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Abstract:
The nematode Pristionchus pacificus has been established as a model system in evolutionary biology with genetic, genomic and transgenic tools. Detailed investigations of vulva formation and other developmental processes revealed that developmental mechanisms differ strongly between C. elegans and P. pacificus. While evo-devo can provide fundamental insight into morphological evolution, the limitations of its gene- centered and development-centered view necessitate the synthesis of evo-devo with other areas of evolutionary biology. Synthesis with “population genetics” can reveal how phenotypic evolution is initiated at the micro-evolutionary level and synthesis with “evolutionary ecology” can add an ecological perspective to these evolutionary processes (Sommer, Nat Rev Genet., 2009). The well-defined association of P. pacificus with scarab beetles, the apparent plasticity of this beetle association, and the ability of this widespread species to thrive in a variety of geographic ranges and ecological conditions, make P. pacificus an ideal model organism for the merger of evo-devo, population genetics and evolutionary ecology. We have started to analyze the ecological interactions of P. pacificus in the beetle ecosystem and more than 400 strains of P. pacificus have been isolated from around the world. In the last few years, our biogeographic work focused on island biology and we discovered that La Réunion, a young volcanic island in the Indian Ocean harbours the complete worldwide genetic diversity of P. pacificus due to independent invasions of this nematode with different carrier beetles. Thus, La Réunion represents a microscosm for studies of population genetic and ecology. After a conceptual introduction, I will report from our most recent work focusing on 1) the evolution of novel morphological structures (P. pacificus forms dimorphic teeth involved in predatory feeding), 2) the integration of this novel predatory behaviour into an existing nervous system, and 3) intraspecific nematode competition in the decaying beetle ecosystem by the means of small molecules. These case studies will highlight the importance of integrative and interdisciplinary approaches in modern biology from development and evolution to ecology and organic chemistry.
