SNAB topic 4- Biodiversity and natural resources

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Unit 4
Biodiversity and natural resources
A species is:
A species is a group of organisms with similar morphology, physiology and behaviour,
which can interbreed to produce fertile off spring, and which are reproductively isolated
(in place, time or behaviour) from other species.
Habitat and community:
A habitat can be thought of literally as the place where an organism lives. Each habitat has
a particular set of conditions which supports a distinctive combination or organisms.
Within a habitat there may be many populations of organisms.
Each population is a group of interbreeding individuals of the same species found in an
area. The various populations in an area make up a community .
A niche can be defined as `the way an organism exploits (uses) its environment'
Each species occupies a particular niche, often referred more fully as an ecological niche
If two species live in the same habitat and have the same role in the habitat they occupy
the same niche and will compete with each other. The betteradapted organism will
outcompete the other and exclude it from the habitat.
This happened to the red squirrel when the North American grey squirrel was introduced
to England in the nineteenth century. The native red squirrel has been outcompeted and
replaced by the grey squirrel in much of England.
Orchid niches:
The niches of some orchids exploit the behaviour of insects as part of their highly
specialised pollinating mechanisms.
Some orchids are so specialised that they can only be pollinated by one species of insect.

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Adapted to their environment:
Features which enable organisms to survive are called adaptations. Adaptations can be classified
as one of the three below and can sometimes overlap:
1. Behavioural adaptations behavioural adaptations are any actions by organisms which
help them to survive or reproduce e.g. plants moving their leaves towards the sun
2. Physiological adaptations physiological adaptations are features of the internal workings
of organisms which help them to survive or reproduce e.g.…read more

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Evolution by natural selection:
Evolution is more precisely defined as `a change in allele frequency in a population over
time (generations)'.
An allele can be selectively neutral (has no advantage or disadvantage) but suddenly
become selectively very advantageous when the environment changes.
The fundamentals of the theory are summarised in the table below:
1 A population has some naturallyoccurring genetic variation with new alleles created
through mutations.…read more

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`Biodiversity' is a shortened form of the words `biological diversity'. Biodiversity is used in
everyday language to mean the variety of life, and in particular the wealth of different
species that exists as a result of natural selection.
In biological terms it refers to the variety of species that belong to every different group of
organisms, animals, plants, fungi, bacteria and other microorganisms, living in all the
habitats on the planet.
Biodiversity also refers to the diversity within a species.…read more

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A hierarchical system:
Placing organisms into groups based on shred features, known as classification or
taxonomy , results in a manageable number of categories and has been the principal aim
of all classification systems.
A taxonomic hierarchy is created. This is a series of nested groups or taxa (singular taxon),
in which the members of all share one or more common features or homologies .…read more

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Biodiversity within a species:
Individuals within a species differ from one another and show variation.
This genetic diversity, and the greater the variety of genotypes the more genetically
diverse the population. Genetic diversity allows the population to adapt to changing
conditions so should be conserved.…read more

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Genetic diversity may be visible:
Sometimes genetic differences within a species show up clearly in the external
Much genetic variation has no visible effect on phenotype. It is made up of molecular
differences which can only be detected using techniques such as gel electrophoresis or
proteins; two alleles at a single locus produce slightly different protein products.
However, these differences may be important in evolutionary terms.…read more

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Endemic species:
An endemic species is one whose habitat is restricted to a particular area. The term could
refer to an animal, a plant, a fungus, or even a microorganism.
Endemic species are often endangered, and particular examples may become a focus
point for campaigns to protect biodiversity in a given environment. Some have become
national, or regional, emblems.
Measuring genetic diversity within a species:
Genetic diversity can be measured directly or indirectly.…read more


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