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The determination of Population Density is carried out by a method called Mark recapture method. It is one of the best methods to determine the population density. This is very important for any competitive exams related to life Science.
Determination of Population Density- By Mark Recapture method:
- Population size (or abundance) is a function of population density and the area that is occupied (geographic distribution).
- Usually, population size is estimated by counting all the individuals from a smaller sample area, then extrapolated over a larger area.
- When the individuals are not mobile- their population size may be estimated by counting individuals within a specified area.
- When individuals are very mobile and frequently move from one area to another, the required number are counted by applying a common method called mark-recapture method.
- Using this method, a small random sample of population is captured, marked. Then marked sample is then released to disperse within the general population. The marked individuals mix freely with unmarked individuals (general population).
- Within a short period, the marked individuals are randomly mixed within the population.
- The population is resampled and the numbers of marked and unmarked individuals are observed.
- Now the assumption is the ratio of marked to unmarked individuals in the second sample taken is the same as the ratio of marked to unmarked individuals in the first sample.
- A simple formula for estimating total population size:
Where N= Total population size; S1= Total individuals marked in the first sample; S2= Size of second sample; M2= Number of marked individuals recaptured in second sample.
The schematic representation of the method:
Other related links:
- Lotka Volterra model: https://thebiologyislove.com/lotka-volterra-model/
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