Fig. 3

Illustration of the five causal OTU scenarios considered in the simulation. Scenarios 1 to 3 consider larger “causal hubs,” each containing about 7–10 causal OTUs; scenario 4 considers smaller causal hubs of 2–3 causal OTUs; scenario 5 considers causal OTUs with random positions in the phylogenetic tree. Red (blue) circles indicate that causal effect size tends to be positive (negative)