pattern of nucleotide substitutions in the Cucurbitaceae. J. Mol. Evol.

ity transcribing and translating nonfunctional genes, sup- (implying passive removal), they might actually be detri-their transcription or translation or through deleterious Update TRENDS in Genetics Vol.23 No.12 601Bacterial pseudogenes are ephemeral Pseudogenes are often cited as the paradigm of neutral evolution, representing regions of the genome that are not under any selective constraints [1]. Pseudogenes have long been known to be present in eukaryotes [2], but until recently, these inactivated genes were considered to be rare in prokaryotes [3]. The elucidation of complete genome sequences revealed that pathogenic bacteria can contain hundreds of disrupted and eroded genes [4,5], and sub-sequent analyses divulged that pseudogenes are a rela-tively common feature of organisms in all domains of life [6–9]. In contrast to eukaryotes, the pseudogene reper-toires of bacteria and archaea are largely genome-specific, suggesting that nonfunctional sequences are removed rapidly from the genome [6].Corresponding author: van Passel, M.W.J