The Hot Zone

Climate change could jumpstart the metabolisms of tropical species

Posted by Alison Hawkes on October 7, 2010
Category : Climate Science and Scientists

Metabolism is more than just what may be responsible for sluggishness or weight gain. In fact, it’s the basis of life, controlling everything from growth and reproduction to energy production and cell formation through a series of chemical reactions.

Air temperature can affect metabolism, especially for species that rely on the external weather to control body temperature. Ectotherms like reptiles and amphibians get lethargic when it’s cold and frisky when it’s warm.

New research published in the October 7 edition of Nature points out that global warming could be having an unsuspecting impact on metabolisms, especially in the tropics. Much concern over species has focused on the Arctic and mid to high latitudes, where shifts in temperature are most extreme.

Earth Lion is a tropical chameleon. Photo: Richards Inyem

But the University of Wyoming-led team writes that species in the tropics (they studied ectotherms) will have greater absolute shifts in metabolic rates than Arctic species, even though the temperature difference in the tropics is smaller. This is due to the way metabolic rate increases.

The impact of climate warming on metabolic rate has never been quantified on a global scale, they write. “Here we show that estimated changes in terrestrial metabolic rates in the tropics are large, and are in fact far greater than those in the Arctic, even though tropical temperature change has been relatively small.”

So what’s the result? Higher metabolic rates mean these species will need to eat more, and thus be vulnerable to starvation unless food resources also increase. The more energy devoted to food could reduce reproductive capacity, while complex food webs could be severely impacted through more predation and herbivory. Insect-borne tropical diseases could increase.

“Because the tropics are the center of Earth’s biodiversity and its chief engine of primary productivity, the relatively large effects of temperature change on the  metabolism of tropical ectotherms may have profound local and global consequences,” they write.

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