Friday, September 4, 2015

Borneo mountain hotbed of young biodiversity

Mount Kinabalu (Source: J. Kong/Sabah Parks)

 A species of stalk-eyed fly (Teleopsis pallifacies that lives along streams, such as the Kemantis waterfall.

 This jumping spider (Myrmarachne malayana) mimics ants, presumably to avoid being predated on. Its large jaws can be seen ready to snap at its own prey. It is a widespread species that lives both on the mountain and on the lowlands.

On the tip of Borneo stands the World Heritage-listed Mount Kinabalu, which like other tropical mountains is known to be a hotbed of biodiversity.
Only now, however, have researchers carried out a systematic DNA analysis of biodiversity on the mountain to get an insight into how it evolved.

By comparing organisms found on the mountain with those found elsewhere, they not only estimated when the species evolved, but where they came from.

The analysis follows collection of tens of thousands of plants, animals (mainly insects, spiders and mites) and mushrooms, many of which are unique to the mountain, says lead author, Professor Menno Schilthuizen, an evolutionary biologist at the Naturalis Biodiversity Center and Leiden University in the Netherlands.

The findings suggest that most of the species have an average age of only 1.5 million years, while the mountain itself is at least six million years old, says Schilthuizen.

The discovery that most of the species on Mount Kinabalu are so much younger than the mountain itself puts another nail in the coffin of the idea that tropical mountains are refuges for plants and animals that have been around for a very long time, says Schilthuizen.

"For example, tablelands in Venezuela are called 'lost worlds'," he says. "The idea is that on top you have these ancient lineages that have been outcompeted elsewhere."

He says about two thirds of the species on Mount Kinabalu are descendants from species at lower altitudes, that became adapted to cooler conditions," he says.

The rest live higher on the mountain and have come from spores, seeds and tiny animals, transported from further afield by high aerial currents.

"There's constantly a soup of very tiny organisms floating in the air and that's a very important source for colonisation for islands and high mountains," says Schilthuizen.

Because the temperature and environment change rapidly as you go up a mountain, this means that niches for different species change similarly rapidly, which means species may be restricted to certain areas, such as the summit of the mountain.

As the climate warms, such species will have limited 'room to move', says Schilthuizen, and may be threatened with extinction.

The findings are published today in the journal Nature.

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