Cereal progenitors differ in stand harvest characteristics from related wild grasses

Abstract

The domestication of crops in the Fertile Crescent began approximately 10,000 years ago indicating a change from a hunter‐gatherer lifestyle to a sedentary, agriculture‐based existence. The exploitation of wild plants changed during this transition, such that a small number of crops were domesticated from the broader range of species gathered from the wild. However, the reasons for this change are unclear.Previous studies have shown unexpectedly that crop progenitors are not consistently higher yielding than related wild grass species, when growing without competition. In this study, we replicate more closely natural competition within wild stands, using two greenhouse experiments to investigate whether cereal progenitors exhibit a greater seed yield per unit area than related wild species that were not domesticated.Stands of cereal progenitors do not provide a greater total seed yield per unit ground area than related wild species, but these crop progenitors do have greater reproductive efficiency than closely related wild species, with nearly twice the harvest index (the ratio of harvested seeds to total shoot dry mass).These differences arise because the progenitors have greater seed yield per tiller than closely related wild species, due to larger individual seed size but no reduction in seed number per tiller. The harvest characteristics of cereal progenitors may have made them a more attractive prospect than closely related wild species for the early cultivators who first planted these species, or could suggest an ecological filtering mechanism. Synthesis. Overall, we show that the maintenance of a high harvest index under competition, the packaging of seed in large tillers, and large seeds, consistently distinguish crop progenitors from closely related wild grass species. However, the archaeological significance of these findings remains unclear, since a number of more distantly related species, including wild oats, have an equally high or higher harvest index and yield than some of the progenitor species. Domestication of the earliest cereal crops from the pool of wild species available cannot therefore be explained solely by species differences in yield and harvest characteristics, and must also consider other plant traits.

Phylogenomic analysis clarifies the evolutionary origin of Coffea arabica

“…Our research clarified the evolutionary relationships between the direct wild relatives of cultivated Arabica coffee, providing a strong instrument for the selection of wild plant species in coffee breeding programs. The closest relatives of a crop often contain more favorable characteristics for breeding than distantly related species, showing the importance of phylogenetic studies on crop wild relatives for crop improvement (Preece et al, 2015(Preece et al, , 2018Martín-Robles et al, 2019…”

Fertile Crescent crop progenitors gained a competitive advantage from large seedlings

“…However, archeobotanical evidence indicates that small-seeded grasses were an (arguably more) important source of food for pre-agricultural groups (Savard et al, 2006;. Furthermore, earlier experiments have shown that large-seeded grass and legume progenitor species are not necessarily higher yielding than smaller-seeded species in the same families (Preece et al, 2015(Preece et al, , 2018.…”

“…However, although domesticated cereals of the Fertile Crescent have a greater potential yield than their wild progenitors (Preece et al, 2017), the wild progenitors do not consistently produce a higher yield than other wild grasses available in the region before and during the transition to agriculture (Preece et al, 2015(Preece et al, , 2018.…”

“…While there is debate over whether or not there was a narrowing in the spectrum of wild plant species collected, and possibly cultivated, over thousands of years (Wallace et al., 2018; Weiss et al., 2004; Willcox et al., 2008), the underlying reasons why some species became domesticated, whereas, others did not remain unknown. Here, we adopt an ecological approach to answering this question, following recent research (Cunniff et al., 2014; Milla & Morente, 2015; Milla et al., 2015; Preece et al., 2015, 2018). We focus on the role of plant traits in the domestication process, through their interaction with the anthropogenic environment including human settlement and early attempts at cultivation, although we acknowledge that there may be other contributing factors, for example, social, economic, and cultural reasons.…”

“…Harvested yield is commonly considered an important characteristic of crops and their progenitors (Evans, 1996; Harlan et al., 1973). However, although domesticated cereals of the Fertile Crescent have a greater potential yield than their wild progenitors (Preece et al., 2017), the wild progenitors do not consistently produce a higher yield than other wild grasses available in the region before and during the transition to agriculture (Preece et al., 2015, 2018). Therefore, we propose that characteristics other than grain yield per se may be important in differentiating cereal crop progenitors from other wild grasses.…”