Current research

Our research group focuses on reconstructing the evolution of ecological traits by molecular systematic methods. The central theme is understanding the rules governing host switches and the role of secondary plant compounds in the evolution of host use in phytophagous insects.

Current research projects deal with the evolution of host use and sequestration of secondary plant compounds in the flea beetle genus Longitarsus. This genus shows a large variety of host associations, with two classes of secondary compounds occurring frequently among Longitarsus host plants: pyrrolizidine alkaloids on one hand, and iridoid glycosides on the other. The genus is thereby especially suited to investigate whether switches between unrelated plant families, for which undetected evolutionary constraints can be excluded, have been guided by shared secondary compounds in the respective host plants. So far we could show that Longitarsus species take up and accumulate both classes of secondary compounds, most likely for their anti-predator defense. Currently we are investigating the physiological mechanisms that allow sequestration and which genes have been recruited to enable the beetles to deal safely with these potentially toxic compounds. (Dr. Susanne Dobler, PhD thesis Ingo Narberhaus, Diploma thesis John Hesselschwerdt, Angela Faller, collaborations with Prof. T. Hartmann, TU Braunschweig, Prof. D. Bowers, University of Colorado, USA).

In a parallel study the evolution of sequestration of cardenolides in leaf beetles of the genus Chrysochus is analyzed on the phylogenetic, biochemical and genetic level (Postdoc project Dr. Estelle Labeyrie, collaboration with Prof. E. Petzinger, Uni Gießen)

Molecular phylogenies of several other beetle groups are also under study: the evolution of brood parasitism in tenebrionid beetles of the tribe Stizopina is clarified by comparing phylogenies of host and parasite species (PhD thesis Sven Geiselhard, project in collaboration with Prof. K. Peschke, Freiburg); the family Silphidae is investigated to understand the evolution of phytophagy among the originally carrion feeding species (Dr. Susanne Dobler and Prof. J. Müller, Freiburg); a molecular reconstruction of the Galerucinae (subfamily of Chrysomelidae) will show whether larval defense glands evolved only once or several times independently (PhD thesis Martina Bünnige, project in collaboration with Prof. M. Hilker, FU Berlin); the genus Psylliodes (Chrysomelidae, Alticinae) has been used as a study system to investigate the evolutionary rates of diverse nuclear and mitochondrial genes and their usefulness in phylogenetic studies on this level and a molecular phylogeny of the genus Aleochara (Staphylinidae) is being established to clarify systematic issues and to understand the evolution of sexual traits and chemical ecology in this genus (project in collaboration with Prof. K. Peschke, Freiburg).