“Evolution
Canyon”
Population genetics of environmental bacteria
The evolutionary dynamics of diversification and speciation of bacteria, presumably driven by selective constraints posed by the environment, remains a hot topic. We approach this by studying natural populations from the environment, thereby complementing entire mathematical or test-tube (“Experimental Evolution”) lines of investigation.
We utilize a population of 131 Bacillus simplex isolates from "Evolution Canyon" I and II in Israel (See figure below for "Evolution Canyon" I) (Ref). These strains, identical in their 16S sequence, split into several putative ecotypes (see figure below) which are adapted to either the sun-exposed south-facing slope (hot, dry) or to the shady north-facing slope (mesic-lush) (Fig). The total of nine putative ecotypes (see figure below) has been proposed by an sequence based evolutionary algorithm termed Ecotype Simulation ( Ref). We also observe that the putative ecotypes express some adaptive phenotypic traits which fit to their habitat distribution, e.g., the strains from the hotter slope are indeed more high-temperature tolerant than the strains from the shady slope (Fig. 1) (Ref1, Ref2). However, the quantitative utilization of carbon sources appears not to be influenced by the different slope type ecology, indicating that some traits are prone to change by natural selection whereas other traits diverge rather neutrally (Ref). Currently we explore further phenotypes which might relate to the observed environmental stresses, for example dehydration stress. We are also interested in the plasmid diversity of this population. In soon, we will further move to full genome sequence comparison in order to elucidate the molecular basis of putative adaptive phenotypes.For a quick overview, you can find here more information about this project.
The "Evolution Canyon" model project
The “Evolution Canyon” is a east-west facing canyon with microclimatically strongly divergent slopes, despite their proximity. The microclimatic heterogeneity results from the slope orientation to the sun: The SFS (red) is always facing the sun, the NFS (blue) is mostly in the shade.
The great advantage of this situation for evolutionary research in natural habitats: Living beings can migrate easily between the slopes, this, however, is ultimately linked to a strong microclimatic habitate change, i.e. to an exposure to natural selection.
Bacillus simplex putative ecotypes
