Population Ecology

Population Ecology - What is population and population...

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Outline What is population and population ecology?  Density and dispersion  How to calculate density Quadrant sampling mark and recapture  Different types of dispersion: uniform, clumped and  random Demography:  life tables ,survivorship curves  Exponential and logistic growth
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Population Ecology
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What are some of the questions studied by population ecologist? Population ecology is the study of how and why the number of individuals in a population changes over time. Galapagos
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Definitions in population ecology A population is a group of individuals from the same species that live in the same area at the same time. Members of a population rely on the same resources These members are influenced by similar environmental factors. There is a high likelihood of interacting and breeding with one another. elephant seal
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Three fundamental characteristics  of individuals in any population  are Density: is the number of individuals  per unit area Dispersion: is the pattern of spacing  among individuals within the  boundaries of the population.  Demographics: study of vital statistics  of population and how it changes.
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Density
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Density Density is the number of individuals per unit area or volume The number of oak tress per squares kilometers in Santa Clara county.
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Factors that affect density .
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Density of a population is affected by Birth (Mortality) Death Immigration is the influx of new individuals from other areas Emigration is the movement of individuals out of a population Births Deaths Deaths and emigration remove individuals from a population. Emigration Births and immigration add individuals to a population. Immigration
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Closed Vs Open population Closed populations --those populations that do not change in size at all due to births, deaths, immigration,or emigration when you are studying the population. Open populations are those that can fluctuate in size and composition. Especially for animals that are mobile (emigration and immigration ).
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How to calculate population density?
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Measuring  density of populations is  a difficult task. 1. It is almost always impractical to count all  the individuals in a population. 1. Ecologists can count individuals, but they  usually estimate population numbers. 2. A variety of sampling techniques to estimate  densities and total population sizes are used.
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Methods of calculating populations Quadrant Sampling Mark and recapture method Census Number of nests Burrows Tracks Fecal droppings.
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Quadrant sampling
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Quadrant sampling: is used for Open population 1. Count the number  of individuals in  randomly located  plots.  2. Calculate the  average density in  the samples. 
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50 feet in 5 foot increments) is laid out, and all of the organisms and plants are counted within each square of the
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Population Ecology - What is population and population...

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