Until a shift occurred 6934.644 generations ago, deme R's population was consistently 7158. Since then, it decreased to 1656, a number that has remained unchanged to the current time.
time_units: generations
demes:
  - name: R
    start_time: .inf
    epochs:
      - start_size: 7158
        end_time: 6934.644
      - start_size: 1656
        end_time: 0