The outcome of competition among species is influenced by the spatial distribution of species and effects such as demographic stochasticity, immigration fluxes, and the existence of preferred habitats. We introduce an individual-based model describing the competition of two species and incorporating all the above ingredients. We find that the presence of habitat preference --- generating spatial niches --- strongly stabilizes the coexistence of the two species. Eliminating habitat preference --- neutral dynamics --- the model generates patterns, such as distribution of population sizes, practically identical to those obtained in the presence of habitat preference, provided an higher immigration rate is considered. Notwithstanding the similarity in the population distribution, we show that invasibility properties depend on habitat preference in a non-trivial way. In particular, the neutral model results results more invasible or less invasible depending on whether the comparison is made at equal immigration rate or at equal distribution of population size, respectively. We discuss the relevance of these results for the interpretation of invasibility experiments and the species occupancy of preferred habitats.
Cyclic dominance between species may yield spiral waves that are known to provide a mechanism enabling persistent species coexistence. This observation holds true even in presence of spatial heterogeneity in the form of quenched disorder. In this work we study the effects on spatio-temporal patterns and species coexistence of structured spatial heterogeneity in the form of habitats that locally provide one of the species with an advantage. Performing extensive numerical simulations of systems with three and six species we show that these structured habitats destabilize spiral waves. Analyzing …
Metacommunity persistence on spatially heterogeneous landscapes
Université de Toulouse, INSA Toulouse（图卢兹大学，法国国立应用科学学院）；CNRS, Institut de Mathématiques de Toulouse（法国国家科学研究中心，图卢兹数学研究所）；École polytechnique（巴黎综合理工学院）；Sorbonne Université（索邦大学）；UPC（巴黎高科国立高等矿业电信学院联盟）；UPEC（巴黎第十一大学）；CNRS（法国国家科学研究中心）；IRD（法国国家科研中心）；INRA（法国国家农业食品与环境研究院）；Institute of Ecology and Environmental Sciences, IEES（生态与环境科学研究所）
Disentangling the interactive effects of anthropogenic disturbances on biodiversity
RIKEN Wako Campus, Division of Fundamental Mathematical Science（理化学研究所和光园区基础数学科学部）；Tokyo Metropolitan University, Department of Biological Sciences（东京都立大学生物科学系）
Habitat heterogeneity and dispersal network structure as drivers of metacommunity dynamics
University of Padova（帕多瓦大学）；National Biodiversity Future Center（国家未来生物多样性中心）；INFN, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；International Centre for Theoretical Physics（理论物理国际中心）；University of Lausanne（洛桑大学）；Department of Civil, Environmental and Architectural Engineering, University of Padova（帕多瓦大学土木、环境与建筑工程系）
To understand the mechanisms underlying species coexistence, ecologists often study invasion growth rates of theoretical and data-driven models. These growth rates correspond to average per-capita growth rates of one species with respect to an ergodic measure supporting other species. In the ecological literature, coexistence often is equated with the invasion growth rates being positive. Intuitively, positive invasion growth rates ensure that species recover from being rare. To provide a mathematically rigorous framework for this approach, we prove theorems that answer two questions: (i) When…
Over the past century, nonlinear difference and differential equations have been used to understand conditions for species coexistence. However, these models fail to account for random fluctuations due to demographic and environmental stochasticity which are experienced by all populations. I review some recent mathematical results about persistence and coexistence for models accounting for each of these forms of stochasticity. Demographic stochasticity stems from populations and communities consisting of a finite number of interacting individuals, and often are represented by Markovian models …
D. discoideum has been recently suggested as an example of bet-hedging. Upon starvation a population of unicellular amoebae splits between aggregators, which form a fruiting body made of a stalk and resistant spores, and non-aggregators. Spores are favored by long starvation periods, but vegetative cells can exploit resources in fast-recovering environments. This partition can be understood as a bet-hedging strategy that evolves in response to stochastic starvation times. A genotype is defined by a different balance between each type of cells. In this framework, if the ecological conditions ar…
In ecology it is widely recognised that many landscapes comprise a network of discrete patches of habitat. The species that inhabit the patches interact with each other through a foodweb, the network of feeding interactions. The meta-foodweb model proposed by Pillai et al. combines the feeding relationships at each patch with the dispersal of species between patches, such that the whole system is represented by a network of networks. Previous work on meta-foodwebs has focussed on landscape networks that do not have an explicit spatial embedding, but in real landscapes the patches are usually d…
Resource are often not uniformly distributed within a population. Spatial variations of concentration of a resource, change the fitness of competing strategies locally. The notion of fitness varying with respect to both genotype and environment is important in modeling cancer initiation, microbial evolution and evolution of drug resistance. Environmental interactions can be asymmetric, that is, they affect the fitness of one type more than the other. The question is how local environmental variations in network population structures change the selection dynamics in a finite population setting.…
