Biology subjects

Fuller, D. Q.

Publications and source records attributed to Fuller, D. Q..

7 recordsLinked to original sources

bioRxiv2024

Differentiating wild and domesticated enset (Musaceae) using phytolith analysis

Enset (Ensete ventricosum, Musaceae) is an important economic crop from Ethiopia which accounts for 20% of the staple diet in Ethiopia today. However, its evolutionary history and spread is poorly understood. Archaeology could provide evidence of past use and contribute to our understanding of its early history, but so far, this has not transpired. Cultivated enset is clonally reproduced and seed production rarely occurs, therefore, looking for seed remains is futile and instead archaeobotanical research should focus on microfossils such as phytoliths. Phytoliths have been shown to be diagnostic for the presence of banana (Musa) and are expected to be similarly useful for identifying enset, but we need a better understanding of phytolith production and variability, and the extent to which this may be used to track domestication. The current study provides a fundamental baseline for the identification of Ensete phytoliths through the examination of phytoliths from leaves and other plant parts based on their size and shape. We consider the differentiation of phytoliths across a single plant, based on location in the leaf, the age of the leaf, and different organs of the plant. We also compare phytoliths in the Musaceae Family, and between the enset cultivar and wild samples. HIGHLIGHTSWe provide the first identification baseline to differentiate wild from domesticated enset by looking at variation across an individual enset plant and comparing these results to phytoliths from wild plants.

plant biology↗

bioRxiv2021

A stepwise route to domesticate rice by controlling seed shattering and panicle shape

Asian rice (Oryza sativa L.) is consumed by more than half of the worlds population. Despite its global importance, the process of early rice domestication remains unclear. During domestication, wild rice (O. rufipogon Griff.) acquired non-seed-shattering behaviour, allowing humans to increase grain yield. Previous studies argued that the sh4 mutation triggered a reduction in seed shattering during rice domestication; but our experiments using wild introgression lines of O. rufipogon show that the domesticated sh4 allele alone is insufficient for shattering loss. Here, we identified the interaction between three key mutations associated with the interruption of abscission layer formation and panicle architecture that were causal in early rice domestication. An interruption of abscission layer formation requires both sh4 and qSH3 mutations, presenting an apparent barrier to the selection of shattering loss. We identified a causal single-nucleotide polymorphism at qSH3 within the seed-shattering gene OsSh1, which is conserved in indica and japonica subspecies but absent in the circum-aus group of rice. Through harvest experiments, we demonstrated that seed shattering alone did not significantly impact yield; rather yield increases were observed with closed panicle formation controlled by SPR3, which is further augmented by the integration of sh4 and qSH3 alleles. Complementary manipulation of seed shattering and panicle shape result in a mechanically stable panicle structure. We propose a stepwise route for the earliest phase of rice domestication, wherein selection of visible SPR3-controlled closed panicle morphology was instrumental in the sequential recruitment of sh4 and qSH3, which led to the loss of shattering. Significance StatementRice is one of the most important crops worldwide. Loss of seed shattering in domesticated rice, previously attributed to single mutations such as those in sh4, is considered the principal genetic change which resulted in yield increases. However, we show that sh4 alone is insufficient and other genes, such as qSH3, are required to cause abscission layer disruption. The evolution of non-seed-shattering therefore required multiple mutations. Furthermore, shattering loss in genetic backgrounds of wild rice does not correspondingly increase yields. We have identified an interaction in which a second trait, closed panicle formation controlled by SPR3, that both increases the yield and facilitates recruitment of sh4 and qSH3, which synergistically augment yield, leading to a stepwise model for rice domestication.

plant biology↗

bioRxiv2021

The Evolutionary History of Wild, Domesticated, and Feral Brassica oleracea (Brassicaceae)

Understanding the evolutionary history of crops, including identifying wild relatives, helps to provide insight for designing new approaches in crop breeding efforts. Cultivated Brassica oleracea has intrigued researchers for centuries due to its wide diversity in forms, which include cabbage, broccoli, cauliflower, kale, kohlrabi, and Brussels sprouts. Yet, the evolutionary history of this species remains understudied. With such different vegetables produced from a single species, B. oleracea is a model organism for understanding the power of artificial selection. Persistent challenges in the study of B. oleracea include conflicting hypotheses regarding domestication and the identity of the closest living wild relative. Using a diversity panel of 224 accessions, which represents 14 different B. oleracea crop types and nine potential wild progenitor species, we integrate phylogenetic and population genetic techniques with ecological niche modeling, archaeological, and literary evidence to examine relationships among cultivars and wild relatives to clarify the origin of this horticulturally important species. Our analyses point to the Aegean endemic B. cretica as the closest living relative of cultivated B. oleracea, supporting an origin of cultivation in the Eastern Mediterranean region. Additionally, we identify several feral lineages, suggesting that cultivated plants of this species are able to revert to a wild-like state with relative ease. By expanding our understanding of the evolutionary history in B. oleracea, these results contribute to a growing body of knowledge on crop domestication that will facilitate continued breeding efforts including adaptation to changing environmental conditions.

evolutionary biology↗

bioRxiv2020

A novel cost framework reveals evidence for competitive selection in the evolution of complex traits during plant domestication

