Press release: Göttingen scientist provides a new framework for delineating biogeographical regions

Nr. 207/2010 - 19.10.2010

(pug) How are animal and plant species distributed across the earth? Controversial discussions have been going on for 150 years about the boundaries between the biogeographical regions that map the pattern of biological diversity on continents and around the globe. The Göttingen biogeographer Prof. Holger Kreft, in collaboration with Prof. Walter Jetz of Yale University, has now developed a new method for charting the world's diversity of mammalian species. Their map exhibits striking differences over earlier classical geographical divisions. Dr. Kreft is junior professor at the University Göttingen and heads the "Biodiversity, Macroecology and Conservation Biogeography Group" within the Free Floater programme funded by the Excellence Initiative at the University of Göttingen. The results of their study were published in the November issue of the Journal of Biogeography.

The two scientists started by feeding their computers with data on the distribution of close to 5,000 of the mammalian species on earth. In a multi-dimensional analysis, they discovered many similarities to the classic delineations, while giving entirely new biogeographical definitions to other regions. The results confirmed the classification into the six major realms: Palaearctic, and Nearctic on the northern hemisphere, and Africa, Oriental, Neotropical and Australia. This classification dates back to Alfred Russel Wallace, one of the founding fathers of biogeography. "However, we grouped Madagascar differently because of its unique mammal fauna. Likewise, according to our calculations, the classic Wallace line separating the Oriental and Australian realms runs much further to the east," explained Prof. Kreft.

Previously, the boundaries were drawn primarily based on the knowledge and subjective judgement of the respective biogeographers. "There are probably more than 20 different answers to the question as to where the boundaries are between the African tropics and the Palaearctic that our animal kingdom belongs to," notes the Göttingen scientist. Computerized analysis allows much greater detail compared to older studies. The two researchers were able to define up to 60 subregions – information that, for instance, is useful for planning nature conservation projects designed to protect all species and communities living on a continent. "We believe that our method is an important step towards putting biogeography on a quantitative foundation and providing answers to previously controversial issues," Prof. Kreft adds.

The new method developed by the two scientists is based on a cluster analysis of globally available digital data. First, they placed a grid of 11,000 equally sized grid cells over a map of the world and assigned the species distribution data to these grid cells. That way each grid cell was assigned its own species list. Next, the researchers compared 55 million pairs of grid cells and combined the grid cells with similar species lists into regions.

Original publication:
Holger Kreft and Walter Jetz: A framework for delineating biogeographical regions based on species distributions. Journal of Biogeography; November 2010, doi: 10.1111/jbi.2010.37.issue-11/issuetoc

Contact address:
Prof. Holger Kreft
Georg-August-University of Göttingen
Free Floater in the "Biodiversity, Macroecology and Conservation Biogeography Group“
Büsgenweg 2, 37077 Göttingen, Germany
Phone (0551) 39-10727
hkreft@uni-goettingen.de
Internet: http://www.uni-goettingen.de/biodiversity