What does Indicator Species Analysis (ISA) illustrate? As I understand, indicator species, are species that are vulnerable to ecosystem perturbation. Even minor changes in the environment will affect them dramatically. So they can demonstrate the health of an ecosystem.
However, indicator analysis identifies those species which are reasonably abundant in an ecosystem but are restricted to that ecosystem. These species identified in ISA are not necessarily vulnerable and are not necessarily good indicator species.
My question, therefore, is what good are indicator species identified from ISA? Or, what is the ecological significance of indicator species determined using ISA?
Hi John,
ISA calculates an indicator value based on the specifity (relative abundance in group, i.e. average abundance of a given species in a given group of samples over the average abundance of that species in all samples) and the fidelity (relative frequency in group, i.e. % of samples in given group where given species is present) for species in predifined categories. Additionally you get a significance level based on a permutation test to identify significant indicator species.
Here is an article (see also literature therein) in Research gate.
Article Improving indicator species analysis by combining groups of ...
Till
In the fields of conservation, development and environmental monitoring, several studies have already used the identification of bioindicators because they are often correlated with sites or groups of given sites (Borja et al, 2000; Legendre & Legendre, 2012) .
1.Borja, A., Franco, J., & Perez, V., (2000) A marine biotic index to Estbaliz the ecological quality of soft-bottom benthos within European estuarine and coastal environments. Marine Pollution Bulletin, 40: 1100-1114.
2.Legendre, P., & Legendre, L., (2012) Numerical ecology, 3rd English edition. Elsevier Science BV, Amsterdam. McGeoch, M. A. & S. L. Chown. 1998. Scaling up the value of bioindicators. Trend Ecol. Evol. 13: 46-47.
ecological significance or perhaps ecological importance although the importance from an ecological process would be meaningless. An ecological process does not "care" about the direction of the process eutrophication/oligotrophication (as far as I believe). Although a fervent believer in a holistic Gaia paradigm might believe differently.
For ISA you need to separate the results of ISA (indicator value; Indval), from the statistical test and the idea of an "good" indicator. Hence, Till Kleinebecker explained the basics. These basics which can also be found on page 351-350
Article Species Assemblages and Indicator Species: The Need for a Fl...
, whereby the calculation can be repeated by hand. The point is that the ISA (I assume you mean Indval) is not a measure of discriminatory power/Accuracy. As you pointed out: "However, indicator analysis identifies those species which are reasonably abundant in an ecosystem but are restricted to that ecosystem." Hence, given the Indval score and statistical test we might suggest that this dataset shows the species was more-or-less "abundant" and "restricted". However, it might be a useful "exploratory" analysis, where you perhaps might create a group of species based on the Indval, which you can try to discriminate/predict with i.e., a Linear Discriminant Analysis https://en.wikipedia.org/wiki/Linear_discriminant_analysis.What you also correctly observe is that "species identified in ISA are not necessarily vulnerable and are not necessarily good indicator species." However, if you mean that if you interpreted p
Dear John R.S. Tabuti ,thank you for this interesting question. Good answers by Till Kleinebecker and Wim Kaijser . You may also find this article helpful: Indicator Species Analysis using ‘indicspecies’ by Miquel De Cáceres, CREAF https://cran.r-project.org/web/packages/indicspecies/vignettes/IndicatorSpeciesAnalysis.html
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