Sex Change in Aquatic Species
Sex change in Aquatic Species
By: Gobezai Abebe
Introduction. Many species of invertebrates, fish and plants undergo a process which is rare and requires detailed research to understand (Allsop and West, 2003). The process that they undergo is known as sex change. Focusing specifically on hermaphroditic fish, sex change can occur in two directions. One direction that sex change can occur is the change from female to male which is known as protogyny (Allsop and West, 2003; Kuwamura et.al, 2002; Munday et.al, 1998). The other direction that sex change can occur is the change from male to female which is also known as protandry (Allsop and West, 2003; Kuwamura et. al, 2002; Munday et. al, 1998). The species use the process of sex change to help maximize the reproductive success of their colony (Warner, 1982).
Sex change is favored when the reproductive success of females or males in a colony is unevenly distributed relative to size or age (Munday et.al, 1998; Oldfield, 2005). In colonies controlled by large male fish, protandry is favored in an attempt to have similar reproductive success in both sexes (Warner, 1982; Munday, 2002; Oldfield, 2005). The opposite directional sex change is true for colonies dominated by large female fish; protogyny is favored in an attempt to balance reproductive success in both sexes (Oldfield, 2005; Kazancioglu and Alonzo, 2009).The social structure amongst each colony also plays a major role in the direction sex change occurs (Munday et. al, 1998; Munday, 2002; Oldfield, 2005). A new phenomenon has been introduced after multiple studies dealing with sex changing hermaphroditic fish, bi-directional sex change. Bi-directional sex change is when a species is primarily either male or female then changes into a female or male and then returns back to it’s to original state as a female (Munday et.al, 1998; Munday, 2002). Bi-directional sex change should be anticipated if the maximum sex specific reproductive success of an organism
By: Gobezai Abebe
Introduction. Many species of invertebrates, fish and plants undergo a process which is rare and requires detailed research to understand (Allsop and West, 2003). The process that they undergo is known as sex change. Focusing specifically on hermaphroditic fish, sex change can occur in two directions. One direction that sex change can occur is the change from female to male which is known as protogyny (Allsop and West, 2003; Kuwamura et.al, 2002; Munday et.al, 1998). The other direction that sex change can occur is the change from male to female which is also known as protandry (Allsop and West, 2003; Kuwamura et. al, 2002; Munday et. al, 1998). The species use the process of sex change to help maximize the reproductive success of their colony (Warner, 1982).
Sex change is favored when the reproductive success of females or males in a colony is unevenly distributed relative to size or age (Munday et.al, 1998; Oldfield, 2005). In colonies controlled by large male fish, protandry is favored in an attempt to have similar reproductive success in both sexes (Warner, 1982; Munday, 2002; Oldfield, 2005). The opposite directional sex change is true for colonies dominated by large female fish; protogyny is favored in an attempt to balance reproductive success in both sexes (Oldfield, 2005; Kazancioglu and Alonzo, 2009).The social structure amongst each colony also plays a major role in the direction sex change occurs (Munday et. al, 1998; Munday, 2002; Oldfield, 2005). A new phenomenon has been introduced after multiple studies dealing with sex changing hermaphroditic fish, bi-directional sex change. Bi-directional sex change is when a species is primarily either male or female then changes into a female or male and then returns back to it’s to original state as a female (Munday et.al, 1998; Munday, 2002). Bi-directional sex change should be anticipated if the maximum sex specific reproductive success of an organism
Cited: Allsop, D.J., and S.A. West. 2003. Constant relative age and size at sex change for a sequentially hermaphroditic fish. Journal of Evolutionary Biology 16:921-929. Chopelet, J., R.S Gardner, A., D.J. Allsop, E.L. Charnov, and S.A. West. 2005. A dimensionless invariant for relative size at sex change in animals: explanation and implications. American Naturalist 165:551-566. Hoffman, S.G., M.P. Schildhauer, and R.R. Warner. 1985. The cost of changing sex and the ontogeny of females under contest competition for mates. Evolution 39:915-927. Kazancioglu, E., S.H. Alonzo. 2009. Costs of changing sex do not explain why sequential hermaphroditism is rare. American Naturalist 173:327-336. Kuwamura, T., N. Tanaka, Y. Nakashima, K. Karino, and Y. Sakai. 2002. Reversed sex-change in the protogynous reef fishes Labroides dimidiatus. Ethology 108:443-450. Munday, P.L, M.J. Caley, and G.P. Jones. 1998. Bi-directional sex change in a coral dwelling goby. Behavioral Ecology and Sociobiology 43:371-377. Munday, P.L. 2002. Bi-directional sex change: testing the growth rate advantage model. Behavioral Ecology and Sociobiology 52:247-254. Oldfield, R.G. 2005. Genetic, abiotic, and social influences on sex differentiation in cichlid fishes and the evolution of sequential hermaphroditism. Fish and Fisheries 6:93-110. Warner, R.R. 1982. Mating systems, sex change, and sexual demography in the rainbow wrasse, Thalassoma-Lucasanum. Copeia 3:653-661. Warner, R.R