Natural selection shapes and regulates the population dynamics of birds and mammals

Abstract

I fit species-specific age-structured population dynamic models to 3,369 and 483 abundance timeseries for 900 and 208 bird and mammal species, using AIC model-selection to differentiate dynamics with and without natural selection. The AIC includes natural selection in 79% to 92% of the accepted models, explaining 80% of the population dynamics variance, with median selection regulation estimated 1.2 (se:0.11) times stronger than density regulation. The estimated regulation is naturally selected by the population dynamic feedback selection of the density-frequency-dependent interactive competition among the individuals in the population, and it accelerates and decelerates population growth around the naturally selected population dynamic equilibrium, generating damped to stable population cycles with median periods around seven and eight generations given stable cycles. These results resolve several population cycle enigmas, highlighting the population dynamic implications of a feedback selection that predicts also the life history and abundance body mass allometries of animals. The selection regulated models are available for online simulations at https://mrLife.org.