(Living things in their environment) members of a single species living in a habitat
A group of interbreeding organisms that represents the level of organization at which speciation begins. Population is measured as the total number of individuals of the species 
population, populations 1. The total number of people inhabiting a country, city, or any district or area. 2. The body of inhabitants of a place; such as, the population of a city. 3. The number or body of inhabitants of a particular race or class in a place; such as, the working-class population. 4. Any finite or infinite aggregation of individua...
groups of living organisms