The document discusses factors that affect biodiversity in ecosystems, including species niches, adaptations, habitat destruction, and competition for resources. It provides examples of how Darwin's finches and desert plants adapted to their environments. Habitat destruction from human activities like agriculture, construction, pollution and overgrazing has reduced biodiversity by destroying habitats and causing species extinction. All animals exhibit behavioral adaptations to environmental stimuli that help their survival, like woodlice moving to damp dark places. Competition for essential resources occurs between members of the same and different species.

1. Environmental Biology &
Genetics
Factors Affecting the Variety
of Species in an Ecosystem.
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2. 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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3. 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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4. 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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5. 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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6. 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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7. Biodiversity
Biodiversity is very important to humans
in a number of different ways:
Importance Example
Food Fish, wheat, etc
Medicines Morphine from opium poppy
Raw Materials Wood, cotton, etc..
Recreation Hill walking, diving, etc..
Genetic material Disease-resistant crops
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8. 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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9. 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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10. 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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11. 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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12. 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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13. 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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14. 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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15. 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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16. 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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17. 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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18. 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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19. 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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