Pulsed-resource dynamics constrain the evolution of predator–prey interactions

Jouni Laakso, Ville-Petri Friman

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    Sammanfattning

    Although temporal variability in the physical environ- ment plays a major role in population fluctuations, little is known about how it drives the ecological and evolutionary dynamics of species interactions. We studied experimentally how extrinsic re- source pulses affect evolutionary and ecological dynamics between the prey bacterium Serratia marcescens and the predatory protozoan Tetrahymena thermophila. Predation increased the frequency of de- fensive, nonpigmented prey types, which bore competitive costs in terms of reduced maximum growth rate, with the greatest reduction in a constant-resource environment. Furthermore, the predator den- sities of the pulsed-resource environment regularly fluctuated above and below the mean predator densities of the constant environment. These results suggest that selection favored fast-growing competitor prey types over defensive but slower-growing prey types more often in the pulsed-resource environment (abundance of resources and low predation risk). As a result, the selection for prey defense fluc- tuated more in the pulsed-resource environment, leading to a weaker mean response in prey defense. At the ecological level, the evolution of prey defense weakened the relative strength of top-down regulation on prey community. This was more evident in the constant-resource environment, whereas the slow emergence of defensive prey types gradually decreased the amplitude of predator peaks in the pulsed- resource environment. Our study suggests that rapid evolution plays a smaller role in the ecological dynamics of communities dominated by resource pulses
    Originalspråkengelska
    TidskriftAmerican Naturalist
    Volym177
    Utgåva3
    Sidor (från-till)334-345
    Antal sidor12
    ISSN0003-0147
    DOI
    StatusPublicerad - mar 2011
    MoE-publikationstypA1 Tidskriftsartikel-refererad

    Vetenskapsgrenar

    • 1181 Ekologi, evolutionsbiologi

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