57,806 research outputs found
A synthetic Escherichia coli predator–prey ecosystem
We have constructed a synthetic ecosystem consisting of two Escherichia coli populations, which communicate bi-directionally through quorum sensing and regulate each other's gene expression and survival via engineered gene circuits. Our synthetic ecosystem resembles canonical predator–prey systems in terms of logic and dynamics. The predator cells kill the prey by inducing expression of a killer protein in the prey, while the prey rescue the predators by eliciting expression of an antidote protein in the predator. Extinction, coexistence and oscillatory dynamics of the predator and prey populations are possible depending on the operating conditions as experimentally validated by long-term culturing of the system in microchemostats. A simple mathematical model is developed to capture these system dynamics. Coherent interplay between experiments and mathematical analysis enables exploration of the dynamics of interacting populations in a predictable manner
Effects of demographic stochasticity on biological community assembly on evolutionary time scales
We study the effects of demographic stochasticity on the long-term dynamics
of biological coevolution models of community assembly. The noise is induced in
order to check the validity of deterministic population dynamics. While
mutualistic communities show little dependence on the stochastic population
fluctuations, predator-prey models show strong dependence on the stochasticity,
indicating the relevance of the finiteness of the populations. For a
predator-prey model, the noise causes drastic decreases in diversity and total
population size. The communities that emerge under influence of the noise
consist of species strongly coupled with each other and have stronger linear
stability around the fixed-point populations than the corresponding noiseless
model. The dynamics on evolutionary time scales for the predator-prey model are
also altered by the noise. Approximate fluctuations are observed with
noise, while fluctuations are found for the model without demographic
noise
Predator-prey cycles from resonant amplification of demographic stochasticity
In this paper we present the simplest individual level model of predator-prey
dynamics and show, via direct calculation, that it exhibits cycling behavior.
The deterministic analogue of our model, recovered when the number of
individuals is infinitely large, is the Volterra system (with density-dependent
prey reproduction) which is well-known to fail to predict cycles. This
difference in behavior can be traced to a resonant amplification of demographic
fluctuations which disappears only when the number of individuals is strictly
infinite. Our results indicate that additional biological mechanisms, such as
predator satiation, may not be necessary to explain observed predator-prey
cycles in real (finite) populations.Comment: 4 pages, 2 figure
Tearing Out the Income Tax by the (Grass)Roots
Landscapes are increasingly fragmented, and conservation programs have started to look at network approaches for maintaining populations at a larger scale. We present an agent-based model of predator–prey dynamics where the agents (i.e. the individuals of either the predator or prey population) are able to move between different patches in a landscaped network. We then analyze population level and coexistence probability given node-centrality measures that characterize specific patches. We show that both predator and prey species benefit from living in globally well-connected patches (i.e. with high closeness centrality). However, the maximum number of prey species is reached, on average, at lower closeness centrality levels than for predator species. Hence, prey species benefit from constraints imposed on species movement in fragmented landscapes since they can reproduce with a lesser risk of predation, and their need for using anti-predatory strategies decreases.authorCount :
Ecological system with fear induced group defence and prey refuge
In this study, we investigate the dynamics of a spatial and non spatial
prey-predator interaction model that includes the following: (i) fear effect
incorporated in prey birth rate; (ii) group defence of prey against predators;
and (iii) prey refuge. We provide comprehensive mathematical analysis of
extinction and persistence scenarios for both prey and predator species. To
better explore the dynamics of the system, a thorough investigation of
bifurcation analysis has been performed using fear level, prey birth rate, and
prey death rate caused by intra-prey competition as bifurcation parameter. All
potential occurrences of bi-stability dynamics have also been investigated for
some relevant sets of parametric values. Our numerical evaluations show that
high levels of fear can stabilize the prey-predator system by ruling out the
possibility of periodic solutions. Also, our model Hopf bifurcation is
subcritical in contrast to traditional prey-predator models, which ignore the
cost of fear and have supercritical Hopf bifurcations in general. In contrast
to the general trend, predator species go extinct at higher values of prey
birth rates. We have also found that, contrary to the typical tendency for prey
species to go extinct, both prey and predator populations may coexist in the
system as intra-prey competition level grows noticeably. The stability and
Turing instability of associated spatial model have also been investigated
analytically. We also perform the numerical simulation to observe the effect of
different parameters on the density distribution of species. Different types of
spatiotemporal patterns like spot, mixture of spots and stripes have been
observed via variation of time evolution, diffusion coefficient of predator
population, level of fear factor and prey refuge. The fear level parameter (k)
has a great impact on the spatial dynamics of model system
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