My laboratory studies two examples of accelerated genetic changes in microbes. The first is called bacterial conjugation, a process that permits the exchange of genetic information between cells and has the potential to deliver as much as an entire bacterial chromosome. Whereas traits are normally inherited according to Mendelian principles, through passage from parents to offspring, bacteria can exchange genes with neighbors thereby creating hybrid genotypes. Conjugation is mediated by plasmids that can be transferred from many bacterial species to a large range of heterologous species, including eukaryotes. The second, called direct or Cairnsian mutation, may engage a quasi-Lamarckian strategy to accelerate genetic changes when microbes encounter a lethal challenge. Although the molecular details of this mechanism remain to be elucidated, documentation of its existence in bacteria and yeast is accumulating. My laboratory has explored a putative example of Cairnsian adaptation in eukaryotes. We found that the phenomenon was an unexpected and partial adaptation to environmental challenge that could be an intermediate phenotype in the pathway to full adaptation.
