Role of the Gut Microbiome in Thermal Stress Tolerance
Research Summary: Despite a wealth of correlational evidence indicating that a host animal’s tolerance to thermal stress varies with its gut microbiome composition, there has been little direct testing of this phenomenon. This research will test the following hypothesis: Environmental microbes shape host stress tolerance and facilitate adaptation to abiotic conditions in the environment, such as temperature. We will test this hypothesis using an endemic Hawaiian picture-wing fly, Drosophila sproati. Two natural populations of this species on the Big Island have previously been characterized to inhabit different climate zones and exhibit different responses to thermal stress (Eldon et al. 2019). The well-characterized ecology of this species and the relative simplicity of Drosophila microbiome composition allows us to directly test the role of microbes in thermotolerance. We will first transplant microbes (with fecal transplants) from the “warm tolerant” and “cool tolerant” populations of D. sproati into lab-reared flies. Each microbially-treated Drosophila population will then be acclimated to a low and a high temperature. The stress tolerance of the four different populations will be measured in terms of lifespan, ability to withstand heat waves, and fertility of females and males. Differences in responses may indicate that microbes acquired from different environments influence host stress tolerance in an environmentally-specific manner. Successful proof-of-concept of our hypothesis will allow us to identify the underlying metabolic pathways and key microbial species. Establishing this foundational knowledge is a critical step if we are to exploit the microbial world as a resource to benefit reintroductions of rare Hawaiian insects to their ancestral ranges.
