Noise Induced Phenomena in Population Dynamics D. Valenti a1 , A. Giuffrida b , G. Denaro a , N. Pizzolato a , L. Curcio a , B. Spagnolo a,c,d , S. Mazzola e , G. Basilone e , A. Bonanno e a Dipartimento di Fisica e Chimica, Universit` a di Palermo, Group of Interdisciplinary Theoretical Physics and CNISM, Unit` a di Palermo, Viale delle Scienze, Ed. 18, I-90128 Palermo, Italy b Dipartimento di Scienze Veterinarie, Universit` a di Messina, Polo Universitario dellAnnunziata, 98168 Messina, Italy c Radiophysics Department, Lobachevsky State University, 23 Gagarin Avenue, 603950 Nizhniy Novgorod, Russia d Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Via S. Sofia 64, I-90123 Catania, Italy e Istituto per l’Ambiente Marino Costiero, CNR, U.O.S. di Capo Granitola Via del Faro 3, I-91020 Campobello di Mazara (TP), Italy Abstract. Noise through its interaction with the nonlinearity of the living systems can give rise to counter-intuitive phenomena. In this paper we shortly review the noise induced effects in different ecosystems. The transient dynamics of these ecosystems are analyzed through generalized Lotka- Volterra equations in the presence of multiplicative noise, which models the interaction between the species and the environment. We find noise induced phenomena such as quasi-deterministic oscillations, stochastic resonance, noise delayed extinction, and noise-induced pattern formation. The spatial pattern of two competing species, obtained with the coupled map lattice, is compared with real data. Finally, the experimental dynamical behavior of two competing bacterial popu- lations in a meat product and the probability distribution at long times of one of them are well reproduced by a stochastic microbial predictive model. Key words: noise induced phenomena, population dynamics, Langevin equation, multiplicative noise, stochastic resonance, predictive microbiology AMS subject classification: 82C05, 82C31, 60H10, 34F15, 92D25, 92D40 1 Corresponding author. E-mail: davide.valenti@unipa.it 1 arXiv:1511.07266v2 [q-bio.PE] 24 Nov 2015