Up until 3122.84 generations ago, the count of D deme was 5452. Following that period, it changed to 3001, where it has persisted until now.
time_units: generations
demes:
  - name: D
    start_time: .inf
    epochs:
      - start_size: 5452
        end_time: 3122.84
      - start_size: 3001
        end_time: 0