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Abstract

Environmental influences on traits and associated transgenerational epigenetic inheritance (TEI) have widespread implications but remain controversial and underlying mechanisms little understood. Fundamental insight could be obtained by integrating experiments that visualize plasticity in response to environmental stimuli with experimental evolution. We used long-term environmental induction on alternative diets in Pristionchus pacificus nematodes that exhibit natural mouth-form plasticity including a predatory morph. Propagation of 110 isogenic lines for 101 generations and associated food-reversal experiments revealed dietary induction of the predatory morph and its subsequent TEI. This memory requires at least five generations of induction, which is phenomenologically different from previous examples of TEI. Coupling dietary induction with mutagenesis identified the ubiquitin ligase EBAX-1. Ppa-ebax-1 mutants responded to dietary induction but showed no memory. We found Ppa-EBAX-1 destabilizes the microRNAs family miR-2235/miR-35. Deletion of a cluster of 44 identical copies of miR-2235 resulted in precocious and extended TEI of the predatory morph.