Biology subjects

Martignoni, M. M.

Publications and source records attributed to Martignoni, M. M..

3 recordsLinked to original sources

bioRxiv2024

Toward a unified theory of microbially mediated invasion

Biological invasions pose major ecological and economic threats, and extensive research has been dedicated to understanding and predicting their dynamics. Most studies focus on the biological invasion of single species, and only in recent years has it been realized that multi-species interactions that involve native and invasive host species and their microbial symbionts can play important roles in determining invasion outputs. A theoretical framework that treats these interactions and their impact is lacking. Here we offer such a framework and use it to explore possible dynamics that may emerge from the horizontal sharing of native and non-native microbial symbionts among native and non-native host individuals and species. Thus, for example, invasive plants might benefit from native mycorrhizal networks in the soil, or might be particularly successful if they carry with them parasites to which competing native hosts are susceptible. On the other hand, invasion might be hindered by native parasites that spread from native to invasive individuals. The mathematical framework that we lay out in this study provides a new mechanistic, cohesive, and intuition-enhancing tool for theoretically exploring the ways by which the subtleties of the relationships between hosts and microbes may affect invasion dynamics. We identify multiple pathways through which microbes can facilitate (or prevent) host invasion, microbial invasion, and the invasion of both hosts and their co-introduced microbes. We disentangle invasion outcomes and highlight modalities of ecological dynamics that have so far not been considered in invasion biology. Our work sets the foundations for invasion theory that includes a community-level view of invasive and native hosts as well as their microbial symbionts.

ecology↗

bioRxiv2023

Microbiome transfer from native to invasive species may increase invasion risk and shorten invasion lag

In a fast-changing world, understanding how organisms adapt to their environment is a pressing necessity. Research has focused on genetic adaptation, while our understanding of non-genetic modes is still in its infancy. Particularly, the host-associated microbiome may strongly influence an organisms ability to cope with its environment. The presence of certain microbes in the gut, for example, can facilitate the utilization of dietary resources, provide protection from pathogens, and increase resilience to diverse abiotic conditions. However, the role that the microbiome may play in species adaptation to novel challenges is largely unexplored, experimentally as well as theoretically. Here, we study the possibility of such adaptation in invasive species. We present and explore a new hypothesis: Invasive species may rapidly adapt to local conditions by adopting beneficial microbes of similar co-occurring native species. Ironically, due to competition, these native species are also those most likely to suffer from the invaders spread. We formulate a mathematical framework to investigate how the transfer of beneficial microbes between a native and an introduced species can alter their competitive dynamics. We suggest that, non-intuitively, the presence of a related native species may facilitate the success of an invasive species establishment. This occurs when the invaders fitness is strongly influenced by adaptation to local conditions that is provided by microbes acquired from the natives microbiomes. Further, we show that in such cases a delayed acquisition of native microbes may explain the occurrence of an invasion lag, and we discuss biological systems that could lend themselves for the testing of our hypotheses. Overall, our results contribute to broadening the conceptualization of rapid adaptation via microbiome transfer and offer possible insights for designing early intervention strategies for invasive species management during their lag phase.

ecology↗

bioRxiv2023

Mutualism at the leading edge: Insights into the eco-evolutionary dynamics of host-symbiont communities during range expansion

The evolution of mutualism between host and symbiont communities plays an essential role in maintaining ecosystem function and should therefore have a pro-found effect on their range expansion dynamics. In particular, the presence of mutualistic symbionts at the leading edge of a host-symbiont community should enhance its propagation in space. We develop a theoretical framework that captures the eco-evolutionary dynamics of host-symbiont communities, to investigate how the evolution of resource exchange may shape community structure during range expansion. We consider a community with symbionts that are mutualistic or parasitic to various degrees, where parasitic symbionts receive the same amount of resource from the host as mutualistic symbionts, but at lower cost. The selective advantage of parasitic symbionts over mutualistic ones is strengthened with resource availability (i.e. with host density), promoting mutualism at the range edges, where host density is low, and parasitism in the population core, where host density is higher. This spatial selection also influences the speed of spread. We find that the host growth rate (which depends on the average benefit provided by the symbionts) is maximal at the range edges, where symbionts are more mutualistic, and that host-symbiont communities with high symbiont density at their core (e.g. resulting from more mutualistic hosts) spread faster into new territories. These results indicate that the expansion of host-symbiont communities is pulled by the hosts but pushed by the symbionts, in a unique push-pull dynamic where both the host and symbionts are active and tightly-linked players.

ecology↗