Dataset Food choice in the nematode Caenorhabtidis elegans A study about the influence of starvation and life stage on the food choice of C. elegans between OP50 and Bacillus megaterium Seven universities in the Netherlands and Belgium are taking part in a project that aims to study which factors influence the predictability of evolution. Caenorhabtidis elegans is the study object in this project. All the universities perform an experiment where they apply a selection pressure in the form of Bacillus megaterium, a food source that nematodes avoid when given a choice. Nematodes avoid this food source because of the poor quality. However, the nematodes are normally kept on a strain of Escherichia coli, OP50, which is also of poor quality. This raises the question to what extent C. elegans has different preferences for the two kinds of bacteria, B. megaterium and E. coli and what factors influence this preference. A study of Avery and Shtonda (2003) points in the direction that OP50 will be chosen over B. megaterium. This study shows that smaller bacteria are better food sources than larger bacteria. B. megaterium is a larger bacterium than E. coli (Vary et al., 2007). The hypothesis that C. elegans prefers OP50 over B. megaterium will be tested in two different experiments, aimed to investigate which factors influence their preference. In the first experiment the influence of starvation on the food choice between B. megaterium and OP50 will be tested. In the second experiment the effect of life stage on the food choice of nematodes will be investigated. In addition, another experiment will be performed to test to what extent food choice experiments in nematodes are repeatable.