Searching for species in haloarchaea

R T Papke, O Zhaxybayeva, E J Feil, K Sommerfeld, D Muise, W F Doolittle

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98 Citations (SciVal)


Prokaryotic (bacterial and archaeal) species definitions and the biological concepts that underpin them entail clustering (cohesion) among individuals, in terms of genome content and gene sequence similarity. Homologous recombination can maintain gene sequence similarity within, while permitting divergence between, clusters and is thus the basis for recent efforts to apply the Biological Species Concept in prokaryote systematics and ecology. In this study, we examine isolates of the haloarchaeal genus Halorubrum from two adjacent ponds of different salinities at a Spanish saltern and a natural saline lake in Algeria by using multilocus sequence analysis. We show that, although clusters can be defined by concatenation of multiple marker sequences, barriers to exchange between them are leaky. We suggest that no nonarbitrary way to circumscribe "species" is likely to emerge for this group, or by extension, to apply generally across prokaryotes. Arbitrary criteria might have limited practical use, but still must be agreed upon by the community.
Original languageEnglish
Pages (from-to)14092-14097
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number35
Publication statusPublished - 2007

Bibliographical note

ID number: ISI:000249187500043


  • definition
  • multilocus sequence analysis
  • recombination
  • halorubrum
  • solar saltern
  • species definition
  • speciation
  • evolutionary
  • salinity gradient
  • DNA
  • archaeal
  • homologous recombination
  • bacterial
  • population


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