# Tuning environmental timescales to evolve and maintain generalists

## TL;DR

This paper demonstrates that intermediate-timescale environmental changes can effectively promote the evolution and maintenance of generalist genotypes in populations, offering new insights into adaptive dynamics.

## Contribution

It reveals that tuning environmental change timescales can reliably evolve generalists, providing design principles for dynamic fitness landscapes.

## Key findings

- Intermediate environmental change timescales enhance generalist evolution.
- Dynamic environments with increasing frequency further increase generalist yield.
- Changing environments on the right timescale funnels populations to otherwise inaccessible genotypes.

## Abstract

Natural environments can present diverse challenges, but some genotypes remain fit across many environments. Such `generalists' can be hard to evolve, out-competed by specialists fitter in any particular environment. Here, inspired by the search for broadly-neutralising antibodies during B-cell affinity maturation, we demonstrate that environmental changes on an intermediate timescale can reliably evolve generalists, even when faster or slower environmental changes are unable to do so. We find that changing environments on timescales comparable to evolutionary transients in a population enhances the rate of evolving generalists from specialists, without enhancing the reverse process. The yield of generalists is further increased in more complex dynamic environments, such as a `chirp' of increasing frequency. Our work offers design principles for how non-equilibrium fitness `seascapes' can dynamically funnel populations to genotypes unobtainable in static environments.