Climate Change May be Responsible for Madagascar's Biodiversity
Why does Madagascar have so many unique animals?
May 24, 2006
Scientists have developed the first comprehensive theory to explain Madagascar's rich biodiversity.
Scientists have long been puzzled by Madagascar's extraordinary levels of biological diversity, but now an international team of researchers has developed an climate change-based explanation for why the island has such a richness of animal life. They say that their research will help prioritize conservation efforts in the last remaining natural habitats of Madagascar.
Scientists develop first comprehensive theory explaining Madagascar's rich biodiversity - News release from the Field Museum in Chicago
High levels of endemism related to the configuration of watershed and geologcally recent shifts in climate, says Science cover story
Chameleon in Madagascar. Photo by Rhett Butler
Lemur land, Madagascar now protected Madagascar is one of the world's most special places. An island slightly larger than the state of California, Madagascar is home to a bewildering array of wildlife from dancing lemurs to absurdly colorful chameleons. Eighty percent of the island's species are endemic, meaning they are found nowhere else on Earth.
Dancing lemur attracts tourists to island of Madagascar In the dry deciduous forests of south western Madagascar there lives a lemur that loudly cusses but "dances" like a ballet performer. Verreaux's sifaka is among the most popular of lemur species, a group of primates endemic to islands off the southeastern coast of Africa. While threatened, Verreaux's sifaka is easily spotted in several of Madagascar's more accessible parks.
First megatransect of Madagascar completed Late last year an international team completed the first known transect of the island of Madagascar, the world's fourth largest island. The eight-month-long journey, dubbed "Hike Madagascar," took the group of intrepid hikers from the southern tip of Madagascar to the northernmost point of the island. The transect targeted rural communities along the eastern forest corridor, surveying villages and providing local farmers with techniques for improving rice yields and putting more food on the table for their families. The hike also provided a glimpse into some of the socioeconomic and environmental issues facing the island nation, which is one of the poorest in the world.
Seeking the world's strangest primate on a tropical island paradise Madagascar has been called the "land that time forgot" for its collection of unique and often downright bizarre plants and animals. Around 75% of the species on the island are found nowhere else on Earth, putting Madagascar atop the list among the world's most biologically diverse countries. Madagascar is famous for its lemurs, a group of primates endemic to the island.
Lemur hunting persists in Madagascar, rare primates fall victim to hunger Armand stares down at the trap made from sticks and ropes in the rainforest of Masoala. "For carnivores," he says. We have stumbled upon a series of traps within Masoala National Park, which holds one of the most biodiverse forests on Earth. In these forests you'll find about 50% of Madagascar's species, despite their making up less than 2% of its land mass. Given the incredible biological richness the Indian Ocean island, finding these traps is particularly sobering. It reminds us that no matter how much land is protected in Madagascar the only way to preserve its rare and unusual species is to ensure that conservation provides immediate and ongoing benefits for local people.
Lemur species named after British comedian Researchers from the University of Zurich have named a newly discovered species of lemur after British comedian John Cleese in honor of his work with the primates from Madagascar. According to the university, the lemur's name is a tribute to Cleese's promotion of the plight of lemurs in the movie "Fierce Creatures" and documentary "Operation Lemur with John Cleese."
Madagascar looks toward a brighter economic future with movie, new aid package The planet's most biologically diverse island is also one of the poorest countries in the world. Madagascar, the world's fourth largest island at about size the size of Texas or France, has an average per capita income of $260 among its 18 million people. About 70 percent of its population lives below the poverty line while nearly half of its children under five years of age are malnourished. In the past three years the country has nearly experienced a civil war and seen the agricultural based economy hit rock bottom during the political turmoil of the past presidential election. Nevertheless Madagascar may well be on its way to a brighter economic future thanks to a blockbuster animated movie, an innovative new aid program, and the capable leadership of the new president.
Explaining Madagascar's extraordinary levels of plant and animal endemism has been called "one of the greatest unsolved mysteries of natural history." The long separation of Madagascar from Africa and India explains only some aspects of the island's endemism. Even more intriguing is that many of these plants and animals have very small distributions on the island, something that is called micro-endemism.
For the first time, this new research presents a comprehensive theory explaining how so many animals came to be limited to such small geographic areas across the island, which lies off the eastern coast of Africa. In some lowland areas of the island these animals tended to be isolated by the configuration of certain watersheds, and this isolation led to speciation, the evolution of new species.
Using an analysis of watersheds in the context of paleoclimatic shifts, the authors provide a new mechanistic model to explain the process of explosive speciation on the island. Existing data show that substantial climatic shifts took place during the end of the Tertiary, as well as more recently during the Quaternary. The latter period is also known as "The Age of Man."
When the climate was dry and cold, considerable portions of the Earth were covered by glaciers. On Madagascar, habitats at higher elevations would have remained more humid, as compared to the drying-out of more lowland areas. Therefore, groups of animals tended to "retreat" to higher elevations along riverine habitat that would have remained relatively humid during these periods of climatic change. The animals that did not "retreat" tended to be left behind in small, limited geographic areas where river sources commenced at relatively low elevations. Since they were isolated, those populations that were able to survive were more likely to develop into new species.
"River catchments with their sources at relatively low elevations were zones of isolation and hence led to the speciation of locally endemic taxa," the authors explain in a paper to be published as the cover story of Science on May 19, 2006.
"This theory provides a clear framework for testing the relationships between different organisms that are closely related to one another, unraveling aspects of their evolutionary histories, and explaining how so many endemic animals can be found on this island nation," says Steve Goodman, one of the authors and Senior Field Biologist at The Field Museum and coordinator of a science educational project at WWF-Madagascar.
The other co-authors are Lucienne Wilmé, an ornithologist who has been living on Madagascar for nearly two decades and has considerable experience in the natural sciences and data analysis; and Jörg U. Ganzhorn of the Department of Animal Ecology and Conservation at the University of Hamburg, Germany, who has been studying the ecology of different groups of vertebrates on this island nation for a comparable period of time.
Data and spatial analyses solve the riddle
The new hypothesis explaining the evolutionary history of regional speciation in Madagascar's forests is based a study of the island's rivers and associated watersheds coupled with an analysis of 35,400 records of different modern animals. This method predicts several centers of endemism that are borne out by current distribution of these endemic animals, including lemurs.
Using the new method to classify different portions of the island as special zones of micro-endemism and then overlaying them on maps of Madagascar showing reserves and parks reveals several areas in need of additional protection.
"This analysis has crucial importance associated with the Malagasy Government's current plan to increase the island's protected areas by three-fold, giving clear priority to zones with high levels of micro-endemism, remaining forests, and little-to-no current protection," Goodman says.
This article features a news release from the Field Museum
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