Until a shift occurred 2457.97 generations ago, deme D's population was consistently 6195. Since then, it grew to 9408, a number that has remained unchanged to the current time.
time_units: generations
demes:
  - name: D
    start_time: .inf
    epochs:
      - start_size: 6195
        end_time: 2457.97
      - start_size: 9408
        end_time: 0