Meeting Abstract
Host-symbiont interactions are a ubiquitous component of animal biology. However, the developmental and ecological relevance of these interactions, as well as their role in evolutionary diversification, has only recently become the subject of intensive investigation. Here we explore the contribution of symbiotic microorganisms to development and survival in the dung beetle, Onthophagus gazella. Onthophagus beetles feed exclusively on nutrient-poor dung, and are thought to rely on a unique microbial community, or microbiome, to digest dung during larval development. Although it is unclear exactly how this microbiome is assembled, recent work has demonstrated that the Onthophagus microbiome can be vertically transmitted through the dung ball in which larvae develop to adulthood. In order to assess the functional relevance of the microbiome, we reared larvae under (a) sterile or non-sterile conditions, and replicated this approach for (b) both low and high levels of a relevant ecological stressor. We assessed the effect of these manipulations on growth, rate of development, and survival to adulthood. We find that under low stress conditions, sterile reared larvae exhibit significantly reduced adult size and take longer to develop to adulthood than non-sterile reared larvae. Under high stress conditions, we additionally recover a strong effect on larval mortality: only a subset of non-sterile, but none of the sterile reared larvae, survive to adulthood. Lastly, we report the effects of inoculating sterile reared beetles with culture-derived members of the vertically transmitted microbiome. Combined, these results demonstrate that microbial symbioses are a critical component of the O. gazella developmental environment, and may adaptively buffer development, in particular under stressful environmental conditions.
