Biodiversity Flashcards
(42 cards)
What is biodiversity?
1) Biodiversity — the variety of living organisms in an area.
What is a species?
2) Species — a group of similar organisms able to reproduce to give fertile offspring.
What is a habitat?
3) Habitat — the area inhabited by a species. It includes the physical factors, like the soil and temperature range, and the living (biotic) factors, like availability of food or the presence of predators.
What is Habitat diversity?
1) Habitat diversity — the number of different habitats in an area. For example, a particular area could contain many different habitats — sand dunes, woodland, meadows, streams, etc.
What is species diversity?
2) Species diversity — the number of different species (species richness) and the abundance of each species (species evenness) in an area. For example, a woodland
could contain many different species of plants, insects, birds and mammals.
What is genetic diversity?
3) Genetic diversity — the variation of alleles within a species (or a population of a species). For example,
the variation of alleles within the dog species gives rise to different breeds, such as a Labrador or poodle.
How can sampling be used to measure biodiversity?
1) Choose an area to sample — a small area within the habitat being studied.
2) Count the number of individuals of each species (see below).
3) Repeat the process — take as many samples as possible. This gives a better indication of the whole habitat.
4) Use the results to estimate the total number of individuals or the total number of different species in the
habitat being studied.
5) When sampling different habitats and comparing them, always use the same sampling technique.
You could investigate the impact of mowing on the biodiversity of your school playing field by sampling a mowed
and an un-mowed field. Calculate the biodiversity for each field using Simpson’s Index
Why do different organisms need different sampling methods?
How you find out how many individuals are in your sample area depends on the organism you are studying. E.g.
1) For crawling ground insects you could use a pitfall trap (a small pit that insects can’t get out of)
or a pooter (a device that allows you to safely suck small insects through a tube into a jar).
2) For small organisms that live in soil or leaf litter you could use a Tullgren funnel — this is where a soil or
leaf litter sample is put on a mesh filter at the top of a funnel and a light is shone down onto it. Organisms
move away from the heat created by the light and fall out of the funnel and into a collecting beaker.
3) For some aquatic organisms you could use kick sampling (you gently kick the bottom of a stream then use
a net to collect the organisms that have been disturbed).
4) For organisms living in long grass you could use a sweep net (a net lined with strong cloth on a pole).
Why can a sample be random/non
1) To avoid bias in your results, the sample should be random. For example, if you were looking at plant species
in a field, you could pick random sample sites by dividing the field into a grid using measuring tapes and
using a random number generator to select coordinates.
2) However, sometimes it’s necessary to take a non-random sample. E.g. when there’s a lot of variety in the
distribution of species in the habitat and you want to make sure all the different areas are sampled.
How many types of non random sampling are there?
3
What are the 3 types of non random sampling?
systematic
opportunity
stratified
What is a systematic sample?
1) Systematic — This is when samples are taken at fixed intervals, often along a line. E.g. if you were counting plant species in a field, quadrats (frames which you place on the ground) could be placed along a line (called a transect) from an area of shade in the corner to the middle of the field. Each quadrat would be a sample site.
Whats a opportunity sample?
2) Opportunistic — This is when samples are chosen by the investigator.
It’s used because it is simple to carry out, but the data will be biased.
What is a stratified sample?
3) Stratified — This is when different areas in a habitat are identified and sampled separately in proportion to
their part of the habitat as a whole. E.g. a heathland may have patches of gorse in it — the heath and gorse
areas would be sampled separately according to how much of each there was in the habitat.
What is species richness?
1) Species richness is the number of different species in an area. The higher the number of species,
the greater the species richness. It’s measured by taking random samples of a habitat (see previous page)
and counting the number of different species.
What is species eveness?
2) Species evenness is a measure of the relative abundance of each species in an area. The more similar the
population size of each species, the greater the species evenness. It’s measured by taking random samples
of a habitat, and counting the number of individuals of each different species.
what is simpsons diversity index?
