In recent years, analytical attempts to shed light on the role of history in determining todays patterns of species richness have focused on the strong residual variation of models using contemporary climate, explains Dr. Carsten Rahbek from the Center of Macroecology at the University of Copenhagen. It has been argued that these residuals provide information about the role of historical rather than contemporary constraints. However, such an analytical approach assumes that contemporary climate is the main explanatory force. In other words, the contemporary and historical hypotheses are not tested simultaneously in a directly comparable manner, and historical hypotheses are only invoked to explain what is left to elucidate after the implementation of contemporary environmental processes, says Dr. Rahbek.
Our results are striking in that they contradict previous studies of large-scale patterns of species richness affirms Dr. Rahbek. They provide the first evidence, using a quantitative analytical approach, that historic climate can contribute to current patterns of richness independently of, and at least as much as contemporary climate. This study has profound implications for the study of diversity on Earth, and challenges the current view that patterns of contemporary climate are sufficient to explain and predict diversity.
Differentiating between contemporary and historical hypotheses is important, not only for theoretical reasons: an understanding of the mechanisms that generate and maintain diversity provides valuable insights for predicting the impacts of contemporary climate changes on biodiversity, says Dr. Arajo. If contemporary climate does drive species richness, then current climate variables could be used to accurately pr
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