Plastic responses to competition: Does bacteriocin production increase in the presence of nonself competitors?

• Published in: Ecology and evolution Vol. 8; no. 14; pp. 6880 - 6888
• Main Authors: Bhattacharya, Amrita, Pak, Hannah Tae‐Young, Bashey, Farrah
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.07.2018; John Wiley and Sons Inc
• Subjects: adaptation; adaptive phenotypic plasticity; allelopathy; Archaea; Bacteriocins; Competition; competition‐sensing hypothesis; Original Research; Toxins; adaptive phenotypic plasticity; bacteriocins; allelopathy; adaptation; competition; competition‐sensing hypothesis
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.4203

Anticompetitor traits such as the production of allelopathic toxins can confer significant competitive benefits but are often costly to produce. Evolution of these traits may be facilitated by environment‐specific induction; however, the extent to which costly anticompetitor traits are induced by competitors is not well explored. Here, we addressed this question using bacteriocins, which are highly specific, proteinaceous anticompetitor toxins, produced by most lineages of bacteria and archaea. We tested the prediction that bacteriocin production is phenotypically plastic and induced by the presence of competitors by examining bacteriocin production in the presence and absence of nonself competitors over the course of growth of a producing strain. Our results show that bacteriocin production is detectable only at high cell densities, when competition for resources is high. However, the amount of bacteriocin activity was not significantly different in the presence vs. the absence of nonself competitors. These results suggest that bacteriocin production is either (a) canalized, constitutively produced by a fixed frequency of cells in the population or (b) induced by generic cues of competition, rather than specific self/nonself discrimination. Such a nonspecific response to competition could be favored in the natural environment where competition is ubiquitous. We test whether the production of costly anticompetitor toxins is phenotypically plastic and responsive to the presence of nonself competitors using bacteriocins which are highly specific, antimicrobial toxins produced ubiquitously in the bacterial kingdom. Using in vitro experimental manipulations and a functional bioassay to compare bacteriocin activity, we find that bacteriocin production occurs regardless of the presence of nonself competitors. Contrary to predictions, we do not find evidence for increased toxin production in the presence of nonself competitors but do see a marked increase in toxin activity during stationary phase which may suggest a generalized response to increased competition regardless of specific competitor identity.