My illustration of limnetic and benthic stickleback, which did not make it onto the cover of any journal.
If you are ever my advisor, you will undoubtedly receive artwork: illustrations for Luke Harmon and Dolph Schluter, respectively, of a “species pair” stickleback community (top) and an unfortunate looking solitary generalist (bottom).
We would test a few different hypotheses regarding the effect of evolution (stickleback diversification and specialization) on ecological parameters. Because the overall ecological effects of stickleback presence were known (Bell et al. 2003), and stickleback population size probably also changed with colonization and diversification, we also decided to include treatments that varied in stickleback density. In fact, the comparison between the effects of differences in stickleback evolution and stickleback density on ecological surroundings became the main focus of this particular project.
Mesocosms in the early early morning... slowly being overtaken by blackberry bushes
Alas, results emerged. Both stickleback evolution (diversification and specialization) and ecology (density) affected ecological variables in some way. When compared to the generalist treatment, the limnetic treatment, the benthic treatment, and the limnetic–benthic treatment differed in zooplankton community composition (that is, the type and abundance of different zooplankton). Productivity – both as indicated by dissolved oxygen and chlorophyll from periphyton and phytoplankton – differed significantly between density treatments, as did abundance of small zooplankton (rotifers). Specifically, productivity and abundance of small zooplankton increased with the presence of, and with increasing density of, stickleback (an expected result, considering the predictions of the trophic cascade hypothesis).
Effect of different treatments on primary productivity: C) phytoplankton and D) periphyton chlorophyll-a, and E) dissolved oxygen concentration.
Illustration for Jon Shurin showing an awkwardly-purple-eyed stickle eying a diaphanosoma.
Pristine mesocosms for the Harmon et al. (2009) project.
The results, which I will not discuss here, were published in Nature (Harmon et al. 2009), and saw a lot of publicity. I was, and still am, infinitely grateful to have been included on this project and publication. At the time of the Nature paper, I was starting my PhD on another system. Unfortunately, I was facing delays with publishing the results of the first project (which was a considerable challenge after the Nature paper’s release). Turns out the final lesson the stickleback had for me was how to distinguish my paper (on a project that we performed first) from a substantially more prominent publication (on a project that we performed second). Reading the publications now, in light of the above, I hope you will see how different the projects really were. In 2013 I published the first project in the very popular open access journal PLOS One.
Bell T, Neill WE, Schluter D. (2003). The effect of temporal scale on the outcome of trophic cascade experiments. Oecologia 134: 578–586.