The colour polymorphism in Enoplognatha ovatum (Clerck) (araneae: theridiidae)--temporal stability and spatial variability.

Colonies of the visually polymorphic spider Enoplognatha ovatum have been studied in Nidderdale, Yorkshire, for up to six years. Morph frequencies are found to be stable within colonies between years but to vary between colonies only short distances apart. The stability of the polymorphism argues in favour of powerful selection acting on this character. The nature of the selective factors are unknown but they are not those which influence time of maturity of the spiders or the mature female population size, both of which have varied between years. A genetic basis proposed for the polymorphism is considered and rejected as being incompatible with stable morph frequencies.