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25 Cards in this Set
- Front
- Back
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What is in situ conservation? |
The conservation of species in their natural habitat |
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What is ex situ conservation? |
The conservation of species outside their natural habitat |
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What are the advantages & disadvantages of in situ conservation? |
* species live in their natural environment and occupy position in the food chain * animals remain wild * retaining the habitat ensures it remains available for other endangered species * develops local awareness * requires active management on site * requires necessary local legislation to receive funding |
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What are the advantages & disadvantages of ex situ conservation? |
* greater control of essential conditions (climate, diet, health) * improve reproduction success by using artificial methods * Animals lost natural behavior * Limited genetic gene pool * doesn't prevent the potential destruction of the natural habitat |
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Give examples to 3 ex situ conservation methods |
Captive breeding Botanical gardens Seed banks |
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What conservation efforts were made for the indian rhino? |
* Is critically endangered because of poaching and habitat loss * numbers increased thanks to captive breeding programs |
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What conservation efforts were made for the mountain chicken frog? |
* became critically endangered because of a fungal disease and threatened by local human consumption * Has been artificially bred in laboratories and reintroduced into the wild |
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What four factors determine population size? |
Natality Immigration Mortality Emigration |
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What is the capture-mark-release-recapture method? |
* a sample area is chosen randomly * a number of individuals are captured, marked and released (n1) * after sufficient time to allow marked individuals to reintegrate randomly, a second capture is made * both marked (n3) and unmarked (n2) individuals are marked * population size = (n1xn2)%n3 |
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What is the biotic potential? |
The maximum growth rate for a population |
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What is exponential growth? |
* Occurs when in an environment with unlimited resources and no competition * initial growth is slow as there's little reproductive individuals * eventually the population begins to grow exponentially |
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Define carrying capacity |
The maximum number of a population that can be sustainably supported by the enviorment |
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Describe logistic growth |
* After a short period of exponential growth, competition and insufficient resources to support the population slow the growth down * Eventually the growth plateaus when it reaches its carrying capacity |
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What are density dependent factors? |
Predators Availability of resources (shelter, water) Nutrient supply (food source) Disease Accumulation of waste |
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What are density independent factors? |
Phenomena (natural disasters) Abiotic factors (climate, CO2 levels) Weather conditions (floods, storms, etc) |
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Describe the stages in sigmoid growth curve (logistic growth) |
* Lag period - few reproductive individuals slowly reproduce * Exponential growth phase - as numbers accumulate, there is a rapid increase in population as natality exceeds mortality Mortality is low because of resource abundance * Transitional phase - as population growth, resources become limited and competition increases. mortality rates rise and natality falls * Plateau phase - the mortality and natality equals, population reaches carrying capacity |
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How can sigmoid population growth be modelled? |
By using simple organisms like yeast or duckweed * Can be populated in small easy to store containers * inexpensive to conduct, nutritional requirements are low * reproduce quickly |
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What is a top down control? |
Pressure applied by a higher trophic level to control the ecosystem dynamics Keystone species commonly exert top down control to prevent lower trophic levels from monopolising resources |
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What is a bottom up control?
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Pressure that limits availability of resources to lower trophic levels (producers). this eventually suppresses the abundance of organisms at higher trophic levels. |
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What are the effects of algal blooms on the ecosystem? |
* spread of algae blocks sunlight and reduces photosynthesis by plankton and seaweed * the reduction in light causes algae to respire, reducing levels of dissolved oxygen * when algae begin to die, an increase in bacterial decomposers further reduces oxygen levels * without enough oxygen, most aquatic organisms struggle to survive |
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How can bottom up control be used to limit algal blooms? |
* by limiting the supply of nitrogen and phosphorus in the water * this can involve reducing the use of fertilizers for farms to limit nutrient output from surface runoff * this is expensive and requires concentrated community effort |
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How can top down control be used to limit algal blooms? |
* by introducing fish eating fish (piscivorous) in the aquatic ecosystem * the piscivores feed on zooplanktivorous (plankton eating) fish * zooplankton increase, which feed on algae and reduce its population * introducing piscivores can have unexpected consequences on the food chain |
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Define maximum sustainable yield (MSY) |
The maximum amount of a natural resources that can be taken from the ecosystem without reducing the maximum yield in the future |
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What should the MSY be in commercial fishing? |
Half the carrying capacity of the species. Harvesting more than that will lead to overfishing and population decline over time |
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Give examples for sustainable fishing practices |
Population size * certain regions decalared as areas of conservation to prevent fishing Age * introducing mesh size restrictions to allow younger smaller fish to escape * using fish farms allows for control over age at which fish are harvested Reproduction * closed seasons to allow fish uninterrupted periods to breed * specific exclusion zones during breeding season to avoid fishing in breeding sites |
