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Microbial endemism: does phosphorus limitation enhance speciation?


There is increasing evidence for the existence of unique ecosystems that are dominated by locally adapted microbiota which harbour distinct lineages and biological capabilities, much like the macrobiota of Darwin's Galapagos Islands. As a primary example of such a system, we highlight key discoveries from the Cuatro Ciénegas basin in Mexico. We argue that high microbial endemism requires a combination of geographical isolation, long-term continuity and mechanisms for reducing the intensity of horizontal gene transfer (HGT). We also propose that strong phosphorus limitation has an important role in microbial diversification by reducing the intensity of HGT.

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Figure 1: The influence of phosphorus (P) limitation on horizontal gene transfer (HGT).
Figure 2: The microorganism-dominated ecosystems of the Cuatro Ciénegas basin, Coahuila, Mexico.
Figure 3: Microbial diversity and endemism at the Cuatro Ciénegas basin.


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We acknowledge M. Breitbart, M. Travisano, L. Falcon, A. Escalante and G. Olmedo who worked with us on the conceptual framework of this paper. This work has been supported by NASA, SEMARNAT/CONACyT CO1-0237, CONACyT 44673Q, CONABIO and AE015. We thank A. Cruz, L. Espinosa-Asuar and M. Kyle for expert technical assistance. The cooperation, logistics and support of CONAP/APFF Cuatro Cienegas, The Nature Conservancy and Pronatura Noreste were paramount for this research.

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Correspondence to Valeria Souza.

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Souza, V., Eguiarte, L., Siefert, J. et al. Microbial endemism: does phosphorus limitation enhance speciation?. Nat Rev Microbiol 6, 559–564 (2008).

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