The Realm of Ecology: Organisms, Evolution, Ecosystems | BIO 112, Study notes of Biology

Download The Realm of Ecology: Organisms, Evolution, Ecosystems | BIO 112 and more Study notes Biology in PDF only on Docsity! 1 Biospherei Ecosystems Communities Populations Organisms Fig. 4.2, p. 72 The Realm of Ecology  Organisms  Populations  Communities  Ecosystems  Biosphere Key Concepts: Pop Ecology  A population is…  Population ecologists study how and why a population changes spatially & temporally.  Density, dispersion, dynamics  Per capita population growth rate  Density dependence & independence  Life history traits are… Population Dispersion Clumped (elephants) Uniform (creosote bush) Random (dandelions) Fig. 9.2, p. 199 Age-structure affects pop’n growth  Life tables  Mortality/reproduction change with age  Questions  Maximum age?  How survivorship changes with age  When is mortality highest? 2 Age distributions Past and future Survivorship curves & life tables forecast population dynamics Population Dynamics  Population change over time  Relate structure to dynamics  Darwin recognized Malthus’ work as important to evolution Real vs. theoretical curves Simple exponential growth  N1 = N0 + B – D + I – E  N1 = N0 + N0Br – N0Dr + N0Ir – N0Er =  NT = (R T) N0 = (e rT) N0  b - d = r  r = per capita population growth rate  b = per capita birth rate (births/ind.)  Plus immigration  d = per capita mortality (deaths/ind.)  Plus emigration  dN/dt = r N = instantaneous rate of change B = 0.5, D = 0.2 0 5000 10000 15000 20000 0 5 10 15 20 25 Time D e n s it y B = 0.33, D = 0.2 0 100 200 300 400 500 600 0 5 10 15 20 25 Time D e n s it y B = 0.2, D = 0.2 0 5 10 15 20 25 0 5 10 15 20 25 Time D e n s it y B = 0.18, D = 0.25 0 5 10 15 20 0 5 10 15 20 25 Time D e n s it y b and d affect growth rate