The place of residence of all cases of childhood cancer occurring in the Northern Region from 1968 to 1982 has been analysed by electoral wards. The wards have been ranked according to rate and Poisson probability. Both rankings show a wide geographical scatter throughout the region of areas with an apparent excess incidence of cancer. These areas are not confined to the Cumbrian coast.

Ecological isolation is a process whereby gene flow between selective environments is reduced due to selection against maladapted dispersers, migrant alleles, or hybrids. Although ecological isolation has been documented in several systems, gene flow can often be high among selective regimes, and more studies are thus needed to better understand the conditions under which ecological gradients o...