In Situ Evolutionary Rate Measurements Show Ecological Success of Recently Emerged Bacterial Hybrids

Abstract

Acid Rate The low species richness of the acid mine drainage in the Richmond Mine (Iron Mountain, California, USA) provides an excellent opportunity to study microbial process on a genome scale in real time. Denef and Banfield (p. 462; see the Perspective by DeLong ) report the further analysis of metagenomic data from 24 microbial biofilm samples collected over 8 years, at different sites. High-throughput, shotgun sequencing of the DNA was used to look for high-frequency, single-nucleotide polymorphisms in six genotypic variants of a chemolithoautotroph, Leptospirillum group II, the dominant primary producer and iron-oxidizer. Thirteen samples collected at one site over 5 years were analyzed to infer the accumulation of single-nucleotide substitutions for free-living populations over time. A series of very recent branching points in the phylogenetic tree that arose via homologous recombination were revealed.