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Environmental Biology & Genetics
Factors Affecting the Variety of Species in an Ecosystem.
Mr G D
avidson
Mr G D
avidson
Thursday, April 13, 2023 2Mr G Davidson
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”.
Thursday, April 13, 2023 3Mr G Davidson
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..
Darwin’s FinchesCharles Darwin investigated the finch population of the Galapagos Islands in the 1830s.
Thursday, April 13, 2023 4Mr G Davidson
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.
Desert Plants
To survive in deserts plants have to adapt to reduce water loss.
Thursday, April 13, 2023 5Mr G Davidson
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.
Thursday, April 13, 2023 6Mr G Davidson
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.
Thursday, April 13, 2023 7Mr G Davidson
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
Thursday, April 13, 2023 8Mr G Davidson
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.
Thursday, April 13, 2023 9Mr G Davidson
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.
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.
Thursday, April 13, 2023 10Mr G Davidson
Thursday, April 13, 2023 11Mr G Davidson
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
Thursday, April 13, 2023 12Mr G Davidson
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.
Thursday, April 13, 2023 13Mr G Davidson
Behavioural Adaptations
All animals show behavioural adaptations.
These are responses to changes in the environment called environmental stimuli.
Such responses are called behavioural responses.
Thursday, April 13, 2023 14Mr G Davidson
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.
Thursday, April 13, 2023 15Mr G Davidson
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.
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.
Thursday, April 13, 2023 16Mr G Davidson
Thursday, April 13, 2023 17Mr G Davidson
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.
Thursday, April 13, 2023 18Mr G Davidson
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.
Thursday, April 13, 2023 19Mr G Davidson
Competition
Plants compete for such things as: Light Space Water Nutrients
Animals compete for such things as: A mate Territory Food shelter