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Question

Assume that the population (N) of a species follows the logistic growth represented by following equation -
$$\frac{dN}{dt} = 0.8N - 0.01N^{2}$$
At what value of N, the population exhibits maximum growth ?

The correct answer is
40

Logistic Growth Maximum Population Dynamics

The provided equation represents logistic population growth:

$\frac{dN}{dt} = 0.8N - 0.01N^{2}$

This equation describes the rate of change of population size (N) over time (t).

Identifying Carrying Capacity

The standard form of the logistic growth equation is:

$\frac{dN}{dt} = rN\left(1 - \frac{N}{K}\right)$

where 'r' is the intrinsic rate of increase and 'K' is the carrying capacity.

To find 'K' from the given equation, we can factor it:

$\frac{dN}{dt} = N(0.8 - 0.01N)$

Factor out 0.8:

$\frac{dN}{dt} = 0.8N\left(1 - \frac{0.01N}{0.8}\right)$

$\frac{dN}{dt} = 0.8N\left(1 - \frac{N}{80}\right)$

By comparing this with the standard form, we identify the carrying capacity:

$K = 80$

Calculating Population for Maximum Growth

In logistic growth, the population growth rate ($\frac{dN}{dt}$) is maximum when the population size (N) is exactly half of the carrying capacity (K).

Maximum growth occurs at:

$N = \frac{K}{2}$

Substitute the value of K:

$N = \frac{80}{2}$

$N = 40$

Therefore, the population exhibits maximum growth at N = 40.

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Important Questions from Population Ecology - Teaching

  1. A population size at t=0 is 80 and has a growth rate of 0.12. If the population follows logistic growth, what is the growth rate constant if the carrying capacity is 240 ?
  2. Assertion (A) : The hypothesis testing can proceed on the basis of null hypothesis.
    Reason (R) : If null hypothesis is true probabilities to different possible sample result can be assigned to it.
    In the context of the two statements, which one of the following is correct ?
  3. Which of the following index is used for estimating population density?
  4. If $\Delta N_n$ is equal to production of new individual in the population, $\Delta t$ and $N$ represent time and initial number of individuals of a population, then natality rate per unit of population is
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