Movie 1.

Development of mybAA^- and wild-type cells. mybAA^- and wild-type cells were grown in axenic medium, harvested and plated on NN agar plated at 1.5 × 10⁶ cells/cm² on NN agar, separated by a narrow strip of overhead sheet inserted in the agar, with wild-type cells on the left and mybAA^- cells on the right. Images were taken every 5 min for 18 h until fruiting structures had formed, using a Leica stereomicroscope. The movie was compiled at 30 frames per second.