The population of deme R held at 7889 until 7625.209 generations back, when it increased reaching 8521, which has been constant since then.
time_units: generations
demes:
  - name: R
    start_time: .inf
    epochs:
      - start_size: 7889
        end_time: 7625.209
      - start_size: 8521
        end_time: 0