Electron. J. Differential Equations, Vol. 2025 (2025), No. 37, pp. 1-16.

Final evolutions for Lotka-Volterra systems in R^3 having a Darboux invariant

Jaume Llibre, Yulin Zhao

Abstract:
The Lotka-Volterra systems have been studied intensively due to their applications. While the phase portraits of the 2-dimensional Lotka-Volterra systems have been classified, this is not the case for the ones in dimension three. Here we classify all the \(3\)-dimensional Lotka-Volterra systems having a Darboux invariant of the form \(x^{\lambda_1} y^{\lambda_2} z^{\lambda_3} e^{st}\), where \(\lambda_i,s\in \mathbb{R}\) and \(s(\lambda_1^2+\lambda_2^2+\lambda_3^2)\ne 0\). The existence of such kind of Darboux invariants in a differential system allow to determine the \(\alpha\)-limits and \(\omega\)-limits of all the orbits of the differential system. For this class of Lotka-Volterra systems we can describe completely their phase portraits in the Poincare ball. As an application we illustrate with an example one of these phase portraits.

Submitted October 15, 2024. Published April 7, 2025.
Math Subject Classifications: 34D45, 34D05, 37N25, 92D25, 34C12, 34C30.
Key Words: Lotka-Volterra systems; Darboux invariants; global dynamics; Poincare compactification
DOI: 10.58997/ejde.2025.37

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Jaume Llibre
Departament de Matemàtiques
Universitat Autònoma de Barcelona
8193 Bellaterra, Barcelona, Catalonia, Spain
email: jaume.llibre@uab.cat
Yulin Zhao
School of Mathematics
Sun Yat-sen University, Zhuhai Campus
Zhuhai 519082, China
email: mcszyl@mail.sysu.edu.cn

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