Adaptation and incipient sympatric speciation of Bacillus simplex under microclimatic contrast at "Evolution Canyons" I and II, Israel

Johannes Sikorski, Eviatar Nevo

Research output: Contribution to journalArticlepeer-review

Abstract

The microevolutionary dynamics of prokaryotes in natural habitats, such as soil, is poorly understood in contrast to our increasing knowledge on their immense diversity. We performed microevolutionary analyses on 945 soil isolates of Bacillus simplex from "Evolution Canyons" I (Carmel, Israel) and II (Galilee, Israel). These canyons represent similar ecological replicates, separated by 40 km, with highly contrasting interslope abiotic and biotic conditions in each (within a distance of only 100-400 m). Strains representing genetic groups were identical in their 16S sequences, suggesting high genetic similarity and monophyletic origin. Parallel and nested phylogenetic structures correlated with ecological contrasts rather than geographical distance. Additionally, slope-specific populations differed substantially in their diversity. The levels of DNA repair (determined by UV sensitivity) and spontaneous mutation rate (resistance to rifampicin) relate to ecological stress and phylogeny. Altogether, the results suggest adaptive radiation at a microscale. We discuss the observed adaptive population structures in the context of incipient sympatric speciation in soil bacteria. We conclude that, despite different biology, prokaryotes, like sexually reproducing eukaryotes, may consist of true species and parallel ecological speciation in eukaryotes.

Original languageEnglish
Pages (from-to)15924-15929
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number44
DOIs
StatePublished - 1 Nov 2005

Keywords

  • Adaptive radiation
  • Bacillus soil isolates
  • Environmental stress
  • Microbial population genetics
  • Natural selection

ASJC Scopus subject areas

  • General

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