Drought mediates the importance of stochastic community assembly - PubMed (original) (raw)

Drought mediates the importance of stochastic community assembly

Jonathan M Chase. Proc Natl Acad Sci U S A. 2007.

Abstract

Historically, the biodiversity and composition of species in a locality was thought to be influenced primarily by deterministic factors. In such cases, species' niches create differential responses to environmental conditions and interspecific interactions, which combine to determine that locality's biodiversity and species composition. More recently, proponents of the neutral theory have placed a premium on how stochastic factors, such as birth, death, colonization, and extinction (termed "ecological drift") influence diversity and species composition in a locality independent of their niches. Here, I develop the hypothesis that the relative importance of stochastic ecological drift and/or priority effects depend on the harshness of the ecological filter in those habitats. I established long-term experimental ponds to explore the relative importance of community assembly history and drought on patterns of community compositional similarity among ponds that were otherwise similar in their environmental conditions. I show considerable site-to-site variation in pond community composition in the absence of drought that likely resulted from a combination of stochastic ecological drift and priority effects. However, in ponds that experienced drought, I found much higher similarity among communities that likely resulted from niche-selection filtering out species from the regional pool that could not tolerate such environmental harshness. These results implicate the critical role for understanding the processes of community assembly when examining patterns of biodiversity at different spatial scales.

PubMed Disclaimer

Conflict of interest statement

The author declares no conflict of interest.

Figures

Fig. 1.

Fig. 1.

The number of species that occurred in each pond (of 10 possible) for the permanent (black) and drought (gray) ponds. In permanent ponds, the majority of species occurred in <1/2 of the ponds, and no single species occurred in every pond. Of the species observed in at least one of the permanent ponds, each was observed in 3.21 [±1.65 (SD)] of the 10 permanent ponds, whereas of the species observed in at least one of the disturbed ponds, each was observed in 5.26 [±3.1 (SD)] of the 10 drought ponds (ANOVA: _F_1,108 = 20.78, P = 0.001).

Fig. 2.

Fig. 2.

Nonmetric multidimensional scaling (NMDS) allows the visualization of the multidimensional composition of communities in two-dimensional space. The Euclidean distance between any two points represents the difference in Jaccard's similarity between those two communities. Drought ponds are indicated by open triangles, and permanent ponds are indicated by filled circles.

Similar articles

Cited by

References

    1. Millennium Ecosystem Assessment. Ecosystems and Human Well-Being: Biodiversity Synthesis. Washington, DC: World Resources Institute; 2005.
    1. Ricklefs RE. Ecol Lett. 2004;7:1–15.
    1. Chase JM, Leibold MA. Ecological Niches: Linking Classical and Contemporary Approaches. Chicago: Univ Chicago Press; 2003.
    1. Hubbell SP. The Unified Neutral Theory of Species Abundance and Diversity. Princeton: Princeton Univ Press; 2001.
    1. Bell G. Science. 2001;293:2413–2418. - PubMed

Publication types

MeSH terms

LinkOut - more resources