Can relative abudance be more than 100?

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In summary, 487.453 bacteria per cent of the bacteria found in the gut were Bacteroidetes. 133.097 bacteria per cent were Firmicutes. And 69.620 bacteria per cent were Akkermansia.
  • #1
Zeynel
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I'm looking at my American Gut results. The last column shows the relative abundance of bacteria.

Code:
#taxon                                                                                                                                     relative_abundance
k__Bacteria;p__Bacteroidetes;c__Bacteroidia;o__Bacteroidales;f__Bacteroidaceae;g__Bacteroides    487.453
k__Bacteria;p__Firmicutes;c__Clostridia;o__Clostridiales;f__Lachnospiraceae;g__    133.097
k__Bacteria;p__Verrucomicrobia;c__Verrucomicrobiae;o__Verrucomicrobiales;f__Verrucomicrobiaceae;g__Akkermansia    69.620

According to this table, relative abundance of Bacteroids is 487.453. I read this as "487.453 per cent". But this does not make sense to me because, relative abundance is described as "the number of organisms of a particular kind as a percentage of the total number of organisms of a given area or community". If so, relative abundance should be less than hundred. Can you explain where I err? Thanks.
 
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  • #2
A definition of relative abundance is:
the number of organisms of a particular kind as a percentage of the total number of organisms of a given area or community;
the number of birds of a particular species as a percentage of the total bird population of a given area

So that figure, for whatever reason, is not a percentage, by definition: percentages have values between 0 and one multiplied by 100.

So something else is going on. Did the American Gut project people not give you explanatory material? Read that very carefully.
 
  • #3
I just read the website - I think it might be an estimate the number of different organisms (species) from that Phylum, not a percentage. Someone involved with the study could certainly get us both on the right path.
 
  • #4
Relative abundance does not necessarily imply percentage. It's useful to think of relative abundance in contrast to its alternative absolute abundance. Absolute abundance tells you the exact number of each species present in your sample. Relative abundance just means that you don't know the total number, but you do know the relative proportion of bacteria in your sample (e.g. you have roughly 2 bacteria of species A for every bacteria of species B).

Anyway, it's trival to convert the data to percentages.
 
  • #5
Sorry, this was my mistake. They had three links for the results and all said "Summary" and I assumed all were in the same format. I will ask American Gut and post here what those numbers represent. Sorry again for the confusion.
 

1. Can relative abundance be more than 100%?

Technically, no. Relative abundance is a measure of the proportion of a particular species in a given sample compared to the total number of individuals in that sample. It is typically expressed as a percentage, with a maximum value of 100%. Anything above 100% would not make sense in this context.

2. Why do some sources report relative abundance values greater than 100%?

There are a few possible reasons for this. One explanation could be a miscalculation or error in the data. Another possibility is that the relative abundance is being compared to a smaller subset of the total sample, rather than the entire sample. Additionally, some sources may use a non-standard definition of relative abundance that allows for values greater than 100%.

3. Is it possible for relative abundance to exceed 100% in certain circumstances?

Yes, there are some cases where relative abundance may exceed 100%. For example, in a situation where a particular species is overrepresented in a sample due to an environmental disturbance or human intervention, the relative abundance may be artificially inflated. However, this would still not be a true measure of relative abundance and would likely be corrected or adjusted in the analysis.

4. What are the implications of reporting relative abundance values greater than 100%?

Reporting incorrect or inflated relative abundance values can have significant implications for scientific research and conservation efforts. It can lead to inaccurate conclusions about the diversity and distribution of species in a given area, and potentially impact management decisions and conservation strategies.

5. How can we ensure accurate reporting of relative abundance?

The best way to ensure accurate reporting of relative abundance is to carefully collect and analyze data using standardized methods. It is important to clearly define and understand the concept of relative abundance and to use appropriate statistical techniques when calculating and interpreting these values. Peer review and replication of studies can also help to identify and correct any errors in reported relative abundance values.

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