Birds and mammals have natural selection regulated population dynamics

Lars Witting

Abstract: Ecological dynamics is increasingly explained by eco-evolutionary processes, with this study analysing natural selection effects on the population dynamics of birds and mammals. Fitting single-species population dynamic models to 3,369 and 483 timeseries for 900 species of birds and 208 mammals, I find selection-based population dynamic models to be 780 (se:1.3) to 150,000 (se:2) times more probable than models with no selection. Selection is essential in 79% to 92% of AIC selected models, explaining 80% of the population dynamics variance, with median selection regulation being 1.2 (se:0.11) times stronger than density regulation. The estimated dynamics is cyclic with median damping ratios of 0.12 (se:0.0071) and 0.062 (se:0.021) for birds and mammals, and median population periods of 8.3 (se:0.99) and 7.2 (se:0.85) generations for stable cycles with damping ratios around zero. These results resolve several enigmas of population cycles, highlighting the importance of integrating natural selection into population dynamics.