Christian Kost, PhD

Studying mechanistically the evolutionary trajectories that are taken to realise complex phenotypes.

My current research focuses on the evolution of complex phenotypes. By using an approach of reverse evolution, in which we have subjected populations of Pseudomonas fluorescens repeatedly to two environments with opposing selection pressures, I try to understand the rules that govern and constrain the evolution of new phenotypes. Analyzing the strains that resulted from the reverse evolution experiment at different levels of biological organisation, I aim at answering the following questions:

Genotype

• What were the mutational causes that allowed P. fluorescens to repeatedly adapt to the two contrasting environments?
• What kinds of genes were affected by mutations (regulatory vs. structural changes)?
• To what extend did parallel evolutionary trajectories occur in the replicate lines?
• What was the temporal order of the mutations?
• To what extend is the suite of possible adaptive mutations dependent on the genetic architecture (i.e. determinism) or chance (i.e. stochasticity)?
• To what extend is the effect of a given mutation determined by the environment (i.e. phenotypic plasticity), the evolutionary history (i.e. epistasis), or an interaction between the two?
• What molecular mechanism entailed the loss of adaptability in one of the reverse selected line?

Phenotype

• How did the phenotype of the reverse selected lines respond to this selection regime?
• What were the fitness consequences of reverse selection?

Poster presented at the 2007 Gordon Research Conference on Microbial Population Biology

Publications from previous work

Venkatesan R., Kost C., Bartram S., Heil M. & Boland, W. (2008). Testing the optimal defence hypothesis for two indirect defences: secretion of extrafloral nectar and emission of volatile organic compounds Planta, accepted.

Kost C. (2008). Chemical communication, in Encyclopedia of Ecology; eds. Jorgensen S. E. & Fath B., Elsevier, in press.

Kost C. & Heil M. (2008). The defensive role of volatile emission and extrafloral nectar secretion for lima bean in nature. Journal of Chemical Ecology 34, 2-13.

Kost C., Lakatos T., Böttcher I., Arendholz W.R., Redenbach M. & Wirth R. (2007). Non-specific association between filamentous bacteria and fungus-growing ants. Naturwissenschaften 94, 821-828.

Mekem Sonwa M., Kost C., Biedermann A., Wegener R., Schulz S. & Boland W. (2007). Dehydrogenation of ocimene by active carbon: artefact formation during headspace sampling from leaves of Phaseolus lunatus. Arkivoc 3, 164-172.

Heil M. & Kost C. (2006). Priming in indirect defences. Ecology Letters 9, 813-817.

Schulze B., Kost C., Arimura G. I. & Boland W. Duftstoffe (2006). Die Sprache der Pflanzen – Signalrezeption, Biosynthese und Ökologie. Chemie in unserer Zeit 40, 366-377.

Leal I. R., Fischer A., Kost C., Tabarelli M. & Wirth R. (2006). Ant protection against herbivores and nectar thieves in Passiflora coccinea flowers. Écoscience 13, 431-438.

Kost C. & Heil M (2006). Herbivore-induced plant volatiles induce an indirect defence in neighbouring plants. Journal of Ecology 94, 619-628.

Kost C. & Heil M. (2005) Increased availability of extrafloral nectar reduces herbivory in Lima beans (Phaseolus lunatus, Fabaceae) Basic and Applied Ecology. 6, 237-248.

Arimura G., Kost C. & Boland W. (2005). Herbivore-induced, indirect plant defences. Biochimica et Biophysica Acta: Lipids and Lipid Metabolism. 1734, 91-111.

Kost C., E. G. Oliveira, Knoch T. A. & Wirth R. (2005). Spatio-temporal permanence and plasticity of foraging trail systems in young and mature leaf-cutting ant colonies (Atta spp.). Journal of Tropical Ecology 21, 1-12.