Darwinian Agriculture: how understanding evolution can improve agriculture R. Ford Denison 2012. Princeton University Press

Agroecosystems not only comprise a significant proportion of land-use, but also involve conflicting imperatives to expand or intensify production while simultaneously reducing environmental impacts. These imperatives are underpinned by food security concerns, climate predictability and global connectivity, reinforcing the likelihood of further major changes in agricultural landscapes and associated production systems in coming decades. These changes are likely to include adoption of novel genetic technologies and agronomic practices, shifts in patterns of land-use and perhaps even new crop species. Ford Denison’s new book, Darwinian Agriculture: how understanding evolution can improve agriculture, makes a strong and very personal case for the application of evolutionary principles to addressing the twin challenges of feeding an expanding human population while working to reduce agriculture’s environmental footprint. Of course, the use of eco-evolutionary principles is not new in agriculture (e.g. crop breeding and management of selection for pest resistance), but given land-use trends and other transformative processes in production landscapes, ecological and evolutionary research in agroecosystems must consider such issues in a broader systems’ context (Thrall et al. 2011). I fully agree with Denison that evolutionary concepts have potential to help us deal more effectively with these complex problems and that multidisciplinary approaches are needed to improve both productivity and sustainability. Darwinian Agriculture focuses primarily on one particular aspect of this broad topic, and that is to do with the opportunities and challenges around producing more food. Fair enough! Meeting projected food demands over the next several decades could prove to be a more difficult challenge than climate change itself. Denison uses this central focus to draw in discussions of a diverse and somewhat idiosyncratic but interesting range of subjects (e.g. leaf-cutter ants, natural selection and the evolution of simple vs. complex traits, his brother Tom’s organic farm, kin selection and male sterility in corn). This seemingly disconnected set of topics is used to variously illustrate points within three central themes that permeate the book. Firstly, Denison argues that the concept of trade-offs is absolutely critical. This is tightly connected with his second major theme, which is that any simple evolutionary advances (i.e. trade-off free) are likely to have already been tried and tested via natural selection. He suggests that further direct ‘improvements’ in species performance (e.g. drought tolerance and perenniality) are generally likely to come with costs. Related to this is his view that, while there may be increasingly limited potential to improve individual traits, there is likely to have been much less optimisation at the community level, so there may be more possibilities for utilising eco-evolutionary principles (Chapter 1). In this context, Denison makes the useful point that improving agriculture may be more of a group selection problem (e.g. Chapters 4, 8), and this also relates to the scarcity of ‘lowhanging’ individual traits. Examples include crops that could better compete with weeds, solar tracking or amongspecies cooperation, for example, with mutualists (Chapters 8, 9). Finally, a third theme that is explored in several contexts is the extent to which we can use natural systems as a model for agriculture, and if so, what components of natural systems could most usefully be transferred to modern agroecosystems. These themes are developed early on and returned to throughout the rest of the book. In many ways, I enjoyed reading this book. We need all the ideas on this topic we can get – maintaining global food security while protecting our natural ecosystems is not going to be easy! I especially like the goal of developing a ‘unified field-crop theory’ (Chapter 4). Overall, Denison does a good job of covering the basic issues in agriculture (population increases, food demand trends, input costs, etc.) that argue why we need an eco-evolutionary perspective for longer-term sustainability (Chapter 2). He also highlights the need for innovative thinking around the challenges of food security and improving the sustainability of our farming systems. While I can’t say I agree with everything he says (more on that below), the book has stimulated plenty of discussion with colleagues and that is certainly worthwhile. It is also an entertaining journey through Ford’s personal perspective on the concept of Darwinian agriculture – something he has clearly thought about for some time. At the same time, it is not 100% obvious to me who the intended audience is. Do scientists really need to be convinced that ecosystems don’t behave like species (who would be likely to debate such a statement)? Overall, the