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.