Schematic diagram depicting the three strategies employed for indicating the presence/ absence of a taxon.

<p>Schematic diagram depicting the three strategies employed for indicating the presence/ absence of a taxon (in various samples) based on their abundance values (in the respective samples). The first strategy (depicted in section A), relies only on the abundance proportion of the taxa in each sample. A taxon whose (normalized) abundance proportion (in a sample) exceeds 0.1% is considered as 'present' (in that sample). In the second strategy (depicted in section B), a taxon is reported as 'present' (in a sample) only if its abundance value (in that sample) lies between the 2nd and 3rd quartile range of the computed mean/median value. Strategy 3 (depicted in section C) involves computing Manhattan distances between individual abundance values of a taxon (in each of the samples) and then hierarchically clustering the samples on basis of the computed distances. Given that hierarchically clustering in this case involves only singular abundance values, the clustering can be achieved by progressively merging sample pairs with the least distance. The sorting mechanism indicated in the figure helps in making the distance calculation process less time consuming (i.e. computationally efficient). Note that the final two clusters obtained indicate that the taxon is reported as 'present' in all samples except for Sample S1.