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Unformatted text preview: POPU LAT ION ECOLOGY LIFE 54 54.1 How do ecologists study populations?-A population consists of the individuals of a species within a given area-The age distribution of individuals in a population and the way those individuals are spread over the environment describe its population structure . Ecologists study population structure because the spatial distributions of individuals and their ages influence the stability of a population and affect how that population interacts with other species .-The number of individuals of a population per unit of area (or volume) is its population density .-The structure of a population changes continually because demographic events births, deaths, immigration (movement of individuals into the area), and emigration (movement of individuals out of the area)are common occurrences. 54.1.3 Birth and death rates can be estimated from population density data-That is, the number of individuals at a given time, N 1 , is given by the equation N 1 = N + B D + I E where N 1 = the number of individuals at time 1 N = the number of individuals at time 0 B = the number of individuals born between time 0 and time 1 D = the number that died between time 0 and time 1 I = the number that immigrated between time 0 and time 1 E = the number that emigrated between time 0 and time 1-A useful way to display information about birth and death rates in a population is to construct a life table . We can construct a life table...
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