The green alga Chlamydomonas spends most of the life cycle in the haploid vegetative phase, asexually producing daughter cells by mitosis.

Unfavorable conditions trigger the sexual phase, where some vegetative cells develop into isogametes, which can fuse to form a diploid resistant zygote adapted for surviving harsh conditions.

When conditions become suitable again, meiosis of the zygote produces two plus mating types and two minus mating types.

Mitosis of these zoospores returns the cells to vegetative colonies.