All of the individuals of a given species that live and reproduce in a

All of the individuals of a given species that live

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All of the individuals of a given species that live and reproduce in a particular place Population size is the number of individuals alive at a particular time in a particular place and is influenced by: Births, deaths, immigration and emigration We will ignore migration in BIOL 241
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© 2019 Population Growth We can study the change in the total numbers of individuals in a population We can track both the birth rate (b) and death rate (d) in a population We can use the per capita growth rate (r) to predict population size changes
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© 2019 Exponential Model of Population Growth Under ideal conditions: 1. The per capita growth rate will be at a maximum: 2. r max is To determine the size of a population growing exponentially, we can use: N t = N 0 (1 + r max ) t F 29.10
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© 2019 r max Varies by Species F 29.11
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© 2019 Organisms Don’t Live Under Ideal Conditions What limits population growth? Most environments can only support a certain population density =
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© 2019 r Changes with N in Logistic Population Growth F 29.12a
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© 2019 Logistic Model of Population Growth As populations grow, death rates increase and birth rates decrease r is influenced by the fraction of K available: r = r max ((K-N t )/K) F 29.12b
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© 2019 Do Populations Show Logistic Growth? F 29.13
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© 2019 Calculating Logistic Growth K = 1000 N 0 = 100 r max = 0.15 What is the population size one generation later? We have to first determine the value of r: r = r max ((K-N t )/K) Now we can determine N 1 : What is the population size after a second generation?
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© 2019 Density-Dependent Factors Influence Population Growth Density-Independent Factors Influence Population Growth
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© 2019 F 29.14 Crowding (Density-Dependent) Influences: Growth Rate Adult Size Survival
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© 2019 F 29.15 Crowding (Density-Dependent) Influences: Reproduction
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© 2019 The birth-death balance in pea aphids on alfalfa plants -Ives (1998; in Ecology; ed. Dodson et al. ; Oxford Univ. Press; pg 242) (b) (d)
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© 2019 F 29.18 Density-Independent Factors Influence Population Growth
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© 2019
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© 2019 Life History Strategies Influence Population Growth r-Selected Species (r strategists) K-Selected Species (K strategists)
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  • Spring '14
  • Reid, Topic 12 - Population Growth

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