Gene frequencies in a population of feral cats in Portsmouth naval Dockyard.

The free-living or feral cats of Portsmouth Dockyard were examined for the frequency of six mutant colour and coat genes. With the exception of one mutant, they were found to differ from the values to be expected for Southern England cat populations. The differences observed may have resulted from selection in the isolated environment (to produce a unique gene profile in terms of frequencies) or from a founder effect. If the latter, the observed frequencies could represent a relict population reflecting the frequencies of the town of Portsmouth before the dockyard was totally enclosed by a high wall. Some evidence of selection related to coat colour was found.