The positive effect of plant species diversity on productivity increases over time in experimental grasslands. Using plant material from a long-term field experiment, we tested whether the effects of biodiversity on evolutionary processes lead to measurable evolutionary changes in the plant communities. Plant individuals may be different in different diversities with plant offspring from high plant diversity producing a higher yield than plants from low species diversity. Debra Zuppinger-Dingley, of the URPP Global Change and Biodiversity, explains this indicates that selection for genetic variants of mixture or monoculture types had occurred in the biodiversity experiment. This evolutionary response could be due to two factors. First, evolution could reduce overlap in the ecological “niche” of neighbours, which in turn would reduce competition. Second, evolution might promote beneficial “facilitative” effects of one plant on its neighbour.
Understanding the circumstances under which these two processes operate is important. As well as helping us to understand the fundamental ecological processes by which communities are structured and function, says Rob Brooker, such results may be of benefit in the applied use of positive biodiversity-function effects, for example in efforts to develop sustainable agricultural systems by breeding for crop mixtures. facilitation was more frequent in mixtures than in monocultures, and more intense (more positive) in communities of plants with a mixture history compared to those with a monoculture coexistence history. Bernhard Schmid commented that although he has worked in biodiversity research for a long time, he is surprised that the effects of biodiversity are more positive than he ever expected!
Our study demonstrates that whilst evolutionary selection for reduced competition enhanced yields in both monocultures and mixtures, increasing yields in mixtures in particular were also due to evolutionary selection for facilitation. Christian Schöb concludes this provides clear evidence that the full benefits of having species rich systems, for example yield benefits of mixture cropping, will only be seen if artificial selection targeted specifically for mixture crops is implemented into breeding programs. Only mixed cropping with plants with mixture coexistence histories has the potential to not only increase niche differentiation but also enable the evolution of facilitative interactions, thereby maximising complementarity effects in plant communities. See Schöb et al.
Christian Schöb, Rob W. Brooker and Debra Zuppinger-Dingley. Evolution of facilitation requires diverse communities. Nature Ecology and Evolution doi: 10.1038/s41559-018-0623-2
Sofia J. van Moorsel, Marc W. Schmid, C.A.M. Wagemaker, Thomas van Gurp, Bernhard Schmid, Philippine Vergeer. Evidence for rapid evolution in a grassland biodiversity experiment. bioRxiv doi: 10.1101/262303
Debra Zuppinger-Dingley, Bernhard Schmid, Jana S. Petermann, Varuna Yadav, Gerlinde B. De Deyn. Dan F. B. Flynn. Selection for niche differentiation in plant communities increases biodiversity effects. Nature doi: 10.1038/nature13869