R_Code.zip

The debate about the relative importance of interspecific competition and environmental factors in annual population fluctuations has persisted in ecology for many decades. Ecologists face the challenge of determining the extent to which interspecific competition and environmental factors impact population growth rates. We assess the predictive ability of models with and without interspecific competition and environmental covariates to predict population size one year beyond the model-building data. We have developed models to predict population fluctuations and used predictive performance on more than 16,000 populations from 14 datasets to compare the understanding captured by those models.