 While physical models of various sorts are used throughout the sciences, model organisms are a kind of model system particular to the life sciences. “Model organism” typically refers to the organisms that are bred, propagated, and studied in laboratories in the biomedical and life sciences. Classic animal examples include nematodes (“worms”), Drosophila (fruit flies) and mice. An important plant model is Arabidopsis (mustard cress). Fungi are represented by yeast, which is also used to model all eukaryotes (Botstein &amp; Fink 2011). While a wealth of important model organism research is carried out on relatively large organisms, microbes are regarded as especially tractable model systems. This is very much the case in experimental evolution and ecology, where microbial systems allow researchers to study dynamical processes in large populations over many generations. These modelling capacities have general philosophical implications.