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Free keywords:
community dynamics; coevolution;
eco-evolutionary dynamics; temporal
fluctuations; Tetrahymena thermophila;
Pseudomonas fluorescens SBW25
Abstract:
Environmental fluctuations, species interactions and rapid evolution are
all predicted to affect community structure and their temporal dynamics.
Although the effects of the abiotic environment and prey evolution on ecological
community dynamics have been studied separately, these factors can also
have interactive effects. Herewe used bacteria–ciliate microcosm experiments
to test for eco-evolutionary dynamics in fluctuating environments. Specifically,
we followed population dynamics and a prey defence trait over time
when populations were exposed to regular changes of bottom-up or topdown
stressors, or combinations of these. We found that the rate of evolution
of a defence trait was significantly lower in fluctuating compared with stable
environments, and that the defence trait evolved to lower levels when
two environmental stressors changed recurrently. The latter suggests that
top-down and bottom-up changes can have additive effects constraining
evolutionary response within populations. The differences in evolutionary trajectories
are explained by fluctuations in population sizes of the prey and the
predator, which continuously alter the supply of mutations in the prey and
strength of selection through predation. Thus, it may be necessary to adopt
an eco-evolutionary perspective on studies concerning the evolution of traits
mediating species interactions.
