Fig. 2
From: Primary case inference in viral outbreaks through analysis of intra-host variant population
Visualization of evolutionary simulation. Dots represent unique variants. The simulation is a random walk that starts from the green potential infector variants with the gray intermediate variant dots and red potential infectee variant dots being unexplored. As the simulation carries out, dots turn blue as they are explored. The simulation is complete when all potential infectee variant dots are reached, or when all the red dots have turned blue. The top 3 frames show sample A evolving into sample B. The bottom 3 frames show sample B evolving into sample A. We can see that it is easier for A to evolve into B as it finishes faster, so we would estimate that A transmitted the virus to B rather than vice versa