r and
K are the poles of a continuum over which species adaptation can be placed. At one end is
reproduction(r), a straight forward flooding of the
environment with offspring. All the reproductive energy is put into finding mates and reproducing. The more offspring produced, the more that will survive and continue the genetic line. Fish, turtles, spiders and many insects are placed far at this end of the
continuum. In the
r strategy, the organism tries to gain the largest share of the
carrying capacity of the habitat.
The K strategy is often taken as the "caring for the young", or nurturing strategy because in most cases more effort is put into a smaller number of offspring. But the overall strategy is really opposed to r strategy in that K strategists seek to expand the carrying capacity of the habitat instead of fighting for a share of it. This is not to say that these organisms don't compete against others as in the r strategy. No organism is a perfect example of either pole. But humans are by far the best example of this group, in living far outside their original habitat and relying heavily on learning and the passage of information from one generation to the next.