Impacts of Natural Selection on Evolution of Core and Symbiotically Specialized () Genes in the Polytypic Species .

Nodule bacteria (rhizobia) represent a suitable model to address a range of fundamental genetic problems, including the impacts of natural selection on the evolution of symbiotic microorganisms. Rhizobia possess multipartite genomes in which symbiotically specialized () genes differ from core genes in their natural histories. Diversification of genes is responsible for rhizobia microevolution, which depends on host-induced natural selection.

Microevolution, speciation and macroevolution in rhizobia: Genomic mechanisms and selective patterns.

Nodule bacteria (rhizobia), N-fixing symbionts of leguminous plants, represent an excellent model to study the fundamental issues of evolutionary biology, including the tradeoff between microevolution, speciation, and macroevolution, which remains poorly understood for free-living organisms. Taxonomically, rhizobia are extremely diverse: they are represented by nearly a dozen families of α-proteobacteria (Rhizobiales) and by some β-proteobacteria. Their genomes are composed of core parts, including house-keeping genes (), and of accessory parts, including symbiotically specialized () genes.