Most models of selection incorporate some notion of environmental degradation where the majority of the population becomes less fit with respect to a character resulting in pressure to adapt. Such models have been variously associated with an adaptation cost, the substitution load. Conversely, adaptative mutations that represent an improvement in fitness in the absence of environmental change have generally been assumed to be associated with negligible cost. However, such adaptations could represent a competitive advantage that diminishes resource availability for others and so induces a cost. This type of adaptation in the form of seedling competition has been suggested as a mechanism for increases in seed size during domestication, a trait associated with the standard stabilizing selection model. We present a novel cost framework for competitive selection that demonstrates significant differences in behaviour to environmental based selection in intensity, intensity over time and directly contrasts to the expectations of the standard model. Grain metrics of nine archaeological crops fit a mixed model in which episodes of competitive selection often emerge from shifting optimum episodes of stabilizing selection, highlighting the potential prevalence of the mechanism outlined here and providing a fundamental insight into the factors driving domestication.

evolutionary biology↗

bioRxiv2019

Genomic history and ecology of the geographic spread of rice

Rice (Oryza sativa) is one of the worlds most important food crops. We reconstruct the history of rice dispersal in Asia using whole-genome sequences of >1,400 landraces, coupled with geographic, environmental, archaeobotanical and paleoclimate data. We also identify extrinsic factors that impact genome diversity, with temperature a leading abiotic factor. Originating [~]9,000 years ago in the Yangtze Valley, rice diversified into temperate and tropical japonica during a global cooling event [~]4,200 years ago. Soon after, tropical rice reached Southeast Asia, where it rapidly diversified starting [~]2,500 yBP. The history of indica rice dispersal appears more complicated, moving into China [~]2,000 yBP. Reconstructing the dispersal history of rice and its climatic correlates may help identify genetic adaptation associated with the spread of a key domesticated species.\n\nOne sentence summaryWe reconstructed the ancient dispersal of rice in Asia and identified extrinsic factors that impact its genomic diversity.

evolutionary biology↗

bioRxiv2019

Reconstruction of nine thousand years of agriculture-based diet and impact on human genetic diversity in Asia

Domestication of crops and animals during the Holocene epoch played a critical role in shaping human culture, diet and genetic variation. This domestication process took place across a span of time and space, especially in Asia. We hypothesize that domestication of plants and animals around the world must have influenced the human genome differentially among human populations to a far greater degree than has been appreciated previously. The range of domesticated foods that were available in different regions can be expected to have created regionally distinct nutrient intake profiles and deficiencies. To capture this complexity, we used archaeobotanical evidence to construct two models of dietary nutrient composition over a 9000 year time span in Asia: one based on Larson et al. (2014) and measured through composition of 8 nutrients, and another taking into account a wider range of crops, cooking and lifestyle variation, and the dietary variables glycemic index and carbohydrate content. We hypothesize that the subtle dietary shifts through time and space have also influenced current human genetic variation among Asians. We used statistical methods BayeScEnv, BayeScan and Baypass, to examine the impact of our reconstructed long-term dietary habits on genome-wide genetic variation in 29 current-day Asian populations (Figure S1, Figure 1, Figure 2). Our results show that genetic variation in diet-related pathways is correlated with dietary differences among Asian populations. SNPs in five genes, GHR, LAMA1, SEMA3A, CAST and TCF7L2, involved in the gene ontologies salivary gland morphogenesis and negative regulation of type B pancreatic cell apoptotic process suggest that metabolism may have been primary targets of selection driven by dietary shifts. These shifts may have influenced biological pathways in ways that have a lasting impact on health. We present a case that archaeobotanical evidence can provide valuable insight for understanding how historical human niche construction might have influenced modern human genetic variation.\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC=\"FIGDIR/small/747709v1_fig1.gif\" ALT=\"Figure 1\">\nView larger version (26K):\norg.highwire.dtl.DTLVardef@1aa917corg.highwire.dtl.DTLVardef@135990forg.highwire.dtl.DTLVardef@1d3e0d3org.highwire.dtl.DTLVardef@14d5112_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Organization of the study and analysis pipeline. The two figures in column Archaeological data refer to the two constructed dietary models, with the boxes beside them referring to the dietary variables from each model.\n\nC_FIG O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC=\"FIGDIR/small/747709v1_fig2a.gif\" ALT=\"Figure 2\">\nO_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC=\"FIGDIR/small/747709v1_fig2b.gif\" ALT=\"Figure 2\">\nView larger version (52K):\norg.highwire.dtl.DTLVardef@1059950org.highwire.dtl.DTLVardef@94662dorg.highwire.dtl.DTLVardef@c01de2org.highwire.dtl.DTLVardef@ea07cb_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 2.C_FLOATNO Summary of Diet Model 1. a) Levels of nutrients contributed by domestication, based on Diet Model 1, as a sum total of values across all three population groups. b) Average levels of nutrients across the three time intervals (9000 YBP-present) in each region, based on Diet Model 1. Supplementary Tables 1-8 contain the data used to generate these figures.\n\nC_FIG

genetics↗

bioRxiv2018

A domestication history of dynamic adaptation and genomic deterioration in sorghum

The evolution of domesticated cereals was a complex interaction of shifting selection pressures and repeated introgressions. Genomes of archaeological crops have the potential to reveal these dynamics without being obscured by recent breeding or introgression. We report a temporal series of archaeogenomes of the crop sorghum (Sorghum bicolor) from a single locality in Egyptian Nubia. These data indicate no evidence for the effects of a domestication bottleneck but instead suggest a steady decline in genetic diversity over time coupled with an accumulating mutation load. Dynamic selection pressures acted sequentially on architectural and nutritional domestication traits, and adaptation to the local environment. Later introgression between sorghum races allowed exchange of adaptive traits and achieved mutual genomic rescue through an ameliorated mutation load. These results reveal a model of domestication in which genomic adaptation and deterioration was not focused on the initial stages of domestication but occurred throughout the history of cultivation.

evolutionary biology↗