Host evolutionary history and ecological context modulate the adaptive potential of the microbiome

Abstract

AbstractCan the microbiome serve as a reservoir of adaptive potential for hosts? To address this question, we leveraged ∼150 generations of experimental evolution in Drosophila melanogaster in a stressful high sugar (HS) diet. We performed a fully reciprocal transplant experiment using the dominant control and HS bacteria and measured life-history and metabolic traits. If the microbiome can indeed confer benefits to hosts, then transplant recipients should gain fitness benefits compared to controls. Interestingly, we found that these benefits do exist, but are non-linear. The benefits depend on specific interactions between host genotype and the microbiome, and these interactions are modulated by the environment. Mismatches between fly evolution and microbiome exerted fitness costs by slowing development and reducing fecundity, especially in the stressful HS diet. The dominant HS bacteria (Acetobacter pasteurianus) uniquely encoded several genes to enable uric acid degradation, mediated the toxic effects of uric acid accumulation due to the HS diet for flies. Our study demonstrates that host genotype x microbiome x environment interactions have substantial effects on host phenotype, highlighting how host evolution and ecological context together shape the adaptive potential of the microbiome.