Dynamic Biological Processes Influence Pop, Density, Dispersion, And Demographics

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53.1 Dynamic biological processes influence pop. density, dispersion, & demographics Density & Dispersion Density - # of individuals per unit area or volume: the # of oak trees per square kilometer in the Minnesota county or the # of Escherichia coli bacteria per milliliter in a test tube Dispersion - pattern of spacing among individuals within the boundaries of the pop. Density: A dynamic perspective Pop. ecologists estimate density from an index (indicator) of pop. size, such as the # of nests, burrows, tracks, or fecal droppings Density isn’t a static property but changes as individuals are + to or - from a pop. + occur through birth & immigration, the influx of new individuals from other areas - occur through death & emigration, the…show more content…
Some plants secrete chemicals that inhibit the germination & growth of nearby individuals that could compete for resources Animals often exhibit uniform dispersion as a result of antagonistic social interactions, such as territoriality—the defense of a bounded physical space against encroachment by other individuals Aren’t as common in pop. as clumped Random dispersion - unpredictable spacing, the position of each individual is independent of other individuals Occurs in absence of strong attractions or repulsions among individuals of a pop. or where key physical or chemical factors are relatively homogenous across the study area Plants established by windblown seeds, dandelions, may be randomly distributed in a fairly consistent habitat Not as common in nature; most pop. show tendency toward clumped Demographics - study of the vital statistics of pop. & how they change over time Birth rates & how they
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