title: The cryptic role of biodiversity in the emergence of host-microbial mutualisms.
abstract: The persistence of mutualisms in host-microbial - or holobiont - systems is difficult to explain because microbial mutualists, who bear the costs of providing benefits to their host, are always prone to being competitively displaced by non-mutualist 'cheater' species. This disruptive effect of competition is expected to be particularly strong when the benefits provided by the mutualists entail costs such as reduced competitive ability. Using a metacommunity model, we show that competition between multiple cheaters within the host's microbiome, when combined with the spatial structure of host-microbial interactions, can have a constructive rather than a disruptive effect by allowing the emergence and maintenance of mutualistic microorganisms within the host. These results indicate that many of the microorganisms inhabiting a host's microbiome, including those that would otherwise be considered opportunistic or even potential pathogens, play a cryptic yet critical role in promoting the health and persistence of the holobiont across spatial scales.
authors.affiliation: Marine Science Center, Northeastern University, 430 Nahant Road, Nahant, MA, 01908, USA.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Pillai
authors.forename: Tarik C
authors.initials: TC
authors.lastname: Gouhier
authors.forename: Steven V
authors.initials: SV
authors.lastname: Vollmer
mesh_terms: D044822:Biodiversity; D017753:Ecosystem; D056084:Genetic Fitness; D064307:Microbiota; D008954:Models, Biological; D013559:Symbiosis
keywords: Competition; holobiont; host microbiome; indirect interactions; metacommunity theory; microbial diversity; mutualisms; patch-dynamic