文档介绍：Lecture 10: Population Growth Lecture 10: Population Growth 起重机立体停车设备电动葫芦 衬塑复合管涂塑复合管钢塑复合管消防涂覆钢管 World population World population Population growth Population growth ?? Definition: how the number of individuals Definition: how the number of individuals in a population increases or decreases in a population increases or decreases with time with time ?? Growth is controlled by rates of birth, Growth is controlled by rates of birth, immigration and death and emigration. immigration and death and emigration. ?? Open or closed population: no immigration Open or closed population: no immigration and emigration, or immig.=emig. and emigration, or immig.=emig. ?? In closed population, growth is determined In closed population, growth is determined by birth rate and death rate. by birth rate and death rate. Population growth reflects the Population growth reflects the difference between rates of birth and death difference between rates of birth and death ?? Model development Model development ?? A population of freshwater hydra growing in an aquarium in A population of freshwater hydra growing in an aquarium in the laboratory. the laboratory. ?? Population size N(t) when time is t. Population size N(t) when time is t. ?? This is a closed population. This is a closed population. ?? Population size change is related to birth rate (b) and death Population size change is related to birth rate (b) and death rate (d) rate (d) ?? dN/dt=(b-d)N=rN dN/dt=(b-d)N=rN ?? The difference between birth rate and death rate is the The difference between birth rate and death rate is the intrinsic growth rate (r) (instantaneous per capita rate of intrinsic growth rate (r) (instantaneous per capita rate of growth). growth). r=b-d r=b-d ?? In a closed population, population size In a closed population, population size change is related to birth rate (b) and change is related to birth rate (b) and death rate (d) death rate (d) ?? The differ