Posted by: oikosasa | December 3, 2013

Editor’s Choice December

Dries

Science makes progress by applying an experimental approach. This holds in ecology and many of us setup experiments to test the impact of stressors on diversity changes all levels of biological organisation, or how certain treatments affect specific ecological and evolutionary mechanisms. While there have been calls to use experimental approaches to understand eco-evolutionary responses to global change, such approaches often fail because of oversimplification of the real world. On the other side, such approaches allow true replication, a principle condition in science; conditions hardly met using natural experiments. In the forum paper of this month, Janneke HilleRisLambers and colleagues outline that we should embrace ongoing global change (from a scientific point of view only though) as they provide us ‘accidental experiments’ to gain fundamental insight into ecological and evolutionary processes. This is especially true when they result in perturbations that are large or long in duration and difficult or unethical to impose experimentally. While we all agree that such an approach will never replace the experimental method, it is clear that such accidental experiments provide considerable advantages relative to more traditional approaches and are able to provide fundamental scientific insights. HilleRisLambers  et al. provide a forum paper in the best Oikos tradition. A must read!

Synthesis of the paper, as outlined by the authors:

Humans have an increasingly large impact on the planet. In response, ecologists and evolutionary biologists are dedicating increasing scientific attention to global change, largely with studies documenting biological effects and testing strategies to avoid or reverse negative impacts. In this article, we analyze global change from a different perspective, and suggest that human impacts on the environment also serve as valuable ‘accidental experiments’ that can provide fundamental scientific insight. We highlight and synthesize examples of studies taking this approach, and give guidance for gaining future insights from these unfortunate ‘accidental experiments’.

We are also happy to highlight Coreen Forbes’ and Edd Hammill’s research paper as editor’s choice. By making use of an excellent multiple generations dataset, the authors demonstrate the importance of non-consumptive effects on food web dynamics. While the impact of such effects have been demonstrated in simple experiments, the authors moved some steps further and installed experimental microbial communities to seek generality of the available theory and experimental evidence. I would argue that accidental experiments would never allow for insights generated by experimental approaches like these, because, as expected by many, such community level effects appear to be highly context dependent. This context-dependency has here been identified and tested: heterotrophic species that rely on active fouraging to acquire resources are more affected by the presence of predators than other species, especially under conditions of darkness. In short, the paper provides novel, highly relevant insights on community functioning, highlights an unexpected impact of a largely neglected, but overall present abiotic condition by using creative experimental approaches of communities under equilibrium conditions. Clearly work that advances community ecology by targeting mechanisms rather than patterns!

Synthesis of the paper, as outlined by the authors:

Predators affect prey through consumptive and non-consumptive effects (NCEs) such as alterations to prey behaviour, morphology, and life history. However, predators and prey do not exist in isolated pairs, but in complex communities where they interact with many other species. Using a long term study (>10 predator generations), we show that predator NCEs alone can alter community structure under conditions of darkness, but not in a 12h:12h light:dark cycle. Our results demonstrate for the first time that although the community-level consequences of predator NCEs may be dramatic, they depend upon the abiotic conditions of the ecosystem.

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