Transcript Environmental Biology & Genetics

Environmental Biology &
Genetics
Factors Affecting the Variety
of Species in an Ecosystem.
Biodiversity
Each species in a habitat or ecosystem
has its own role to play and this role is
called its niche, e.g. an owl would occupy
the niche of “small mammal-eating bird
of prey”.
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Biodiversity
Organisms from different niches have
special features which allow them to be
successful and these features are called
adaptations, e.g. behaviour, body
structure, etc..
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Darwin’s Finches
Charles Darwin investigated the finch
population of the Galapagos Islands in the
1830s.
On each island there is a
different food source.
He found that the beaks of
the finches there had
adapted to suit the diet of
the birds.
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Desert Plants
To survive in deserts plants have to
adapt to reduce water loss.
Roots go deep in the soil to
find water.
Leaves are reduced to
spines to reduce
evaporation.
Surfaces are covered with
a thick waxy cuticle.
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Biodiversity
Biodiversity is the range of species
which exists within an ecosystem.
A stable ecosystem:
Contains a wide variety of species.
Can exist for a very long time.
Is not affected by small changes.
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Biodiversity
Biodiversity is very important to humans
in a number of different ways:
Importance
Food
Medicines
Raw Materials
Recreation
Genetic material
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Example
Fish, wheat, etc
Morphine from opium poppy
Wood, cotton, etc..
Hill walking, diving, etc..
Disease-resistant crops
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Habitat Destruction
Human activities such as agriculture,
construction and industry have lead to
huge areas of natural habitat being
cleared.
This clearing has lead to the
destruction of habitats and has
drastically reduced the biodiversity of
these areas.
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Habitat Destruction
Deforestation occurs in many parts of
the world today, e.g. the Brazilian
rainforests.
This results in:
Erosion of the land and loss of fertility in
the soil.
Reduction in biodiversity.
Changes in climate.
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Habitat Destruction
Pollution results in such things as
acid rain being produced from sulphur
dioxide killing fish and trees.
untreated sewage being released into
rivers which causes the number of
invertebrate species to decrease.
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Habitat Destruction
These have lead to a “Biodiversity
Crisis” which is resulting in some species
becoming extinct, e.g.
Dodo
Black rhinoceros
Giant panda
Blue whale
Snow leopard
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Habitat Destruction
Grazing can also have a major effect on
biodiversity, e.g.
Over-grazing can lead to plant species
being destroyed.
Under-grazing can lead to a small number
of very vigorous plant species becoming
dominant.
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Behavioural Adaptations
All animals show behavioural
adaptations.
These are responses to changes in the
environment called environmental
stimuli.
Such responses are called behavioural
responses.
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Behavioural Adaptations
Examples of behavioural responses
include:
Sea anemones are responsive to touch.
Blowfly larvae are responsive to light.
Swallows are responsive to daylength.
Earthworms are responsive to vibrations.
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Behavioural Adaptations
These behavioural responses are
important to the survival of the
organism, e.g.
Woodlice move towards conditions which
are damp and dark and this is of “survival
value” because:
The damp conditions prevent the organisms
from drying out.
The darkness protects them from predators.
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Resources
Every species needs certain resources
(essential materials) from the
environment to survive.
E.g we need food, water, warmth and
shelter.
When any resource is in short supply
there will be competition for it.
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Competition
Competition occurs when a number of
organisms require the same resource.
Competition between members of the
same species is very intense because
they are competing for the same
resource.
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Competition
Competition between members of
different species is less intense
because they are not always competing
for the same resource.
In such cases a compromise is often
reached to reduce the competition.
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Competition
Plants compete for such things as:
Light
Space
Water
Nutrients
Animals compete for such things as:
A mate
Territory
Food
shelter
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