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We determine the asymptotic spreading speed of the solutions of a Fisher-KPP reaction-diffusion equation, starting from compactly supported initial data, when the diffusion coefficient is a fixed bounded monotone profile that is shifted at a given forcing speed and satisfies a general uniform ellipticity condition. Depending on the monotonicity of the profile, we are able to characterize this spreading speed as a function of the forcing speed and the two linear spreading speeds associated to the asymptotic problems at \begin{document}$$ x = \pm \infty $$\end{document}. Most notably, when the profile of the diffusion coefficient is increasing we show that there is an intermediate range for the forcing speed where spreading actually occurs at a speed which is larger than the linear speed associated with the homogeneous state around the position of the front. We complement our study with the construction of strictly monotone traveling front solutions with strong exponential decay near the unstable state when the profile of the diffusion coefficient is decreasing and in the regime where the forcing speed is precisely the selected spreading speed.
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Asymptotic spreading of predator-prey populations in a shifting environment
Inspired by a recent study associating shifting temperature conditions with changes in the efficiency with which predators convert prey to offspring, we propose a predator prey model of reaction-diffusion type to analyze the consequence of such effects on the population dynamics and spread of {the predator} species. In the model, the predator conversion efficiency is represented by a spatially heterogeneous function depending on the variable $$\xi=x-c_1t$$ for some given $$c_1>0$$. Using the Hamilton-Jacobi approach, we provide explicit formulas for the spreading speed of the predator species. When the conversion function is monotone increasing, the spreading speed is determined in all cases and non-local pulling is possible. When the function is monotone decreasing, we provide formulas for the spreading speed when the rate of shift of the conversion function is sufficiently fast or slow.
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- Award ID(s):
- 2325195
- PAR ID:
- 10529530
- Publisher / Repository:
- Western Ontario University
- Date Published:
- Journal Name:
- Mathematics in Applied Sciences and Engineering
- Volume:
- 5
- Issue:
- 3
- ISSN:
- 2563-1926
- Page Range / eLocation ID:
- 199 to 221
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5206/mase/18029
