A ridge-to-reef ecosystem microbial census reveals environmental reservoirs for animal and plant microbiomes.

Microbes are found in nearly every habitat and organism on the planet, where they are critical to host health, fitness, and metabolism. In most organisms, few microbes are inherited at birth; instead, acquiring microbiomes generally involves complicated interactions between the environment, hosts, and symbionts. Despite the criticality of microbiome acquisition, we know little about where hosts' microbes reside when not in or on hosts of interest. Because microbes span a continuum ranging from generalists associating with multiple hosts and habitats to specialists with narrower host ranges, identifying potential sources of microbial diversity that can contribute to the microbiomes of unrelated hosts is a gap in our understanding of microbiome assembly. Microbial dispersal attenuates with distance, so identifying sources and sinks requires data from microbiomes that are contemporary and near enough for potential microbial transmission. Here, we characterize microbiomes across adjacent terrestrial and aquatic hosts and habitats throughout an entire watershed, showing that the most species-poor microbiomes are partial subsets of the most species-rich and that microbiomes of plants and animals are nested within those of their environments. Furthermore, we show that the host and habitat range of a microbe within a single ecosystem predicts its global distribution, a relationship with implications for global microbial assembly processes. Thus, the tendency for microbes to occupy multiple habitats and unrelated hosts enables persistent microbiomes, even when host populations are disjunct. Our whole-watershed census demonstrates how a nested distribution of microbes, following the trophic hierarchies of hosts, can shape microbial acquisition.

Functions of personal experience and of expression of regret.

Although learning and preparing for future behavior are well-established functions of regret, social functions have been largely ignored. We suggest a new model of the functions of regret, the Privately Experienced Versus Expressed Regret model, in which private experience and public expression differentially serve these functions. The current research examined this model using both naturalistic and experimental approaches. In Study 1, we coded tweets about regret posted on social media to examine whether this content emphasized social relationships versus learning and preparation. Study 2 experimentally examined the hypothesized social closeness function for expression of regrets. Study 3 further examined how privately experienced and publicly expressed regrets differ on the social closeness and learning and preparatory functions. Studies 4 and 5 confirmed the specific social closeness function rather than global social benefits. This research suggests that the social expression of regret differs from private experience in both form and function.