Metabolic trade-offs and the maintenance of the fittest and the attest.

Department of Mathematics, Imperial College London, Huxley Building, 180 Queen's Gate, London SW7 2A7, UK.
Nature (Impact Factor: 41.46). 03/2011; 472(7343):342-6. DOI: 10.1038/nature09905
Source: PubMed


How is diversity maintained? Environmental heterogeneity is considered to be important, yet diversity in seemingly homogeneous environments is nonetheless observed. This, it is assumed, must either be owing to weak selection, mutational input or a fitness advantage to genotypes when rare. Here we demonstrate the possibility of a new general mechanism of stable diversity maintenance, one that stems from metabolic and physiological trade-offs. The model requires that such trade-offs translate into a fitness landscape in which the most fit has unfit near-mutational neighbours, and a lower fitness peak also exists that is more mutationally robust. The 'survival of the fittest' applies at low mutation rates, giving way to 'survival of the flattest' at high mutation rates. However, as a consequence of quasispecies-level negative frequency-dependent selection and differences in mutational robustness we observe a transition zone in which both fittest and flattest coexist. Although diversity maintenance is possible for simple organisms in simple environments, the more trade-offs there are, the wider the maintenance zone becomes. The principle may be applied to lineages within a species or species within a community, potentially explaining why competitive exclusion need not be observed in homogeneous environments. This principle predicts the enigmatic richness of metabolic strategies in clonal bacteria and questions the safety of lethal mutagenesis as an antimicrobial treatment.

1 Follower
12 Reads
  • Source
    • "Recent studies have suggested some potential mechanisms , such as the flattening of the " fitness landscape " by the combined effects of multiple, convex trade-offs (Beardmore et al., 2011). A typical linear trade-off defines a zero-sum game, where the benefits of allocating more of a given resource to one use are counter-balanced in direct proportion by the opportunity cost of decreased benefits from alternative uses. "
  • Source
    • "We use observational and theoretical insights to guide our incorporation of microbial physiological processes into predictions of SOM stabilization. Physiological differences across species have been linked to life-history strategies optimized for different resource environments (Resat et al., 2012; Beardmore et al., 2011; Russell and Cook, 1995). For instance , in resource-rich environments, fast-growing r strategists (copiotrophs) are typically characterized by a lower MGE but higher growth rates, relative to slower-growing K strategists (oligiotrophs; Fierer et al., 2012; Ramirez et al., 2012; Fierer et al., 2007; Klappenbach et al., 2000; Pianka, 1970). "
    [Show abstract] [Hide abstract]
    ABSTRACT: A growing body of literature documents the pressing need to develop soil biogeochemistry models that more accurately reflect contemporary understanding of soil processes and better capture soil carbon (C) responses to environmental perturbations. Models that explicitly represent microbial activity offer inroads to improve representations of soil biogeochemical processes, but have yet to consider relationships between litter quality, functional differences in microbial physiology, and the physical protection of microbial byproducts in forming stable soil organic matter (SOM). To address these limitations, we introduce the MIcrobialMIneral Carbon Stabilization (MIMICS) model, and evaluate it by comparing site-level soil C projections with observations from a long-term litter decomposition study and soil warming experiment. In MIMICS, the turnover of litter and SOM pools is governed by temperature-sensitive MichaelisMenten kinetics and the activity of two physiologically distinct microbial functional types. The production of microbial residues through microbial turnover provides inputs to SOM pools that are considered physically or chemically protected. Soil clay content determines the physical protection of SOM in different soil environments. MIMICS adequately simulates the mean rate of leaf litter decomposition observed at temperate and boreal forest sites, and captures observed effects of litter quality on decomposition rates. Moreover, MIMICS better captures the response of SOM pools to experimental warming, with rapid SOM losses but declining temperature sensitivity to long-term warming, compared with a more conventional model structure. MIMICS incorporates current microbial theory to explore the mechanisms by which litter C is converted to stable SOM, and to improve predictions of soil C responses to environmental change.
    Biogeosciences 07/2014; 11(14-14):3899-3917. DOI:10.5194/bg-11-3899-2014 · 3.98 Impact Factor
  • Source
    • "Similarly, seven different genotypes of tick-transmitted bacterium Borrelia afzelii were reported in the bank vole Myodes glareolus which favours greatly antigenic diversity (Andersson and Scherman, 2013) and this presumably is a key influence on the evolution of virulence (Alizon et al., 2013). Since the principle may be applied to lineages within a species or species within a community (Beardmore et al., 2011) it seems appropriate to consider BFDV as a multiple-variant infections within the Order Psittaciformes, given its high degree of antigenic conservation and apparent equal host susceptibility. The Psittaciformes most likely originated in Australasia during the Cretaceous period when New Zealand and Australasia were still part of the Gondwanan supercontinent and the richest diversity of extant genera is endemic to the region (Wright et al., 2008). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Phylogenetic analyses of the highly genetically diverse but antigenically conserved, single-stranded circular, DNA genome of the avian circovirus, beak and feather disease virus (BFDV) from cockatoo species throughout Australia demonstrated a high mutation rate for BFDV (orders of magnitude fall in the range of 10–4 substitutions/site/year) along with strong support for recombination indicating active cross-species transmission in various subpopulations. Multiple variants of BFDV were demonstrated with at least 30 genotypic variants identified within nine individual birds, with one containing up to 7 variants. Single genetic variants were detected in feathers from 2 birds but splenic tissue provided further variants. The rich BFDV genetic diversity points to Australasia as the most likely geographical origin of this virus and supports flexible host switching. We propose this as evidence of Order-wide host generalism in the Psittaciformes characterised by high mutability that is buffered by frequent recombination and slow replication strategy
    Virology 07/2014; s 460–461(1):72–82. DOI:10.1016/j.virol.2014.04.021 · 3.32 Impact Factor
Show more

Preview (2 Sources)

12 Reads