The physiological and genetic basis of reproductive dormancy in Drosophila fruit flies
Dissertation - Veterinärmedizinische Universität Wien - 2021
Dissertation - University of Veterinary Medicine Vienna - 2021
Organisms are regularly exposed to unfavorable environmental conditions, but deal with them via genetic adaptations that provide resilience against these conditions and increase fitness. Dormancy is such an important adaptation to survive unfavorable conditions in many invertebrates. Although a reproductive dormancy has been characterized in Drosophila fruit flies, the trait has long been surrounded by controversy at the physiological, evolutionary and genetic level. The work presented here aims at shedding light on these aspects of the syndrome in Drosophila. The physiological mechanism underpinning the dormancy-related block of oogenesis is shared with other stress responses, such as starvation and heat stress. As a result, dormancy is better understood as a general stress response under cold temperatures. Both D. melanogaster and D. simulans express the syndrome, in tropical and temperate regions including the regions of their respective ancestry (Sub-Saharan Africa and Madagascar). Hence, this stress response has a more ancient origin than previously believed. In D. simulans, the trait has a polygenic basis consistent with genome-wide scans in fruit flies and other insects and can be affected by stress-induced transgenerational effects. These transgenerational effects do not seem to be mediated by the microbiome. These results challenge many established notions of reproductive dormancy in Drosophila. Since some of the aforementioned controversies are directly or indirectly linked to the oogenesis scoring used to study dormancy, I highly encourage future studies to turn to other dormancy-related traits too, preferably relevant at particularly low temperatures.
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