A "deme" is a term used in biology to describe a local population of organisms that are genetically similar and interbreed. Demes are often part of a larger species but can exhibit distinct characteristics due to their specific environment or geographic isolation. This concept is important in the study of evolution and ecology, as it helps scientists understand how populations adapt to their surroundings. In the context of genetics, demes can contribute to the formation of new species over time through processes like natural selection and genetic drift. By studying demes, researchers can gain insights into the dynamics of population genetics and the mechanisms that drive speciation.