r and K selection in kangaroos

Abstract

MACARTHUR and Wilson¹ used the terms ‘K selection’ and ‘r selection’ to describe two general kinds of selection they believed could be functioning in nature. Where there is no crowding, evolution favours productivity (r selection). Alternatively in a crowded situation where some resource is scarce, evolution favours the efficient use of this resource in the production of offspring (K selection). Thus r selection occurs when it is more important to increase numbers and K selection when population size is near the maximum that can be carried in the prevailing environmental conditions. Pianka² summarised a number of theoretical correlates of r and K selection, and some of these are given in Table 1.