Stability and complexity in emergent complex ecological networks

• Ano de defesa: 2019
• Autor(a) principal: Carvalho, Sylvestre Aureliano
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Ecologia - Modelos matemáticos; Padrão de formação (Biologia); Predação; Mutualismo; Alelopatia; Estabilidade estrutural; Física da Matéria Condensada
• Link de acesso: https://locus.ufv.br//handle/123456789/28496

One of the main goals of theoretical ecology consists of determining the ecological forces that favor or not the maintenance of biodiversity in the face of species interactions and environmental perturbations. An approach to reach this goal is to describe the dynamics of the populations that form an ecological community through mathematical models of ecological interactions of different kinds (allelopathy, competition, mutualism, predation, etc), which are studied through numerical simulations and analytical approximations. In recent times, the evidence is mounting that the race of living organisms for adaptation to the chemicals synthesized by their neighbours may drive community structures. Particularly, some bacterial infections and plant invasions disruptive of the native community rely on the release of allelochemicals that inhibit or kill sensitive strains or individuals from their own or other species. On the other hands, the concept of structural stability, i.e., the maintenance of the model ecosystem under random changes in the parameters of the dynamical model, in particular, changes in the growth rates of the species that model environmental perturbations, has emerged as a key theoretical tool for characterizing the response of ecosystems to the fluctuations of the environment. In this thesis, an eco-evolutionary model and metacommunity pattern formation for community assembly through resource competition, allelopathic interactions, and evolutionary branching are presented and studied by numerical analysis. Our major findings are that stable com- munities with increasing biodiversity can emerge at weak allelopathic suppression, but stronger allelopathy is negatively correlated with community diversity. Furthermore, the heterogeneous patterns of these species emerge when diffusivity is low and the allelochemical network has cyclic interactions. The structural stability analysis of interactions as mutualism, competition, and predation shows that increasing biodiversity can be observed in mutualistic species (when the interspecific competition is weak), is impaired when the intragroup competition is considered, and predation interactions can increase or decrease the biodiversity (if the interspecific competition is weak or strong). Keywords: Complex networks. Community structure. Ecological and evolutionary theory. Pattern formation. Competition. Predation. Mutualism. Allelopathy. Structural stability.