Dataset Information

Leibovich2022 - multispecies eco-competition describes by Master equation

ABSTRACT: We are using a minimal model of interacting multispecies ecological communities that incorporates competition, immigration, and demographic noise. Importantly, the dynamics of the system are described by a birth-death process with interactions, whereby the abundance (the number of individuals) of any species is discrete, where the number of individuals from a given species increases or decreases by one following given birth or death rates (respectively). We find rich behavior with many unexpected regimes. We apply the insights and implications of our model to the range of behaviors observed experimentally in different ecosystems—from bacteria to the immune system. This repository stores the code used to study the population dynamics described in the PNAS publication: Phenomenology and Dynamics of Competitive Ecosystems Beyond the Niche-Neutral Regimes by Nava Leibovich, Jeremy Rothschild, Sidhartha Goyal and Anton Zilman. See more at (https://github.com/jbRothschild/project-abundance/tree/PNAS)

SUBMITTER: Nava leibovich

PROVIDER: MODEL2212080001 | BioModels | 2023-03-17

REPOSITORIES: BioModels

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Publications

Phenomenology and dynamics of competitive ecosystems beyond the niche-neutral regimes.

Leibovich Nava N Rothschild Jeremy J Goyal Sidhartha S Zilman Anton A

Proceedings of the National Academy of Sciences of the United States of America 20221017 43

Structure, composition, and stability of ecological populations are shaped by the inter- and intraspecies interactions within their communities. It remains to be fully understood how the interplay of these interactions with other factors, such as immigration, controls the structure, the diversity, and the long-term stability of ecological systems in the presence of noise and fluctuations. We address this problem using a minimal model of interacting multispecies ecological communities that incorp ...[more]

PMID: 36251996

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Project description:An epidemic disease caused by a new coronavirus has spread in Northern Italy with a strong contagion rate. We implement an SEIR model to compute the infected population and the number of casualties of this epidemic. The example may ideally regard the situation in the Italian Region of Lombardy, where the epidemic started on February 24, but by no means attempts to perform a rigorous case study in view of the lack of suitable data and the uncertainty of the different parameters, namely, the variation of the degree of home isolation and social distancing as a function of time, the initial number of exposed individuals and infected people, the incubation and infectious periods, and the fatality rate. First, we perform an analysis of the results of the model by varying the parameters and initial conditions (in order for the epidemic to start, there should be at least one exposed or one infectious human). Then, we consider the Lombardy case and calibrate the model with the number of dead individuals to date (May 5, 2020) and constrain the parameters on the basis of values reported in the literature. The peak occurs at day 37 (March 31) approximately, with a reproduction ratio R0 of 3 initially, 1.36 at day 22, and 0.8 after day 35, indicating different degrees of lockdown. The predicted death toll is approximately 15,600 casualties, with 2.7 million infected individuals at the end of the epidemic. The incubation period providing a better fit to the dead individuals is 4.25 days, and the infectious period is 4 days, with a fatality rate of 0.00144/day [values based on the reported (official) number of casualties]. The infection fatality rate (IFR) is 0.57%, and it is 2.37% if twice the reported number of casualties is assumed. However, these rates depend on the initial number of exposed individuals. If approximately nine times more individuals are exposed, there are three times more infected people at the end of the epidemic and IFR = 0.47%. If we relax these constraints and use a wider range of lower and upper bounds for the incubation and infectious periods, we observe that a higher incubation period (13 vs. 4.25 days) gives the same IFR (0.6 vs. 0.57%), but nine times more exposed individuals in the first case. Other choices of the set of parameters also provide a good fit to the data, but some of the results may not be realistic. Therefore, an accurate determination of the fatality rate and characteristics of the epidemic is subject to knowledge of the precise bounds of the parameters. Besides the specific example, the analysis proposed in this work shows how isolation measures, social distancing, and knowledge of the diffusion conditions help us to understand the dynamics of the epidemic. Hence, it is important to quantify the process to verify the effectiveness of the lockdown.

Project description:In many animals living in groups the reproductivestatus of individuals is determined by their social status. In specieswith social hierarchies, the death of dominant individuals typicallyupheaves the social hierarchy and provides an opportunity for subordinateindividuals to improve their social status. Such a phenomenon occursin the monogyne form of the fire ant\emph{, Solenopsis invicta, }wherecolonies typically contain a single wingless reproductive queen, thousandsof workers and hundreds of winged non-reproductive virgin queens.Upon the death of the mother queen, many virgin queens shed theirwings and initiate reproductive development instead of departing ona mating flight. Workers progressively execute almost all of themover the following weeks. The workers base their collective decisionon pheromonal cues associated with the onset of reproductive developmentof the virgin queens which occurs after orphaning. To examine the factors that determine which virgin queens are executed and which survive, we set up artificial competitions between queens from different colonies. Using microarrays, we found that queens from winning colonies showed higher mitochondrial as well as organ development activities 24 hours after orphaning than did queens from colonies that lost the competitions. Furthermore, queens from colonies where queens shed their wings faster after orphaning were more likely to survive competitions. Finally, higher wing shedding speed is linked to higher mitochondrial activity. Eight competitions were initially conducted between queens form pairs of colonies. Six competitions clearly identified one winning colony and one losing colony. We thus have microarray data for six competitions (ie biological replicates), with one winning and one losing colony within each competition. Thus 12 colonies total. For each colony, RNA extracted from five queens was pooled, and hybridized against an unrelated common reference RNA that had been made from a pool of many S. invicta individuals of all castes and developmental stages. Lab work was conducted in blocks (by competition) with randomized order within competition to avoid introducing bias. No technical replication was performed.

Dataset Information

Leibovich2022 - multispecies eco-competition describes by Master equation

Publications

Phenomenology and dynamics of competitive ecosystems beyond the niche-neutral regimes.

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