LONDON: Scientists are staking out part of Britain's coastline to monitor the apparent birth of a new species - an exceptionally unusual chance to record evolution in action.

Research on the "fossil coast" of Yorkshire in north-eastern England - famous for a string of geological breakthroughs - has discovered two colonies of sea-snails which are almost certainly dividing to form a distinct new species.

The grey-brown rough periwinkle Littorina saxatilis is described modestly by the team as "unremarkable and lacking charisma", but it stands to earn a place in the textbooks.

"We are increasingly certain that we are seeing one species become two," said John Grahame, a biologist at Leeds University, who is leading the project. The snail is found by the million on beaches. Two different "morphs" of Littorina saxatilis occupy different areas of foreshore, and are moving steadily apart after centuries of communal life and interbreeding.

The Leeds team has established genetic differences between the separated colonies and evidence that "divorce" is, in evolutionary terms, imminent. "The really exciting development - the holy grail of speciation - is evidence that the morphs are becoming reproductively isolated and no longer freely interbreeding," said Dr Grahame.

"Individual snails prefer to mate with others of the same morph, and when interbreeding does happen, the viability of the young is reduced." Observations will continue while modern DNA-testing techniques build up a more detailed picture of the snails' genes than has been possible in the past.

The project is also comparing different techniques used by the different colonies against their main predators, crabs. One set of snails, closer to the tideline, has been nicknamed "crab resisters".

The others, higher up on the beach and less well protected, are called "crab avoiders". Their strategy is to hide. "There are alternative explanations for what is going on and the process could easily be reversed," said Dr Grahame.

"The point of no return, when we can truly say a new species has been born, will come when there is no interbreeding at all, and no gene-flow between the morphs."-Dawn/The Guardian News Service.