Table 1.

Symbols and notation.

$\overline{X}$	average value of X across its frequency distribution
$\hat{A}$ or E(A)	expected value of random variable A
$[[X,Y]]$	frequency covariance of X and Y
$⟨⟨A,B⟩⟩$	probability covariance of random variables A and B
$\left[\left[{\hspace{0.17em}}_b^a\right]\right]$	simple regression of a on b
w	absolute fitness (number of descendants after one generation)
Ω	relative fitness ($\mathit{\Omega }=w/\overline{w}$), conditional on $\overline{w}\ne 0$
ϕ	phenotype of an individual
ϕo	average phenotype of an individual’s offspring
δ	ϕo − ϕ
${\mathbb{P}}^j$	simple biorthogonal polynomial in trait ϕj
${\mathbb{P}}_{\bullet }^j$	conditional biorthogonal polynomial in trait ϕj