title: Domestication impacts on plant-herbivore interactions: a meta-analysis.
abstract: For millennia, humans have imposed strong selection on domesticated crops, resulting in drastically altered crop phenotypes compared with wild ancestors. Crop yields have increased, but a long-held hypothesis is that domestication has also unintentionally decreased plant defences against herbivores. To test this hypothesis, we conducted a phylogenetically controlled meta-analysis comparing insect herbivore resistance and putative plant defence traits between crops and their wild relatives. Our database included 2098 comparisons made across 73 crops in 89 studies. We found that domestication consistently reduced plant resistance to herbivores, although the magnitude of the effects varied across plant organs and depended on how resistance was measured. However, domestication had no consistent effects on the specific plant defence traits underlying resistance, including secondary metabolites and physical feeding barriers. The values of these traits sometimes increased and sometimes decreased during domestication. Consistent negative effects of domestication were observed only when defence traits were measured in reproductive organs or in the plant organ that was harvested. These results highlight the complexity of evolution under domestication and the need for an improved theoretical understanding of the mechanisms through which agronomic selection can influence the species interactions that impact both the yield and sustainability of our food systems.This article is part of the themed issue 'Human influences on evolution, and the ecological and societal consequences'.
authors.affiliation: Department of Entomology, Cornell University, Comstock Hall 4117, Ithaca, NY 14853, USA swhitehead@vt.edu.
authors.forename: Susan R
authors.identifier: 0000-0002-7089-4594
authors.initials: SR
authors.lastname: Whitehead
authors.affiliation: Center for Adaptation to a Changing Environment, CHN G35.1, Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, Zürich 8092, Switzerland.
authors.forename: Martin M
authors.identifier: 0000-0003-3949-6958
authors.initials: MM
authors.lastname: Turcotte
authors.affiliation: Department of Entomology, Cornell University, Comstock Hall 4117, Ithaca, NY 14853, USA.
authors.forename: Katja
authors.initials: K
authors.lastname: Poveda
mesh_terms: D000818:Animals; D000898:Antibiosis; D005075:Biological Evolution; D018556:Crops, Agricultural / Q000502:physiology*; D000071278:Domestication; D020387:Food Chain; D060434:Herbivory; D007313:Insecta / Q000502:physiology*
keywords: agronomic selection; crop yield; herbivore resistance; plant defence theory; resource allocation; secondary metabolites