Ralf Sommer

Integrative Evolutionary Biology

Max Planck Insitute for Developmental Biology
Faculty in: TIPP, IMPRS


  • Diplom in Biology 1989, RWTH Aachen & University of Tübingen
  • PhD work 1989-92 at the Ludwig-Maximilians University Munich
  • Research fellow 1993-95 at CALTECH, Pasadena, USA
  • Director at the MPI since 1999
  • Adjunct Professor, University of Tübingen since 2002

Research Interest
My primary scientific interest is to unravel the mechanisms that give rise to evolutionary alterations and novelty. We use an interdisciplinary approach that integrates development, ecology and population genetics. We study the nematode Pristionchus pacificus, which we have established as a model system. P. pacificus combines laboratory studies building on forward genetic, CRISPR-engineering, genomic and transgenic tools with field work. A core aspect of our current research is developmental plasticity, a concept that has recently received a lot of attention as a facilitator of phenotypic diversity.
A striking feature of novelty in P. pacificus is predatory feeding. P. pacificus forms teeth-like denticles in its mouth, which enable predation on other nematode species in their natural environment. These teeth occur as a dimorphism, representing an example of developmental plasticity (Bento et al, 2010; Bumbarger et al., 2013). Recent genetic studies have identified a multigene locus including a developmental switch gene, the eud-1 sulfatase and the nuclear-hormone-receptor nhr-40 (Ragsdale et al., 2013, Sieriebriennikov et al., 2018). Additionally, we found an unexpected role for epigenetic mechanisms and chromatin remodeling in the regulation of this developmental switch (Serobyan et al., 2016). We are investigating various aspects associated with predatory feeding, from its neurobiological basis (i.e. connectomics, Hong et al., 2019) to self-recognition mechanisms (Lightfoot et al., 2019). Current work includes (1) detailed mechanistic studies about epigenetic mechanisms associated with mouth-form plasticity, (2) the identification of target genes involved in final morphogenetic processes, (3) investigations of the micro-evolutionary divergence, (4) the analysis of trans-generational effects and evolutionary canalization processes, and (5) plasticity and predation-related self-recognition and kin selection.

Figure 1. Scanning electron micrograph of Pristionchus pacificus.


Figure 2. Predatory feeding of P. pacificus on another nematode.


Available PhD Projects

  • 2 potential projects in the general area: 'Developmental plasticity of mouth-form structures and their significance for evolutionary novelty and predation in nematodes’

Selected Reading

  • Lightfoot, J. W., Wilecki, M., Roedelsperger, C., Moreno, E., Susoy, V., Witte, H. & Sommer, R.J. (2019): Small peptide mediated nematode self-recognition prevents cannibalism. Science, 364, 86-89
  • Hong, R.L., Riebesell, M., Bumbarger, D., Cook, S.J., Sarpolaki, T., Carstensen, H.R., Cochella, L., Castrejon, J., Moreno, E., Siebriebriennikov, B., Hobert, O. & Sommer, R.J. (2019): Evolution of neuronal anatomy and circuitry in highly divergent nematode species. eLIFE,
  • Sieriebriennikov, B., Prabh, N., Dardiry, M., Witte, H., Rödelsperger, C., Röseler, et al. (2018): A developmental switch regulating phenotypic plasticity is apart of a conserved multi-gene locus. Cell Report, 23, 2835-2843
  • Serobyan, V., Xiao, H., Rödelsperger, C., Namdeo, S., Röseler, W., et al. (2016). Chromatin remodeling and antisense-mediate up-regulation oft he developmental switch gene eud-1 control predatory feeding plasticity. Nature Commun. 7, 12337
  • Ragsdale, E., Müller, M., Roedelsperger, C. & Sommer, R. J. (2013): A developmental switch coupled to the evolution of plasticity acts through a sulfatase. Cell 155, 922-933.
  • Bumbarger, D. J., Riebesell, M., Rödelsperger, C. & Sommer, R. J. (2013): System-wide rewiring underlies behavioral differences in predatory and bacterial-feeding nematodes. Cell 152, 109-119.
  • Bento, G., Ogawa, A. & Sommer, R. J. (2010): Co-option of the endocrine signaling module Dafachronic Acid-DAF-12 in nematode evolution. Nature 466, 494-497.

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