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Discrete and Continuous Dynamical Systems - Series B (DCDS-B)
 

Inside dynamics of solutions of integro-differential equations

Pages: 3057 - 3085, Volume 19, Issue 10, December 2014      doi:10.3934/dcdsb.2014.19.3057

 
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Olivier Bonnefon - INRA, UR 546 Biostatistique et Processus Spatiaux (BioSP), F-84914 Avignon, France (email)
Jérôme Coville - INRA, UR 546 Biostatistique et Processus Spatiaux (BioSP), F-84914 Avignon, France (email)
Jimmy Garnier - INRA, UR 546 Biostatistique et Processus Spatiaux (BioSP), F-84914 Avignon, France (email)
Lionel Roques - INRA, UR 546 Biostatistique et Processus Spatiaux (BioSP), F-84914 Avignon, France (email)

Abstract: In this paper, we investigate the inside dynamics of the positive solutions of integro-differential equations \begin{equation*} \partial_t u(t,x)= (J\star u)(t,x) -u(t,x) + f(u(t,x)), \ t>0 \hbox{ and } x\in\mathbb{R}, \end{equation*} with both thin-tailed and fat-tailed dispersal kernels $J$ and a monostable reaction term $f.$ The notion of inside dynamics has been introduced to characterize traveling waves of some reaction-diffusion equations [23]. Assuming that the solution is made of several fractions $\upsilon^i\ge 0$ ($i\in I \subset \mathbb{N}$), its inside dynamics is given by the spatio-temporal evolution of $\upsilon^i$. According to this dynamics, the traveling waves can be classified in two categories: pushed and pulled waves. For thin-tailed kernels, we observe no qualitative differences between the traveling waves of the above integro-differential equations and the traveling waves of the classical reaction-diffusion equations. In particular, in the KPP case ($f(u)\leq f'(0)u$ for all $u\in(0,1)$) we prove that all the traveling waves are pulled. On the other hand for fat-tailed kernels, the integro-differential equations do not admit any traveling waves. Therefore, to analyse the inside dynamics of a solution in this case, we introduce new notions of pulled and pushed solutions. Within this new framework, we provide analytical and numerical results showing that the solutions of integro-differential equations involving a fat-tailed dispersal kernel are pushed. Our results have applications in population genetics. They show that the existence of long distance dispersal events during a colonization tend to preserve the genetic diversity.

Keywords:  Traveling waves, integro-differential equation, pulled and pushed solutions, monostable, long distance dispersal, thin-tailed/fat-tailed kernel.
Mathematics Subject Classification:  Primary: 35R09, 45K05; Secondary: 35B06, 35K57.

Received: July 2013;      Revised: January 2014;      Available Online: October 2014.

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