Originally, deme J had a population size of 5398, which increased to 9831 around 9436.0 generations ago and has not changed since.
time_units: generations
demes:
  - name: J
    start_time: .inf
    epochs:
      - start_size: 5398
        end_time: 9436.0
      - start_size: 9831
        end_time: 0