Chapter 11- Biodiversity Flashcards
What is biodiversity and its importance?
Biodiversity refers to the variety of living organisms present in an area.
- important for maintaining a balanced ecosystem for all organism as all species are interconnected and depend on one another.
Explain the general level of biodiversity in different areas.
Tropical,moist regions that are warm all year have the most biodiversity.
Very cold areas (eg Arctic), or very dry areas (deserts) have the least biodiversity.
- generally the closer a region to the equator, the greater the biodiversity.
Why is measuring biodiversity important?
Plays an important role in conservation.
It informs scientists of the species that are present, providing a baseline for the level of biodiversity in an area.
- from this info, the effect of changes in the environment can be measured.
What is EIA?
Before a major project is undertaken, such as building a new road or the creation of a new reserve, an Environmental Impact Assessment is undertaken.
- it attempts to predict the +ve and -ve effects of a project on the biodiversity of that area specifically.
What are the levels biodiversity can be studied at?
- habitat biodiversity.
- species biodiversity.
- genetic biodiversity.
Habitat biodiversity.
Refers to the number of different habitats found within an area.
- each habitat can support a number of different species.
- the greater the habitat biodiversity, the greater the species biodiversity will be in that area.
Meadow, woodland, stream, sand dunes > high habitat biodiversity
Species biodiversity.
Has two components:
1. Species richness- number of different species living in particular area.
2. Species evenness- a comparison of the numbers of individuals of each species living in a community.
Therefore an area can differ in its species biodiversity even if it has the same number of species.
What is meant by community?
All the populations of living organisms in a particular habitat.
Genetic biodiversity.
Refers to the variety of genes that make up a species.
- many of these genes are the same for individuals within a species.
- however for some genes, different versions (alleles) exist.
- this leads to genetic biodiversity within a species which can lead to different characteristics being exhibited
Greater genetic biodiversity within a species allows for better adaptation to a changing environment and is more likely to result in individuals who are resistant to disease.
What is sampling?
Sampling means taking measurements of a limited number of individuals organisms present in a particular area.
- can be random or non-random.
What can sampling be used for?
- to estimate the number of organisms in an area without having to count them all. Number of individuals of a species in an area= abundance of organism.
- to measure a particular characteristic of an organism (eg. Height).
After measuring a sample, you can use results to make generalisations or estimations throughout the entire habitat.
Random sampling.
Means selecting individuals by chance.
- each individual in the population has an equal probability of selection.
- random number tables or computers can be used.
Non random sampling.
Sample is not chosen at random. It can be divided into 3 techniques: 1. Opportunistic. 2. Stratified. 3. Systematic.
Opportunistic sampling.
Uses organisms that are conveniently available.
- weakest form of sampling as it may not be representative.
Stratified sampling.
Some populations can be divided into a number of strata (sub-groups) based on a particular characteristic.
- a random sample is then taken from each of these strata, proportional to the size.
Systematic sampling.
Different areas within an overall habitat identified.
They are then sampled separately.
Often carried out using a line or belt transect:
- line transect: involves making a line between two poles and taking sample at specified points.
- belt transect: provides more info. Two parallel lines marked, and sample is taken of the area between the two lines.
Reliability of sampling.
A sample is never entirely representative of the organisms present in a habitat due to :
- sampling bias- selection process may be biased. Could occur accidentally or deliberately. Can be reduced by using random sampling.
- Chance- the organism selected by chance may nit be representative of the whole population. Cannot be eliminated but can be reduced by using large sample size.
Factors that increase genetic biodiversity?
For genetic biodiversity to increase, no of alleles in a population must also increase. Can occur through:
1. Mutations in the DNA of an organism, creating a new allele.
2. Interbreeding between different populations. When an individual moves from one population and breeds with a member of another, alleles are transferred between the 2 populations.
= known as gene flow.
Factors that decrease genetic biodiversity?
In order for genetic biodiversity to decrease, the no of alleles in population must also decrease. Can occur through:
- Selective breeding/ artificial selection- only a few individuals within a population are selected for their advantageous characteristics and bred.
- Captive breeding programmes- only a small number of captive individuals are available for breeding.
- Artificial cloning/ asexual reproduction.
- Natural selection- species evolve to contain primarily the alleles coding for advantageous characteristics.
- Genetic bottlenecks- few individuals of a species survive an event, reducing the genetic pool.
- Founder effect- small no of individuals create new colony. Genetic pool for this new population is small.
- Rare breeds- selective breeding has been historically used to produce less popular characteristics so numbers fall dramatically.
- Genetic drift.
How can genetic biodiversity be measured?
By measuring polymorphism- polymorphic genes gave more than one allele.
-Most genes are monomorphic (single allele exist for this gene).
Proportion of polymorphic gene loci = no. of polymorphic gene loci / total number of loci.
- the greater the proportion of polymorphic gene loci, the greater the genetic biodiversity within the population.
What is meant by locus?
Loci = plural.
Loci of a gene refers go its position on a chromosome.
What factors of human activity affect biodiversity?
