Professor Bryan Clarke,he geneticist, who has died aged 81, demonstrated the importance of the role of predators in maintaining biological diversity and co-founded the “Frozen Ark” project to preserve the DNA of threatened animal species.
In a 1962 paper entitled “Balanced polymorphism and the diversity of sympatric species” (polymorphic species have a variety of different forms, or “phenotypes”), Clarke coined the term “apostatic selection”. This describes a process whereby common forms of certain species of animal can lose out to less common forms (“apostates”) in ways which tend to maintain polymorphic diversity.
Much of his early research involved studying the English grove snail Cepaea nemoralis, whose shell colours and patterns can be highly variable — reddish, brownish, yellow or whitish, with or without dark brown colour bands.