The islands of Madagascar and the Galapagos could also be home to a number of the most iconic creatures on Earth, however the title of the world’s highest concentration of unique mammal species seems to belong to the island of Luzon within the Philippines.
A team of American and Filipino authors concluded that it was the island of Luzon within the Philippines. Their 15-year project was summarized in an article published in a scientific journal The limits of biogeographyshowed that of the 56 species of non-flying mammals known to survive the island, 52 don’t live anywhere else on the planet. During the project, 28 of those 56 species were discovered. Nineteen species have been formally described in scientific journals and nine are currently “in work.”
“We began our research on Luzon in 2000 because we already knew that almost all of the island’s native mammal species were found only on the island, and we wanted to grasp why this was the case. We didn’t expect the number to double, the number is already known,” said Lawrence Heaney, project leader and curator of Negaunee mammals at The Field Museum in Chicago.
Luzon is the biggest island within the Philippines; At roughly 40,000 square miles, it’s barely larger than Indiana. According to the authors, Luzon was never connected to any continental land – these species were isolated, identical to the animals living in Hawaii. However, Luzon is way larger and at the least five times older than the oldest island in Hawaii, so it has had time for the few species which have arrived from the Asian continent to evolve and diversify significantly.
On islands, scientists sometimes see an “accelerated” version of evolution – when animals are cut off from the remainder of the world, in places where there are few or no predators or competitors, they’re able to develop special adaptations, ultimately creating recent species. The island of Luzon isn’t only isolated, but covered with mountains. Mountain peaks create what scientists call “sky islands” – small clusters of distinctive habitats to which animals adapt. “The animals are isolated high in scattered mountains, so they are inevitably different from each other. If you give it enough time, you’ll start to see a huge amount of biodiversity,” Heaney explained. “In trying to understand how this happens, we have doubled the number of known species in Luzon.”
The 28 recent species discovered by the team include 4 species of tiny tree mice with whiskers so long that they almost reach the ankles, and five species of mice that appear to be shrews and feed mainly on earthworms. Most of the brand new species live in tropical cloud forests high within the mountains, where frequent typhoons can dump 4 to 5 meters (12 to fifteen feet) of rain a yr.
“All 28 species we discovered during the project belong to two branches of the tree of life found in the Philippines,” says Eric Rickart, a team member on the Utah Museum of Natural History. “There are isolated mountains on the island of Luzon that are home to five species of mammals that don’t live anywhere else. That’s more unique species living on one mountain than in any country in continental Europe. The concentration of unique biodiversity in the Philippines is truly astounding.”
There are also 57 species of bats in Luzon; most live in hot and humid lowlands. These include the golden-crowned flying fox, which is certainly one of the heaviest bats on the planet, weighing as much as two and a half kilos. Another, smaller flat-headed bat, is so small that it might roost within the empty spaces inside bamboo stalks.
“We also wanted to learn more about the conservation status of these wonderful animals,” said Danny Balete, a research associate on the Field Museum based within the Philippines. “The Philippines is one of the most deforested countries in the tropics; only about seven percent of the old-growth tropical forest remains. We have learned that quite a few species are seriously threatened by habitat loss and overhunting, but none are extinct yet.” Luzon has a population of about 50 million, including about 23 million in greater Manila, the country’s capital. “Protecting all these species from extinction might be a serious challenge. The excellent news is that when native forest is allowed to regenerate, native mammals will move back in and the rat pests might be driven out.”
The paper’s other co-authors are on the University of the Philippines, the University of Minnesota and Florida State University. Heaney, Balete and Rickart are also the authors of a book on the mammals of Luzon, just published by Johns Hopkins University Press, which might be used as a university-level textbook within the Philippines. The team works closely with conservation organizations and the Philippine government, and plenty of of their recommendations for expansion and recent national parks have been adopted.
“Understanding the enormous diversity of mammal species found on Luzon is critical to conservation efforts,” Heaney explained. “To effectively protect the environment, we need to know what is happening there.”
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Field Museum. “The world’s largest concentration of unique mammal species is found on a Philippine island: a 15-year study found that 93% of Luzon’s land mammals are found nowhere else.” ScienceDaily. ScienceDaily, July 14, 2016
Griffiths, Sarah. “Luzon boasts the very best concentration of strange mammals, including ‘cloud rats’.” Daily mail onlineAssociated Newspapers, July 14, 2016, www.dailymail.co.uk/sciencetech/article-3690461/Is-strangest-island-Earth-Luzon-boasts-highest-concentration-weird-mammals-including-cloud-rats- mice-whisker-cubes.html.
