What's so unique about the tropics? 'Less than we thought'

Sep 23, 2011
Ecuadoran lowland forest. Credit: Nathan J.B. Kraft

(PhysOrg.com) -- The temperate forests of Canada or Northern Europe may have much more in common with the tropical rainforests of Southeast Asia or South America than commonly believed, according to a research group led by a University of British Columbia ecologist.

The assertion, published today in the journal Science, is focused on the concept of “beta-diversity” – a measure of the change in species composition between two sites, such as neighboring patches of forest. High beta-diversity means that two given sites have few species in common.

Typically, beta-diversity increases as you move from the poles towards the equator, often leading ecologists to conclude that there is something inherently different about the ecology of the tropics that leads to greater turnover of species from place to place.

But a group led by Nathan J.B. Kraft, a postdoctoral fellow at UBC’s  Biodiversity Research Center, challenged this interpretation, using an extensive dataset of tree inventories from around the world and archived at the University of Arizona. Using computer modeling, the researchers demonstrated that current patterns of beta-diversity in the tropics and the temperate zone are much more similar than ecologists once thought.

Kraft and colleagues found that the crucial factor in shaping beta-diversity at large scales is how many species are present in the region in the first place. Once they accounted for these differences, the resulting beta-diversity patterns were the same in forests at tropical and temperate latitudes. They found the same consistency between high and low elevations in mountain regions.

“It was believed that something ‘extra’ must be going on in the ecology of the tropics to produce greater beta diversity there,” says Kraft, who will become an assistant professor at the University of Maryland next year. “We now see that the patterns can all be explained not by current ecological processes, unfolding over one or two generations, but by much longer-term historical and geologic events.”

Kraft’s group included researchers from institutions in the U.S., Canada, Panama and New Zealand and was supported by the U.S. National Center for Ecological Analysis and Synthesis and the U.S. National Science Foundation.

“We were surprised to see that the causes of these patterns might actually be a lot more simple and share a lot more in common than we first thought,” Kraft says. “For decades now, ecologists have gone to the tropics to try to explain the often incredibly high diversity found there. But what our results show is that the same ecological mechanisms might operate in similar ways in Costa Rica and Calgary.”

Explore further: Dwindling wind may tip predator-prey balance

Related Stories

Why more species live in the Amazon rainforests

May 04, 2011

(PhysOrg.com) -- For more than two hundred years, the question of why there are more species in the tropics has been a biological enigma.  A particularly perplexing aspect is why so many species live ...

Stable temperatures boost biodiversity in tropical mountains

Jun 08, 2011

We often think of rainforests and coral reefs as hotspots for biodiversity, but mountains are treasure troves for species too -- especially in the tropics, scientists say. But what drives montane biodiversity? The diversity ...

Finding the missing pieces

Mar 25, 2011

(PhysOrg.com) -- Missing pieces in the biodiversity puzzle make it impossible to accurately predict the effects of climate change on most plant species in the Amazon and other tropical areas, according to ...

Three new bat species discovered in Indochina

Sep 05, 2011

Three new bat species have been discovered after an international team of scientists from the Hungarian Natural History Museum (HNHM) and Fauna & Flora International (FFI) embarked on a study in southern Indochina.

Cool species can take the heat

May 17, 2011

(PhysOrg.com) -- Two scientists from Simon Fraser University and one from Deakin University (DU) in Australia have made a discovery that is overturning conventional wisdom about how land and marine animals react to heat.

Study links forest health to salmon populations

Mar 25, 2011

(PhysOrg.com) -- A new research paper written by Simon Fraser University biologists and published in the journal Science concludes that the abundance of salmon in spawning streams determines the diversity and productivity of pla ...

Recommended for you

Dwindling wind may tip predator-prey balance

Sep 19, 2014

Bent and tossed by the wind, a field of soybean plants presents a challenge for an Asian lady beetle on the hunt for aphids. But what if the air—and the soybeans—were still?

Asian stars enlisted to fight African rhino poaching

Sep 19, 2014

Increasingly desperate South African conversationists are turning to a multi-national team of "rhino ambassadors" to try to end the scourge of poaching—and Vietnamese pop diva Hong Nhung has been recruited ...

Tropical fish a threat to Mediterranean Sea ecosystems

Sep 18, 2014

The tropical rabbitfish which have devastated algal forests in the eastern Mediterranean Sea pose a major threat to the entire Mediterranean basin if their distribution continues to expand as the climate ...

User comments : 0