An Improved Lotka–Volterra Model Using Quantum Game Theory

Human decision-making does not conform to the independent decision-making hypothesis from classical decision-making theory. Thus, we introduce quantum decision-making theory into the Lotka–Volterra model (L–V model), to investigate player population dynamics while incorporating the initial strategy, game payoffs and interactive strategies in an open social system. Simulation results show that: (1) initial strategy, entanglement intensity of strategy interaction, and payoffs impact population dynamics; (2) In cooperative coexistence, game players mutually exceed the initial environmental capacity in an open system, but not in competitive coexistence; (3) In competitive coexistence, an initial strategy containing an entanglement intensity of strategies plays a vital role in game outcomes. Furthermore, our proposed model more realistically delineates the characteristics of population dynamics in competitive or cooperative coexistence scenarios.

Doomed to Repetition? Havana, Washington, Miami, and Moscow, from the Cold War to Today

This paper offers a broad historical overview of US economic sanctions against Cuba, starting with the imposition of the partial trade embargo on 19 October 1960, taking the story up to the present day. Additionally, it develops a comprehensive survey of the numerous scholarly and policy debates which closely follow the changes in United States’ post-Cold War attitudes and actions towards its southern neighbor and which demonstrate the thinking behind centers of power in Washington and Miami related to US’ Cuba policies. The paper also glances over the latest developments under Cuba’s new President Miguel Díaz-Canel and the notable return to the harsh Cold War rhetoric, which transcends the boundaries of the localized Washington-Miami-Havana axis of the past thirty years. Referring to historic patterns, the paper concludes that the conjecture between the recent complication in the US-Cuba relations and Moscow’s ambition to reinstate its erstwhile position as an unavoidable international factor would afford Havana with the opportunity to reclaim once again the dubious honor of becoming one of the focal points in the renewed competitive coexistence between the United States and Russia.

Polyrhythmic foraging and competitive coexistence

The current ecological understanding still does not fully explain how biodiversity is maintained. One strategy to address this issue is to contrast theoretical prediction with real competitive communities where diverse species share limited resources. I present, in this study, a new competitive coexistence theory-diversity of biological rhythms. I show that diversity in activity cycles plays a key role in coexistence of competing species, using a two predator-one prey system with diel, monthly, and annual cycles for predator foraging. Competitive exclusion always occurs without activity cycles. Activity cycles do, however, allow for coexistence. Furthermore, each activity cycle plays a different role in coexistence, and coupling of activity cycles can synergistically broaden the coexistence region. Thus, with all activity cycles, the coexistence region is maximal. The present results suggest that polyrhythmic changes in biological activity in response to the earth’s rotation and revolution are key to competitive coexistence. Also, temporal niche shifts caused by environmental changes can easily eliminate competitive coexistence.

Competitive Coexistence in a Two-Strain Epidemic Model with a Periodic Infection Rate

In this article, we study the global dynamical behavior of a two-strain SIS model with a periodic infection rate. The positivity and boundedness of solutions are established, and the competitive exclusion conditions are given for the model. The conditions for the global stability of the disease-free equilibrium and persistence of the model are obtained. The conditions of coexistence in this model are also found. Finally, the conditions of uniqueness of the solution are proved.

The role of dietary competition in the origination and early diversification of North American euprimates

The conditions under which early euprimates (adapids and omomyids) originated and evolved is an area of longstanding debate. The leading hypotheses of euprimate origins promulgate diet as a core component of the early evolution of this group, despite the role of dietary competition in euprimate originations never being tested directly. This study compared three competition models (non-competition, competitive displacement, competitive coexistence) with observed patterns of dietary niche overlap, reconstructed from three-dimensional molar morphology, at the time of the euprimate radiation in North America (at the Paleocene–Eocene boundary). Overlap of reconstructed multidimensional dietary niches between euprimates and members of their guild were analysed using a modified MANOVA to establish the nature of the competitive environment surrounding euprimate origins in North America (an immigration event). Results indicated that adapids entered the mammalian guild in the absence of competition, suggesting dietary adaptations that were unique within the community. Conversely, omomyids experienced strong, but transitory, competition with nyctitheriids, suggesting that omomyids possessed the ability to out-compete this group. These results show that adapids and omomyids experienced different competitive scenarios upon their arrival (origination) in North America and confirm the significance of diet (and dietary adaptations) in euprimate origination and early diversification in mammalian communities.

The ‘filtering’ metaphor revisited: competition and environment jointly structure invasibility and coexistence

‘Filtering’, or the reduction in species diversity that occurs because not all species can persist in all locations, is thought to unfold hierarchically, controlled by the environment at large scales and competition at small scales. However, the ecological effects of competition and the environment are not independent, and observational approaches preclude investigation into their interplay. We use a demographic approach with 30 plant species to experimentally test: (i) the effect of competition on species persistence in two soil moisture environments, and (ii) the effect of environmental conditions on mechanisms underlying competitive coexistence. We find that competitors cause differential species persistence across environments even when effects are lacking in the absence of competition, and that the traits which determine persistence depend on the competitive environment. If our study had been observational and trait-based, we would have erroneously concluded that the environment filters species with low biomass, shallow roots and small seeds. Changing environmental conditions generated idiosyncratic effects on coexistence outcomes, increasing competitive exclusion of some species while promoting coexistence of others. Our results highlight the importance of considering environmental filtering in the light of, rather than in isolation from, competition, and challenge community assembly models and approaches to projecting future species distributions.

The ‘filtering’ metaphor revisited: competition and environment jointly structure invasibility and coexistence

Abstract‘Filtering’, or the reduction in species diversity that occurs because not all species can persist in all locations, is thought to unfold hierarchically, at large scales due to the environment and at small scales due to competition. However, the ecological effects of competition and the environment are not independent, and observational approaches preclude investigation into their interplay. We use a demographic approach with 30 plant species to experimentally test (i) the effect of competition on species persistence in two soil moisture environments, and (ii) the effect of environmental conditions on the mechanisms underlying competitive coexistence. We find that competitors cause differential persistence of species across environments even when these effects are lacking in the absence of competition, and that the traits that determine persistence depend on the competitive environment. Changing environmental conditions generated idiosyncratic effects on coexistence outcomes, increasing competitive exclusion of some species while promoting coexistence of others. Our results highlight the importance of considering environmental filtering in light of, rather than in isolation from, competition, and challenge community assembly models and approaches to projecting future species distributions.