Environmental fluctuations restrict eco-evolutionary dynamics in predator–prey system

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. Here we 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.

Eco‐evolutionary dynamics in a coevolving host–virus system

“…; Hiltunen et al . ). The simultaneous changes in ecological and evolutionary properties (eco‐evolutionary dynamics) have important consequences for population and community dynamics, ecosystem structure and functioning, and the generation and maintenance of genetic variation and stability (Pelletier et al .…”

Sublethal streptomycin concentrations and lytic bacteriophage together promote resistance evolution

“…We followed standard protocols for microcosm experiments with bacteria -phage systems [43][44][45][46][47][48][49]. The culture medium for bacteria contained M9 salts and King's B (KB) nutrients at a 5% concentration compared with full-strength medium (concentrations used: 1 g peptone number 3 and 0.5 ml of 85% glycerol in 1 l of dH 2 O).…”

Conjugation is necessary for a bacterial plasmid to survive under protozoan predation

“…We followed standard protocols for microcosm experiments with bacteria -ciliate systems [10,11]. The culture medium for bacteria contained M9 salts and King's B nutrients at a 5% concentration.…”

“…In the 10-day experiment, plasmid prevalence was determined from diluted samples as the proportion of bacteria growing on PPY agar-plates containing 25 mg ml -1 kanamycin compared with plates without antibiotic. Prey defence level, D, was measured as described previously [10,11] ( protocol in the electronic supplementary material), with a D value of 0 indicating no evolution of defence against predation compared with ancestral strain and 1 indicating complete inability of predator to feed on bacterial prey.…”

“…Predation by bacteriophages can limit plasmid persistence through the joint ecological and population genetic effects of phages on bacterial populations [3]. Protozoan predation has strong effects on bacterial growth dynamics and can prevent bacteria from reaching stationary phase, when conjugation is slowed down [10]. As conjugation can be essential for the maintenance of plasmids, predation may therefore indirectly prevent loss of plasmids by creating conditions for enhanced conjugation.…”