Biology subjects

Ona, L.

Publications and source records attributed to Ona, L..

4 recordsLinked to original sources

bioRxiv2020

Obligate mutualistic cooperation limits evolvability

Cooperative mutualisms are widespread in nature and play fundamental roles in many ecosystems. Due to the often obligate nature of these interactions, the Darwinian fitness of the participating individuals is not only determined by the information encoded in their own genomes, but also the traits and capabilities of their corresponding interaction partners. Thus, a major outstanding question is how obligate cooperative mutualisms affect the ability of organisms to respond to environmental change with evolutionary adaptation. Here we address this issue using a mutualistic cooperation between two auxotrophic genotypes of Escherichia coli that reciprocally exchange costly amino acids. Amino acid-supplemented monocultures and unsupplemented cocultures were exposed to stepwise increasing concentrations of different antibiotics. This selection experiment revealed that metabolically interdependent bacteria were generally less able to adapt to environmental stress than autonomously growing strains. Moreover, obligate cooperative mutualists frequently regained metabolic autonomy, thus resulting in a collapse of the mutualistic interaction. Together, our results identify a limited evolvability as a significant evolutionary cost that individuals have to pay when entering into an obligate mutualistic cooperation.

evolutionary biology↗

bioRxiv2020

Obligate cross-feeding expands the metabolic niche of bacteria

Bacteria frequently engage in obligate metabolic mutualisms with other microorganisms. However, it remains generally unclear how the resulting metabolic dependencies affect the ecological niche space accessible to the whole consortium relative to the niche space available to its constituent individuals. Here we address this issue by systematically cultivating metabolically dependent strains of different bacterial species either individually or as pairwise coculture in a wide range of carbon sources. Our results show that obligate cross-feeding is significantly more likely to expand the metabolic niche space of interacting bacterial populations than to contract it. Moreover, niche expansion occurred predominantly between two specialist taxa and correlated positively with the phylogenetic distance between interaction partners. Together, our results demonstrate that obligate cross-feeding can significantly expand the ecological niche space of interacting bacterial genotypes, thus explaining the widespread occurrence of this type of ecological interaction in natural microbiomes.

evolutionary biology↗

bioRxiv2020

Metabolic dissimilarity determines the establishment of cross-feeding interactions in bacteria

The exchange of metabolites among different bacterial genotypes profoundly impacts the structure and function of microbial communities. However, the factors governing the establishment of these cross-feeding interactions remain poorly understood. While shared physiological features may facilitate interactions among more closely related individuals, a lower relatedness should reduce competition and thus increase the potential for synergistic interactions. Here we investigate how the relationship between a metabolite donor and recipient affects the propensity of strains to engage in unidirectional cross-feeding interactions. For this, we performed pairwise cocultivation experiments between four auxotrophic recipients and 25 species of potential amino acid donors. Auxotrophic recipients grew in the vast majority of pairs tested (78%), suggesting metabolic cross-feeding interactions are readily established. Strikingly, both the phylogenetic distance between donor and recipient and the dissimilarity of their metabolic networks were positively associated with the growth of auxotrophic recipients. Analysing the co-growth of species from a gut microbial community in-silico also revealed that recipient genotypes benefitted more from interacting with metabolically dissimilar partners, thus corroborating the empirical results. Together, our work identifies the metabolic dissimilarity between bacterial genotypes as key factor determining the establishment of metabolic cross-feeding interactions in microbial communities. HighlightsO_LIThe exchange of essential metabolites is common in microbial communities C_LIO_LIMetabolic cross-feeding interactions readily establish between auxotrophic and prototrophic bacterial strains C_LIO_LIBoth the phylogenetic and the metabolic dissimilarity between donors and recipients determines the successful establishment of metabolic cross-feeding interactions C_LI

ecology↗

bioRxiv2020

Cooperation increases robustness to ecological disturbance in microbial cross-feeding networks

Microorganisms mainly exist within complex networks of ecological interactions. Given that the growth and survival of community members frequently depend on an obligate exchange of essential metabolites, it is generally unclear how such communities can persist despite the destabilizing force of ecological disturbance. Here we address this issue using a population dynamics model. In contrast to previous work that suggests the potential for obligate interaction networks to evolve is limited, we find the opposite pattern: natural selection in the form of ecological disturbance favors both specific network topologies and cooperative cross-feeding among community members. These results establish environmental selection as a key driver shaping the architecture of microbial interaction networks.

evolutionary biology↗