time_units: generations
demes:
- name: deme1
  start_time: .inf
  epochs:
  - {end_size: 1000, end_time: 0, start_size: 1000}
- name: deme2
  start_time: 400000.0
  epochs:
  - {end_size: 1000, end_time: 0, start_size: 1000}
  ancestors: [deme1]
- name: deme3
  start_time: .inf
  epochs:
  - {end_size: 1000, end_time: 0, start_size: 1000}
migrations:
- {source: deme3, dest: deme2, start_time: 400000.0, end_time: 0.0, rate: 0.00025}