1) Species present in a habitat in very small numbers shouldn’t
be treated the same as those with bigger populations.
2) Simpson’s Index of Diversity takes into account both
species richness and species evenness.
3) Simpson’s Index of Diversity (D) can be calculated using this formula.
4) Simpson’s Index of Diversity is always a value between 0 and 1.
The closer to 1 the index is, the more diverse the habitat.
The greater the species richness and evenness, the higher the number.
Simpsons equation
D=1- (Σ (n/N)^2)
n = Total number of individuals of one species N = Total number of organisms of all species Σ = ‘Sum of’ (i.e. added together)
Genetic Diversity Can be Assessed
Genetic Diversity Can be Assessed
1) You know from page 110 that genetic diversity is the variation of alleles
within a species (or within a population of a species).
2) You can do calculations to work out the genetic diversity of a population.
3) This is important because if a population has low genetic diversity, they might
not be able to adapt to a change in the environment and the whole population
could be wiped out by a single event (e.g. a disease).
4) Populations in which genetic diversity may be low include isolated populations
such as those bred in captivity (e.g. in zoos, and pedigree animals and rare breeds).
5) Calculations can be used to monitor the genetic diversity of these populations over time and efforts can be
made to increase the genetic diversity of the population if needed. E.g. breeding programmes in zoos are
very closely managed to maximise genetic diversity.
How is Genetic Polymorphism is Used to Measure Genetic Diversity
Genetic Polymorphism is Used to Measure Genetic Diversity
1) You know that alleles are different versions of a gene.
2) Alleles of the same gene are found at the same point (called a locus) on
a chromosome.
3) Polymorphism describes a locus that has two or more alleles.
4) Working out the proportion of polymorphic gene loci in an
organism (i.e. those points on a chromosome which can have
more than one allele) gives you a measure of genetic diversity.
5) There’s a nifty formula you can use:
Genetic Polymorphism equation?
proportion of polymorphic gene loci =
number of polymorphic gene loci/ total number of loci
Example:
If 40 of the genes sampled in a population are polymorphic out of
100 genes sampled in total, then the proportion of polymorphic gene loci =40/100
= 0.4
What 3 factors affect biodiversity?
Human population growth
increased agriculture
climate change
How does Human Population Growth affect biodiversity?
1) Human Population Growth
The human population of the planet has grown hugely in the last couple of centuries and is continuing to rise.
This is decreasing global biodiversity because of the following factors: )
Habitat loss — human development is destroying habitats, e.g. there is deforestation in the Amazon to make way for grazing and agriculture. This decreases habitat diversity.
2) Over-exploitation — a greater demand for resources (such as food, water and energy) means a lot of resources are being used up faster than they can be replenished. E.g. industrial fishing can deplete the
populations of certain fish species and may even cause extinction (a species to die out). This decreases genetic diversity within populations, as well as decreasing species diversity (as a result of extinction).
3) Urbanisation — sprawling cities and major road developments can isolate species, meaning populations are unable to interbreed and genetic diversity is decreased.
4) Pollution — high amounts of pollutants can kill species or destroy habitats, e.g. high levels of fertiliser flowing into a river can lead to a decrease in fish species in that river. This decreases biodiversity.
How does Increased Use of Monoculture in Agriculture affect biodiversity?
2) Increased Use of Monoculture in Agriculture
In order to feed an ever growing number of people, large areas of land are devoted to monoculture — the growing of a single variety of a single crop. E.g. in Africa, large areas of land are used for palm oil plantations. This leads to a decline in global biodiversity because of the following factors:
1) Habitats are lost as land is cleared to make way for the large fields, reducing habitat diversity.
2) Local and naturally occurring plants and animals are seen as weeds and pests, and so are
destroyed with pesticides and herbicides, reducing species diversity.
3) Heritage (traditional) varieties of crops are lost because they don’t make enough money and
so are not planted any more, which reduces species diversity.