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Equation 51 · Part 2 · The Valley of Stability Is a Fitness Landscape

Symbol Z

(N,Z)(N,Z)
ZZ

What this part means

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

Its job in the formula

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

The passage around this formula

There is a further reason the borrowed vocabulary fits with unusual precision here, and it runs backward through the history of the metaphor itself. Sewall Wright introduced the image of a landscape of gene combinations, graded by adaptive value and read by its topography of peaks and valleys, in a 1932 paper to the Sixth International Congress of Genetics. Wright’s own diagram is worth reading in his own words: having reduced an intractably high-dimensional “field of gene combinations” to a two-dimensional contour plot for the sake of illustration, he wrote that “there may be innumerable other peaks which are higher but which are separated by ‘valleys,’” and that “the problem of evolution…

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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

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