Trioecy
Presence of males, females, and hermaphrodites in a population
From Wikipedia, the free encyclopedia
Trioecy is a sexual system characterized by the coexistence of males, females, and hermaphrodites. It has been found in both plants and animals.[1][2] Like androdioecy and gynodioecy, trioecy is a mixed mating systems.[3]
Terminology
Evolution of trioecy
Trioecy may be an unstable transient state[6] associated with evolutionary transitioning from gynodioecy to dioecy.[7][6] In brachiopod species, trioecy usually breaks into androdioecy or gynodioecy.[8] Other studies show that trioecious populations originated from gonochoristic ancestors which were invaded by a mutant selfing hermaphrodite, creating a trioecious population.[1] It has been suggested that chromosomal duplication plays an important part in the evolution of trioecy.[9]
But one study found that trioecy can be stable under nucleocytoplasmic sex determination.[10] Another theoretical analysis indicates that trioecy could be evolutionary stable in plant species if a large amount of pollinators vary geographically.[11]
Occurrence
Trioecy is a relatively common sexual system in plants,[12] estimated to occur in about 3.6% of flowering plant species,[10] although most reports of trioecy could be misinterpretations of gynodioecy.[13] It is rare as well as poorly understood in animals.[12]
Species that exhibit trioecy
The following species have been observed to exhibit a trioecious breeding system.
Plants
Animals
- Aiptasia diaphana[21]
- Auanema rhodensis[1][6]
- Auanema freiburgensis[6]
- Hydra viridissima[22] (green hydra)
- Thor manningi [3] (Manning grass shrimp)
- Semimytilus algosus (Pacific mussel)[12]