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Lecture 22

# Lecture 22 - When food is unlimited r is at a maximum(r max...

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BIOLOGY 1001: LECTURE 22 POPULATION ECOLOGY: POPULATION GROWTH AND REGULATION EVOLUTIONARY TIME - time spans long enough for changing gene frequencies to produce conspicuous changes in morphology or behavior. ECOLOGICAL TIME - time spans measured in months or years. POPULATION ECOLOGISTS - study the size, structure and distribution of populations of particular species. COMMUNITY ECOLOGISTS - study the relationships between different species coexisting in a single habitat. ECOSYSTEMS ECOLOGISTS - study the interaction between species through the overall flow of energy and the cycling of materials in the physical environment. Population size depends on: Birth, Immigration, Death, Emigration In a closed system (e.g. island, test tube, planet): r= annual per capita growth rate = annual per capita birth rate - annual death rate
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Unformatted text preview: When food is unlimited, r is at a maximum (r max = a population's INTRINSIC RATE OF INCREASE). Population increase will be EXPONENTIAL (accelerating) and is given by: dN/dt = r max N whereN = population size t = time If resources are limiting, population growth is DENSITY DEPENDENT and follows a LOGISTIC (s-shaped) curve which is given by: dN/dt = r max N(K-N)/K where K = carrying capacity (maximum population size) if N << K, growth will be rapid (exponential) if N = K, growth will stop if N > K, population size will decline Human population growth can be decreased by: 1.Improved contraception 2.Lowering preferred family size 3.Increasing age of first reproduction...
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