Code from: Evolution of phenotypic plasticity owing to migration

Phenotypic plasticity enables organisms to produce better-suited phenotypes when the environment changes, enhancing fitness under adverse conditions. Yet responding to environmental cues may provide little use in a constant environment, where organisms already express optimal phenotypes. The forces that sustain plasticity and account for its widespread presence, thus, remain unclear, as plasticity must remain advantageous to persist. Although typically associated with changing environments, maintenance of plasticity requires generational turnover such that parents and offspring regularly encounter different conditions. Here, we demonstrate that even low number of migrants between locally adapted populations, in constant environments, can promote the emergence and persistence of phenotypic plasticity even when plasticity is costly, never associated with the fittest genotype, and independent of its genetic architecture. We support this conclusion by exploring the parameter space of a two-..., , # Code from: Evolution of phenotypic plasticity owing to migration

Dataset DOI: [10.5061/dryad.37pvmcvzg](https://doi.org/10.5061/dryad.37pvmcvzg)

## Description of the data and file structure

This C program simulates evolutionary dynamics at a plasticity locus following the introduction of a single plasticity-conferring allele (*M*) into one of two locally adapted demes that exchange migrants, as described in Gulisija and Newberry (2025).

At the structural locus, alleles *a* and *b* encode locally adapted, non-plastic phenotypes in demes A and B. At the modifier locus, alleles *m* and *M* determine whether plastic environmental responses occur, with specified benefits and costs.

Input parameters for deme A are provided in the **pars** file:

1.    Selection coefficient against non-plastic immigrants (sel, *s*~A~)

2.    Plasticity benefit (pla, *p*~A~)

3.    Plasticity cost (cost, *c*~A~)

\
A sample *pars* file includes *s*~A~ = 0.01, *p*~A~ = 0.01, and *c*~A~ = 0.0. Parameters ...,