The idea of a species - How do we define a species over time?
Temporal and non-temporal concepts
A distinction among species concepts is between temporal and non-temporal concepts. The species concepts we have discussed so far aim to define how, and explain why, individuals should be grouped into species at one time-instant: they are non-temporal concepts.
Temporal concepts take account of the time dimension of evolution, and aim to define which individuals are members of a species not only at one time, but throughout all time.