Environmental Biology & Genetics

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Environmental Biology Genetics

• Factors Affecting the Variety of Species in an
  Ecosystem.

Mr G Davidson
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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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Darwins 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

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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