K-Selected populations help maintain ecosystem constancy. Selected populations are like scar tissue on the biosphere, they quickly cover disturbed areas, remove dead plants and animals, etc. When conditions become good so that death rate drops, r - Selected species with a high biotic potential can increase populations dramatically. By contrast, in bad years elephants take longer to starve than rabbits. The population of a species at a given time is a function of its history as well as present conditions with respect to b and d .
All responses also have a built in lag time.
In a good spring for rabbits, all rabbits are running around mating. Forty days later, when there are baby rabbits everywhere, things may be drying up and food may be scarce. The population thus exceeds the carrying capacity of the environment before any negative effect is felt. The resultant population overshoot inevitably leads to starvation and death although the associated weakening of individuals may cause death to be expressed as disease or predation rather than starvation. Severe winter drought flood pesticides Density-dependent factors usually bring about population control.