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The Price equation (also known as Price's equation or Price's theorem) describes how a trait or gene changes in frequency over time. The equation uses a covariance between a trait and fitness to give a mathematical description of evolution and natural selection. It provides a way to understand the effects that gene transmission and natural selection have on the proportion of genes within each new generation of a population. The Price equation was derived by George R. Price, working in London to re-derive W.D. Hamilton's work on kin selection. The Price equation also has applications in economics. ==Statement== The Price equation shows that a change in trait ''z'' (''Δz'') is determined by the covariance between each value of ''z'' (''zi'') and fitness (''wi'') and the expected change in the trait value due to fitness (''wi''), (''E(wi Δzi)''): : where ''w'' is the mean fitness, and E and cov represent the population mean and covariance respectively. The covariance term captures the effects of natural selection; if the covariance between fitness (''wi'') and the trait value (''zi'') is positive then the trait value is predicted to increase on average over population i. If the covariance is negative then the trait is deleterious and is predicted to decrease in frequency. The second term (''E(wi Δzi)'') is more nuanced and represents factors other than direct selection that can affect trait evolution. This term can encompass genetic drift, mutation bias, or meiotic drive. Additionally, this term can encompass the effects of multi-level selection or group selection. 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」の詳細全文を読む スポンサード リンク
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