WWD and JDH designed the research, WWD and NJE conducted the research, WWD, OTE, and JDH analyzed data and wrote the manuscript.
ALLELOPATHY AS AN EMERGENT, EXPLOITABLE PUBLIC GOOD IN THE BLOOM-FORMING MICROALGA PRYMNESIUM PARVUM
Article first published online: 11 JAN 2013
© 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.
Volume 67, Issue 6, pages 1582–1590, June 2013
How to Cite
Driscoll, W. W., Espinosa, N. J., Eldakar, O. T. and Hackett, J. D. (2013), ALLELOPATHY AS AN EMERGENT, EXPLOITABLE PUBLIC GOOD IN THE BLOOM-FORMING MICROALGA PRYMNESIUM PARVUM. Evolution, 67: 1582–1590. doi: 10.1111/evo.12030
- Issue published online: 4 JUN 2013
- Article first published online: 11 JAN 2013
- Accepted manuscript online: 12 DEC 2012 05:01PM EST
- Manuscript Accepted: 30 OCT 2012
- Manuscript Received: 30 JUN 2012
- NSF. Grant Number: IOS-1010669, OCE-0723498
- NIH. Grant Number: GM084905
- NIH grant. Grant Number: 5 K12 GM000708
- multilevel selection;
- Prymnesium parvum;
- public goods;
- toxic algal bloom
Many microbes cooperatively secrete extracellular products that favorably modify their environment. Consistent with social evolution theory, structured habitats play a role in maintaining these traits in microbial model systems, by localizing the benefits and separating strains that invest in these products from ‘cheater’ strains that benefit without paying the cost. It is thus surprising that many unicellular, well-mixed microalgal populations invest in extracellular toxins that confer ecological benefits upon the entire population, for example, by eliminating nutrient competitors (allelopathy). Here we test the hypotheses that microalgal exotoxins are (1) exploitable public goods that benefit all cells, regardless of investment, or (2) nonexploitable private goods involved in cell-level functions. We test these hypotheses with high-toxicity (TOX+) and low-toxicity (TOX−) strains of the damaging, mixotrophic microalga Prymnesium parvum and two common competitors: green algae and diatoms. TOX+ actually benefits from dense populations of competing green algae, which can also be prey for P. parvum, yielding a relative fitness advantage over coexisting TOX−. However, with nonprey competitors (diatoms), TOX− increases in frequency over TOX+, despite benefiting from the exclusion of diatoms by TOX+. An evolutionary unstable, ecologically devastating public good may emerge from traits selected at lower levels expressed in novel environments.