Deme S maintained a population of 9548 until there was a shift 8875.9 generations ago that decreased its numbers to 7509, a figure that has remained the same since.
time_units: generations
demes:
  - name: S
    start_time: .inf
    epochs:
      - start_size: 9548
        end_time: 8875.9
      - start_size: 7509
        end_time: 0