The number of individuals in deme Z remained at 4280 until 4982.835 generations ago, at which time it increased to a new stable size of 5064.
time_units: generations
demes:
  - name: Z
    start_time: .inf
    epochs:
      - start_size: 4280
        end_time: 4982.835
      - start_size: 5064
        end_time: 0