Microbial populations can be dispersal limited. However, microorganisms that successfully disperse into physiologically ideal environments are not guaranteed to establish. This observation contradicts the Baas-Becking tenet: ‘Everything is everywhere, but the environment selects’. Allee effects, which manifest in the relationship between initial population density and probability of establishment, could explain this observation. Here, we experimentally demonstrate that small populations of Vibrio fischeri are subject to an intrinsic demographic Allee effect. Populations subjected to predationby the bacterivore Cafeteria roenbergensis display both intrinsic and extrinsic demographic Allee effects. The estimated critical threshold required to escape positive densitydependence is around 5, 20 or 90 cells ml-1 under conditions of high carbon resources, low carbon resources or low carbon resources with predation, respectively. Thiswork builds on the foundations ofmodern microbial ecology, demonstrating that mechanisms controlling macroorganisms apply to microorganisms, and provides a statistical method to detect Allee effects in data.
Original Publication Citation
Kaul, R. B., Kramer, A. M., Dobbs, F. C., & Drake, J. M. (2016). Experimental demonstration of an allee effect in microbial populations. Biology Letters, 12(4). doi:10.1098/rsbl.2016.0070
Kaul, RajReni B.; Kramer, Andrew M.; Dobbs, Fred C.; and Drake, John M., "Experimental Demonstration of an Allee Effect in Microbial Populations" (2016). OES Faculty Publications. 337.