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Abstract

Nutrition is a well-established stimulus capable of inducing plastic phenotypic outcomes in various organisms. We study the isolated effect of nutrition on mouth form plasticity in Pristionchus pacificus. Adults of P. pacificus have one of two alternative mouth morphs. The eurystomatous form enables predatory feeding while the stenostomatous form leads to strict bacterial feeding, at least under laboratory conditions. Here, we supplement the standard diet of the worm with monosaccharides and fatty acids to manipulate its nutritional status. We then monitor changes in mouth morph ratios and lipid storage through Oil-Red-O staining which stains predominantly neutral lipids representing fat storage. We show that fat-inducing diets render worms nonpredatory (stenostomatous). For instance, 100mM glucose supplementation reduces predatory (eurystomatous) mouth form percentage of a wild type population from 100% to approximately 10%. We also test responses of metabolic mutations in genes of the Δ-9-desaturase family and of the peroxisomal β-oxidation pathway and reveal that intact lipid metabolism is needed to mediate the effect of the diet on mouth form plasticity. Overall, we introduce lipid storage as a measure of nutritional status and highlight its significance in mouth form plasticity in P. pacificus.