TABLE 1.

Comparison between current and related models

	This study	Matessi et al. (2001)	Pennings et al. (2008)	de Cara et al. (2008)
No. of selected loci	One	One	One	Arbitrary
Method of analysis	Stability and QLEa	Stability	Stability	QLE
Form of selection on trait	General	Quadratic frequency dependence	Gaussian competition	General
Dynamics of trait allele	Equilibrium or changing	Equilibrium	Equilibrium	Equilibrium
Frequency at trait locus	General		General (focus on
Form of assortment	Preference based or group based	Preference based	Preference based or neutralizedb	Preference based or neutralizedb
Preference function	General	General (focus on Gaussianc)	General (focus on Gaussianc)	General (focus on Gaussian or quadraticc)
Sexual selection	Present or absent	Present	Present or absent	Present or absent
Costs of assortment	General	General	Absent	Strong (plant model) or absent (neutralizedb)

These studies focus on a trait that is subject to natural selection and that forms the basis of assortative mating, the strength of which is determined by a modifier locus.

^aQLE denotes a “quasi-linkage equilibrium” analysis, which assumes that genetic associations equilibrate faster than allele frequencies change. We use the term QLE even when considering genetic associations, such as the departure from Hardy–Weinberg, that do not involve “linkage.”

^bTo eliminate sexual selection, these articles consider a “neutralized” model of preference-based assortative mating, where females mate preferentially but then the mating success of all genotypes is equalized (not necessarily for each sex separately, but across both sexes).

^cWith one locus, a Gaussian preference function is a particular form of matrix (3), where , while a quadratic preference function sets .