The effect of the environment on development is critical to human health, and animal and plant ecological strategies. However, the molecular mechanisms that regulate developmental (phenotypic) plasticity remain poorly understood. When exposed to different environments, the nematode Pristionchus pacificus expresses one of two possible mouth forms: either the 'Stenostomatous' morph with a narrow buccal cavity and one tooth-like denticle, or the 'Eurystomatous' morph that has a wide buccal cavity and two teeth-like denticles. In my project, I have been assessing whether morph choice, an experimentally tractable example of developmental plasticity, is mediated by nutrition. Specifically, I performed two experiments to test the putative connection between nutritional status and phenotype: 1) grew and collected P. pacificus on different environments - poor and rich nutrition - for metabolomic analysis and 2) conducted dietary restriction experiments with different Pristionchus species to assess the generality and conservation of the diet:phenotype connection. For the primary project, I initiated the growth of ten worm-pellets collected from each NGM agar and liquid culture dietary conditions, that result in differing phenotypic expression, and submitted samples to the University of Utah Metabolomics Core Facility. In the second project, I phenotyped four different species grown on high- or low-bacterial food conditions. Results thus far from the first experiment LC/GC- Mass Spectrometry metabolomics reveal that there are significant metabolite differences between conditions, specifically those related to the lipid and protein metabolic pathways. Results from the second experiment show that all four species exhibited significant differences in mouth form under dietary restrictive conditions. Collectively, these results suggest that the effect of diet on morph choice is a deeply-rooted phenomenon feasibly connected to lipid and protein catabolism. My current experimentation aims to use free fatty acid and amino acid assays on samples from the two conditions to deeper analyze differences in these pathways that could have significance in the mechanism behind chromatin modifications.