Rethinking “mutualism” in diverse host‐symbiont communities

  title={Rethinking “mutualism” in diverse host‐symbiont communities},
  author={Alexandra A. Mushegian and Dieter Ebert},
While examples of bacteria benefiting eukaryotes are increasingly documented, studies examining effects of eukaryote hosts on microbial fitness are rare. Beneficial bacteria are often called “mutualistic” even if mutual reciprocity of benefits has not been demonstrated and despite the plausibility of other explanations for these microbes' beneficial effects on host fitness. Furthermore, beneficial bacteria often occur in diverse communities, making mutualism both empirically and conceptually… 

Cooperation and Conflict Within the Microbiota and Their Effects On Animal Hosts

It is inferred that the explicit consideration of social dynamics within symbiont communities of varying complexity is crucial to advance the understanding of how microbes shape animal function and evolution.

Fitness effects of host-bacterial interactions – the microbial perspective

It is found that rare microbiome members are essential for achieving the observed community composition, which ultimately sets the maximum carrying capacity.

Can They Make It on Their Own? Hosts, Microbes, and the Holobiont Niche

A model that describes how hosts and their microbial symbionts alter each other's niche and thereby fitness is presented, and a mathematical model is provided to test whether interactions between hosts and microbes are necessary to describe the niche of either partner.

Mode and Fidelity of Bacterial Symbiont Transmission and Its Impact on Symbiont Genome Evolution

This work supports the existence of mixed transmission modes in symbiotic associations and indicates they have distinct consequences for symbiont evolution.

Co-niche construction between hosts and symbionts: ideas and evidence

Standard evolutionary theories are adequate to explore selection pressures on their composite or individual traits, and composite organisms that are physically nested within each other are found.

Microbial evolution and transitions along the parasite–mutualist continuum

The mechanisms underpinning these evolutionary shifts, as well as the ecological drivers and why some host–microorganism interactions may be stuck at the end of the continuum are discussed.

Extended genomes: symbiosis and evolution

It is argued that microbial heredity—the direct passage of microbes from parent to offspring—is a key factor determining the degree to which the holobiont can usefully be considered a level of selection.

Association with a novel protective microbe facilitates host adaptation to a stressful environment

The findings demonstrate that the context under which hosts evolve is important for the evolution of beneficial associations and that protective microbes can facilitate host adaptation to stress and in turn, such host adaptation can benefit the microbe.



The symbiont side of symbiosis: do microbes really benefit?

It is indicated that reduced competition and predation are not universal benefits for symbionts, and experiments to test symbiont fitness using current experimental systems of symbiosis and detail considerations for other systems are recommended.

Horizontally Transmitted Symbionts and Host Colonization of Ecological Niches

An out-of-body experience: the extracellular dimension for the transmission of mutualistic bacteria in insects

It is emphasized that the evolutionary implications of symbiont transmission routes (intracellular versus extracellular) do not necessarily correspond to those of the transmission mode (vertical versus horizontal), a distinction of vital significance when addressing the genomic and physiological consequences for both host and symbia.

Mutualisms and aquatic community structure: The enemy of my enemy is my friend

The dynamic, and context dependent, nature of mutualisms can transform consumers, competitors, and parasites into mutualists, even while they consume, compete with, or parasitize their partner species.

The Epidemiology and Evolution of Symbionts with Mixed-Mode Transmission

This review explores the conceptual issues surrounding the dynamics of mixedmode symbionts by reviewing literature from the entire range of host and symbiont taxa and comparing MMT with the authors' expectations for single-mode strategies.

Episymbiotic microbes as food and defence for marine isopods: unique symbioses in a hostile environment

Molecular phylogenetic analyses demonstrated that the symbiotic microbial communities are diverse and probably dominated in terms of population size by bacteria and small unicellular Synechococcus-type cyanobacteria.

An ecological and evolutionary perspective on human–microbe mutualism and disease

The shared evolutionary fate of humans and their symbiotic bacteria has selected for mutualistic interactions that are essential for human health, and ecological or genetic changes that uncouple this shared fate can result in disease.

Multiple mutualist effects: conflict and synergy in multispecies mutualisms.

A synthesis of two approaches using graphical models to define the multiple mutualist effects (MMEs) that occur when a focal species has multiple partner mutualists illustrates how the consideration of MMEs can improve the ability to predict the outcomes of losses or gains of mutualisms from ecosystems.

Niche engineering demonstrates a latent capacity for fungal-algal mutualism

It is shown that an obligate mutualism between the yeast Saccharomyces cerevisiae and the alga Chlamydomonas reinhardtii—two model eukaryotes with very different life histories—can arise spontaneously in an environment requiring reciprocal carbon and nitrogen exchange.

Insects Recycle Endosymbionts when the Benefit Is Over