Assessing elements of an extended evolutionary synthesis for plant domestication and agricultural origin research

Abstract

The development of agricultural societies, one of the most transformative events in human and ecological history, was made possible by plant and animal domestication. Plant domestication began 12,000–10,000 y ago in a number of major world areas, including the New World tropics, Southwest Asia, and China, during a period of profound global environmental perturbations as the Pleistocene epoch ended and transitioned into the Holocene. Domestication is at its heart an evolutionary process, and for many prehistorians evolutionary theory has been foundational in investigating agricultural origins. Similarly, geneticists working largely with modern crops and their living wild progenitors have documented some of the mechanisms that underwrote phenotypic transformations from wild to domesticated species. Ever-improving analytic methods for retrieval of empirical data from archaeological sites, together with advances in genetic, genomic, epigenetic, and experimental research on living crop plants and wild progenitors, suggest that three fields of study currently little applied to plant domestication processes may be necessary to understand these transformations across a range of species important in early prehistoric agriculture. These fields are phenotypic (developmental) plasticity, niche construction theory, and epigenetics with transgenerational epigenetic inheritance. All are central in a controversy about whether an Extended Evolutionary Synthesis is needed to reconceptualize how evolutionary change occurs. An exploration of their present and potential utility in domestication study shows that all three fields have considerable promise in elucidating important issues in plant domestication and in agricultural origin and dispersal research and should be increasingly applied to these issues.

The Impact of Genetic Changes during Crop Domestication

“…However, new insights into evolutionary processes have also contributed to our understanding of domestication [12,39,40].…”

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

“…We limit our treatment of V p and V G because they have been discussed elsewhere (Olsen and Wendel, 2013;Piperno, 2017). In contrast, there has been a minimal effort to understand the contributions of V E and V GxE to crop domestication and diversification.…”

“…An emerging frontier is to understand the role of transgenerational epigenetics in crop adaptation to local environmental conditions (Piperno, 2017). Epigenetics studies can reveal how the environment can shape heritable gene expression (and thus the phenotype) without changing the underlying DNA sequence (Jablonka and Raz, 2009;Laland et al, 2014).…”

“…Field sampling of Mexican teosinte populations helped to clarify that maize adaptation to the Mexican highlands resulted due to introgression from wild teosinte . Understanding the genomic basis of local adaptation in crops relies on multiple in situ localities, where the ecological history can be reconstructed by testing for genomic regions under divergence , and the responses of candidate genes can be observed in local environments (Doust et al, 2014;Piperno, 2017). Traditional Mesoamerican agroecosystems are living biological and ethnographic systems that are suitable for studying how human-created niches in agroecosystems interact with local biotic and abiotic environments to shape landrace phenotypes.…”

“…We examine the role of human selection and niche construction activities on crop phenotypic plasticity, a major factor in local adaptation (Piperno, 2017). We conceptually address two questions that could deepen our understanding of crop evolution and local adaptation: (1) To what extent are crop plants locally adapted?…”