Fixation Probabilities in Weakly Compressible Fluid Flows

TL;DR

This study investigates how weakly compressible fluid flows influence genetic fixation probabilities in marine organisms, revealing that such flows can reduce the impact of selective advantages even when population structure remains largely unchanged.

Contribution

It introduces a coupled agent-based simulation approach to analyze genetic dynamics in weakly compressible flows, highlighting flow effects on fixation probabilities.

Findings

Flow diminishes the effect of selective advantage on fixation.

Flow enhances survival of organisms born at sources.

Flow influences Fisher genetic wave dynamics.

Abstract

Competition between biological species in marine environments is affected by the motion of the surrounding fluid. An effective 2D compressibility can arise, for example, from the convergence and divergence of water masses at the depth at which passively traveling photosynthetic organisms are restricted to live. In this report, we seek to quantitatively study genetics under flow. To this end, we couple an off-lattice agent-based simulation of two populations in 1D to a weakly compressible velocity field--first a sine wave and then a shell model of turbulence. We find for both cases that even in a regime where the overall population structure is approximately unaltered, the flow can significantly diminish the effect of a selective advantage on fixation probabilities. We understand this effect in terms of the enhanced survival of organisms born at sources in the flow and the influence of Fisher genetic waves.