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ecological terms

3 Pages

Course Code
BIL 118
O' Sullivan

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Ecological Terms  Ecosystem: all the abiotic and biotic factors in an area/environment surrounding a species  Community: "all the organisms present in an area/habitat/ecosystem"1  Population: "all the individuals of one species in an area"2  Environment: sum of all conditions in the ecosystem outside the organism  Habitat: place within an ecosystem where a particular population is found  Niche: species' function in its habitat o Two species occupy different niches when they NOT compete  Feeding at different times on different organisms o "Two species NO LONGER occupy the same niche when  one species displaces other species (better adapted)/one species survives/none survive due to  competition (for environmental resources)/insufficient  food, territory, mates (animals); light, CO2, H2O, mineral ions (plants)"2 Investigating Numbers and Distribution Investigating Variation  Several samples eliminate chance and anomalies (eg three averaged readings)  Random sampling eliminates bias (favour of one type) o Random coordinates achieved by calculator  Any differences must reflect real differences in the population of sampled data Frame Quadrats  Three measurements can be taken / population size of a particular species occupies in a quadrat  Assumptions o Stationary organisms / must not move o Quadrats must be chosen randomly o Sample represents whole population  To investigate an area o Area is divided into a grid by measuring tapes o Quadrats are chosen at random by using random numbers from a calculator o Organisms under investigation are counted in each quadrat  To investigate a volume o Container of known volume is immersed at random points in the pond o Number of tadpoles are counted each time  Limitation: Area being studied is much larger than the small quadrats  POPULATION SIZE = (Sorganisms per quadrat * A of field)/A of quadrat) o S = Sum of; A = Area; Line Transects  Measures distribution of species in a straight line across a habitat  Useful for identifying changes in a habitat  Records all species which touch a tape stretched acros
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