In the first, the rich abundance of life at the tropics was shown to be due to constant year-round temperatures, rather than a warm and sunny climate. The study, published in Paleobiology, compared the insect diversity of a Canadian fossil bed created when global temperatures were constant across latitudes with that found in present-day temperate and tropical forests. The  diversity of the ancient site corresponded closely with the tropical forests of today, despite the fact that when it was formed, it was found at a lower latitude.

According to one of the study’s authors, Brian Farrell of Harvard University, the findings suggest that it isn’t that the heat of the tropics promotes diversity – as previously thought – but rather that the temperate zone’s seasonality suppresses it.

A separate study published in Nature also demonstrated strong links between the distribution of biodiversity in the oceans and water temperature. An international team of scientists mapped the distribution of more than 11,000 species, from plankton to whales. They found biodiversity hotspots of coastal species around Southeast Asia and open-ocean species, such as whales, in mid-latitude oceans. In each case, temperature was strongly tied to species distribution.

‘It was striking how consistently temperature was linked with marine diversity,’ said lead author Derek Tittensor of Dalhousie University in Nova Scotia, Canada. ‘This relationship suggests that ocean warming, such as that due to climate change, may rearrange the distribution of oceanic life.’       

KARA MOSES
October 2010