Protandry

Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropoda and plants. Sequential hermaphroditism occurs when the individual changes sex at some point in its life. They can change from a male to female (protandry), or from female to male (protogyny) or from female to hermaphrodite (protogynous hermaphroditism), or from male to hermaphrodite (protandrous hermaphroditism). Those that change gonadal sex can have both female and male germ cells in the gonads or can change from one complete gonadal type to the other during their last life stage. Individual flowers are also called sequentially hermaphrodite, although the plant as a whole may have functionally male and functionally female flowers open at the same time.

Protandrous hermaphrodites refer to organisms that are born male and at some point in their lifespan change sex to female. Protandrous animals include clownfish. Clownfish have a very structured society. In the Amphiprion percula species, there are zero to four individuals excluded from breeding and a breeding pair living in a sea anemone. Dominance is based on size, the female being the largest and the male being the second largest. The rest of the group is made up of progressively smaller non-breeders, which have no functioning gonads. If the female dies, the male gains weight and becomes the female for that group. The largest non-breeding fish then sexually matures and becomes the male of the group.

Other protandrous fishes can be found in the classes clupeiformes, siluriformes, stomiiformes, and within the perciform families pomacentridae and sparidae. Since these groups are distantly related and have many intermediate relatives that are not protandrous, it strongly suggests that protandry evolved multiple times. Other examples of protandrous animals include:

Protogynous hermaphrodites refer to organisms that are born female and at some point in their lifespan change sex to male. As the animal ages, based on internal or external triggers, it shifts sex to become a male animal. Male fecundity increases greatly with age, unlike female.

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