How the interaction between host organisms and their gut microbiota promotes rapid adaptation to trophic niches in threespine stickleback

• Applicant: Dr. Andreas Härer
• Subject Area: Evolution, Anthropology ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 458274593

Gut-associated microbial communities, the so-called gut microbiota, influence many aspects of their host’s biology such as nutrient metabolism and regulation of the immune system. Despite such wide ranging effects, gut microbiota composition varies considerably not only among but also within host species. Recently, we have come to recognize the tremendous microbial diversity associated with a wide range of host organisms. Yet, we are still lacking sound knowledge on how the interaction between ecological and genetic characteristics of the host and the gut microbiota shape its composition and how differences in microbial communities affect host fitness. This is particularly important as it will help us understand the enormous variation among gut microbial communities and how these microbes can help or hinder adaptation of their hosts to new ecological niches. Combining comparative field surveys of natural populations with controlled laboratory experiments presents a promising way to identify the factors that drive gut microbiota composition and allows us to answer how the gut microbiota influences host adaptation in nature. The central objectives of this proposal are to determine how the ecology and genotype of our host fish species, the threespine stickleback, interact with environmental factors to produce patterns of gut microbiota variation within and among populations, and to examine how this variation influences host specialization to different trophic niches. Further, I will assess whether populations differing in the extent of trophic specialization show different levels of gut microbiota plasticity, defined as the capacity to restructure the gut microbiota, when presented with a novel diet. I hypothesize that high levels of gut microbiota plasticity translate to a higher fitness in the more plastic populations. Threespine stickleback are an excellent system to investigate the eco-evolutionary dynamics of host-microbiota interactions as they exhibit profound ecological and evolutionary parallelism across independent populations, are amenable for laboratory experiments, and show substantial phenotypic and genetic variation within and among populations.Identifying the factors that structure the assembly of gut microbial communities will enable us to predict how a host, its gut microbiota and the environment interact during the adaptation to different ecological niches. This will further help us to understand how microbial diversity is sustained within and among populations. My research will also gain novel insights into the previously untested idea of whether host-specific differences in gut microbiota plasticity might affect the potential of host organisms to adapt to novel ecological niches.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Dr. Diana Rennison, Ph.D.