captive breeding programmes are an example of ex situ conservation?
They produce offspring of species in a human-controlled environment and are often run by zoos or aquatic centres.
Aim to create a stable, healthy population of a species, and then gradually reintroduce the species to the habitat.
Captive programmes provide the animals with shelter, abundant supply of nutritious food, an absence of predators and veterinary treatment.
However, maintaining genetic biodiversity within a captive population can be difficult due to the small numbers of breeding partners available.
Some may not be suitable for the wild.
Why might organisms born in captivity not be suitable for the wild?
Diseases- there may be a loss of resistance to local diseases and new diseases in the wild that they are yet to develop resistance to.
Behaviour- some is innate but most is learned through copying or experience which captive animals dpo not have.
Genetic races- the genetic makeup of captive animals can become so different to the wild population that they can no longer interbreed.
Habitat- the natural habitat may need to be restored to allow the captive populations to be reintroduced so they do not have to fight over limited territory or food with existing populations.
How does the International Union for the Conservation of Nature (IUCN) help to conserve biodiversity?
Assist in securing agreements between nations by publishing the Red List which details the current conservation status of threatened animals. Countries can then work together to conserve these species.
Also involved in the establishment of the Convention on International Trade in Endangered Species (CITES), which regulates international trade of wild plant and animal specimens and their products.
This helps to prevent over-exploitation.
How has the Rio Convention helped with conservation?
Convention on Biological Diversity (CBD), requires countries to develop national strategies for sustainable development ensuring the maintenance of biodiversity.
United Nations Framework Convention on Climate Change (UNFCCC) between nations agreement to stabilise greenhouse gas concentrations in the atmosphere.
United Nations Convention to Combat Desertification (UNCCD), prevents fertile land being transferred to desert and reduce the effects of drought.
What was the Countryside Stewardship Scheme?
Operated in England from 1991-2014, and offered governmental payments to farmers and landowners to conserve the English landscape.
Some aims included:
sustaining the beauty and diversity of the landscape
improving, extending and creating wildlife habitats
restoring neglected land and conserving historic features
improving opportunities for countryside employment
