Fig. 1.

Marine origin of B. coahuilensis, isolated from a pond in the Chihuahuan desert. (A) Sierra de San Marcos is a prominent mountain system in the middle of CCB where >400 ponds sustain most of the biodiversity. The geomorphological origin of CCB has been recently reviewed (2). (B) Churince system (shown with a red triangle in A) consists of a springhead that feeds a 2-km-long stream with an intermediate lagoon terminating at a large shallow desiccation lagoon. (C) Phylogenomic reconstruction. Maximum likelihood phylogenomic reconstruction by using Tree-Puzzle (29) was carried out with 20 universally conserved COGs from the sequenced Bacillus spp. and closely related species (Table S3). Maximum likelihood bootstrap percentage support values are only indicated for major nodes; numbers in red represent tentative timescale, in million years, calculated with the method proposed by Battistuzzi et al. (30). Genome size (represented as bars) and GC content of each Bacillus spp. genome is shown to the right.