title: Searching for species in haloarchaea.
abstract: 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.
authors: Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269-3125, USA.
authors: R Thane
authors: RT
authors: Papke
authors: Olga
authors: O
authors: Zhaxybayeva
authors: Edward J
authors: EJ
authors: Feil
authors: Katrin
authors: K
authors: Sommerfeld
authors: Denise
authors: D
authors: Muise
authors: W Ford
authors: WF
authors: Doolittle
mesh_terms: D019605:Euryarchaeota / Q000145:classification* / Q000235:genetics*; D005618:Fresh Water / Q000382:microbiology; D005798:Genes, Bacterial; D020745:Genome, Archaeal; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D010802:Phylogeny; D011995:Recombination, Genetic; D012623:Seawater / Q000382:microbiology; D014871:Water Microbiology
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