Back to the Origin: In Situ Studies Are Needed to Understand Selection during Crop Diversification

Abstract

Crop domestication has been embraced as a model system to study the genetics of plant evolution. Yet, the role of the environment, including biotic forces such as microbial and insect communities, in contributing to crop phenotypes under domestication and diversification has been poorly explored. In particular, there has been limited progress in understanding how human selection, agricultural cultivation (soil disturbance, fertilization, and irrigation), and biotic forces act as selective pressures on crop phenotypes. For example, geographically-structured pathogenic, pestiferous, and mutualistic interactions with crop plants have likely given rise to landraces that interact differently with local microbial and insect communities. In order to understand the adaptive role of crop traits, we argue that more studies should be conducted in the geographic centers of origin to test hypotheses on how abiotic, biotic, and human selective forces have shaped the phenotypes of domesticated plants during crop domestication and subsequent diversification into landraces. In these centers of origin, locally endemic species associated with wild ancestors have likely contributed to the selection on plant phenotypes. We address a range of questions that can only be studied in the geographic center of crop origin, placing emphasis on Mesoamerican polyculture systems, and highlight the significance of in situ studies for increasing the sustainability of modern agricultural systems.

Potential and limits of exploitation of crop wild relatives for pea, lentil, and chickpea improvement

“…As a result, CWRs have experienced selection resulting in adaptation to a given habitat, reflected by allelic composition across the genome (Piperno, 2017). However, more studies should be conducted in the geographic centers of origin to test hypotheses on how abiotic, biotic, and selective human forces have altered domesticated plants during domestication and subsequent diversification (Chen, Shapiro, Benrey, & Cibrián‐Jaramillo, 2017; Perez‐Jaramillo, Mendes, & Raaijmakers, 2016). The role of ecological factors especially in the centers of crop origin has received rather little attention.…”

Morphological and Genetic Variation in Monocultures, Forestry Systems and Wild Populations of Agave maximiliana of Western Mexico: Implications for Its Conservation

“…As a result, we cannot make direct conclusions about the extent to which the wild and managed populations (either in situ or monocultures) of A. maximiliana are locally adapted. In addition, adoption of new approaches regarding developmental plasticity, variation in quantitative trait loci related to natural and artificial selection or niche construction theory (Chen et al, 2017;Piperno, 2017) could complete the understanding of diversification versus domestication contexts (Pickersgill, 2018). Despite this, we consider that the general patterns of intraspecific diversity in in situ contexts of management practices are still poorly documented, and that this study constitutes a valuable base on which to establish more specific research questions to further the understanding of the origin of domestication processes.…”

The Impact of Genetic Changes during Crop Domestication

“…For instance, weed species have evolved to morphologically mimic crops and, in this way, evade eradication by practices such as hand-weeding or seed sorting and cleaning [116]. Similarly, despite limited study, it is clear that crop domestication has had large impacts on herbivorous insect communities and on natural enemies of herbivores, such as parasitoids [117]. Evolution of wild species in response to agricultural practices can both directly and indirectly impact the provision of multiple ecosystem services, such as rapid evolution in pests, pathogens, and weeds causing stark declines in crop production [118].…”