Thursday, September 6, 2012

A Visual Depiction of Vertebrate Biodiversity Distribution


The following is a post placedon the savingspecies.org website yesterday (September 5) its author Clinton Jenkins is a Research Scholar in the Biology Department at North Carolina State University. Clinton specializes in using spatial analysis and remote-sensing technologies to answer conservation questions and identify priorities for action. The images are remarkable because they visually portray vertebrate biodiversity on the planet.

The variety of life on Earth is not spread evenly, but is concentrated in very special places. SavingSpecies has been working to map the diversity of vertebrate life across the world and thereby identify the very best places where we can protect and restore the most biodiversity for the buck. These beautiful new maps, seen here for the first time, illustrate some of the intriguing patterns of life in the world. As well as being gorgeous images of life’s diversity, the maps help us use science to prioritize our conservation efforts.


Map 1. World map of color coded density of endemic vertebrate species. (Click image for larger version.)

In our first view (Map 1), we see colors that indicate the highest concentrations of the number of animal species across the world’s land masses. Deep reds and yellows cover much of the tropics, indicating a huge number of species. The world’s high latitudes and its deserts are blue, indicating relatively low vertebrate diversity. We can see clear geographic and geological patterns in these maps of life.

In the globe below (Map 2), we take a closer look at biodiversity in the Americas. The deep reds of Amazonian diversity stretch west into the Andes, but as one crosses over the Andes and toward the Pacific coast, total diversity drops off rapidly into greens and blues.
Map 2. Color coded number of vertebrate species in the Americas. (Click for larger map.)

The different vertebrate groups do not follow the same patterns. If we split our map (Map 3) into its three constituent animal groups (birds, mammals, and amphibians*), then our view of the world begins to change. Below we show this split view for the Americas. The Amazon region is certainly diverse for everything, but we can see that the amphibians show exceptional concentrations of species in far western Amazonia. Both amphibians and birds show a peak of diversity in the southeast of Brazil, where SavingSpecies has been actively supporting local conservation.

Map 3. South America showing color coded density of endemic species of birds (left), mammals (middle), and amphibians (right). *For now, we can represent only the birds, mammals, and amphibians, because the reptiles and fish are still too poorly known to produce such detailed maps. (Click for larger map.)

However, from previous work we know that not all species are equally prone to extinction. Some animals have exceptionally small ranges, making them particularly vulnerable. It is these species and their homes that most concern us here at SavingSpecies. They are the low-hanging fruit for preventing extinction. But where are those species? Well, they are in the truly special places of the world. For birds, the Andes are simply unparalleled for their concentrations of rare birds (bright yellow and red streaks in Map 4). Within the Americas, only southeastern Brazil and parts of Central America come close to showing such concentrations of rare birds. Rare mammals are concentrated in much the same pattern.


Map 4. In the Andes, endemic bird species are highly concentrated in narrow ranges. (Click for larger map.)

For amphibians, the concentration of these super-rare species is even more extreme. The map below (Map 5) shows how a handful of small regions in the Andes have exceptional concentrations of rare amphibians. In these and nearby regions scientists are discovering many new amphibians, just at the time when their habitats are disappearing faster than ever before. SavingSpecies’ newest project, in collaboration with Colombia’s The Hummingbird Conservancy, has identified such an area, near Medellin, in which nine new species of frogs were recently discovered.

Our project in southeast Brazil’s Atlantic forest is similarly focused on areas of high endemism, protecting species with very small ranges in our effort to prevent their extinction. Initial reports are that our Brazil project is meeting with considerable and earlier-than expected success. (Read my progress report from August 2011.) But that’s a topic for another blog post. For now, let’s just say that with this work, using such maps to identify areas with the most species at the highest risk of extinction, our donors’ dollars will save species.



Map 5. South America showing color coded density of endemic amphibian species. (Click for larger map.)

Acknowledgements
Thanks to Félix Pharand-Deschênes at Globaïa (http://globaia.org) for help in designing the biodiversity globes. Original data on the distributions of bird species are from BirdLife (BirdLife 2011) and for mammals and amphibians are from the IUCN (IUCN 2010), who distribute data from the Global Mammal and Global Amphibian Assessments. Threatened species are those considered vulnerable, endangered, or critically endangered in the IUCN Red List. BirdLife (2011) Bird species distribution maps of the world. BirdLife International, Cambridge, UK and NatureServe, Arlington, USA.

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