Equation 6 · Part 9 · From Origins to Frontier: A History of Evolutionary Biology and Ecology
Denominator: 1 + sp_t
What this part means
The complete quantity below the fraction bar; it must be nonzero for this division.
Its job in the formula
1 + s occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Full expression→Denominator: 1 + sp_t→Article meaning
The passage around this formula
A basic case illustrates the kind of prediction this apparatus makes possible. For a single locus with two alleles under simple directional selection with selection coefficient s favoring an allele at frequency p , one classical discrete-generation recursion is . This is a deliberately simplified model — haploid, one locus, constant s , no drift, no linkage — and real populations violate several of its assumptions routinely. Its value is not as a literal forecast of any specific population but as a baseline against which departures (frequency-dependent selection, epistasis, drift-dominated dynamics in small populations) can be identified and measured.
Learn the underlying idea
A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.
Open the illustrated fractions: division written vertically guide →
Sources cited in the article section
These citations provide research context; check each source for the exact claim it supports.