There are several distribtions in use
The main server runs debian mainly because of safety. Centos was needed in order to get the 'shiny server' from the R community up and running in the digiphyll project. Ubuntu was the distribution of the oldest web server of the museum. Ubuntu is also the distribution of all nodes in the SMNS Linx cluster, there is however, a transition to the most recent LTS version 18.04. The choice of ubuntu over debian for the internal use comes from the phylogeny application BEAST, which could not be installed on neither centos nor debian.