An international research team has updated a Victorian map that has been the blueprint for our understanding of the diversity of life-forms across the world. The original map was created in 1876 by Alfred Russel Wallace, who co-discovered the theory of natural selection with Charles Darwin.
Using advances in modern technology and data on more than 20,000 species, scientists have compiled the next generation map, which is published online in Science Express today. The study was led by Carsten Rahbek and a team at the Center for Macroecology, Evolution and Climate at the University of Copenhagen in collaboration with others, including Oxford University.
The digital version provides fundamental information about the diversity of life on our planet, giving conservationists an essential new tool. In order to improve our understanding of life on earth, one of the big questions scientists ask is why species are distributed the way they are. Wallace divided the world into six land-based units, which largely mirror what we now know as the continental plates. His map, still in use today, shows the distribution and inter-relation of species and ecosystems in geographic space and through geological time.
The new revised global map divides nature into 11 large realms, combining both evolutionary and geographical data for all known mammals, birds and amphibians – a process that has taken 20 years to complete. It combines existing data on the global distributions and evolutionary relationships of 6,110 species of amphibians, 10,074 species of birds and 4,853 species of non-marine mammals – a total of 21,037 vertebrate species.
British researcher Dr Ben Holt from the Center for Macroecology, Evolution and Climate at the University of Copenhagen, the co-leader of the study, said: 'Our study is a long overdue update of one of the most fundamental maps in natural sciences. For the first time since Wallace's attempt we are finally able to provide a broad description of the natural world based on incredibly detailed information for thousands of vertebrate species.'
Co-author Robert Whittaker, Professor of Biogeography at the University of Oxford, who is also affiliated to the University of Copenhagen, said: 'Bio-geographical regions are central to the way we think about conservation priorities. This means that it is vital that we can trust these regions to reflect reality. With this update, we have taken an important step to ensure this.'
The new realms, based on the most up-to-date information, will alert conservationists to regions of the world where there might be a lack of support for species. For example, the new map reveals that vertebrates in the southern hemisphere are more evolutionarily distinct than in the northern hemisphere. It also reveals that vertebrates of central and eastern Siberia are more evolutionarily similar to the arctic parts of the Nearctic region (a region covering most of North America) than they are to the rest of the Palaearctic (which runs across Eurasia from western Europe to the Bering Strait). The researchers have also quantified just how unique particular regions of the world are. For example, Australia, Madagascar and South American regions show the most distinct species of vertebrates.
Dr Jean-Philippe Lessard, the other co-lead-author from the Copenhagen centre, who is currently based at McGill University, Canada, said: 'The map provides important baseline information for future ecological and evolutionary research. It also has major conservation significance in light of the ongoing biodiversity crisis and global environmental change. Whereas conservation planners have been identifying priority areas based on the uniqueness of species found in a given place, we can now begin to define conservation priorities based on millions of years of evolutionary history.'
Researcher Michael Borregaard, who was based at the University of Copenhagen but is now at the University of Oxford, added: 'This new map of the world greatly strengthens our confidence that biogeographical regions reflect the evolutionary history of biotas. In many ways, it is incredible that Wallace was able to create a scheme that would hold for 200 years given it was just based on his own knowledge of natural history.'
The new maps will be available in Science Express, Google Earth as well as the University of Copenhagen website: www.macroecology.ku.dk/resources/wallace/