What is Sex determination?
'''Sex determination''' is a process of [[Developmental biology|development]] by which the sex of an individual is settled. [[Sex]] is a method of reproduction which is widespread among living things. It requires two individuals of the same [[species]]. Usually, the sexes are separate. Sex may be determined in one of two ways: * [[Genetics|Genetically]], by [[gene]]s and [[chromosome]]s the [[organism]] inherits from its parents. * [[Environment]]ally, by some outside agent acting as a trigger to development.<ref>King R.C. Stansfield W.D. & Mulligan P.K. 2006. ''A dictionary of genetics'', 7th ed. Oxford.</ref> Where both sexes occur on the same individual, that individual is an [[hermaphrodite]]. Hermaphrodite systems can be found in some animals, for example [[snail]]s, and in most [[flowering plant]]s.<ref name=dellaporta_1993/> == Determination by the environment == [[Image:Ocellaris clownfish.JPG|thumb|upright=1.1|[[Clownfish]] are initially male; the largest fish in a group becomes female.]] For many species, sex is determined by [[environment]]al factors experienced during development. Many [[reptile]]s have [[temperature]]-dependent sex determination. The temperature embryos experience during their development determines the sex of the organism. In some [[turtle]]s, for example, males are produced at lower incubation temperatures than females; this difference in critical temperatures can be as little as 1-2&nbsp;°C. Many [[fish]] change sex over the course of their life. This phenomenon is called ''sequential hermaphroditism''. In [[clownfish]], smaller fish are male, and the dominant and largest fish in a group becomes female. In many [[wrasse]] the opposite is true–most fish are female at birth and become male when they reach a certain size. Sequential hermaphrodites may produce both types of gametes over the course of their lifetime, but at any given point they are either female or male.<ref>Munday, Philip L; Buston, Peter M; and Warner, Robert R. 2006. Diversity and flexibility of sex-change stra