GEOG 1220 Chapter Notes - Chapter 3: Logistic Function, Exponential Growth
18 Apr 2016
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Chapter 3 - evolution, biodiversity, and population ecology. Population growth and decline: births within the population, or natality, deaths within the population, or mortality, immigration, the arrival of individuals from outside the population, emigration, the departure of individuals from the population. Natural rate of population growth = crude birth rate - crude death rate. Population growth=(crude birth rate - crude death rate) + (immigration rate - emigration rate) Adding a fixed amount every year is arithmetic growth or linear growth. J-shaped population growth curves is an example of exponential population increase. Exponential growth usually occurs in nature when a population is small, competition is minimal, and environmental conditions are ideal for the organism in question. Every population eventually is constrained by limiting factors - physical, chemical, and biological characteristics of the environment that restrain population growth. Combination of these factors exerts environmental resistance on the population.
