Researchers want to estimate the size of one population of Singing vole versus o

Question

Researchers want to estimate the size of one population of Singing vole versus one population of Tundra vole to determine if their population sizes will be differentially affected by climate change. They do this by making two trips to each of their favored habitats.   

   On the first trip to the Tundra vole habitat, 50 voles are captured and marked, and on the second trip, 55 voles are captured, of which 15 are marked.

On the first trip to the Singing vole habitat, 47 voles are captured and marked, and on the second trip, 42 are captured, of which 17 are marked.

In 5 years, if there was an estimated 245 Tundra voles, and 150 Singing voles, which population has a higher growth rate? What will the population size of each species be in another 5 years?

Explanation / Answer

On the first trip 50 tundra voles are captured and marked. and on the second trip, 55tundra voles are captured, of which 15 are marked that means Pr(Marked voles) = 15/55 = 3/11 , so by estimation there may be 50 * 11/3 = 183.33number of tundra vole in population of tundra vole

similarly for singing voles, 47 voles are captured and marked, and on the second trip, 42 are captured of which 17 are marked that means Pr( Marked singing voles) = 17/42 so by estmation there may be 47 * 42/17 = 116.12 number of singing vole in population of singing vole.

after 5 years, there are 245 tundra voles and 150 singing voles.

so % growth in tundra voles = (245- 183)/ 183 * 100 = 33.88%

and % growth in singing voles = ( 150- 116)/116 * 100 = 29.31%

so population of tundra voles increased with higher rate.

Population of tundra voles in another 5 years maintaing same rate = 250 * [ 1 + 33.88/100] = 335

Population of singing voles in another 5 years maintaing same rate = 150 * [ 1 + 29.31/100] = 194

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