Equation 13 · Part 1 · The Peacock Problem: Darwin's Second Theory and Its Hard Tests

Symbol beta_t

\beta_t

\beta_t

What this part means

the write.

Its job in the formula

bet $a_t$ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Full expressionSymbol beta_tArticle 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

Read the first line on its own and the trait looks stable: natural selection ( $\beta_t$ ) pulls the ornament back down every generation. But the second term, B\, $\beta_p$ , imports a push from the preference side through the genetic covariance the mating system itself has created. When B is large enough relative to the stabilising pull of $\beta_t$ , the two equations no longer…

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Sources cited in the article section

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