Perspective ARTICLE

Front. Microbiol., 02 August 2012 | doi: 10.3389/fmicb.2012.00268

When should we expect microbial phenotypic traits to predict microbial abundances?

  • Department of Biological Sciences, University of Calgary, Calgary, AB, Canada

Species' phenotypic traits may predict their relative abundances. Intuitively, this is because locally abundant species have traits making them well-adapted to local abiotic and biotic conditions, while locally rare species are not as well-adapted. But this intuition may not be valid. If competing species vary in how well-adapted they are to local conditions, why doesn't the best-adapted species simply exclude the others entirely? But conversely, if species exhibit niche differences that allow them to coexist, then by definition there is no single best adapted species. Rather, demographic rates depend on species' relative abundances, so that phenotypic traits conferring high adaptedness do not necessarily confer high abundance. I illustrate these points using a simple theoretical model incorporating adjustable levels of “adaptedness” and “niche differences.” Even very small niche differences can weaken or even reverse the expected correlation between adaptive traits and abundance. Conversely, adaptive traits confer high abundance when niche differences are very strong. Future work should be directed toward understanding the link between phenotypic traits and frequency-dependence of demographic rates.

Keywords: trait-abundance correlations, coexistence, competitive exclusion, local adaptation, frequency dependence

Citation: Fox JW (2012) When should we expect microbial phenotypic traits to predict microbial abundances? Front. Microbio. 3:268. doi: 10.3389/fmicb.2012.00268

Received: 31 May 2012; Accepted: 09 July 2012;
Published online: 02 August 2012.

Edited by:

Cyrille Violle, CNRS, France

Reviewed by:

Cyrille Violle, CNRS, France
Robin Snyder, Case Western Reserve University, USA

Copyright © 2012 Fox. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.

*Correspondence: Jeremy W. Fox, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada. e-mail:

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