By using the legend below the diagram, you can assume that Phase 1 indicates that meiosis has occurred because of the color of the arrow. The dark gray indicates haploid, and haploid is the result of meiosis. Diploid is the result of mitosis.
Another indication is the presence of sex cells or gametes in Phase 1. Meiosis produces gametes and in phase 1, you can see that egg cells and sperm cells were produced.
