Code from: The effects of intersexual interactions on survival can drive the evolution of female ornaments in the absence of mate limitation
Data files
Oct 16, 2024 version files 2.03 MB
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README.md
3.84 KB
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SurvivalModel_Clean_20240813.nb
2.03 MB
Abstract
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.
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
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>0) and their preference for ornamented females (parameter m>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>0 and s>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>0), and these males also provide overall greater survival benefits (s>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>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.
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.