FishHermaphroditism
From coraldigest
Hermaphroditism in Fish
Protogyny
- Sex change from female to male
- Displayed as normal part of life history in 14 fish families, including wrasses and parrotfishes[1]
Protandry
- Sex change from male to female; less common than protogyny
- Observed in 8 different families of fish; coral reef examples including porgies, damselfishes, and moray eels[1]
Sequential Hermaphroditism
- Sequential hermaphrodites function as one gender and then switch to the other, often as a result of changing population dynamics [2]
Size Advantage Model
- In a mating system in which large males monopolize the spawning of females, larger males have higher mating success than smaller males. Size is less important for females. In such a mating system, it can be beneficial to begin life as a female when small and then change sex to a male once a large enough size is reached to maximize mating ability. A mating system in which large males monopolize the spawning of females thus favors protogyny.[1]
- In other mating systems where no monopolization occurs, there is no size advantage for males to be large. However, in such systems where random fertilization occurs, it is beneficial for females to be larger because larger females are able to hold more eggs. Such a mating system would favor protandry, or the the changing of sex from male to female, once the male grows large enough to change sex.[1]
- In general, individual fish should change sex when the other sex would have a higher reproductive value at that stage in life.[1]
Common Hermaphroditism in Wrasses and Parrotfishes
- Dominant male defends group of female fish from other males; only dominant male mates with multiple females (polygny)
- When dominant male dies, largest female in harem changes sex and becomes the new dominant male (sequential hermaphroditism) [3]
Simultaneous Hermaphroditism
- Simultaneous hermaphrodites have both female and male gender roles at the same time [2]
- Only common in deep-sea fishes, but not often seen elsewhere[1]
- Example: small sea basses (Serranidae)[1]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Warner, Richard R. "Mating Behavior and Hermaphroditism in Coral Reef Fishes." American Scientist 72.2 (1984): 128-36. Web.
- ↑ 2.0 2.1 Sumich, James L. An Introduction to the Biology of Marine Life, Seventh Edition. WCB/McGraw Hill. 1999.
- ↑ Hixon, M.A. "Coral Reef Fishes." Encyclopedia of Ocean Sciences 2 (2009): 655-59. Web.