Evolutionary genetics, speciation, adaptive radiation and biogeography of bacteria.

Microbial population biologists have recently determined that the character of genetic exchange in bacteria is very different from that in eukaryotes: bacteria do not exchange genes often, but when they do, they are not fussy about their partners. We have modeled the effects of rare but promiscuous genetic exchange on the population structure of bacteria. Recombination is too rare to hinder adaptive divergence between bacterial populations. Therefore, speciation in bacteria does not require evolution of barriers to genetic exchange.