Inhaltszusammenfassung

The study of the emergence of group living and its evolution into permanent and complex societal systems is a major topic of interest in evolutionary biology, entailing careful study of the costs and benefits constraining and driving social evolution. One of the most prominent challenges group living species face is an increased risk of pathogen infection. To overcome this threat, individuals in groups can not only increase their investment into personal defenses, such as physiological and be...The study of the emergence of group living and its evolution into permanent and complex societal systems is a major topic of interest in evolutionary biology, entailing careful study of the costs and benefits constraining and driving social evolution. One of the most prominent challenges group living species face is an increased risk of pathogen infection. To overcome this threat, individuals in groups can not only increase their investment into personal defenses, such as physiological and behavioral immunity, but also exhibit collective defenses known as social immunity. Recent studies suggest that social immunity plays a key part in the early emergence of sociality – yet little is known about their role in primitive groups, such as facultative family associations. In particular, it remains largely unknown to what degree social immunity in subsocial species is mediated by parental care, or how collective immunity shapes investment into personal immunity in these family groups. In this thesis, I examine these questions in the European earwig Forficula auricularia, an insect exhibiting facultative family life. The first part of this thesis focuses on better understanding the role and effectiveness of social immunity in the European earwig. In Chapter 1, I show that social immunity occurs in this species through antimicrobial activity from the feces excreted by both the caring mother and the offspring. In Chapter 2, I demonstrate that the feces of offspring provide starvation resistance to siblings if no regular food sources are available, suggesting an additional and non-immune related role of feces production. In Chapter 3, I demonstrate that the presence of pathogens does cause offspring to overexpress immunity related genes during family life, but only in absence of a caring mother. Nevertheless, maternal care does not seem to shape offspring immunity long-term: in Chapter 4, my data reveal that the presence of a pathogen, but not of the mother, affects the immunity of earwig offspring in adulthood. Finally, I address the recent findings of social immunity in subsocial species and their implications on social evolution in Chapter 5. In the second part of this thesis, I focused on advancing our understanding of personal pathogen defenses, a critical component in the role and effectiveness of social immunity in social evolution. In particular, we aimed to highlight the difficulty of correctly assessing personal immune investment by investigating insect immune functions in the light of key physiological constraints. In Chapter 6, I showed that larger forceps trade-off with earwig immunity, but only in relatively small earwig males, and only after an immune challenge – overall highlighting the importance of a careful, multipronged approach when measuring immunocompetence. The data presented in Chapter 7 finally shows that shorter winter length during development increases key parts of adult female immunity, but only if specimen were kept with unfamiliar conspecifics, which emphasizes the role of social stresses in immune investment. In conclusion, this dissertation emphasizes how the proposed important redefinition of social immunity sets the stage for future inquiries into the role of pathogen pressure in early social evolution. By also highlighting key trade-offs between individual immunity and physical constraints, my work may lay the groundwork for new perspectives and informed investigations into the crucial interplay of personal immunity, social immunity, and the consolidation of facultatively social individuals into interdependent and complex social systems.» weiterlesen» einklappen

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DDC Sachgruppe:
Allgemeines, Wissenschaft