DOI: 10.5061/dryad.nvx0k6f25
title: The contributions of direct and indirect selection to the evolution of mating preferences

description: Many influential mathematical models of sexual selection have stressed
 that mating preferences evolve due to correlations that build between
 mating preferences and preferred display traits – that is, through
 indirect selection. Nevertheless, there is a perception that indirect
 selection should generally be overwhelmed by direct selection, for example
 in the form of search costs. Recent work by Fry has used quantitative
 genetic models to argue that in many cases, including when there are
 direct benefits (a fecundity advantage to mating with the preferred male),
 direct and indirect selection may be of similar magnitude. Here I use
 population genetic models, in which the strength of the genetic
 correlation is an emergent property of evolution at mating preference and
 display trait loci, to assess the relative contributions of direct and
 indirect selection to the evolution of mating preferences. For the cases
 of direct benefits and of indirect benefits with fixed and
 frequency-dependent search costs, I outline parameter values of fecundity
 benefits, preference strengths, and search costs for which indirect
 selection on female preferences can potentially predominate. I also
 analyze male mate choice under polygyny, showing that direct selection
 will always outweigh indirect selection except when there are direct
 benefits.
description: Equations were derived in the archived Mathematica files and
 simulations were run in C.  
description: # The contributions of direct and indirect selection to the evolution of
 mating preferences
 [https://doi.org/10.5061/dryad.nvx0k6f25](https://doi.org/10.5061/dryad.nvx0k6f25) ## Description of the data and file structure The equations used for the project were derived in the Mathematica files and simulations were run in the C files. ### Variables and parameters in files int verticalres         // vertical resolution of final table 1000 int horizontalres    // horizontal resolution of final table 1000 double maxx          // maximum value for x-axis variable on figures double maxy          // maximum value for y-axis variable double intervalx    // step size for x-axis variable double intervaly    // step size fot y-axis variable double r                  // recombination rate double alpha          // preference strength double f                  // fecundity advantage double Diseq         // linkage disequilibrium D float dirsel              // measure of direct selection float indirsel           // measure of indirect selection double p2t1           // p2 in next generation double t2t1            // t2 in next generation double Diseqt1     // D in next generation.  double t2              // p2 double p2             // t2 double sp              // selection on preference double spmin        // minimum value of sp for plots double spexp         // scaling factor to put sp on a log scale float measure1       // measure of the association between the preference and trait in mated   pairs float p2atmax        // p2 at the maximum value of D across starting frequencies float t2atmax         // t2 at the maximum value of D across starting frequencies double t2val          // starting values of t2 before iteration double p2val          // starting values of p2 before iteration double cumdirsel   // cumulative direct selection double cumindirsel   // cumulative indirect selection int gen                         // current generation number double prec                 // difference between successive generation values of the frequencies to use as a stopping criterion for the while loops ## Code/software The Mathematica files using Mathematica, or on Wolfram Cloud.