Crop domestication and the disruption of species interactions

The process of crop domestication involves artificial selection for beneficial traits in plants, such as yield, standard development times for ease of harvest, and pest and disease resistance. This process has greatly improved crop performance and can allow farmers to produce viable harvests in previously un-profitable circumstances. However, there is growing evidence that domestication may impact species interactions perhaps through the amplification of effects across spatial scales and so have a pervasive influence on the functioning and sustainability of agro-ecosystems. This can occur directly, through unintentional alteration to crop traits that disrupt the host-finding ability of natural enemies; or indirectly through alterations to within-plant nutritional quality that impacts herbivore size and density and then ramifies throughout food chains. At the field level, the low variability in traits between individual plants means that particular weed and invertebrate communities are associated with each crop type. At the landscape level, the use of one or a few varieties across wide spatial scales, planted and harvested relatively synchronously, further reduces diversity. This process acting across multiple spatial scales represents a considerable selection pressure that may result in feedback-loops which favour the occurrence of particular traits within the community (e.g. resistance to pesticides). In order to properly balance the 'pros and cons' of the widespread adoption of new varieties, for the future, we must consider how particular traits influence interactions within the wider ecological community, and how these effects amplify across spatial scales. Here we argue that the process of domestication (with the primary goal of yield increases) and the widespread use of a few varieties has led to potentially detrimental impacts on species interactions, and suggest possible strategies for mitigating some of these negative impacts in the future. (C) 2010 Gesellschaft fur Okologie. Published by Elsevier Gmbh. All rights reserved.