Reasons for conservation programmesSpec 20.4.7, 20.4.9
Reasons for conservation programmes
- Maintaining or increasing biodiversity, so that there are many species in an area.
- Reducing extinction, because extinction is permanent.
- Protecting vulnerable ecosystems, such as rainforests and coral reefs, which are easily damaged.
- Maintaining ecosystem functions: nutrient cycling and resource provision, including food, drugs, fuel and genes.
Nutrient cycling relies on decomposers and a variety of organisms. Resource provision means ecosystems supply food, medicines (drugs from plants), fuel such as wood, and genes in wild species that may be useful for breeding crop plants and livestock or for genetic engineering.
Risks of reduced population size
When the population of a species decreases, genetic variation is reduced because there are fewer different alleles in the population. This brings risks:
- Fewer individuals have alleles that give resistance to a new disease, so the disease can kill most or all of the population.
- If the environment changes, there may be no individuals with features suited to the new conditions, so the species is less able to adapt and survive.
- Related individuals are more likely to breed together, which can increase inherited disorders.
Link the small population to the loss of variation, then to what happens when the environment changes or disease arrives. Genetic drift is not required.
Quick check
Define a sustainable resource.
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One which is produced as rapidly as it is removed from the environment so that it does not run out.
Give four reasons why species become endangered or extinct.
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Any four of: climate change, habitat destruction, hunting, overharvesting, pollution, introduced species.
What is a seed bank?
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A store of seeds from rare plants, kept so that the plants can be grown again if wild populations are lost.
Supplement Why does a small population have a greater risk of dying out?
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Less genetic variation, so fewer individuals may survive disease or environmental change.
Supplement Why does a larger mesh size help conserve fish stocks?
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Young fish escape and can grow and breed.