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==Example: Evolution of sight== As an example of the simple Price equation, consider a model for the evolution of sight. Suppose ''z''''i'' is a real number measuring the visual acuity of an organism. An organism with a higher ''z''''i'' will have better sight than one with a lower value of ''z''''i''. Let us say that the fitness of such an organism is ''w''''i''=''z''''i'' which means the more sighted it is, the fitter it is, that is, the more children it will produce. Beginning with the following description of a parent population composed of 3 types: (''i'' = 0,1,2) with sightedness values ''z''''i'' = 3,2,1: : Using Equation (4), the child population (assuming the character ''z''''i'' doesn't change; that is, ''z''''i'' = ''z''''i''') : We would like to know how much average visual acuity has increased or decreased in the population. From Equation (3), the average sightedness of the parent population is ''z'' = 5/3. The average sightedness of the child population is ''z = 2, so that the change in average sightedness is: : which indicates that the trait of sightedness is increasing in the population. Applying the Price equation we have (since ''z''′''i''= ''z''''i''): : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Price equation examples」の詳細全文を読む スポンサード リンク
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