During community assembly, species may accumulate not only by immigration, but also by in situ diversification. Diversification has intrigued biologists because its extent varies even among closely related lineages under similar ecological conditions. Recent research has suggested that some of this puzzling variation may be caused by stochastic differences in the history of immigration (relative timing and order of immigration by founding populations), indicating that immigration and diversification may affect community assembly interactively. However, the conditions under which immigration history affects diversification remain unclear. Here we propose the hypothesis that whether or not immigration history influences the extent of diversification depends on the founding populations’ prior evolutionary history, using evidence from a bacterial experiment. To create genotypes with different evolutionary histories, replicate populations of Pseudomonas fluorescens were allowed to adapt to a novel environment for a short or long period of time (approximately 10 or 100 bacterial generations) with or without exploiters (viral parasites). Each evolved genotype was then introduced to a new habitat either before or after a standard competitor genotype. Most genotypes diversified to a greater extent when introduced before, rather than after, the competitor. However, introduction order did not affect the extent of diversification when the evolved genotype had previously adapted to the environment for a long period of time without exploiters. Diversification of these populations was low regardless of introduction order. These results suggest that the importance of immigration history in diversification can be predicted by the immigrants’ evolutionary past. The hypothesis proposed here may be generally applicable in both micro- and macro-organisms.
Keywords: adaptive peaks, colonization, dispersal, eco-evolutionary dynamics, fitness trade-off, historical contingency, niche pre-emption, priority effect
Citation: Knope ML, Forde SE and Fukami T (2012) Evolutionary history, immigration history, and the extent of diversification in community assembly. Front. Microbio. 2:273. doi: 10.3389/fmicb.2011.00273
Received: 21 September 2011; Accepted: 21 December 2011;
Published online: 09 January 2012.
Edited by:Diana Reid Nemergut, University of Colorado Boulder, USA
Reviewed by:Susannah Green Tringe, DOE Joint Genome Institute, USA
Copyright: © 2012 Knope, Forde and Fukami. This is an open-access article distributed under the terms of the Creative Commons Attribution Non Commercial License, which permits non-commercial use, distribution, and reproduction in other forums, provided the original authors and source are credited.
*Correspondence: Tadashi Fukami, Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA 94305-5020, USA. e-mail: email@example.com