A theoretical model for host-controlled regulation of symbiont density

There is growing empirical evidence that hosts (such as insects and corals) actively control the density of their mutualistic symbionts according to their requirements. Such active regulation can be facilitated by compartmentalisation of symbionts within host tissues, which confers a high degree of control of the symbiosis to the host. Here, we build a general theoretical framework to predict the underlying ecological drivers and evolutionary consequences of host-controlled endosymbiont density regulation for a mutualistic association between a host and a compartmentalised, vertically transmitted symbiont. Building on the assumption that the costs and benefits of hosting a symbiont population increase with symbiont density, we use state-dependent dynamic programming to determine an optimal strategy for the host, i.e., that which maximises host fitness, when regulating the density of symbionts. Simulations of active host-controlled regulation governed by the optimal strategy predict that..., R code is used for dynamic programming and model simulations., , # A theoretical model for host-controlled regulation of symbiont density

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Code used to generate model output and visualisations for the manuscript \"A theoretical model for host-controlled regulation of symbiont density\"
Code was written by M Whittle

## Description of the file structure

Each script must be saved in the same folder.
To reproduce the model output and visualisations used in the manuscript the only script which needs to be run is \"MANUSCRIPT_CODE\", which will source the other scripts as necessary.
For each version of the model, a folder will be created into which all files produced will be saved.

## Code/Software

Code written in R version 4.2.1

The following packages are required:
rstudioapi
dplyr
reshape2
ggplot2
RColorBrewer
gridExtra
sjmisc