For a century the Partula, a Polynesian tree snail, had been the focus of debate on the relationship between environment and evolution. It has now been driven to extinction in all its natural habitats by another snail, the Euglandina. See today's choices.
Written and produced by Kate O'Sullivan ; Editor John Lynch Repeated next Saturday
TRANSCRIPT: please send a cheque for £2.00, payable to BSS. to [address removed]
♦ See This Week: page 13