Environmental Biology & Genetics Factors Affecting the Variety of Species in an Ecosystem. M r G D a v i d s o n

Wednesday, June 11, 20142Mr 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.

Wednesday, June 11, 20143Mr 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..

Darwins Finches Charles Darwin investigated the finch population of the Galapagos Islands in the 1830s. Wednesday, June 11, 20144Mr 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. Wednesday, June 11, 20145Mr 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.

Wednesday, June 11, 20146Mr 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.

Wednesday, June 11, 20147Mr G Davidson Biodiversity Biodiversity is very important to humans in a number of different ways: ImportanceExample FoodFish, wheat, etc MedicinesMorphine from opium poppy Raw MaterialsWood, cotton, etc.. RecreationHill walking, diving, etc.. Genetic materialDisease-resistant crops

Wednesday, June 11, 20148Mr 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.

Wednesday, June 11, 20149Mr 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. Wednesday, June 11, Mr G Davidson

Wednesday, June 11, Mr 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

Wednesday, June 11, Mr 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.

Wednesday, June 11, Mr 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.

Wednesday, June 11, Mr 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.

Wednesday, June 11, Mr 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. Wednesday, June 11, Mr G Davidson

Wednesday, June 11, Mr 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.

Wednesday, June 11, Mr 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.

Wednesday, June 11, Mr G Davidson Competition Plants compete for such things as: Light Space Water Nutrients Animals compete for such things as: A mate Territory Food shelter