Influence of Biotic and Abiotic Stressors on the Coevolution of the Tapeworm Schistocephalus Solidus with Its Specific Host, the Three-Spined Stickleback CLUSTER: "Evolutionary Genetics of Three-Spined Stickleback - Parasite Interactions"

• Applicants: Dr. Martin Kalbe (†); Jörn Peter Scharsack, Ph.D.
• Subject Area: Evolution, Anthropology
• Term: from 2009 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 130482565

For the second funding period, we propose to have a stronger focus on the parasite, in particular the ability of the model parasite (S. solidus) to interfere with (manipulate) the immune system of its stickleback hosts. From previous experiments it is known that S. solidus parasites from different locations differ substantially in their potential to infect and exploit their stickleback hosts. Consequently differences in immune-modulatory capabilities of parasites from different locations are expected. As a major read out we are planning to use transcriptome sequencing in cooperation with the project of M. Stoll, TBH Reusch and E. Bornberg-Bauer. Two cDNA libraries of S. solidus established by Samonte-Padilla et al. will be used as a backbone for the annotation of the transcriptome sequences. If possible, the transcriptomic data will be linked to a planned S. solidus genome project (initiated by James Cotton, Sanger Institute, and Klaus Brehm, University of Würzburg). In addition to the parasite transcriptomes, transcriptomes of the corresponding host sticklebacks will be analysed, enabling to investigate the whole host-parasite interactome on the RNA level. Despite the comparison of differentially adapted S. solidus, we are planning to use environmental stressors as additional experimental variables. (1) Co-infections with other sympatric and allopatric parasite species, since previous experiments showed that S. solidus is capable to induce different levels of concomitant immunity against different species of eye flukes, which, furthermore, serve as highly sensitive indicators for the timing of host immune manipulation (experiments to be conducted in Plön, one PhD position); and (2) temperature variation based on previous experiments indicating that at high temperatures (24°C), immune manipulation of S. solidus starts earlier, but is more prominent at low temperatures (13°C) at later time points, even if the parasites are still relatively small (experiments to be conducted in Münster, one PhD position). Both, infections of the infested stickleback host with other parasites than S. solidus, as well as temperature variation interfere with the activity of the host’s immune system and cause strong selective pressure on S. solidus. Consequently it is likely, that S. solidus is adapted to adjust its immune modulatory activity in the stickleback host in response to environmental factors such as heterologous infections and temperature variation to minimize its fitness loss. Main goals of the projects are to investigate the transcriptomics background of host manipulation induced by S. solidus and to unravel potential interaction(s) of host manipulation with environmental stressors.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1399: Host-Parasite Coevolution - Rapid Reciprocal Adaptation and its Genetic Basis
• Participating Person: Dr. Irene Samonte-Padilla