Seven Comments on the Theory of Sosigonic Selection

In 1982, Hamilton and Zuk suggested that an important factor in sexual selection and mate choice is a need to produce parasite-resistant descendants. The resulting selection was named “sosigonic” by Hamilton in 1990. The Hamilton–Zuk theory has at times been much misconstrued. This paper addresses some of the misapprehensions. It emphasizes on the one hand that the theory of sosigonic selection is more general than is sometimes appreciated, and on the other hand that it does not discount other simultaneous sexual selection processes. It also discusses why the association between sosigonic parasite pressure and sexual selection intensity is fundamentally positive, and why the “within species” prediction of the theory is not, contrary to one suggestion, contradicted by the “across species” prediction. The postulated role of host–parasitic coevolutionary cycling in maintaining sufficient fitness variation, and the opportunity for sexual selection, in host species where parasites are prominent is highlighted; and the ecological perspective of the comparative aspect of the theory is reiterated.