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genetic diversity
- the total genetic information contained within all the individuals of a species
- it is measured as the number and relative frequency of all alleles present in a species
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species diversity
- is based on the variety of species on Earth
- measured by quantifying the number and relative frequency of species in a particular region
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ecosystem diversity
the array of biotic communities in a region along with abiotic components, such as soil, water, and nutrients
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endemic species
species that are found in an area and nowhere else
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invasive species
- species that are nonnative competitors, diseases, or predators
- grow to large population size
- disrupt species native to the area
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endangered species
species which are almost certain to go extinct unless effective conservation programs are put in place
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factors that cause endangerment
- 1. habitat loss - most important factor in terrestrial environments
- 2. invasive species
- 3. overexploitation - dominant problem for marine species
- 4. pollution - dominant problem for freshwater species
- 5. native species interactions
- 6. natural causes
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problems with habitat fragmentation
- 1. it can reduce habitats to a size that is too small to support some species
- 2. it reduces the ability of individuals to disperse from one habitat to another
- 3. creates large amounts of "edge" habitat (subject to invasion by weedy species and are exposed to more intense sunlight and wind)
- 4. large drop in biomass or the total amount of fixed Carbon
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strategies of a lasting solution to the biodiversity crisis
- 1. sustainability - the managed use of resources at a rate only as fast as the rate at which they are replaced
- 2. stabilizing human population size and resource use
- 3. ex situ conservation - the preservation of species in zoos, aquaria, wildlife ranches, seed banks, or other artificial settings
- 4. ecosystem restoration
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ecology
the study of how organisms interact with each other and their environment
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biotic factors
living things that organisms interact with--all the organisms that are part of the individual's environment
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abiotic factors
non-living things organisms interact with--all the chemical and physical factors, such as temperature, light, water, and nutrients, that influence the distribution and abundance of organisms
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ecosystem
all of the organisms within a given area as well as the abiotic factors with which they interact
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niche
- the sum of a species' use of biotic and abiotic resources in its environment (range of resources it can use and range of conditions it can tolerate)
- the presence or absence of a particular species depends on whether its niche requirements are met
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species richness
the number of different species in an environment
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biodiversity
the totality of genes, species, and ecosystems in a region. These three levels describe different aspects of living systems and are measured in different ways
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Manipulative experiment
- you manipulate the independent variable and then look for an effect on the dependent variable
- your controls make sure that any effect you observe actually occurs as a result of your manipulation of the independent variable
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Non-manipulative or correlational studies
- you look for naturally occurring differences in the independent variable and then see if the dependent variable changes in relation to the independent variable
- limitation of this kind of study is that it is harder to demonstrate a causal relationship
- use controls to reduce this limitation
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