GENETIC STABILITY IN POPULATIONS OF THE POLYMORPHIC SNAIL, CEPAEA NEMORALIS (L.)

Authors


SUMMARY.

Collections of the polymorphic snail Cepaea nemoralis (L.) have been taken from three small and well-defined localities after intervals of 40 to 50 years.

In one of the areas the original colony has probably become extinct and it has recently been recolonized by a new population which is significantly different from the original one.

In the other two colonies the genetic composition of the populations has remained remarkably constant over the period covered by the observations, although in one of them there has been an increase of 10 to 15 per cent in the dominant gene for bandless shells. There is evidence that this change has been brought about by selective predation by birds.

Ancillary