<Dd> d N d t = r N (1 − N K) (\ displaystyle (\ frac (dN) (dt)) = rN \ left (1 - (\ frac (N) (K)) \ right)) </Dd> <P> where N is the population, r is the maximum growth rate, K is the carrying capacity of the local environment, and dN / dt, the derivative of N with respect to time t, is the rate of change in population with time . Thus, the equation relates the growth rate of the population N to the current population size, incorporating the effect of the two constant parameters r and K. (Note that decrease is negative growth .) The choice of the letter K came from the German Kapazitätsgrenze (capacity limit), while r came from rate . </P> <P> r - selected species are those that emphasize high growth rates, typically exploit less - crowded ecological niches, and produce many offspring, each of which has a relatively low probability of surviving to adulthood (i.e., high r, low K). A typical r species is the dandelion (genus Taraxacum). </P> <P> In unstable or unpredictable environments, r - selection predominates due to the ability to reproduce quickly . There is little advantage in adaptations that permit successful competition with other organisms, because the environment is likely to change again . Among the traits that are thought to characterize r - selection are high fecundity, small body size, early maturity onset, short generation time, and the ability to disperse offspring widely . </P>

Explain why a population may vary between k and r strategies