B3.5

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Population size and ecosystems
Tiffany Gama
Mind Map by Tiffany Gama, updated more than 1 year ago
Tiffany Gama
Created by Tiffany Gama over 3 years ago
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Resource summary

B3.5
  1. Factors in an ecosystem that affect all living organisms constantly change
    1. ecosystems are dynamic
      1. intensity of energy flowing through ecosystem varies
        1. biological cycles vary mineral availability
          1. nitrogen cycle
            1. habitats change overtime as succession occurs
              1. new species arrive
                1. some no longer present
      2. number of individuals in a population changes
        1. birth rate
          1. increases population
          2. death rate
            1. decreases population
            2. immigration
              1. increase population
              2. emigration
                1. decrease population
              3. different strategies for population growth are used by different species
                1. depends on their characteristics
                  1. fugitive species
                    1. poor at competition, rely on a large capacity for reproduction and disposal to increase their numbers
                      1. invade a new environment rapidly
                        1. algae colonising bare rock
                    2. equilibrium species
                      1. control their population by competition within a stable habitat
                        1. usual pattern of growth is sigmoid curve
                          1. one-step growth curve
                            1. bacteria put into fresh nutrient solution
                            2. 1. lag phase
                              1. period of slow growth, adaptation/adjustment to environment, intense metabolic activity
                                1. enzyme synthesis, sexual maturity
                              2. 2. log/exponential phase
                                1. no factors limiting growth, constant cell division, more individuals reproduce
                                  1. can't be maintained
                                    1. environmental resistance
                                      1. less food, conc of waste products becomes toxic, space
                                        1. overcrowding, competition
                                      2. abiotic factors
                                        1. temperature, light intensity
                                        2. biotic factors
                                          1. predation, parasitism, disease, competition
                                    2. 3. Stationary phase
                                      1. number of cells being produced = number of cells dying
                                        1. max carrying capacity
                                          1. population fluctuates
                                            1. no. of predators
                                      2. 4. death/decline phase
                                        1. factors that slow population growth becomes more significant
                                          1. population decreases
                              3. abundance of prey limits the number of predators
                                1. controls number of prey
                                  1. predator-prey relationship causes both populations to oscillate
                                    1. regulated by negative feedback
                                    2. lynx and snow-shoe hares
                                      1. large numbers of lynx predate hares
                                        1. population decreases
                                          1. not enough food for lynx
                                            1. population decreases
                                              1. less predation on hares
                                                1. population increases
                                                  1. more prey for lynx
                                                    1. population increases
                                              2. llustrates how population numbers at the carrying capacity can depend on the number in other species
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