BRAZIL: A species of ant living in Brazil may be the latest "canary in a coal mine", giving an early warning of the impact of climate change. The insect's physiology has changed, allowing it to cope better in a warmer urban environment.
Researchers around the world are looking for examples of how a warmer climate might affect life on our planet. But rather than waiting for global change, a group from Indiana State University (ISU) decided to focus on the urban environment, where warmer temperatures already exist.
Cities can be more than 10 degrees hotter than the surrounding countryside because of solar heat retention, vehicle emissions and the heating of buildings, says project leader Prof Michael Angilletta of ISU.
These metropolitan hot spots are referred to by scientists as "urban heat islands". They are also places, however, where the implications of a warmer climate can already be gauged.
An international team of biologists joined to identify city animals that have already been affected, and they found one in an ant species living in South America's largest city, São Paulo, Brazil.
They discovered the ant has already changed, providing it with a higher heat tolerance. The same ant species recovered from outside the city was less able to cope with the extra heat, leading the researchers to suggest the city ants had already modified their physiology in response to urban warming.
The findings could be useful in future climate change studies, said Prof Angilletta, who with colleagues released the findings yesterday in the online open-access scientific journal PLoS ONE, published by the Public Library of Science (www.plosone.org).
"We don't know whether this pattern will hold up for other species or other cities, but people should certainly be looking," Prof Angilletta said.
"Ultimately this research could help us to understand how species will respond to global climate change."
The biologists have now joined with geographers to measure and map the urban heat island effect in other large cities, starting with nearby Indianapolis.
"We will construct thermal maps using satellite images recorded over several years," said Prof Qihao Weng, associate professor of geography at ISU.
"These maps will enable us to assess the potential biological consequences of urban warming and identify suitable sites for future experiments."