- Deforestation- permanent removal of large areas of forest to provide wood for building and fuel, and to create space for roads,building and agriculture.
- Agriculture- an increasing amount of land has to be farmed in order to feed the growing population. This results in large amounts of land being cleared.
- Climate change- release of carbon dioxide and other pollutants from the burning of fossil fuels have led to increasing global temperatures.
How does deforestation affect biodiversity?
- directly reduces number of trees in an area.
- if only a specific type of tree is felled, the species diversity is reduced.
- reduces the number if animal species present in an area as it destroys their habitat, including their food source and home. This reduces no of other animal species present, by removing their food source.
- animals are forced to migrate to other areas to ensure their survival. May result in biodiversity of neighbouring areas increasing.
How does agriculture affect biodiversity?
- Deforestation- to increase the area of land available for growing crops or rearing animals.
- Removal of hedgerows- reduces number of plant species in an area and destroys habitats of animals like black birds and hedgehogs.
- Use of chemicals like pesticides and herbicides.
- Monoculture- Farms specialise in one species of crop over large acres of land
Lowers plant biodiversity (low species richenss) as its unlikely that many animal species can be supported by one crop.
How does a tullgren funnel and kick sampling work?
Tullgren Funnel:
-Used to extract invertebrates from soil or leaf littter
-Place the sample in a funnel above the perforated disk
-Shine a bright light over the funnel
-Rise in temp. and drying effect will force the organisms to move and fall through the disc into a collecting funnel (takes 2-3 days)
Insects land into a preservative liquid such as alcohol
Kick Sampling: Studies organisms in rivers.
River bed/bank is kicked to disturb substrate, a net is held downstream to capture flowing dislodged organisms
State the 5 animal sampling techniques.
- Pooter
- Sweep Nets
- Pitfall Trap
- Tullgren Funnel
- Kick Sampling
How do pitfall traps,sweep nets and a potter work.
Pitfall Traps: Catch small crawling insects. Dig hole in ground, deep enough so insects cannot crawl out. Have a roof-prop above the hole. Leave trap overnight (for nocturnal). Sample
Sweep Nets: They catch insects in areas such as long grass.
Pooter: 2 tubes present inside a chamber. One connceted to the insect habitat, one in your mouth. Both feed into a tube, suck on it to draw insects in
State and describe the 2 plant sampling methods.
Point Quadrat: Uses a frame with a horizontal bar. Long pins along the bar can be pushed into the ground. Each species of plant touching the pin is recorded
Frame Quadrat: Square frame, divided into a grid. Type and number of species in each section is recorded
How is species richness measured?
Use a combination of techniques to identify all species in a habitat
Produce a list of the species and calculate the total number of species.
Identification keys are used – help scientists identify organisms – may contain images, or a series of questions based on the presence of characteristics to identify the species.
How is species evenness measured?
Identify the number of each species to decide the evenness of species spread in a habitat.
Describe the 3 ways to sample using a frame quadrat.
Density – count number of plants in 1m by 1m square quadrat – gives density per m2 - an absolute measure, not an estimate.
Frequency – used where individual members of species are hard to count (e.g. grass). Use frame quadrat, in each grid count the number of plant species present. If there are, for e.g. 65 clovers present in 100 squares, there is an estimate 65% coverage.
Percentage cover – used for speed, useful when a species is abundant or hard to count. Eye estimate of the area within a quadrat a plant covers
Describe the method used to estimate animal population size.
Animals are constantly moving through their habitat, so counting them is difficult
Capture-mark-release-recapture is used:
– capture as many individuals of a species as you can, mark them in a way that doesn’t harm the animals, or inhibit their survival chances, then release them.
This gives them time to redistribute. Capture as many as you can again.
The greater the number of marked organisms recaptured, the smaller the population
Define abiotic factor and give some examples.
Non-living conditions of a habitat. {light intensity; water; pH; temperature etc.}
What are the advantages of using accurate sensors?
- Rapid changes can be detected
- Reduced human error
- High precision degree
- Data can be stored and tracked for analysis
How can biodiversity be calculated?
Simpsons index of biodiversity(D)
D = 1-Σ(n/N)^2
n = total number of organisms of a particular species N = total number of organisms present
Always gives a value between 0 and 1:
1 represents infinite biodiversity, 0 represents no biodiversity.
What does a high Simpson’s Index number represent?
High biodiversity High species richness High species evenness Stable habitat and can survive disruption Worth conserving
What does a low Simpson’s Index number represent?
Low biodiversity
Habitat dominated by one or a few species
Unstable habitat, may be damaged if there is disruption
Could be a man made habitat
Effect of climate change on biodiversity?
- melting of polar ice caps: may lead to extinction of the few animal/plant species living here.
- rising sea level as result of ^ : could flood low lying land, reducing available terrestrial habitats.
- high temps and less rainfall: will lead to xerophytes becoming more dominant. Loss of non drought resistant species will lead to loss of the animal species dependent on them.
- insect life cycles and populations will change as they adapt to climate change.
