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The influence of migration on the stochastic dynamics of subdivided populations is still an open issue in various evolutionary models. We develop here a self-consistent mean-field-like method in order to determine the effects of migration…

Statistical Mechanics · Physics 2014-04-10 Pierangelo Lombardo , Andrea Gambassi , Luca Dall'Asta

Ecologists have long investigated how demographic and movement parameters determine the spatial distribution and critical habitat size of a population. However, most models oversimplify movement behavior, neglecting how landscape…

Populations and Evolution · Quantitative Biology 2024-03-11 Vivian Dornelas , Pablo de Castro , Justin M. Calabrese , William F. Fagan , Ricardo Martinez-Garcia

The spatial arrangement of trees in a tropical forest reflects the interplay between aggregating processes, like dispersal limitation, and negative feedback that induces effective repulsion among individuals. Monitoring the variance-mean…

Populations and Evolution · Quantitative Biology 2014-11-11 Efrat Seri , Nadav M. Shnerb

We consider the model of spatially distributed population consisting of two species with "\textsl{predator\,--\,prey}" interaction; each of the species occupies two stations. Transfer of individuals between the stations (migration) is not…

Populations and Evolution · Quantitative Biology 2014-05-13 Michael G. Sadovsky , Maria Yu. Senashova

In this paper, we investigate a delayed reaction-diffusion-advection equation, which models the population dynamics in the advective heterogeneous environment. The existence of the nonconstant positive steady state and associated Hopf…

Dynamical Systems · Mathematics 2018-07-23 Shanshan Chen , Junjie Wei , Xue Zhang

Two mathematical models of macroevolution are studied. These models have population dynamics at the species level, and mutations and extinction of species are also included. The population dynamics are updated by difference equations with…

Populations and Evolution · Quantitative Biology 2014-04-16 Yohsuke Murase , Takashi Shimada , Nobuyasu Ito , Per Arne Rikvold

Fixed effects models are very flexible because they do not make assumptions on the distribution of effects and can also be used if the heterogeneity component is correlated with explanatory variables. A disadvantage is the large number of…

Methodology · Statistics 2015-12-17 Moritz Berger , Gerhard Tutz

We consider stochastic growth models for populations organized in colonies and subject to uniform catastrophes. To assess population viability, we analyze scenarios in which individuals adopt dispersion strategies after catastrophic events.…

Probability · Mathematics 2026-02-09 Joan Amaya , Valdivino V. Junior , Fábio P. Machado , Alejandro Roldán-Correa

Range expansion and range shifts are crucial population responses to climate change. Genetic consequences are not well understood but are clearly coupled to ecological dynamics that, in turn, are driven by shifting climate conditions. We…

Populations and Evolution · Quantitative Biology 2016-09-29 Jimmy Garnier , Mark Lewis

This paper explores the challenges and benefits of a trainable destruction process in diffusion samplers -- diffusion-based generative models trained to sample an unnormalised density without access to data samples. Contrary to the majority…

The presence of a phase transition in a finite system can be deduced, together with its order, from the shape of the distribution of the order parameter. This issue has been extensively studied in multifragmentation experiments, with…

Nuclear Theory · Physics 2008-11-26 F. Gulminelli

Food-web perturbations stemming from climate change, overexploitation, invasive species, and habitat degradation often cause an initial loss of species that results in a cascade of secondary extinctions, posing considerable challenges to…

Populations and Evolution · Quantitative Biology 2011-03-10 Sagar Sahasrabudhe , Adilson E. Motter

We consider general multi-species models of reaction diffusion processes and obtain a set of constraints on the rates which give rise to closed systems of equations for correlation functions. Our results are valid in any dimension and on…

Statistical Mechanics · Physics 2009-11-07 Vahid Karimipour

We propose a reaction--diffusion model of predator--prey interaction in which the predators occupy only a subset of the prey's territory, leaving a predator-free exclusion zone. Ecological examples include marine protected areas where it is…

Analysis of PDEs · Mathematics 2026-04-10 Henri Berestycki , William F. Fagan , Alex Safsten

The spatial scale of population synchrony gives the characteristic distance at which the population fluctuations are correlated. Therefore, it gives also the characteristic size of the regions of simultaneous population depletion, or even…

Populations and Evolution · Quantitative Biology 2020-12-22 Miguel Ángel Fernández-Grande , Francisco Javier Cao-Garcia

Environmental stochasticity is known to be a destabilizing factor, increasing abundance fluctuations and extinction rates of populations. However, the stability of a community may benefit from the differential response of species to…

Populations and Evolution · Quantitative Biology 2016-02-10 Matan Danino , Nadav M. Shnerb , Sandro Azaele , William E. Kunin , David A. Kessler

Patterns in reaction-diffusion systems often contain two spatial scales; a long scale determined by a typical wavelength or domain size, and a short scale pertaining to front structures separating different domains. Such patterns naturally…

patt-sol · Physics 2009-10-22 Aric Hagberg , Ehud Meron

In this work, we investigate an intriguing and prevalent phenomenon of diffusion models which we term as "consistent model reproducibility": given the same starting noise input and a deterministic sampler, different diffusion models often…

Machine Learning · Computer Science 2024-06-11 Huijie Zhang , Jinfan Zhou , Yifu Lu , Minzhe Guo , Peng Wang , Liyue Shen , Qing Qu

In this paper, a single population model with memory effect and the heterogeneity of the environment, equipped with the Neumann boundary, is considered. The global existence of a spatial nonhomogeneous steady state is proved by the method…

Dynamical Systems · Mathematics 2020-05-25 Yujia Wang , Chuncheng Wang , Dejun Fan

Methods for predicting the probability and timing of a species' extinction are typically based on a combination of theoretical models and empirical data, and focus on single species population dynamics. Of course, species also interact with…

Populations and Evolution · Quantitative Biology 2012-06-11 Gian Marco Palamara , Gustav W. Delius , Matthew J. Smith , Owen L. Petchey