PVC bacteria and the prokaryote to eukaryote transition... maybe not.

It was an interesting hypothesis, but it seems the evidence for an origin of eukaryotes in the Planctomycetes, Verrucomicrobia, Chlamydiae (PVC) bacterial superphylum, as proposed by Devos and Reynaud in a Science article doesn't hold up to scrutiny.

In a recent paper by James McInerney et al. in Bioessays, the authors address each of the claimed eukaryote-like features and show that they are all likely to be either analogous (the result of parallel evolution, not shared ancestry), or are the result of horizontal gene transfer (HGT) events. In the words of the authors:

PVC are no more intermediates in the prokaryote-to-eukaryote transition than dragonflies are intermediates in the evolutionary sequence linking bony fish and birds.

The Bioessays paper is an important reminder that for any grand hypotheses about evolution, distinguishing between homologous and analogous characters is critical, as is establishing the direction of inheritance. And by far the best way to address these points is by taking advantage of the mass of genomic data available.