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Following the Dynamics of Structural Variants in Experimentally Evolved Populations
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Evolutionary dynamics of the Trivers-Willard effect: A nonparametric approach.
1University of Bamberg Bamberg Germany.
Ecology and Evolution
|October 1, 2021
Summary
Parents adjust offspring sex ratios based on condition, influencing reproductive values. This study reveals Trivers-Willard effects can evolve to be much larger than predicted, with complex dynamics.
Area of Science:
- Evolutionary biology
- Behavioral ecology
- Population dynamics
Background:
- The Trivers-Willard hypothesis (TWH) predicts parental condition influences offspring sex ratio bias.
- Existing models often overlook how offspring sex ratio adjustments affect population-level reproductive values.
Purpose of the Study:
- To model the full evolutionary dynamics of the Trivers-Willard effects (TWE).
- To investigate how dynamic feedback between sex ratio and reproductive value influences evolutionary trajectories.
- To analyze the evolution of continuous strategies in structured populations.
Main Methods:
- Utilized a two-sex integral projection model for Columbian ground squirrels (Urocitellus columbianus).
- Treated offspring sex ratio as a continuous function of maternal condition.
- Simulated evolutionary change via successive invasion of mutant strategies until an evolutionarily stable strategy (ESS) was reached.
Main Results:
- The magnitude of evolving TWE can be significantly greater than previously predicted.
- Evolutionary dynamics exhibit substantial nonlinearities, influenced by starting conditions.
- Evolutionary change is fastest from extreme initial sex ratios and weaker for high-condition parents.
Conclusions:
- Dynamic feedback is crucial for understanding natural selection and TWE evolution.
- The study provides a novel methodological framework for analyzing continuous strategies in structured populations.
- Evolving TWE does not necessarily maximize population fitness or minimize sex ratio deviation.
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