Figure 3. Microbiome abundances correlate with some host physiology traits. (A) Gnotobiotic flies were associated with defined bacterial flora for 10 d before washing, crushing, and CFU enumeration. (B) Mean microbiome load (log10scale) and relative abundances of the different species (linear scale) for all 32 possible combinations of the five species (n = 24 replicate flies from two independent biological replicates were measured per combination). (C) Total bacterial load increases as the number of species increases, but Lb abundance drops. Mean abundances were calculated from B as a function of the number of species present (complete data are provided in SI Appendix, Fig. S6). The black line indicates mean total bacterial load per fly computed over all combinations with the given number of species. (D) Lp abundance (from B) correlates with increased female fly fecundity (from Fig. 1C). (E) Aoabundance (from B) correlates with decreased fly lifespan (from Fig. 1C). (F) Development time from embryo to adult is accelerated by live bacteria. The development assay from Fig. 2B was repeated with variation in food preparation and source of embryos. The term “standard” indicates data from the fitness experiment in Fig. 2B; “germ-free” indicates embryos from germ-free females placed directly on fresh food inoculated with defined bacteria; and “heat-killed” and “non–heat-killed” indicate vials from the fitness experiment cleared of flies and either seeded directly with germ-free embryos (non–heat-killed) or placed at 60 °C for 1 h and checked for sterility (heat-killed) before being seeded with germ-free embryos. The number below the x axis indicates the number of replicate vials assessed. Complete bacterial combinations and individual replicates of F are provided in SI Appendix, Fig. S10. All error bars show SEM.