PopulationsEcology - Number at or around carrying capacity...

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1 Chapter 34 Populations in Ecology Units of Ecology Populations Communities Ecosystems Biosphere Population Members of a species living in one defined area Community All the populations in a defined area Ecosystem Community plus nonliving elements that interact with it (weather, geology, chemistry) Biosphere All the life on Earth, plus the physical environment it interacts with
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2 Exponential Growth Under ideal conditions, populations can double and redouble very quickly Carrying capacity In the real world, exponential growth is limited by resources (space, food, clean water, etc.) Carrying capacity, K, is the maximum sustainable population Intrinsic Rate of Increase r = rate at which a population would grow without external limits Factors: generation time, number of offspring, typical death rate, etc. Equilibrium vs. Opportunity K-selected (equilibrium) species
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Unformatted text preview: Number at or around carrying capacity Large, long-lived, few offspring but much care r-selected (opportunist) species Fluctuating numbers Small, short-lived, many offspring & little care 3 Survivorship curves Population Pyramids Show percent of population in each age range Wide base = large pre-reproductive population Predictive of future growth Industrial Revolution Birth rates have fallen, but death rates fell more Medical advances Improved sanitation Increased food production Human population grew exponentially for a while, but may be starting to level off 4 Some countries have had dramatic fertility changes Pressure of human population The growing number of people is related to most of todays environmental threats Habitat loss Global warming Water scarcity...
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PopulationsEcology - Number at or around carrying capacity...

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