Early-life exposure to adult feces and natural substrate are necessary for development of a natural gut microbiome and improves body condition in carnivorous lizards (Sceloporus occidentalis)

Current research on oviparous lizards has provided three potential mechanisms for microbiome transmission: (1) gestation, (2) digestive tract, and (3) external environment. We wanted to test which of these mechanisms are responsible for how S. occidentalis obtain their gut microbiome. Further, we looked to test whether the gut microbiome positively impacted fitness hypothesized within the literature. Thus, if juvenile lizards' gut microbiome positively influences digestion, fitness, and survival, then we expect healthy juveniles to have a microbiome that looks similar to adults. Additionally, if the gut microbiome constituents came from vertical transmission, then most juvenile lizards should have a similar gut microbiome composition. Vertical transmission being defined as transfer from mother to offspring. Comparatively, if the gut microbiome constituents were obtained through horizontal transmission, then most juvenile lizards should display a similar gut microbiome to conspecifics. Given treatment groups and design, horizontal transmission between community members would not be observed. Lastly, if the gut microbiome constituents came from environmental transmission, then most juvenile lizards exhibit similar gut microbiome to the natural substrate and diet. Diet would include food inoculated with fecal matter.