72,583 research outputs found
Understanding evolutionary processes during past Quaternary climatic cycles: Can it be applied to the future?
Climate change affected ecological community make-up during the Quaternary which was probably both the cause of, and was caused by, evolutionary processes such as species evolution, adaptation and extinction of species and populations
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Robust permanence for ecological equations with internal and external feedbacks.
Species experience both internal feedbacks with endogenous factors such as trait evolution and external feedbacks with exogenous factors such as weather. These feedbacks can play an important role in determining whether populations persist or communities of species coexist. To provide a general mathematical framework for studying these effects, we develop a theorem for coexistence for ecological models accounting for internal and external feedbacks. Specifically, we use average Lyapunov functions and Morse decompositions to develop sufficient and necessary conditions for robust permanence, a form of coexistence robust to large perturbations of the population densities and small structural perturbations of the models. We illustrate how our results can be applied to verify permanence in non-autonomous models, structured population models, including those with frequency-dependent feedbacks, and models of eco-evolutionary dynamics. In these applications, we discuss how our results relate to previous results for models with particular types of feedbacks
Notes from the Greenhouse World: A Study in Coevolution, Planetary Sustainability, and Community Structure
This paper explores coevolution and governance of common goods using models
of coevolving biospheres, in which adapting populations must collectively
regulate their planet's climate or face extinction. The results support the
Gaia hypothesis against challenges based on the tragedy of the commons: model
creatures are often able to work together to maintain the common good (a
suitable climate) without being undermined by "free riders." A long-term
dynamics appears in which communities that cannot sustain Gaian cooperation
give way to communities that can. This result provides an argument why a Gaia
scenario should generally be observed, rather than a tragedy of the commons
scenario. Second, a close look at how communities fail reveals failures that do
not fit the tragedy of the commons framework and are better described in terms
of conflict between differently positioned parties, with power over different
aspects of the system. In the context of Norgaard's work, all these
observations can be read as narratives of coevolution relevant to social
communities as well as ecological ones, contrasting with pessimistic scenarios
about common governance and supporting respect for traditional arrangements and
restraint in intervention.Comment: To appear in a special issue of Ecological Economics in honor of
Richard B. Norgaar
Genome-driven evolutionary game theory helps understand the rise of metabolic interdependencies in microbial communities
Metabolite exchanges in microbial communities give rise to ecological interactions that govern ecosystem diversity and stability. It is unclear, however, how the rise of these interactions varies across metabolites and organisms. Here we address this question by integrating genome-scale models of metabolism with evolutionary game theory. Specifically, we use microbial fitness values estimated by metabolic models to infer evolutionarily stable interactions in multi-species microbial “games”. We first validate our approach using a well-characterized yeast cheater-cooperator system. We next perform over 80,000 in silico experiments to infer how metabolic interdependencies mediated by amino acid leakage in Escherichia coli vary across 189 amino acid pairs. While most pairs display shared patterns of inter-species interactions, multiple deviations are caused by pleiotropy and epistasis in metabolism. Furthermore, simulated invasion experiments reveal possible paths to obligate cross-feeding. Our study provides genomically driven insight into the rise of ecological interactions, with implications for microbiome research and synthetic ecology.We gratefully acknowledge funding from the Defense Advanced Research Projects Agency (Purchase Request No. HR0011515303, Contract No. HR0011-15-C-0091), the U.S. Department of Energy (Grants DE-SC0004962 and DE-SC0012627), the NIH (Grants 5R01DE024468 and R01GM121950), the national Science Foundation (Grants 1457695 and NSFOCE-BSF 1635070), MURI Grant W911NF-12-1-0390, the Human Frontiers Science Program (grant RGP0020/2016), and the Boston University Interdisciplinary Biomedical Research Office ARC grant on Systems Biology Approaches to Microbiome Research. We also thank Dr Kirill Korolev and members of the Segre Lab for their invaluable feedback on this work. (HR0011515303 - Defense Advanced Research Projects Agency; HR0011-15-C-0091 - Defense Advanced Research Projects Agency; DE-SC0004962 - U.S. Department of Energy; DE-SC0012627 - U.S. Department of Energy; 5R01DE024468 - NIH; R01GM121950 - NIH; 1457695 - national Science Foundation; NSFOCE-BSF 1635070 - national Science Foundation; W911NF-12-1-0390 - MURI; RGP0020/2016 - Human Frontiers Science Program; Boston University Interdisciplinary Biomedical Research Office ARC)Published versio
