Demographic strategies in animal populations: a regression analysis

JORGE RABINOVICH

Trends in Tropical Ecology

Springer-Verlag

Lugar: New York; Año: 1975; p. 19 - 40

The idea put forward by Dobzhansky (1950) that tropics and teluperatezones are areas where selection operates differently generated fruitful lines ofthinking and research. His contention was that in tcnlperate areas mortality wasessentially climatically determined, with little or no competition pressure, whilein the tropics, where the environnlent is relatively luore constant, mortality isthe result of the effects of population size. In the first case, high fecundity andshort developmental tillle are favored by selection, while in the latter selectionwould favor competitive ability through lower fecundity and longer developmentaltinle, increasing overall fitness by allocating l1lore energy into each individualbut producing fewer offspring.A similar type of analysis, but including a comparison of the luode of selectionoperating in different types of ecosystelus, was presented by Margalef(1958), who showed that differences in mortality curves would be expectedbetween species belonging to luature comnlunities and those belonging to pioneercommunities. However, this line of thinking remained relatively undevelopeduntil the appearance of MacArthur and Wilson's (1967) work, where the differencesbetween the two types of selection were formally defined, and the resultingproperties of these processes were clearly characterized; these authors coinedthe terms r and K selection.