Coexistence of competing metabolic pathways in well-mixed populations

Abstract

Understanding why strains with different metabolic pathways that compete for a single limiting resource coexist is a challenging issue within a theoretical perspective. Previous investigations rely on mechanisms such as group or spatial structuring to achieve a stable coexistence between competing metabolic strategies. Nevertheless, coexistence has been experimentally reported even in situations where it cannot be attributed to spatial effects [Heredity 100, 471 (2008)HDTYAT0018-067X10.1038/sj.hdy.6801073]. According to that study a toxin expelled by one of the strains can be responsible for the stable maintenance of the two strain types. We propose a resource-based model in which an efficient strain with a slow metabolic rate competes with a second strain type which presents a fast but inefficient metabolism. Moreover, the model assumes that the inefficient strain produces a toxin as a by-product. This toxin affects the growth rate of both strains with different strength. Through an extensive exploration of the parameter space we determine the situations at which the coexistence of the two strains is possible. Interestingly, we observe that the resource influx rate plays a key role in the maintenance of the two strain types. In a scenario of resource scarcity the inefficient is favored, though as the resource influx rate is augmented the coexistence becomes possible and its domain is enlarged.

The cancer Warburg effect may be a testable example of the minimum entropy production rate principle

“…However, no satisfactory explanation is yet provided for the function of the Warburg effect [3]. Kinetic analyses show that cells with higher rates of substrate consumption favorably compete for shared limited resources [4][5][6], thus providing a mathematic-supported description for the rapid growth of the cancer mass that consumes glucose at a high rate to the detriment of noncancerous tissues.…”

The influence of the composition of tradeoffs on the generation of differentiated cells

“…The evolution of tradeos is an issue of intense debate in the current literature as tradeos have played a central role in shaping life histories and ecological/evolutionary dynamics in nature [1]. It has been addressed in the context of distinct frameworks such as evolutionary game theory [2][3][4][5], resource-based modeling [6][7][8][9], developmental plasticity [10,11], and so on. It is believed that much of the observed biodiversity on Earth stems from the existence of tradeos [12].…”

A resource-based game theoretical approach for the paradox of the plankton

“…A high level of phytoplankton diversity can be achieved at low nutrient environments both in experiments (Leibold, 1999) and theoretical studies (Tubay et al, 2013). Other possible mechanisms of the high species richness in nature include emergent neutrality where species have similar fitness within clumps (Segura et al, 2011), simultaneous multiple resource limitation which leads to complex dynamics including non-equilibrium states as oscillations and chaos (Dutta, Kooi & Feudel, 2014) and production of toxin by some species (Chakraborty, Ramesh & Dutta, 2016; Fernández et al, 2016). …”