Fisher's (1930) maximum principle in ecology states that \Any net advantage gained by an organism will be conserved in the form of an increase in population, rather than in an increase in the average Malthusian parameter, which is
kept by this adjustment always near zero." We know today that we cannot make
such general statements. Nevertheless, several ecologists, including Nicholson (1960),
have stressed this principle as a general ecological principle. Based on a number of
theoretical counterexamples, we cannot conclude that this principle is not supported
by any essential biological facts.
This paper examines simple examples that illustrate when the principle is valid.
We use a discrete modeling approach to account for the fact that several boreal
populations are constrained to reproduce at well-defined discrete moments. Several
authors have pointed out that the above maximum principle ceases to be valid when
predation is present. With reference to the Ricker competition case, we suggest how
the principle could be reformulated so as to cover that case.