Lesson-4-Population-dynamics-1.ppt

Population Dynamics,Lesson 4,,Characterising a population,Static population pattern property of a population that can be assessed with a measurement or estimate at a single point in time (a “snapshot”) Dynamic population pattern property of a population that can only be assessed with measurements or estimates taken at two or more points in time,,Characterising a population,Static population pattern property of a population that can be assessed with a measurement or estimate at a single point in time (a “snapshot”) Dynamic population pattern property of a population that can only be assessed with measurements or estimates taken at two or more points in time,,Population Dynamics,Most populations are not static, they change with time Geographic range Population size Density Dispersion Demography,,Population Dynamics,Cycles in population size Populations grow and decline, grow and decline,Lynx,Snowshoe hare,,Population dynamics,Forest development over time the structure of tree populations (N) change over time,,Population Dynamics,Population Dynamics is the growth, decline or maintenance of populations,,Population Dynamics,What factors influence populations?,,Population Dynamics,Factors Influencing Dynamics Population Size (N) Population Density (N/unit area) Dispersal (uniform, clustered, random) Immigration Emigration Births Deaths Survivorship,,Population Dynamics,Factors Influencing Dynamics Population Size (N) Population Density (N/unit area) Dispersal (uniform, clustered, random) Immigration Emigration Births Deaths Survivorship,Immigration movement of individuals into a population Emigration movement of individuals out of a population Births to be born Deaths to die or be killed (predation) Survivorship rate of survival by an organism,,Population Dynamics,,Population Dynamics,,,,,Birth,Death,Emigration,Immigration,Population (N),Figure 1. The size of a population is determined by a balance between births, immigration, deaths and emigration,,Population Dynamics,,,,,Birth,Death,Emigration,Immigration,Population (N),N/t = B + I D E,N(t+1) = N(t) + B + I D E,,Population Dynamics,Like a water tank Births and immigration add to the water tank Deaths and emigration take away from the water,,,,,,Shrinking population,,Population Dynamics,Like a water tank Births and immigration add to the water tank Deaths and emigration take away from the water,,,,,,Growing population,,Population Dynamics,Like a water tank Births and immigration add to the water tank Deaths and emigration take away from the water,,No change,,,Stable population,Change (% Growth),% Growth = (N(t+1)-N(t)) X 100 N(t),Change (% growth) is the percent change in a population over a given time,Change (% Growth),% Growth = (N(t+1)-N(t)) X 100 N(t),* thousands,Change (% Growth),% Growth = (N(t+1)-N(t)) X 100 N(t),* thousands,Change (% Growth),% Growth = (N(t+1)-N(t)) X 100 N(t),* thousands,Change (% Growth),N(t)x % Growth + N(t)= N(t+1) 100,* thousands,,,,Population Dynamics,Review Populations are not static, they change with time Population Dynamics is the growth, decline or maintenance of populations over time Factors Influencing Dynamics: Population Size, Population Density, Dispersal, Immigration, Emigration, Births, Deaths, Survivorship Calculate % growth,知识回顾Knowledge Review,祝您成功！,。