Stationary frequencies and mixing times for neutral drift processes with spatial structure

TL;DR

This paper demonstrates that in neutral evolution with spatial structure, the trait distribution converges to a stationary distribution independent of population size and structure, and provides insights into the convergence rates through mixing times.

Contribution

It establishes that stationary trait frequencies are determined solely by the mutation process, regardless of population size, spatial structure, or update rules, and analyzes mixing times for convergence rates.

Findings

Trait distributions converge to mutation process stationary distribution

Stationary frequencies are independent of population size and structure

Mixing times depend on demographic variables

Abstract

We study a general setting of neutral evolution in which the population is of finite, constant size and can have spatial structure. Mutation leads to different genetic types ("traits"), which can be discrete or continuous. Under minimal assumptions, we show that the marginal trait distributions of the evolutionary process, which specify the probability that any given individual has a certain trait, all converge to the stationary distribution of the mutation process. In particular, the stationary frequencies of traits in the population are independent of its size, spatial structure, and evolutionary update rule, and these frequencies can be calculated by evaluating a simple stochastic process describing a population of size one (i.e. the mutation process itself). We conclude by analyzing mixing times, which characterize rates of convergence of the mutation process along the lineages, in terms of demographic variables of the evolutionary process.