A generalization of the informational view of non-random mating: Models with variable population frequencies

The mating distribution caused by mate choice can be expressed as a gain in information with respect to random mating. In that view, the population phenotype frequencies had been considered constant during the breeding season. Here, such restriction was relaxed to consider encounter-mating processes in which first, the encounter between partners depends on the phenotype distribution of the population, and second, the mating after the encounter depends on the mutual mating propensities. Under this setting, the population phenotype frequencies are no longer constant because the process of pair formation occurs in discrete intervals of time, called mating rounds where at least one mating pair is formed, and the frequency of phenotypes available for the next mating, changes. Provided that there are more than one mating round per breeding season, the population phenotype frequencies are no longer constant. Similarly to the constant case, we describe the change in the mating phenotypes by the flow of information with respect to random mating. This information can be partitioned into sexual selection, assortative mating (sexual isolation) and their mixed effect. Likewise, the pairwise statistics for total change, sexual selection and assortative mating are generalized for variable population phenotype frequencies. The new tests had more power to detect the effects of non-random mating when the phenotype frequencies varied during the breeding season. The differences in power were high for sexual selection but minor for assortative mating scenarios. However, the application of the new formulas requires the estimation of phenotype frequencies at each mating round. Therefore, choosing one or another type of statistics would depend on the biological scenario as well as the availability and easiness to split the sampling in more than one mating round.