Up until 4032.525 generations ago, the count of Z deme was 1671. Following that period, it changed to 7926, where it has persisted until now.
time_units: generations
demes:
  - name: Z
    start_time: .inf
    epochs:
      - start_size: 1671
        end_time: 4032.525
      - start_size: 7926
        end_time: 0