On the sympatric evolution and evolutionary stability of coexistence by relative nonlinearity of competition
If two species exhibit different nonlinear responses to a single shared
resource, and if each species modifies the resource dynamics such that this
favors its competitor, they may stably coexist. This coexistence mechanism,
known as relative nonlinearity of competition, is well understood
theoretically, but less is known about its evolutionary properties and its
prevalence in real communities. We address this challenge by using adaptive
dynamics theory and individual-based simulations to compare community
stabilization and evolutionary stability of species that coexist by relative
nonlinearity. In our analysis, evolution operates on the species'
density-compensation strategies, and we consider a trade-off between population
growth rates at high and low resource availability. We confirm previous
findings that, irrespective of the particular model of density dependence,
there are many combinations of overcompensating and undercompensating
density-compensation strategies that allow stable coexistence by relative
nonlinearity. However, our analysis also shows that most of these strategy
combinations are not evolutionarily stable and will be outcompeted by an
intermediate density-compensation strategy. Only very specific trade-offs lead
to evolutionarily stable coexistence by relative nonlinearity. As we find no
reason why these particular trade-offs should be common in nature, we conclude
that the sympatric evolution and evolutionary stability of relative
nonlinearity, while possible in principle, seems rather unlikely. We speculate
that this may, at least in part, explain why empirical demonstrations of this
coexistence mechanism are rare, noting, however, that the difficulty to detect
relative nonlinearity in the field [...]Comment: PLOS ONE, in pres
Evolutionary dynamics of group cooperation with asymmetrical environmental feedback
In recent years, there has been growing interest in studying evolutionary
games with environmental feedback. Previous studies exclusively focus on
two-player games. However, extension to multi-player game is needed to study
problems such as microbial cooperation and crowdsourcing collaborations. Here,
we study coevolutionary public goods games where strategies coevolve with the
multiplication factors of group cooperation. Asymmetry can arise in such
environmental feedback, where games organized by focal cooperators may have a
different efficiency than the ones by defectors. Our analysis shows that
co-evolutionary dynamics with asymmetrical environmental feedback can yield
oscillatory convergence to persistent cooperation, if the relative changing
speed of cooperators' multiplication factor is above a certain threshold. Our
work provides useful insights into sustaining group cooperation in a changing
world
Evolutionary comparison between viral lysis rate and latent period
Marine viruses shape the structure of the microbial community. They are,
thus, a key determinant of the most important biogeochemical cycles in the
planet. Therefore, a correct description of the ecological and evolutionary
behavior of these viruses is essential to make reliable predictions about their
role in marine ecosystems. The infection cycle, for example, is indistinctly
modeled in two very different ways. In one representation, the process is
described including explicitly a fixed delay between infection and offspring
release. In the other, the offspring are released at exponentially distributed
times according to a fixed release rate. By considering obvious quantitative
differences pointed out in the past, the latter description is widely used as a
simplification of the former. However, it is still unclear how the dichotomy
"delay versus rate description" affects long-term predictions of host-virus
interaction models. Here, we study the ecological and evolutionary implications
of using one or the other approaches, applied to marine microbes. To this end,
we use mathematical and eco-evolutionary computational analysis. We show that
the rate model exhibits improved competitive abilities from both ecological and
evolutionary perspectives in steady environments. However, rate-based
descriptions can fail to describe properly long-term microbe-virus
interactions. Moreover, additional information about trade-offs between
life-history traits is needed in order to choose the most reliable
representation for oceanic bacteriophage dynamics. This result affects deeply
most of the marine ecosystem models that include viruses, especially when used
to answer evolutionary questions.Comment: to appear in J. Theor. Bio
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