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Population Ecology
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What is Ecology? Study of organisms, their environment and interactions Different types of ecology Not environmentalists!
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What is Ecology? Abiotic factors: –Water –Sun –Temperature –Wind –Soil –Disturbance
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What is Ecology? Organismal responses: –Physiological – acclimation –Anatomical –Behavioral
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Population Ecology Characteristics of Populations Described by demographics –Size –Age structure –Density –Dispersion pattern
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Dispersion – Clumped Common Patchy resources clumpedclumped
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Dispersion – Random Uniform conditions
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Dispersion – Uniform Harsh competition
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Determining Population Size Direct counts Sampling –Plants –Mark and recapture
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Changes in Population Size Adds: –Births – Immigration Subtract: –Death –emigration
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Exponential Growth
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Limits on Growth Environmental conditions Limiting factors: Predation, food supply, etc.
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Carrying Capacity (K) Sustainable resource supply for a population
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Logistic Growth As size of the population increases, rate of reproduction decreases When the population reaches carrying capacity, population growth ceases
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Density-Dependent Controls Disease, predation, competition, toxicity of waste
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Density-Independent Controls Natural disasters, climate events
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LE 18-20a Decreasing birth rate with increasing density
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LE 18-20b Increasing death rate with increasing density
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LE 18-22 Exponential growth Sudden decline
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Human Population Growth 6 billion Average annual increase is 1.26% Increase exponentially
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Human Population Growth
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Future Growth 2 Million yrs for population to reach 1 billion Only 12 yrs to reach 5 th billion 1.26% growth is not sustainable
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Ecological Footprints 16 14 12 10 8 6 4 2 0 02 4 68 121416 Available ecological capacity (ha per person) Ecological footprint (ha per person) Japan UK Spain Germany Netherlands Norway USA World China India Sweden Canada Australia New Zealand Figure 36.9B Traffic in downtown Cairo, Egypt Manhattan, New York City Refugee camp in Zaire Figure 36.9C
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Age Structure Diagrams Show age distribution of a population Rapid Growth Slow Growth Zero Growth Negative Growth
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Resource Consumption U. S. has 4.7% world’s population India has 16% U.S. uses 25% of processed minerals and energy and produces 25% of global pollution India is mere 3%
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Life History Patterns Patterns of survival and reproduction
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Survivorship Curves Graph of age-specific survivorship
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Type I – K selected
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Type II
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Type III – r selected
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Table 18.2
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Life Tables Population is divided into age categories Birth rates and mortality risks are calculated for each age category
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Table 18.1
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Life Tables
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Question of the Day
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