Predation increases prey fitness via transgenerational priming

Preparing your offspring for future challenges via priming can directly enhance its fitness. However, evidence for transgenerational priming has been limited to eukaryotic organisms. Here we test the hypothesis that predation primes bacteria such that their future generations respond with a more effective defence induction. In an evolution experiment, Escherichia coli was cultivated either in monoculture or in coculture with the predatory ciliate Tetrahymena thermophila. After 18 days, fitness and defensive clustering capabilities of derived bacterial populations were determined. Our results reveal that (i) predation can prime E.coli to induce their defensive cluster formation across generations and that (ii) three days of predation are sufficient to increase the fitness of predator-exposed over that of predator-free populations. Thus, our study shows that predation can have priming effects in bacterial populations that operate across generations, which concurs with the emerging perception that bacteria feature mechanisms to actively shape their evolutionary fate.