Bio1b Summer 2008 Ecology Lecture 4 Eric Harris Page 1 of 2 Updated on 06/30/08 ECOLOGY LECTURE 4: POPULATION BIOLOGY II - GROWTH AND REGULATION Reading: 7th ed., 1143–1158; 8th ed., 1181–1197. A. Exponential Growth Growth in an idealized, unlimited environment i) Derivation of equation staring with Nt+1 = Nt+B-D+I-E (Births/Deaths/Immigrants/Emigrants) ii) Discrete time vs. continuous time – dN/dt – the population rate of change B. Logistic Growth Growth in a limited environment i) Four features of competition – between individuals, shared requirement for a resource, resource is in limited supply, leads to a reduction in vital rates ii) Derivation of the logistic equation: dN/dt = rN( K-N/K) K - the carrying capacity r - the intrinsic rate of increase of the population iii) Note: The negative effects of small population size – the Allee effect iv) Life histories - ‘K’ and ‘r’ selected populations K-selected – long lifespan, low mortality, good competitors producing few, high quality offspring r-selected – short lifespan, high mortality, good dispersers and colonizers producing many small offspring with little parental care. C. Regulation of population growth i) regulation vs. limitation ii) Population density determined by: density dependent factors AND density independent factorsBio1b Summer 2008 Ecology Lecture 4 Eric Harris Page 2 of 2 Updated on 06/30/08 D. Population Dynamics = variations in the size of populations i) Population cycles ii) Metapopulation = a group of populations of a single species linked by immigration and emigration E. Human Population Growth i) ‘The population explosion is over’? ii) The demographic transition – describes the transition from high birth and death rates to low birth and death rates. iii) Infant mortality and life expectancy iv) Global carrying capacity v) Ecological
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