DOI: 10.5061/dryad.7wm37pw2n
title: Code from: The effects of intersexual interactions on survival can drive the evolution of female ornaments in the absence of mate limitation

description: The evolution of sexual ornaments in animals is typically attributed to
 reproductive competition. However, sexual ornaments also arise in contexts
 where the ornamented sex is neither mate nor gamete limited, and
 explanations for ornamentation in these cases remains incomplete. In many
 species, particularly those with slow life histories, lifetime
 reproductive success depends more strongly on adult survival than
 fecundity, and survival can depend on intersexual interactions. We develop
 a population genetic model to investigate how the effect of intersexual
 interactions on survival may contribute to ornament evolution in the
 absence of competition for mates. Using female ornamentation in polygynous
 mating systems as a case study, we show that, indeed, ornaments can evolve
 when the ornament functions to modify interactions with males in ways that
 enhance a female’s own survival. The evolutionary dynamics depend on
 qualitatively on the specific behavioral mechanism by which the ornament
 modifies social interactions. In all cases, the ornament’s long-term
 persistence is ultimately determined by the coevolution of the male locus
 that determines how males affect female survival. We outline the scenarios
 that are most likely to favor the evolution of female ornaments through
 effects of intersexual interactions on survival, and we urge empirical
 researchers to consider the potential for this social selection mechanism
 to shape traits of interest across taxa.
description: The archive includes a Mathematica notebook
 ("SurvivalModel_Clean_20240813.nb") that details the
 construction and analysis of a population genetic model to explore the
 potential for sexual ornamentation to evolve in female animals through
 effects of intersexual interactions on female survival. The notebook
 describes the premises and construction of the model, the analysis of
 direct selection arising from the model dynamics, and forward simulations
 of example evolutionary trajectories. The population genetic model is
 constructed in such a way that it may be used to explore multiple
 mechanistic hypotheses about how female ornaments might modify social
 interactions to increase their own survival. See README for additional
 details.
description: ## README for "The effects of intersexual interactions on survival
 can drive the evolution of female ornaments in the absence of mate
 limitation" ##### Manuscript Authors: J. Colton Watts, Courtney L.
 Fizpatrick ##### README Author: J. Colton Watts ##### Code Author: J.
 Colton Watts ##### Contact:
 [j.colton.watts@gmail.com](mailto:j.colton.watts@gmail.com) #### Overview
 The archive includes a Mathematica notebook
 ("SurvivalModel_Clean_20240813.nb") that details the
 construction and analysis of a population genetic model to explore the
 potential for sexual ornamentation to evolve in female animals through
 effects of intersexual interactions on female survival. The notebook
 describes the premises and construction of the model, the analysis of
 direct selection arising from the model dynamics, and forward simulations
 of example evolutionary trajectories. The population genetic model is
 constructed in such a way that it may be used to explore multiple
 mechanistic hypotheses about how female ornaments might modify social
 interactions to increase their own survival (details below). No additional
 data or analyses are required to replicate the study findings from the
 archived notebook. #### Hypotheses Examined The four hypotheses address in
 the analysis are... (1) Differential Total Benefits: Some males benefit
 the survival of their female partners more than others, and the female
 ornament increases the probability of pairing with these males. This
 hypothesis implies that males differ in both their consequences for female
 survival (parameter s&gt;0) and their preference for ornamented females
 (parameter m&gt;0). Previous theory shows that a necessary condition for
 such dynamics to generate a fitness benefit for ornamented females is that
 these effects are related among males, such that the preference for
 ornamented females causes females to more often pair with the beneficial
 males. Thus, this hypothesis corresponds to m&gt;0 and s&gt;0, where both
 are associated with a single male genotype. (2) Differential Allocation:
 Some males benefit the survival of their ornamented partners more so than
 their unornamented ones (controlled by parameter a). This hypothesis does
 not require that some males have an overall greater benefit for female
 survival (s = 0) nor does it require that some males prefer to pair with
 ornamented females in the first place (m = 0). (3) Differential Allocation
 with Differential Total Benefits: Some males benefit the survival of their
 ornamented partners more so than their unornamented ones (a&gt;0), and
 these males also provide overall greater survival benefits (s&gt;0). This
 would be consistent with a case in which the differential allocation of
 male time or resources to his ornamented mates is achieved by increasing
 his total allocation to the survival of his female partners. (4)
 Differential Allocation with Male Mate Choice: Some males benefit the
 survival of their ornamented partners more so than their unornamented ones
 (a&gt;0), and these males are also more likely to pair with ornamented
 females to begin with. This might be the case if males have a generalized
 preference for ornamented females that affects both their courtship and
 post-pairing behavior. #### Mathematica Dependencies and Version All
 analyses and figures in our manuscript are replicated in the archived
 Mathematica notebook titled "SurvivalModel_Clean_20240813.nb".
 The overall order of the analysis follows the content of the manuscript,
 with the exception that the forward simulations and final figures for each
 hypothesis are generated at the end of the file after all symbolic
 analysis is complete. Mathematica requires no particular dependencies to
 run the analyses and plots contained in the notebook. This notebook was
 created and tested with Mathematica 12.3.1.0 on a Mac OSX ARM (64-bit)
 platform.