Context-dependent evaluation of prospective mates in a fish

Abstract

Female choice is often assumed to be based on absolute preference, driven by a threshold value of mate attractiveness. However, increasing evidence suggests that females may instead perform a comparative evaluation of prospective mates, possibly incurring in violation of rational decision rules (e.g. independence from irrelevant alternative, IIA). A prototypical case is the ‘asymmetrically dominated decoy’ effect where the preference for a target option over a competitor is altered by the addition of an irrelevant alternative. Here, we test for this effect in the peacock blenny Salaria pavo. Females, in binary test (i.e. focal option dyad differing in body size and extension of a yellow spot), strongly preferred one of the options. The effect of decoys, asymmetrically dominating the focal options for either yellow spot extension or body size, varied according to the initially preferred trait and the decoy type. Indeed, the addition of a decoy caused a shift in preference only when the decoy exhibited the intermediate expression of the trait less preferred initially. By contrast, females did not modify their preference in the presence of the decoy for their preferred trait. Although females’ evaluation was context-dependent, the violation of IIA was clearly observed only with respect to the initially less preferred trait. This does not exclude that females are in any case using comparative decision rules. Indeed, when faced with three alternatives, two of which are proportionally closer to each other than to the third one, they might not be able to discriminate among them, perceiving stimulus absolute magnitude.

Rational choice of social group size in mosquitofish

“…Additional control tests were done to ensure preferences did not decay over the course of the trial and that the stimulus shoal did not affect preferences (see the electronic supplementary material). To test the constant ratio rule, we calculated the preference for the shoal of four compared to the shoal of two, excluding time spent with the third shoal, because we were only interested in changes in relative preference between the initial two options (as in [10]). We used Tukey post hoc tests from a linear mixed model to determine whether this ratio changed between the dichotomous and trichotomous trials.…”

Selection for relative brain size affects context-dependent male preferences, but not discrimination, of female body size in guppies

“…However, current sexual selection theory acknowledges that mate choice can be context dependent and therefore does not necessarily correlate with absolute preference functions (Jennions and Petrie, 1997;Widemo and Saether, 1999). Indeed, empirical studies across different taxa have demonstrated that, for instance, social context can shift mate preference and mate choice (Royle et al, 2008;Reaney, 2009;Lea and Ryan, 2015;Locatello et al, 2015;Griggio et al, 2016). Intrinsic condition and acquired experience have additionally been suggested to be important factors shifting innate preference functions and generating variability in mate choice (Ryan et al, 2007;Verzijden et al, 2012;Gilman and Kozak, 2015).…”

Context‐dependent female preference for multiple ornaments in the bearded reedling

“…; Reaney ; Locatello et al. ). A recent study on great bowerbirds ( Ptilonorhynchus nuchalys ) suggests that cognitive constraints and perspective distortions may have strong implications for the evolution of particular traits under sexual selection (Kelley and Endler ,b).…”

“…Comparing several alternative mates differing by two or more uncorrelated traits is likely to be a difficult cognitive task and it has been proposed that the possible effect of cognitive constraints and perceptive distortions on female choice should not be ignored (Bateson and Healy 2005). Surprisingly, few studies have investigated the effects of modifying different ornaments and composition of the male choice set (Royle et al 2008;Reaney 2009;Locatello et al 2015). A recent study on great bowerbirds (Ptilonorhynchus nuchalys) suggests that cognitive constraints and perspective distortions may have strong implications for the evolution of particular traits under sexual selection (Kelley and Endler 2012a,b).…”