Equation 2 · Part 1 · The Peacock Problem: Darwin's Second Theory and Its Hard Tests

Symbol bar p

\bar p

\bar p

What this part means

the population mean of the corresponding female preference.

Its job in the formula

bar p is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Full expressionSymbol bar pArticle meaning

Where the article explains it

Let $\bar t$ be the population mean of a male display trait and $\bar p$ the population mean of the corresponding female preference; write $\beta_t$ and $\beta_p$ for the direct selection gradients acting on each (natural selection pulling $\beta_t$ downward, since the ornament is costly), $h_t^2$ and $h_p^2$ for their heritabilities, and B for the genetic covariance that non-random mating builds between the two traits.

The passage around this formula

…depends critically on the genetic variation parameters and initial conditions of a population” [ 4 ] . One compact way to see why sits in the coupling itself. Let $\bar t$ be the population mean of a male display trait and $\bar p$ the population mean of the corresponding female preference; write $\beta_t$ and $\beta_p$ for the direct selection gradients acting on each (natural selection pulling $\beta_t$ downward, since the ornament is costly), $h_t^2$ and $h_p^2$ for their heritabilities, and B for the genetic covariance that…

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the surrounding passage

[4] Models of speciation by sexual selection on polygenic traits ↗

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