What Madagascar’s Extreme Biodiversity Tells Us About the Impact of Climate Change on Wildlife
The isolated island of Madagascar is filled with plants and animals—thousands of them—found nowhere else on Earth.
There’s no one answer, however, for why an island off Africa’s east coast that makes up just 0.5 percent of the planet’s surface surpasses the entire African continent in biodiversity, according to a new study published in Nature Communications.
“No single climatic, geographic and geologic factors were responsible for generating a majority of Madagascar’s diversity,” study coauthor Jason Brown of City College of New York said in an email.
The study is part of a larger body of work looking at what has led plant and animal species to end up in certain areas, with the aim of better identifying how historical changes in climate and geology and other environmental factors have affected unique regions.
“One of the lessons learned is that when trying to assess the impacts of future climate change on species distribution and survival, we have to deal in specifics rather than generalities, since each group of animals experiences its environment in a way that is unique to its life history and other biological characteristics,” Anne Yoder, a Duke University biologist and the study’s coauthor, told Duke Today.
Other studies have identified reptiles and amphibians on Madagascar are moving to higher elevations as temperatures rise.
Brown said that species with limited ecological tolerances—such as narrow temperature ranges or certain water requirements—could be at particularly high risk from climate change.
“Species that exist on mountain tops or near the poles that require cold temperatures cannot go further north or higher up a mountain to continue living in cold temperatures—at some point they will reach the peaks or the poles, respectively,” Brown said. “Our study suggests all organisms are constrained by their own genetic inheritance and evolutionary inertia, and travel a unique path that led to the diversity we observe today.”
The study analyzed more than 700 species of reptiles and amphibians living on Madagascar. The researchers found that each species responded differently to changes in their environment, and no single development led to the island’s formation as a biodiversity hotspot.
“It means that there won’t be a uniform decline of species—some species will do better, and others will do worse,” Brown told Duke Today.
With 90 percent of its animals and plants found nowhere else in the world, Madagascar has become a hotbed of research on why biodiversity has flourished there, and what effect climate change might have.
Brown, along with researchers from Duke University; Queens University in Belfast, Ireland; and Braunschweig University of Technology in Braunschweig, Germany, determined Madagascar’s biodiversity by relying on three indicators: the number of species in an area, the number of unique species in a given area, and the similarity of species found in one zone compared to another.
Their model then looked at the current range and population of 700-plus species of amphibians and reptiles compared with historical data on the animals.
"Not surprisingly, we found that different groups of species have diversified for different reasons," Yoder said.