Earth's biodiversity generally increases as temperatures rise over the long term, but rapid global warming is expected to have the opposite effect, according to Scots scientists.

The increase in the number of species depends on the evolution of new plants and animals over millions of years, research found.

The long timescale necessary for new forms to evolve means that present trends of rising temperatures are unlikely to boost biodiversity, said the scientists from the universities of York, Glasgow and Leeds.

Instead, the current speed of change is expected to cause diversity loss.

Researchers came to the conclusion after analysing fossil and geological records going back 540 million years.

It reverses the findings of a previous study that warm periods in the geological past led to a drop in diversity.

Professor Tim Benton, of the faculty of biological sciences at the University of Leeds, said: "Our results seem to show that temperature improves biodiversity through time as well as across space. However, they do not suggest that current global warming is good for existing species."

Alistair McGowan, of the school of geographical and earth sciences at the University of Glasgow, said: "The previous findings always seemed paradoxical. Ecological studies show that species richness consistently increases towards the equator where it is warm, yet the relationship between biodiversity and temperature through time appeared to be the opposite.

"Our new results reverse these conclusions."