1. How many freshwater diatoms are pH specialists? A response to Pither & Aarssen (2005)
- Author
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Vigdis Vandvik, Harry John Betteley Birks, and Richard J. Telford
- Subjects
Diatoms ,Ecology ,Null model ,Population Dynamics ,Niche ,Reproducibility of Results ,Hydrogen-Ion Concentration ,Biology ,Classification ,biology.organism_classification ,Generalist and specialist species ,Adaptation, Physiological ,Taxon ,Diatom ,Ph gradient ,Ecology, Evolution, Behavior and Systematics - Abstract
Pither & Aarssen (2005) propose a null model approach to assess the proportion of niche specialist taxa along ecological gradients. They apply this methodology to a large data set of lacustrine diatom assemblages and conclude that a majority of the taxa are generalists on a pH gradient. This conflicts with previous work, which shows that many diatom taxa have a statistically significant relationship with pH. We demonstrate the methods used by Pither & Aarssen (2005) have a high Type II error for rare taxa, and that this problem is compounded by the non-uniform sampling of the pH gradient which effectively precludes acid-lake specialist diatoms from being recognized as such. We re-analyse the data used by Pither & Aarssen (2005) and show that most of the diatoms have a statistically significant relationship with pH, and we thus refute their conclusions that few diatom species are specialists.
- Published
- 2006