University of Copenhagen

First comparative test on climate impact on species diversity undertaken

Geographic patterns of species diversity and their underlying processes have intrigued scientists for centuries, and continue to spur scientific debate.

Washington, Nov.22 : Geographic patterns of species diversity and their underlying processes have intrigued scientists for centuries, and continue to spur scientific debate.

Studies carried out over the past 20 years have led to the conclusion that species diversity is best predicted by contemporary patterns of energy and water. But are current projections of climate change-impacts on biodiversity misleading?

In this regard, a study on "Quaternary climate changes to explain diversity among reptiles and amphibians" has been undertaken and published in the journal Ecography.

Using new high-resolution data on historic climate patterns, Dr. Ara�jo, Dr. Rahbek and other colleagues have sought to directly test the "historic climate" versus "contemporary climate" hypotheses of biological diversity.

Contrary to the expectations of many scientists they found that historic climate variability was a better predictor of reptilian and amphibian diversity in Europe than contemporary climate.

"The lack of quantitative spatial data on variation in climate over historical time has prevented more rigorous testing of these diverging hypotheses", says Dr. Miguel B. Ara�jo from the National Museum of Natural Sciences (CSIC) in adrid.

As a consequence, "the debate on the causes of diversity gradients has turned to some degree into a discussion of semantics," he adds.

"In recent years, analytical attempts to shed light on the role of history in determining today's patterns of species richness have focused on the strong residual variation of models using contemporary climate", explains Dr. Carsten ahbek from the Center of Macroecology at the University of Copenhagen.

"Our results are striking in that they contradict previous studies of large-scale patterns of species richness. 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," affirms Dr. Rahbek.

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. Ara�jo.

"If contemporary climate does drive species richness, then current climate variables could be used to accurately predict the effects of climate change on biodiversity. If, as shown in our study, the mechanisms underlying contemporary patterns of species richness are in fact strongly influenced by the history of climate, then current-climate predictions may be seriously misleading and alternative approaches to predict the effects of climate change on biodiversity must be developed".

ANI