Answer these questions in Excel and upload the Excel file as an attachment to th

Question

Answer these questions in Excel and upload the Excel file as an attachment to this assignment.

1. For low density sea otter populations in the North Pacific Ocean, the overall annual per capita birth rate (b) is about 0.7 and the death rate is about 0.45. Birth rate is not density-dependent but death rate is density dependent, such that d’ = d+cN (where N = number of otters per km of coastline). If c = 0.0157, what is the carrying capacity sea otter density in number of animals per km of coastline?

2. The intrinsic rate of increase (r) for northern elephant seals about 0.19 (per annum). We will assume that population regulation is linearly density dependent.

a. If the carrying capacity of elephant seals at a recently recolonized island is 1400 adult females and the initial population size is 120, how many more years (approximately) will it take for the population to grow to K?

b. If the island population overshot carrying capacity to 2300 adult females, how many more years (approximately) will it take for the population to decline to K?

3. The carrying capacity of meadow voles fluctuates periodically roughly on a 7 year cycle. If the long-term carrying capacity of voles in a patch of meadow is 90 individuals and total amplitude of fluctuations around carrying capacity is 23 (i.e., from the low to the high), plot the trajectory of the population over 35 years, beginning with a population size that is exactly at K.

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Explanation / Answer

1) Birth rate is 0.7 and death rate is 0.45

Death rate is density dependent.

Carrying capacity is the maximum population size that can be sustained without degradation of the environment. At carrying capacity, birth rate is equal to death rate.

d' = d + cN

0.7 = 0.45 + 0.0157N

0.25 = 0.0157N

N = 0.25/0.0157

= 15.92

There is maximum population growth at carrying capacity.

So, N = K/2

Where K is the carrying capacity

So, K = 2N

= 2(15.92)

= 31.84

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