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Biol Lett. Jun 23, 2009; 5(3): 425–428.
Published online Apr 15, 2009. doi:  10.1098/rsbl.2009.0091
PMCID: PMC2679934
Inferring evolutionarily significant units of bacterial diversity from broad environmental surveys of single-locus data
Timothy G. Barraclough,1* Martin Hughes,1,2 Natalie Ashford-Hodges,1 and Tomochika Fujisawa1,2
1NERC Centre for Population Biology and Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK
2Department of Entomology, Natural History Museum, London SW7 5BD, UK
*Author for correspondence (t.barraclough/at/
Received February 4, 2009; Revised March 12, 2009; Accepted March 13, 2009.
By far the greatest challenge for diversity studies is to characterize the diversity of prokaryotes, which probably encompasses billions of species, most of which are unculturable. Recent advances in theory and analysis have focused on multi-locus approaches and on combined analysis of molecular and ecological data. However, broad environmental surveys of bacterial diversity still rely on single-locus data, notably 16S ribosomal DNA, and little other detailed information. Evolutionary methods of delimiting species from single-locus data alone need to consider population genetic and macroevolutionary theories for the expected levels of interspecific and intraspecific variation. We discuss the use of a recent evolutionary method, based on the theory of coalescence within independently evolving populations, compared with a traditional approach that uses a fixed threshold divergence to delimit species.
Keywords: bacteria, 16S rRNA, species, DNA barcodes, diversity
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