A novel method for estimating the strength of positive mating preference by similarity in the wild

Abstract

Mating preference can be a driver of sexual selection and assortative mating and is, therefore, a key element in evolutionary dynamics. Positive mating preference by similarity is the tendency for the choosy individual to select a mate which possesses a similar variant of a trait. Such preference can be modelled using Gaussian‐like mathematical functions that describe the strength of preference, but such functions cannot be applied to empirical data collected from the field. As a result, traditionally, mating preference is indirectly estimated by the degree of assortative mating (using Pearson's correlation coefficient, r) in wild captured mating pairs. Unfortunately, r and similar coefficients are often biased due to the fact that different variants of a given trait are nonrandomly distributed in the wild, and pooling of mating pairs from such heterogeneous samples may lead to “false–positive” results, termed “the scale‐of‐choice effect” (SCE). Here we provide two new estimators of mating preference (C rough and C scaled) derived from Gaussian‐like functions which can be applied to empirical data. Computer simulations demonstrated that r coefficient showed robust estimations properties of mating preference but it was severely affected by SCE, C rough showed reasonable estimation properties and it was little affected by SCE, while C scaled showed the best properties at infinite sample sizes and it was not affected by SCE but failed at biological sample sizes. We recommend using C rough combined with the r coefficient to infer mating preference in future empirical studies.

Mate choice based on body size similarity in sexually dimorphic populations causes strong sexual selection

“…Here we have used experimental data from mating pairs captured in the wild from 15 populations belonging to 7 different species to estimate the mate choice parameters C (Crough) and B by using the FND function (Table 1). The utility of Crough to estimate C has already been studied by simulations (Fernández-Meirama et al, 2017b), and here we have confirmed that our estimates of bias are proportional to empirical estimates of bias and are perhaps valid as preliminary rough estimates as well. True validation, however, would come from experimental laboratory studies that are capable of directly estimating B and comparing these values to those in Table 1.…”

Assortative Mating in Animals and Its Role for Speciation

“…There are many mechanisms that can give rise to assortative mating, of which sexual selection involving mating preferences is only one of them (reviewed in Crespi 1989). Notably, individuals with similar phenotypes are often temporally or spatially clustered in terms of phenotypically plastic responses to environmental conditions, which may lead to assortative mating in the absence of mate choice simply because mating pairs were sampled across the entire population, ignoring this temporal and spatial heterogeneity (Fernández-Meirama et al 2017). Even if this type of assortative mating of individuals living in the same microhabitat is not based on mating preferences, it can still be critical to speciation because it could be effective in preventing gene flow (e.g., speciation by host choice in tephritid fruit flies of the genus Rhagoletis; Bush 1969).…”

Assortative mating patterns of multiple phenotypic traits in a long‐lived seabird

“…pooling of mating pairs from heterogeneous samples might potentially lead to ‘false–positive’ results, Fernández‐Meirama et al . ).…”