Lab 4 Mark Recapture

Lab 4 Mark Recapture - Name: Group:...

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Name: Group: Lab 4: Estimating population size Introduction :  Knowing the size of a population can be very valuable when trying to answer ecological  questions.  Among other things, we can use such information to understand where organisms actually  live, what habitats they prefer, and whether or not the population is changing over time.   Counting each member of a population can be practically impossible; imagine trying to count each ant  invading the trashcans around RCC.  Therefore, ecologists must rely on sampling techniques for estimates  of population size.  One common technique is a  Mark/Release/Recapture  method first attributed to  C.G.J. Peterson (1896) who estimated fish populations in the North Sea.  The method involves capturing  and marking a sample of organisms, releasing them, and then resampling the same population at a later  time.  We want to know the total number of individuals in the population (N) at the time of sampling.  If  the number of individuals marked in the first sample = n 1 , then the proportion of individuals marked in  the population = n 1 /N.  At resampling, if we capture a number of marked individuals (x) and a number of  unmarked individuals (u) for a total of x+u=n 2 , then the proportion of marked individuals in the second  sample = x/n 2 .  We can expect that the proportion of marked individuals in the second sample equals the  proportion in the initial sample (n 1 /N = x/n 2 ) and do a little algebra to estimate N. N = n 1 × n 2 /x This method makes the following ASSUMPTIONS: 1) marked and unmarked individuals do not change marking status. 2)
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This note was uploaded on 01/13/2012 for the course BIO 8 taught by Professor Prestongalusky during the Fall '11 term at Riverside Community College.

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Lab 4 Mark Recapture - Name: Group:...

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