Unit 7 Test

Unit 7 Test - U nit 7 Test Study populations to learn about...

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Unit 7 Test Study populations to learn about o Evolution o Natural history of particular species o Wildlife management o Species conservation o Environmental impact assessment o Life insurance Attributes of populations o Size (number of individuals) Humans ames 51,500 Direct counting (aerial observation of large herd mammals) Random sampling and extrapolation Mark-recapture (species that move quickly or are often hidden from view) o Density (number of individuals per unit area) Affects intra-specific interactions (spread of disease) Affects inter-specific interactions (competition with other species for resources) o Dispersion (pattern of spacing of individuals) Clumped dispersion Suggests positive interactions: o Protection o Reproduction o Social structure o Habitat variability o Exhibited by most organisms, at least some of the time (advantages of groups frequently outweigh the disadvantages of competition) Uniform dispersion Indicates negative interactions o Competition for limited resources o Direct antagonism (territoriality in animals) Random dispersion Indicates lack of strong intra-population interactions- not common o Ferns on forest floor o Krill populations have decreased substantially since 1979 o Though to be a result of less sea ice due to global climate change and to commercial harvest of krill as food for fish farms o Could lead to very dramatic impacts on other species including various species of whales
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Population dynamics o Demography- the study of factors that control population size o Population growth- births and immigration o Population loss- deaths and emigration o Population change Population ecology focuses on the processes that cause population change Requires an understanding of Controls over birth rate Controls over death rate Describing population change o (delta)N/(delta)t= B- D= rmaxN N Change in the number of individuals T change in time B= births D= deaths o A more complete equation would require inclusion of immigration and emigration o Growth rate (r) = per capita birth rate- per capita death rate Effects the steepness of the exponential growth curve Maximum growth rate for a population= r Max Varies among species Influenced by: o Age at the beginning of reproduction o Number of young produced o Elapsed time between production of young o Survival rate of young o The exponential growth model assumes unlimited resources- never the case in the read world o There is always a limit to the number of individuals that can occupy a particular habitat called the carrying capacity (K) Community-a group of populations of different species living close enough to interact Biome- more general term o Community structure The diversity and abundance of species in a community depends on: Historical features (what seeds/animals are or were present or nearby) Landscape features Biotic factors (interactions with other species)
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This note was uploaded on 09/19/2011 for the course BIO 212 taught by Professor Mayfield during the Spring '10 term at Iowa State.

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Unit 7 Test - U nit 7 Test Study populations to learn about...

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