Question

Organisms with very high intrinsic growth rates have

• A. long generation times
• B. short generation times
• C. no courtship behaviour
• D. no carrying capacities

Answer 1

The correct option is B short generation times

The rate at which a population increases in size if there are no density-dependent forces regulating the population is known as the intrinsic rate of increase.
According to the Verhulst-Pearl Logistic Growth curve,
$\frac{\mathrm{dN}}{\mathrm{dt}}=\mathrm{rN}\left[\frac{K-N}{K}\right]$
where N = Population density at time t, r = Intrinsic rate of natural increase, K = Carrying capacity

The intrinsic rate of increase is inversely related to generation time t. Therefore, organisms with very high intrinsic growth rates have short generation time.
The intrinsic rate of natural increase can be used to compare growth rates of populations of a species that have different generation times. Some human populations have higher intrinsic rates of natural increase partially because individuals in those groups begin reproducing earlier than those in other groups. Mice have higher intrinsic rates of natural increase than elephants because they reproduce at a much earlier age and have a much shorter mean generation time.