Tropical climate affects metabolic rate

The study appears in the journal
Proceedings of the National Academy of Sciences. http://www.pnas.org/


http://www.guardian.co.uk/science/story/0,,1765546,00.html

Researchers get warm in quest to solve evolutionary mystery

· Study shows why species evolve faster in tropics
· Climate affects metabolic rate and generation length

Ian Sample,
science correspondent
Tuesday May 2, 2006
The Guardian (c)


"Scientists believe they have cracked one of the most enduring mysteries since Charles Darwin returned from the Galapagos islands: why is there such a variety of life in the tropics?

"Scientists have proposed that evolution, the natural process that saw modern life develop out of a primitive broth, speeds up at the equator, so more species are able to flourish there. One theory is that creatures living along the equator are more likely to evolve into different species for two reasons: firstly, they have a higher rate of metabolism, which leads to more genetic mutations; secondly, they have shorter generations, so genetic changes can be rapidly passed down.

"Tropical plants were taken from New Guinea, north-eastern Australia, Borneo, India, Tahiti and South America, with temperate species plucked from North America, southern Australia, New Zealand and Eurasia.

"Dr Wright [Shane Wright, a plant geneticist at the University of Auckland] said the study supported the idea that the equator was home to the lion's share of the world's species because organisms there respond to the warm conditions by speeding up their metabolism and reproducing faster.

""Biodiversity is always much higher in the tropics. The closer you go to the equator, the more species you have and that is true for viruses, bacteria, plants, mammals, the whole lot," said Francois Balloux, a geneticist at Cambridge University. "In many cases, these ecosystems are very complex, so this offers many niches and it is easier for populations to split.""


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