protandry

Protandry is a biological pattern in which male reproductive organs or male reproductive function mature before female ones. In sequential hermaphroditism, individuals may begin life as males and later transition to females. The term contrasts with protogyny, where individuals first function as females and later become males.

In animals, protandry occurs in several fish and invertebrate species. Many protandrous fishes start life as males and switch to females as they grow, so larger individuals bear eggs. This size-based strategy can maximize reproductive success, particularly when female fecundity increases disproportionately with body size. Social and environmental factors often influence the timing of sex change; in clownfish, for example, a strict social hierarchy governs sex change, and removing the dominant female can trigger a male to transition to female.

In plants, protandry refers to a form of dichogamy where pollen is released before the stigma becomes receptive. This reduces self-fertilization and promotes cross-pollination. Protandrous flowering is contrasted with protogyny, in which the stigma is receptive before pollen release. The prevalence and ecological significance of protandry vary among plant groups and pollination systems.

Protandry intersects with broader themes in mating systems, including sequential hermaphroditism and the evolution of reproductive strategies. Its occurrence highlights how sex expression can be flexible and context-dependent rather than fixed.