The rarefaction curve is a very useful statistical tool for biodiversity analysis. It represents the number of species on Y axis, adjsted by individuals, samples (Gotelli & Graves,1996; Gotelli & Colwell, 2001) or even ponds (Gioria et al 2011) on X axis. Since X axis deals with distinct kinds of units, I was wondering if other types of units could be used on X axis. Below I try to explain my doubt with this hypothetical situation: Imagine a sampling procedure** that registers on sp1 trees***, all the birds species that use this tree species for make nests. Next, on sp2 trees, again register all the birds species that use sp2 trees to make nests. Continue to collect this data on other tree species of the study area and you will end with a data table like this:
Now here comes the questions:
(1) - With this dataset, is wrong to make a rarefaction curve using the number of tree species on X axis, and the number of nesting birds on Y axis?****
(2) - Does anyone knows any paper describing something similar to the rarefaction procedure described in question 1?
** Supose also that this example is aplied during mating season only
*** Data from sp1 tree can include only one tree(or individual) or many trees (or individuals), and so on to other tree species. This is because some tree species will be naturally rare or abundant.
**** I belive that in pratical terms, the construction of this curve is analogue to a sample-based rarefation curve, so, in other words, it is possible to made. But, it is conceptually right to made it? if so, wich kind of conclusions could and could not be made. this is a valid procedure, so one can construct a rarefaction curve for nesting bird species adjusted by the number of tree species, that we could call: tree species-based rarefaction curve for nesting bird species (a more detailed nomenclature) or species-based rarefaction curve ( a more generalized nomenclature). This kind of analysis could give anwser to this type of question: "With 5 tree species, on average, how many nesting birds species could we find?"
Gotelli, N. J., & Graves, G. R. (1996). Null models in ecology.
Gotelli, N. J., & Colwell, R. K. (2001). Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness. Ecology letters, 4(4), 379-391.
Gioria, M., Bacaro, G., & Feehan, J. (2011). Evaluating and interpreting cross-taxon congruence: potential pitfalls and solutions. Acta Oecologica, 37(3), 187-194.