A single animal species is likely to become extinct from different locations on Earth around the same time if a common external factor, or "forcing", is applied, say two Indian researchers.
In a joint study, Professor Govindan Rangarajan of the Indian Institute of Science, Bangalore, and Professor RE Amritkar, Physical Research Laboratory, Ahmedabad, say that "synchronisation" of the specie precedes extinction if there is a common external forcing.
"Such a forcing could be anything from an ice age, global warming or a volcanic eruption to meteorites hitting the earth, threat from predators and even large-scale hunting by humans," their study states.
The separated communities of the specie synchronise together before becoming extinct. Animal populations all over the world are likely to synchronise their numbers before dying out, the researchers say.
More than 99 percent of the species that ever existed on the surface of the earth are now extinct, and their extinction on a global scale has been a puzzle for scientists worldwide. Many are of the opinion that a specie under an external threat like climate change, asteroids hitting the earth and volcanic eruptions may survive in some isolated locations - leading to the revival of the specie.
However, the latest research conducted over a year suggests that if a specie becomes extinct in one location, it becomes extinct globally in all locations. Populations of a single animal specie will become extinct at the same time due to the common external factor, or "forcing", according to the study that has appeared in the June issue of the journal Physical Review Letters.
They have based their findings on a theory called Special Spatial Synchronisation.
The model, if correct, implies that isolating an endangered specie will not necessarily mean it survives - a strategy often proposed by conservationists and wildlife groups, it said.
For example many species, including the giant dinosaurs, have disappeared. Thus was due to catastrophic events. "They became extinct since the climatic conditions became unfavourable," Rangarajan told IANS in an e-mail interview.
There are many species facing extinction like the spider monkey of Colombia and the black howler monkey among other species, said Rangarajan. He got his Ph.D. from University of Maryland, College Park, USA, and also served at the Lawrence Berkeley Laboratory, University of California, Berkeley, for two years before joining the Indian Institute of Science in 1992.
"We started with some experimental data showing that a predator can synchronize prey populations across different locations," he said.
The data obtained were from a 2000 Norwegian survey, which looked at the fate of 481 voles (a kind of rodent) in different locations that had been tagged with a radio-marker.
By measuring the growth rates of these populations, results showed that the predators had a "synchronising" influence on the voles (that is, the growth rates of voles in different places began to decline in step).
"We developed a general model based on this and applied techniques from non-linear dynamics to study the problem," said Rangarajan, who did his MSc from the Birla Institute of Technology and Science at Pilani.
"It is not clear whether human beings face extinction. If there is a catastrophic event like large asteroids hitting the earth, this can happen," he said. Similarly, global warming can play a role in future extinctions.