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16 Cards in this Set
- Front
- Back
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Endemism |
Species only found within a particular area, happens because organism evolves in an area and doesn't migrate out due to geographical restrictions |
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Example of endemism: Australia |
Marsupials (young in pouches) and monotremes (egg-laying mammals) unlike in rest of world where placental mammals dominate because these mammals evolved after Australia separated from the other continents |
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Biodiversity |
Variety of life: organisms and their alleles, and the ecosystems in which they live |
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Why is biodiversity important? |
Ecosystems interlink so natural balance is maintained by biodiversity e.g. photosynthesis stabilises atmosphere and transpiration influences rain fall. Biodiversity provides genetic diversity to cope with changes in selection pressures. Certain species can be useful e.g. plants which can be used as medicines |
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Keystone species |
Plant or animal that plays a unique or crucial role in the way an ecosystem functions. E.g. Sea otters eat the predators of Kelp forests, which enables kelp to grow and provide a home for many species |
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Biodiversity hotspots |
These are areas such as rainforests with a high level of species richness or places like Madagascar with lots of endemic species |
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Species richness |
The number of different species found within a habitat |
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Indicator species (bioindicators) |
A species in a habitat which is particularly susceptible to change, and so can be used to judge the balance of an ecosystem. |
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Comment on population size in relation to biodiversity |
If there aren't enough then there might not be a sustainable breeding population; small gene pool will be more likely to show up and there is less variety so changes in the environment can affect the whole population. Changes in keystone population numbers can affect the whole ecosystem |
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When to measure biodiversity? |
Time of day or season can affect number of organisms from a species present: wetland sites full in winter but relatively empty in summer |
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Quantitative sampling |
Use of quadrats, random, many different areas to increase reliability, limited by area of site and amount of randomness |
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Capture/recapture techniques |
Capture, mark and release animals; examine next batch of captured animals and determine proportion which have been marked; determine population size estimate based on this |
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Genetic diversity |
Analyse DNA and compare for similarities and differences. Low genetic diversity makes the population more susceptible to threats |
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Extinction |
The permanent loss of all members of a species due to change in habitat e.g temperature affecting food supplies or rising sea levels causing flooding |
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Critically endangered; endangered; vulnerable |
facing an extremely high risk of extinction in the wild; facing a very high risk of extinction in the wild; facing a high risk of extinction in the wild |
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Causes of extinction |
Habitat destruction due to road building, houses and crops; pollution e.g. pesticides (a particular problem in closed-water systems); hunting; new diseases or predators; climate change |
