Cause and effect in the natural selection of the population ecological life histories of mammals

Abstract

The inter-specific life history and ecological variation of mammals is often explained as allometric consequences of physiological adaptations to unexplained body mass variation. But these hypotheses are unnecessary because the allometric scaling is explained already by the natural selection that explains the variation in mass. I decompose the population ecological life histories of 4,936 species of mammals to show how the selection of mass accounts for the life history and population ecological variation in mammals. This shows that 55% of the within order variance, and 91% of the between order differences, in the body mass, demography, and population ecological traits are reconciled by the response of population dynamic feedback selection to variation in net energy, mortality, and intra-specific interactive competition.