Cooperation mitigates diversity loss in a spatially expanding microbial population

Gandhi, Saurabh R.; Korolev, Kirill S.; Gore, Jeff

doi:10.1073/pnas.1910075116

Cited by 27 publications

(37 citation statements)

References 40 publications

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“…in edge patches) (see e.g. Gandhi, Korolev, & Gore, 2019). The ratio of the actual expansion velocity v to the velocity v F expected for a pulled expansion with the same low-density behaviour has been proposed as a quantitative indicator discriminating pulled, “semi-pushed” and pushed expansions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Shifts from pulled to pushed range expansions caused by reduction of landscape connectivity

Dahirel

Bertin

Haond

et al. 2020

Preprint

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While species ranges have always moved, the ecological and evolutionary dynamics of range expansions have become especially relevant today, as human influence reshapes ecosystems worldwide. As a consequence, there have been many attempts to explain and predict evolutionary and demographic dynamics observed during range expansions. However, many of these predictions are based, explicitly or implicitly, on a subset of possible range expansion types, so-called “pulled” dynamics, in which the low-density front populations provide most of the “fuel” for the advance. Some expansions may exhibit very different dynamics, with high-density populations behind the front “pushing” the expansion forward. Studying the ecological and evolutionary consequences of pushed vs. pulled dynamics remains challenging, due to difficulties in reliably generating or identifying pushed and pulled waves in experimental or natural settings. Manipulations of the within-habitat quality to create Allee effects have successfully created pushed waves, but may only be applicable in some contexts. We here propose that manipulating, and specifically reducing the degree of structural connectivity among habitats may prove a more generalizable way to create pushed waves, through density-dependent dispersal. We demonstrate this using both individual-based simulations as well as replicated experimental range expansions (with the parasitoid wasp Trichogramma brassicae as model). Analysing expansion velocities and neutral genetic diversity, we showed that restricting connectivity did lead to pushed dynamics. Interestingly, our results suggest that reducing connectivity led to density-dependent spread (and thus pushed waves) through two different mechanisms in simulated and experimental expansions. In the current context of habitat loss and fragmentation, we need to better account for this relationship between connectedness and expansion regimes to be able to successfully predict the ecological and especially evolutionary consequences of range expansions.

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Section: Introductionmentioning

confidence: 99%

Shifts from pulled to pushed range expansions caused by reduction of landscape connectivity

Dahirel

Bertin

Haond

et al. 2020

Preprint

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“…In this section, we show that one specific design principle is embedded in the previous example and that it is a requirement for propagating populations by exploiting a cooperative loop. The key is a mutualistic cycle where different species help others to replicate [145,146], using a closed set of catalytic interactions known as the hypercycle.…”

Section: Ecological Hypercycles: Design Principles For Terraformationmentioning

confidence: 99%

Synthetic Biology for Terraformation Lessons from Mars, Earth, and the Microbiome

Conde-Pueyo

Vidiella

Sardanyés

et al. 2020

Life

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What is the potential for synthetic biology as a way of engineering, on a large scale, complex ecosystems? Can it be used to change endangered ecological communities and rescue them to prevent their collapse? What are the best strategies for such ecological engineering paths to succeed? Is it possible to create stable, diverse synthetic ecosystems capable of persisting in closed environments? Can synthetic communities be created to thrive on planets different from ours? These and other questions pervade major future developments within synthetic biology. The goal of engineering ecosystems is plagued with all kinds of technological, scientific and ethic problems. In this paper, we consider the requirements for terraformation, i.e., for changing a given environment to make it hospitable to some given class of life forms. Although the standard use of this term involved strategies for planetary terraformation, it has been recently suggested that this approach could be applied to a very different context: ecological communities within our own planet. As discussed here, this includes multiple scales, from the gut microbiome to the entire biosphere.

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“…Furthermore, when the spatial expansion of a species is considered, an Allee effect counteracts genetic drift of a species as it creates a pushed wave rather than a pulled wave corresponding to logistic growth 43,44 . This has been observed experimentally in a system of two cross-feeding species whereby the mutualistic strength was modulated by the inflow of nutrients 45 .…”

Section: /15mentioning

confidence: 99%

Mutualistic cross-feeding in microbial systems generates bistability via an Allee effect

Gonze

Gelens

Vet

2019

Preprint

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ABSTRACTMutualistic interactions are characterized by the positive influence that two species exert on each other. Such mutualism can lead to bistability. Depending on the initial population size species will either survive or go extinct. Various phenomenological models have been suggested to describe bistability in mutualistic systems. However, these models do not account for interaction mediators such as nutrients. In contrast, nutrient-explicit models do not provide an intuitive understanding of what causes bistability. Here, we reduce a theoretical nutrient-explicit model of two mutualistic cross-feeders in a chemostat, uncovering an explicit relation to a growth model with an Allee effect. We show that the dilution rate in the chemostat leads to bistability by turning a weak Allee effect into a strong Allee effect. This happens as long as there is more production than consumption of cross-fed nutrients. Thanks to the explicit relationship of the reduced model with the underlying experimental parameters, these results allow to predict the biological conditions that sustain or prevent the survival of mutualistic species.

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Cooperation mitigates diversity loss in a spatially expanding microbial population

Cited by 27 publications

References 40 publications

Shifts from pulled to pushed range expansions caused by reduction of landscape connectivity

Shifts from pulled to pushed range expansions caused by reduction of landscape connectivity

Synthetic Biology for Terraformation Lessons from Mars, Earth, and the Microbiome

Mutualistic cross-feeding in microbial systems generates bistability via an Allee effect

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