Range of habitat less important during mass extinctions: study

Animals with widerranges of habitatmight have a better chance of surviving the effects of global climate change, but would still be vulnerable, a new study has found.

Geographic range has been shown to have an impact on survival,as animals with more localized habitats are generally more likely to become extinct.

But Stanford paleobiologists Jonathan Payne and Seth Finnegan found that during times of mass extinctions the correlation isn't as strong, suggesting widespread climate change could affect more than already at-risk species in dwindling habitats.

The authors looked at fossil records of marine invertebrates from the Middle Cambrian Epoch to the Middle Miocene sub-Epoch, or roughly from 510 million to 15 million years ago.

They confirmed that geographic range was the single biggest factor in determining whether marine invertebrates were able to avoid extinction during the intervals between mass extinctions.

During times of mass extinctions, geographic range was still important, but less so in determining which genus wouldsurvive.

"Mass extinctions and several second-order extinction events exhibit less geographic range selectivity than predicted by range alone," the authors said.

"Widespread environmental disturbance can explain the reduced association between geographic range and extinction risk by simultaneously affecting genera with similar ecological and physiological characteristics on global scales."

The authors found that each of the three major mass extinctions during the period studied was also associated with "geological and geochemical evidence for rapid, global environmental disruption."

During these periods, otherissues separating the survivorswere differences in physiology, feeding methods and local habitat preference.

A report from the Intergovernmental Panel on Climate Change on the potential fallout of climate change warned thatup to 30 per cent of the Earth's species face an increased risk of extinction if average global temperaturesrise by1.5 to 2.5 C.