The final issue of Journal of Ecology’s Centenary volume is now available online. Our latest Editor’s Choice is ‘Plant species diversity and genetic diversity within a dominant species interactively affect plant community biomass’ by Crawford and Rudgers. As always let us know what you think of Associate Editor JC Cahill’s commentary in the comments section below.

Editor’s Choice 100:6

There was a time, not too long ago, when the incorporation of evolutionary concepts into studies of plant community ecology was potentially interesting, but rarely done.  Over the last several years, the scientific landscape has shifted, and the fields of ecological genetics, community phylogenetics, and old-school evolutionary ecology are thriving.  The Journal of Ecology has long been the ‘go-to’ journal for studies in this field, particularly those researchers ambitious enough to try and experimentally determine the functional consequences of genetic diversity on plant communities.  For example, Turkington and Harper (1979) present evidence that variation in the species identity of a plant’s competitors can result in alternative evolutionary trajectories.  Booth and Grime present one of the first experimental studies documenting that genetic diversity among co-occuring species promotes species coexistence (Booth and Grime, 2003).  Fridley et al. (2007) and Cahill et al. (2005), using very different methods, both show competition among plants to be influenced by an interaction among soil fertility and the genetic identity of the competing plants.  Following in this tradition, I am pleased to highlight a new study by Kerri Crawford and Jennifer Rudgers ‘Plant species diversity and genetic diversity within a dominant species interactively affect plant community biomass’ (2012) in which they integrate two areas of research:  the functional consequences of genetic diversity and diversity-function relationships.

In a series of elegant experiments, Crawford and Rudgers manipulate the genetic diversity of a dominant plant, Ammophila breviligulata, as well as the number of co-occurring species.  Neither factor had a main effect on overall biomass production; instead, they combined to have an interesting interactive effect.  Specifically, the “traditional” positive effect of species diversity of biomass production was only found when A. breviligulata was of high genetic diversity.  When the dominant was of low genetic diversity, there was an overall negative effect of species diversity on this particular ecosystem function.  In other words – the impacts of species diversity on ecosystem function was itself contingent on the genetic diversity of the dominant plant species.

The potential impacts of this study are significant.  First, they reinforce the preexisting idea that genetic diversity is of functional importance in ecological processes.  In an era in which the study of ecology and evolution are becoming ever more intertwined, their work is a critical reminder that though ‘species’ may be a convenient level of organization to study, ignoring population genetics may come at a cost of ecological understanding.  Second, though I imagine there are few topics more heavily studied in the last 20 years than diversity-function relationships, Crawford and Rudgers beautifully demonstrate how even well worn ideas may be hiding new insight – but only when researchers have the creativity to address the question from a new direction.

JC Cahill
Associate Editor, Journal of Ecology

References

Booth, R.E. & Grime, J.P. (2003) The effects of genetic impoverishment on plant community diversity. Journal of Ecology, 91, 721-730.

Cahill, J.F., Kembel, S.W. & Gustafson, D.J. (2005) Differential genetic influences on competitive effect and response in Arabidopsis thaliana. Journal of Ecology, 93, 958-967.

Fridley, J.D., Grime, J.P. & Bilton, M. (2007) Genetic identity of interspecific neighbours mediates plant responses to competition and environmental variation in a species-rich grassland. Journal Of Ecology, 95, 908-915.

Turkington, R. & Harper, J.L. (1979) The growth, distribution and neighbor relationships of Trifolium repens in a permanent pasture.  IV.  Fine-scale biotic differentiation. Journal of Ecology, 67, 245-254.