demographymurray

# demographymurray - DEMOGRAPHY READINGS: FREEMAN, 2005...

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DEMOGRAPHY READINGS: FREEMAN, 2005 CHAPTER 52 Pages 1192-1196

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What is a Population? A group of individuals living in a particular area. Individuals that interact while seeking resources and in producing offspring. Members of a group that are subject to the same local conditions of the environment. Members of a single species.
Patterns of Dispersion Individuals in a population may be distributed according to 3 basic patterns of dispersion: * Random * Uniform * Clumped

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Random What? Scattered; no regularity and affinity Why? Environment uniform; individuals solitary
Uniform What? About equal distance apart; regular with no affinity Why? Resource competition; antagonism

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Clumped What? Grouped in some places, absent in others; irregular with affinity Why? Resources patchy; individuals aggregate
The Frog Problem Dr. T., an ecologist, wanted to find out how many frogs live in a small pond. On the first trip to the pond, 55 frogs were caught, banded, and released. The second trip to the pond, 72 frogs were caught, of those 72 frogs, 12 were banded. Assuming the banded frogs had thoroughly mixed with the unbanded frogs, how many frogs live in the pond ?

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CAPTURE/RECAPTURE OF FROGS How many frogs in the pond? If X= number of frogs in pond, the proportion of marked frogs on the 1st day must equal the proportion of marked frogs on the 2nd day. X = 72 or X = 55 x 72 = 330 frogs 55 12 12
ABUNDANCE Most population studies begin with a statement of abundance. The number of individuals in a population may be obtained by: 1. census- Counting all individuals. 2. sampling- Counting a known fraction to arrive at an estimate of total number. Many ecological studies require use of sampling, such as capture/recapture or the plot method.

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PLOT METHOD OF SAMPLING 1. Subdivide an area into equal sized plots. 2.
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## This note was uploaded on 04/07/2008 for the course BIOS 101 taught by Professor Molumby during the Spring '08 term at Ill. Chicago.

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demographymurray - DEMOGRAPHY READINGS: FREEMAN, 2005...

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