In biology, a deme, in the strict sense, is a group of individuals that belong to the same taxonomic group.[1] However, when biologists, and especially ecologists, use the term ‘deme’ they usually refer to it as the definition of a gamodeme:[2] a local group of individuals (from the same taxon) that interbreed with each other and share a gene pool.[1] The latter definition of a deme is only applicable to sexual reproducing species, while the former is more neutral and also takes asexual reproducing species into account, such as certain plant species. In the following sections the latter (and most frequently used) definition of a deme will be used.
In evolutionary computation, a "deme" often refers to any isolated subpopulation subjected to selection as a unit rather than as individuals.