A zygote will not undergo meiosis in an environmental state that is not favorable for the zygote’s survival i.e. the chance of the zygote to survive is not certain. Take for example, chlamydomonas will form a zygote under normal asexual mitotic reproduction in a favorable environmental condition. However, under unfavorable environmental conditions the organism also reproduce sexually to form a zygote but will never proceed to meiotic division because of the unfavorable environmental state.