Dynamic Genomes: Generating Genetic Novelty in Evolution by Andrew Berry

We think of genomes as relatively fixed.  Most vertebrates, for example, have genomes with more or less the same complement of genes.  Given this evolutionary conservation, how can evolutionary innovation occur at the genetic level?  Vertebrates may all follow the same basic developmental blue print, but they are nevertheless stunningly diverse.  Genomes, we are increasingly coming to appreciate, are more prone to drastic change than we have hitherto appreciated: freak events that occur very, very rarely may have a big impact on the evolutionary process.  The number of individual organisms there are + the dizzying extent of time over which the evolutionary process has played out means that we cannot overlook these inconceivably rare events.  Innovation may arise through quirky intra-genome transposition events, from the activity of transposable elements that can change the topology of chromosomes, and from horizontal gene transfer whereby 'alien' DNA is acquired and re-purposed.  Genomes are not fixed at all: they are dynamic maelstroms of evolutionary innovation.