A fundamental yet vexing problem for microbiologists interested in studying microbial diversity is how to define microbial species and whether there is a universal genetic boundary between species. By comparing the sequences of 91,761 microbial (bacterial and archaeal) genomes, a recent study suggests that there is a universal genetic boundary among microbial species and a 95% ANI (average nucleotide identity) can be used to accurately delineate all named microbial species (https://doi.org/10.1038/s41467-018-07641-9). Taking phylogenetic relationships into account and using a more balanced analysis approach, the new study from the Wu lab shows that the conclusions of the original paper resulted from the substantial biased sampling in genome sequencing and there is no evidence of a universal genetic boundary among named microbial species. This research has been published in Nature Communications (https://doi.org/10.1038/s41467-021-24128-2). In the new paper, the authors caution against being overly confident in using 95% ANI for microbial species delineation. This research started as a rotation project for then the first year graduate student Connor Murray. It grew into a collaboration with Yingnan Gao, a graduate student in the Wu lab. Murray, C.S., Gao, Y. & Wu, M. Re-evaluating the evidence for a universal genetic boundary among microbial species. Nat Commun 12, 4059 (2021). https://doi.org/10.1038/s41467-021-24128-2