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Some strange properties of the logistic equation defined with r and K : Inherent defects or artifacts?
Author(s) -
Kuno Eizi
Publication year - 1991
Publication title -
population ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 59
eISSN - 1438-390X
pISSN - 1438-3896
DOI - 10.1007/bf02514572
Subject(s) - logistic function , competition (biology) , outcome (game theory) , biology , population , logistic regression , statistics , pure mathematics , combinatorics , mathematics , mathematical economics , ecology , demography , sociology
Summary In some situations the logistic equation in the usual expression, d N /d t=r(1−N/K)N , exhibits properties that are biologically unrealistic. For example, when r ≦0 the population can no longer show any normal, negative response in per‐capita growth rate to increasing density. Also, when the equation is employed in the Volterra's competition model, a familiar but incredible conclusion is derived which says that the outcome of competition is entirely independent of the reproductive potential r of each species. It is shown that all such strange properties are mere artifacts arising peculiarly in this r‐K model from its misleading implicit supposition that K could be independent of r , and they can be readily removed by alternative use of a plainer, classical form of the model, d N /d t=(r−hN)N .