The microbiota influences theDrosophila melanogasterlife history strategy

Abstract

19Organismal life history traits are ideally adapted to local environments when an organism has a 20 fitness advantage in one location relative to conspecifics from other geographies. Local 21 adaptation has been best studied across, for example, latitudinal gradients, where organisms 22 Significance statement 39Explanations of local adaptation have historically focused on how animal genotypes respond to 40 environmental selection. Although the impact of variation in host life histories on the composition 41 of the microbiota has been investigated for many associations, the scale and pattern of 42 microbial effects on host life history strategy are largely unknown. Here we demonstrate in the 43 fruit fly Drosophila melanogaster that microbiota effects on host life history strategy in the 44 laboratory are matched by patterns of microbiota composition in wild host populations. In 45 particular, microbiota composition varies with latitude and the effects of the microbiota on life 46 history traits are greater than host genetic adaptations. Together, these findings demonstrate 47

Common structuring principles of the Drosophila melanogaster microbiome on a continental scale and between host and substrate

“…This is consistent with a model in which genome‐wide differentiation of the host populations might also affect loci that interact with the microbiome. Given previous evidence for microbe‐interacting loci that vary between natural populations (Corby‐Harris and Promislow, ; Lazzaro et al ., ; Behrman et al ., ; Walters et al ., ) this seems a reasonable model.…”

Continent-wide structure of bacterial microbiomes of European Drosophila melanogaster suggests host-control

“…This correlation is consistent with a model, in which stronger genetic differentiation leads, on average, to larger differences in host-control, and hence host-associated microbiomes. Given ample evidence for variation in host-control between natural populations that depends on genotype (Lazzaro et al, 2008;Corby Harris and Promislow, 2008;Behrman et al, 2018;-Walters et al, 2018) this seems a reasonable model.…”

“…For instance, reproductive (Pais et al, 2018) and nutritional (Sannino et al, 2018) benefits as well as protection from pathogens (Shin et al, 2011) can be derived from members of the family Acetobacteraceae. This family dominates the natural microbiome (Corby-Harris et al, 2007;Cox and Gilmore, 2007;Chandler et al, 2011;Barata et al, 2012;Staubach et al, 2013;Adair et al, 2018;Walters et al, 2018). However, the role of host-control in the prevalence of these potentially beneficial bacteria is unclear because the ability of D.…”

“…If host-control is important for D. melanogaster, imprints of host-control on the microbiome should also become apparent in a natural setting. Such imprints could be reflected by co-structure of host population genetic variation and the microbiome because host-control in D. melanogaster varies between natural populations Walters et al, 2018) and depends on host genotype (Unckless et al, 2015;Chaston et al, 2016;Pais et al, 2018). Furthermore, if the natural D. melanogaster microbiome is subject to host-control, it should show general properties of host-associated microbiomes, for example elevated levels of 16S gene copies.…”

Why evolve reliance on the microbiome for timing of ontogeny?

“…For example, mosquito larvae will not pupate in the absence of bacteria [1,4], and adding bacteria or yeast rescues development [5]. As an example of modulation, Drosophila colonized with Acetobacter develop more rapidly than when colonized with Lactobacillus [6,7]; and in Brassica, soil microbes associated with drought led to accelerated flowering time compared to microbes associated with wet soils [8]. The question then emerges: why would such an important aspect of the fitness of eukaryotic hosts be driven by the presence or absence of a completely different branch of the tree of life?…”