Deme D maintained a population of 1843 until there was a shift 2025.438 generations ago that reduced its numbers to 1664, a figure that has remained the same since.
time_units: generations
demes:
  - name: D
    start_time: .inf
    epochs:
      - start_size: 1843
        end_time: 2025.438
      - start_size: 1664
        end_time: 0