Response to technical comment by Muir (2022) on "Negative-assortative mating for color in wolves".

Abstract

There are very few well-documented examples of negative-assortative mating in vertebrates (see Hedrick et al. [2016] for summaries). The example of negative-assortative mating between gray and black wolves in Yellowstone National Park appears to be the only documented example of negative-assortative mating in mammals and the only documented example in vertebrates for a naturally occurring, single gene, color polymorphism. Muir (2022) has suggested that the partial negative-assortative mating model that Hedrick et al. (2016) used to investigate matings of wolves with different coat colors in Yellowstone is incorrect. Below I show that the model Muir (2022) suggests gives incorrect results and that the model that Hedrick et al. (2016) used is appropriate and that it is analogous to models for selection for other fitness components. For the Yellowstone wolves, the only matings that are between different colors are gray × black matings. From Hedrick et al. (2016), these matings occur with a frequency of 2AP(H + Q) where A and 1 – A are the proportions of negative-assortative and random matings in the population, respectively, assuming that reciprocal matings are equally likely to occur. It is assumed that the recessive kk gray wolves have a frequency of P, the heterozygous Kk black wolves have a frequency of H, and the KK black wolves have a frequency of Q. Notice that the proportion of negative-assortative mating A does not vary but is weighted by the product of the frequencies of the potentially phenotypically different mates. The total frequency of both negative-assortative and random gray × black matings (kk × K−) (and its reciprocal hereafter) is 2AP(H + Q) + 2P(H + Q)(1 − A) = 2P(H + Q) (Table 1). The frequency of gray × gray matings (kk × kk), all of which are from the random-mating proportion of matings, is P2(1 − A) and the frequency of black × black matings (K− × K−), also all of which are from the random-mating proportion, is (H + Q)2(1 − A) (Table 1).