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Department 4 Evolutionary Biology
Director: Dr. Ralf J. Sommer
Administrative Assistant: Kostadinka Krause
Phone: +49 (0)7071 - 601 441
Fax: +49 (0)7071 - 601 498
Staff: Alphabetical List
Alumni
Mission Statement and Introduction
Integrative Evolutionary Biology
Life on Earth resulted in an astonishing diversity of form and phenotype. But our understanding on how this diversity is generated as a result of historical processes is still limited. We use a highly interdisciplinary approach that integrates development, ecology and population genetics to unravel the mechanistic changes that give rise to evolutionary alterations and novelty (Sommer, 2009). For this to be achieved well-selected model organisms with a sophisticated toolkit for functional investigations have to be developed. We have established the nematode Pristionchus pacificus as a model system in evolutionary biology. P. pacificus combines laboratory studies building on genetic, genomic and transgenic tools with field work in ecology and population genetics.
One of our core activities is in evolutionary developmental biology (evo-devo). By investigating the evolution of developmental processes, we aim for a mechanistic understanding of phenotypic change. Our studies on vulva development show that Caenorhabditis elegans and P. pacificus form their egg-laying structure from the same precursor cells, but use distinct molecular mechanisms. An unusual Wnt pathway regulates vulva development in P. pacificus representing an example of developmental systems drift (Wang & Sommer, 2011). This diversity is also reflected at the level of the genome with massive expansions in gene number and a strong influence of novel genes, in part acquired by horizontal gene transfer (Dieterich et al., 2008; Rödelsperger & Sommer, 2011).
Our interdisciplinary research program tries to integrate evo-devo with population genetics and ecology to i) indicate the contribution of natural variation to the evolution of development and ii) reveal how developmental processes evolve under changing environmental conditions. Since 2004, we could show that P. pacificus and related worms live on scarab beetles in a necromenic association. Worms rest on the living beetle in the dauer stage and only start feeding on microbes after the beetles´ death. These findings have opened many new research avenues that are currently explored to investigate the developmental basis of ecologically relevant traits (Bento et al., 2010).
Our third goal is to provide integration of evo-devo with population genetics. More than 400 P. pacificus strains and nearly 30 Pristionchus species have been isolated, providing material for studies of natural variation. In 2010, we have opened a field station on La Réunion in the Indian Ocean, an island on which P. pacificus is associated with several different scarab beetles and that harbors the complete worldwide genetic diversity of P. pacificus (Herrmann et al., 2010; Morgan et al., 2012). We use the La Réunion microcosm for the population level analysis of ecological and developmental traits by performing genome wide association studies and QTL analysis. In this tripartite system – evo-devo, ecology and island population genetics - we link micro – and macroevolutionary investigations to provide a comprehensive and integrative view of evolution (Sommer, 2009).
To this end the Pristionchus research in the Department focuses on four different areas:
1) The evolutionary analysis of developmental processes (evo-devo),
2) The genetic analysis of species interactions and the ecology of Pristionchus nematodes (evolutionary ecology),
3) Population genetics of P.pacificus in the context of La Réunion Island in the Indian Ocean,4) Resource and Methods development.
Introductory References:
Sommer, R. J. & Ogawa, A. (2011): Hormone signaling and phenotypic plasticity in nematode development and evolution. Curr. Biol., 21, R758-R766.
Bento, G., Ogawa, A. & Sommer, R. J. (2010): Co-option of the hormone-signalling module dafachronic acid–DAF-12 in nematode evolution. Nature, 466, 494-497 .
Sommer, R. J. (2009): The future of evo-devo: model systems and evolutionary theory. Nature Rev. Genetics, 10, 416-422.Dieterich, C. & Sommer R. J. (2009): How to become a parasite – lessons from the genomes of nematodes. Trends in Genetics, 25, 203-209.
Dieterich, C., Clifton, S.W., Schuster, L.N., Chinwalla, A., Delehaunty, K., Dinkelacker, I., Fulton, L., Fulton, R., Godfrey, J., Minx, P., Mitreva, M., Roeseler, W., Tian, H., Witte, H., Yang, S.P., Wilson, R.K., Sommer, R.J. (2008): The Pristionchus pacificus genome provides a unique perspective on nematode lifestyle and parasitism. Nature Genetics, 40, 1193-1198.
Sommer, R. J. (2008): Homology and the hierarchy of biological systems. BioEssays, 30, 653-658.
Hong, R. L. and Sommer, R. J. (2006): Pristionchus pacificus – a well rounded nematode. BioEssays, 28, 651-659.
Research Projects
Vulva development in Pristionchus pacificus
Pristionchus pacificus Genomics and Proteomics
Microevolution of vulva development in Pristionchus pacificus
The evolution of dauer formation
Pristionchus – biology and taxonomy
Evolutionary field station on Reunion island
Pristionchus - Population Genetics and Ecology
Comparative Connectomics: Whole animal dense neural circuit reconstruction
Developmental plasticity: A facilitator of novelty
Microbial interactions - pathogenicity
Associated Research Groups
Nematode development (Adrian Streit)
Links
www.pristionchus.org
The Genome Sequencing Center Washington St Louis