Advantages of storage in a fluctuating environment

Kooi, B.W. and Troost, T.A. 2006 Advantages of storage in a fluctuating environment. Theor. Pop. Biol 70: 527 - 541


We will elaborate the evolutionary course of an ecosystem consisting of a population in a chemostat environment with periodically fluctuating nutrient supply. The population consists of structural and energy storage compartments. In a constant chemostat environment a species without energy storage always out-competes a species with energy reserves. This hampers evolution of species with storage from those without storage. Using the adaptive dynamics approach for non-equilibrium ecological systems we will show that in a fluctuating environment there are multiple stable evolutionary singular strategies (ss's): one for a species without, and one for a species with energy storage. The evolutionary end-point depends on the initial evolutionary state. We will formulate the invasion fitness in terms of Floquet multipliers for the oscillating non-autonomous system. Bifurcation theory is used to study points where due to evolutionary development by mutational steps, the stability of the ecological system changes qualitatively. In a constant environment there is a unique stable equilibrium for one species following the ``competitive exclusion'' principle. In contrast, in a fluctuating environment an evolutionary branching point arises and two species may coexist. That is, the non-equilibrium dynamics enhances biodiversity. However, we show that this coexistence is not stable on the evolutionary time scale and always a single species survives.

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