Integrative Evolutionary Biology

Ralf Sommer

ralf sommer
  • 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

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 allow worms to feed 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 swich gene, the eud-1 sulfatase (Ragsdale et al., 2013, Sieriebriennikov et al., 2018) and the nuclear-hormone-receptor nhr-40 (Kieninger et al., 2016). Additionally, we found an unexpected role for epigenetic mechanisms and chromatin remodeling in the regulation of this developmental switch (Serobyan et al., 2016). 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, and (4) the analysis of trans-generational effects and evolutionary canalization processes.

  • ralf sommer-fig01
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Scanning electron micrograph of Pristionchus pacificus.

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Predatory feeding of P. pacificus on another nematode.

Available PhD Projects

Project 1: Molecular mechanisms in the genetic and environmental regulation of feeding plasticity in Pristionchus pacificus.

Project 2: Experimental evolution of mouth-form plasticity in Pristionchus.

Project 3: Bioinformatics of regulatory gene networks involved in mouth-form plasticity control.

Selected Reading

1) 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

2) Kieninger, M. R., Ivers, N. A., Rödelsperger, C., Markov, G. V., Ralf J. Sommer & Ragsdale, E. J. (2016): The nuclear hormone receptor NHR-40 acts downstream of the sulfatase EUD-1 as part of a developmental plasticity switch in Pristionchus. Curr. Biol. 26, 2174-2179.

3) 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

4) 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.

5) 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.

6) 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.