OTU count in Heat tree output?


In Heat tree analysis for viewing abundance in all samples, how is OTU count calculated when annotation is based on ASVs? The size of circles at genus level seems all close to one and the root seems to have 96 OTU count, but I can’t figure out what this exactly means. Thanks.

Here OTU and ASV are used interchangeably - we will update the label in future. Regarding your 2nd question, I will refer to the text from this page:

The heat tree analysis leverages the hierarchical structure of taxonomic classifications to quantitatively (using the median abundance) and statistically (using the non-parametric Wilcoxon Rank Sum test) depict taxonomic differences between microbial communities (View mode: Comparison) or abundance profiles for a sample, a group or the overall (View mode: Abundance). The result from statistical comparison can be obtained from the “Difference Table” hyper-link from the download panel on the top right of this page. Please refer to the paper by Foster et al. for more details.

Thank you, Xia. I also figured out by checking filtered data. It is indeed total ASV count.

Also, the size of circle seems to indicate the number of ASV within each taxon. I tried to measure the size of circle using the scale bar and compared with actual ASV count. It’s approximately similar but I was not sure if the size (or number) is actully correct as the scale of OTU count increases by 1, 2, 5, 10…

Some suggestions for heat tree analysis (as this is very cool analysis).

  1. Option to adjust detection threshold (like in core microbiome analysis) for calculating samples with reads so that we can see consistent results between these two analyses.

  2. Option to show taxon names in the figure with a cutoff number for samples with reads (or prevalence). This will be very useful for large data set because it can get really crowd like this.

  1. Being able to download actual numbers in Excel for samples with reads and ASV/OTU count for each node (taxon). This will be useful if #2 is not available as we can manually edit taxon names with a cutoff in the heat tree figure.