Dimitri Stucki

For my PhD thesis I study stress-induced changes in insect immune defenses, focusing on a rather broad palette of extrinsic and intrinsic stress factors. Extrinsic factors encompass for example seasonal constraints on food availability or rapid changes in temperature and/or humidity, whereas, intrinsic factors arise at the genetic level, such as inbreeding depression. Stress is a frequent, but rarely predictable force which can rapidly alter an individuals fitness prospects. Thus, the ablity to adapt to various stressors, often achieved through cutbacks in other physiological functions, is vital to any organism, in order to maximize its own fitness. In my research I investigate whether and how stress-induced responses in gene expression are compensated/complemented by changes in immune functions. For these investigations I analyze the expression levels of various immunity-related genes through quantitative PCR, and analyze how the given stress factors affect survival. The protagonist of my work is the excised wood ant Formica exsecta, a eusocial insect characterized by the production of a distinct worker caste and close interactions among the members of a colony. As antagonists, i.e. parasites, I either feed living entomopathogenic bacteria, or expose the ants to spores of the entomopathogenic fungus Beauveria bassiana.
In general I am fascinated by the vast variety of forms and functions that arose from the evolution of single cells to complex, multicellular organisms. I am highly intrested in the proximate mechanisms that led to this variation, and to me one of the most intriguing aspects of evolution encompasses selection on complex traits which involve more than one individual. Traits which mediate interactions among individuals are not only selected on one single geneome, but lead to convoluted selection on all involved individuals, as well as on several levels. This convolution can lead to hardly predictable outcomes, which often strongly depend on the circumstances under which selection happened, such as for example the presence or absence of a specific stress factor.

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