All the individuals of a species that live together in one place at the same time

All the individuals of a species that live together in one place at the same time is called as population.

Explanation:

When organisms of same group or species live in a particular area they are defined as population. Along with living in a particular area the species should also have the 'capability of interbreeding' in order to be called as population. Demography is a social science that deals with the 'statistical study of population'. A term 'sex population' is often visualized in 'population genetics', it refers to a organisms group in which a 'pair of members' can breed together.