We recently submitted a paper to biorxiv on the estimation of average genome size from shotgun metagenomics data and it’s application to the human microbiome (http://biorxiv.org/content/biorxiv/early/2014/09/11/009001.full.pdf). It is currently undergoing peer review. This study was motivated by the troubling observation that many universal single-copy genes appear to vary significantly across metagenomes. How can this be? …