Publications by authors named "Leilani Lucas"

6 Publications

  • Page 1 of 1

Geographic mosaics and changing rates of cereal domestication.

Philos Trans R Soc Lond B Biol Sci 2017 Dec;372(1735)

Institute of Archaeology, UCL, London, UK

Domestication is the process by which plants or animals evolved to fit a human-managed environment, and it is marked by innovations in plant morphology and anatomy that are in turn correlated with new human behaviours and technologies for harvesting, storage and field preparation. Archaeobotanical evidence has revealed that domestication was a protracted process taking thousands of plant generations. Within this protracted process there were changes in the selection pressures for domestication traits as well as variation across a geographic mosaic of wild and cultivated populations. Quantitative data allow us to estimate the changing selection coefficients for the evolution of non-shattering (domestic-type seed dispersal) in Asian rice ( L.), barley ( L.), emmer wheat ( (Shrank) Schübl.) and einkorn wheat ( L.). These data indicate that selection coefficients tended to be low, but also that there were inflection points at which selection increased considerably. For rice, selection coefficients of the order of 0.001 prior to 5500 BC shifted to greater than 0.003 between 5000 and 4500 BC, before falling again as the domestication process ended 4000-3500 BC. In barley and the two wheats selection was strongest between 8500 and 7500 BC. The slow start of domestication may indicate that initial selection began in the Pleistocene glacial era.This article is part of the themed issue 'Process and pattern in innovations from cells to societies'.
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http://dx.doi.org/10.1098/rstb.2016.0429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5665816PMC
December 2017

Between China and South Asia: A Middle Asian corridor of crop dispersal and agricultural innovation in the Bronze Age.

Holocene 2016 Oct 1;26(10):1541-1555. Epub 2016 Jun 1.

Institute of Archaeology, University College London, UK.

The period from the late third millennium BC to the start of the first millennium AD witnesses the first steps towards food globalization in which a significant number of important crops and animals, independently domesticated within China, India, Africa and West Asia, traversed Central Asia greatly increasing Eurasian agricultural diversity. This paper utilizes an archaeobotanical database (AsCAD), to explore evidence for these crop translocations along southern and northern routes of interaction between east and west. To begin, crop translocations from the Near East across India and Central Asia are examined for wheat () and barley () from the eighth to the second millennia BC when they reach China. The case of pulses and flax () that only complete this journey in Han times (206 BC-AD 220), often never fully adopted, is also addressed. The discussion then turns to the Chinese millets, and , peaches () and apricots (), tracing their movement from the fifth millennium to the second millennium BC when the reaches Europe and Northern India, with peaches and apricots present in Kashmir and Swat. Finally, the translocation of rice from China to India that gave rise to rice is considered, possibly dating to the second millennium BC. The routes these crops travelled include those to the north via the Inner Asia Mountain Corridor, across Middle Asia, where there is good evidence for wheat, barley and the Chinese millets. The case for rice, apricots and peaches is less clear, and the northern route is contrasted with that through northeast India, Tibet and west China. Not all these journeys were synchronous, and this paper highlights the selective long-distance transport of crops as an alternative to demic-diffusion of farmers with a defined crop package.
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http://dx.doi.org/10.1177/0959683616650268DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5125436PMC
October 2016

Ancient crops provide first archaeological signature of the westward Austronesian expansion.

Proc Natl Acad Sci U S A 2016 06 31;113(24):6635-40. Epub 2016 May 31.

School of Archaeology, University of Oxford, Oxford OX1 2PG, United Kingdom; Department of Archaeology, Max Planck Institute for the Science of Human History, D-07743 Jena, Germany.

The Austronesian settlement of the remote island of Madagascar remains one of the great puzzles of Indo-Pacific prehistory. Although linguistic, ethnographic, and genetic evidence points clearly to a colonization of Madagascar by Austronesian language-speaking people from Island Southeast Asia, decades of archaeological research have failed to locate evidence for a Southeast Asian signature in the island's early material record. Here, we present new archaeobotanical data that show that Southeast Asian settlers brought Asian crops with them when they settled in Africa. These crops provide the first, to our knowledge, reliable archaeological window into the Southeast Asian colonization of Madagascar. They additionally suggest that initial Southeast Asian settlement in Africa was not limited to Madagascar, but also extended to the Comoros. Archaeobotanical data may support a model of indirect Austronesian colonization of Madagascar from the Comoros and/or elsewhere in eastern Africa.
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http://dx.doi.org/10.1073/pnas.1522714113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4914162PMC
June 2016

Current perspectives and the future of domestication studies.

Proc Natl Acad Sci U S A 2014 Apr 22;111(17):6139-46. Epub 2014 Apr 22.

Durham Evolution and Ancient DNA, Department of Archaeology, Durham University, Durham DH1 3LE, United Kingdom.

It is difficult to overstate the cultural and biological impacts that the domestication of plants and animals has had on our species. Fundamental questions regarding where, when, and how many times domestication took place have been of primary interest within a wide range of academic disciplines. Within the last two decades, the advent of new archaeological and genetic techniques has revolutionized our understanding of the pattern and process of domestication and agricultural origins that led to our modern way of life. In the spring of 2011, 25 scholars with a central interest in domestication representing the fields of genetics, archaeobotany, zooarchaeology, geoarchaeology, and archaeology met at the National Evolutionary Synthesis Center to discuss recent domestication research progress and identify challenges for the future. In this introduction to the resulting Special Feature, we present the state of the art in the field by discussing what is known about the spatial and temporal patterns of domestication, and controversies surrounding the speed, intentionality, and evolutionary aspects of the domestication process. We then highlight three key challenges for future research. We conclude by arguing that although recent progress has been impressive, the next decade will yield even more substantial insights not only into how domestication took place, but also when and where it did, and where and why it did not.
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http://dx.doi.org/10.1073/pnas.1323964111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035915PMC
April 2014

Convergent evolution and parallelism in plant domestication revealed by an expanding archaeological record.

Proc Natl Acad Sci U S A 2014 Apr 21;111(17):6147-52. Epub 2014 Apr 21.

Institute of Archaeology, University College London, London WC1H OPY, United Kingdom.

Recent increases in archaeobotanical evidence offer insights into the processes of plant domestication and agricultural origins, which evolved in parallel in several world regions. Many different crop species underwent convergent evolution and acquired domestication syndrome traits. For a growing number of seed crop species, these traits can be quantified by proxy from archaeological evidence, providing measures of the rates of change during domestication. Among domestication traits, nonshattering cereal ears evolved more quickly in general than seed size. Nevertheless, most domestication traits show similarly slow rates of phenotypic change over several centuries to millennia, and these rates were similar across different regions of origin. Crops reproduced vegetatively, including tubers and many fruit trees, are less easily documented in terms of morphological domestication, but multiple lines of evidence outline some patterns in the development of vegecultural systems across the New World and Old World tropics. Pathways to plant domestication can also be compared in terms of the cultural and economic factors occurring at the start of the process. Whereas agricultural societies have tended to converge on higher population densities and sedentism, in some instances cultivation began among sedentary hunter-gatherers whereas more often it was initiated by mobile societies of hunter-gatherers or herder-gatherers.
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http://dx.doi.org/10.1073/pnas.1308937110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035951PMC
April 2014

Stress-induced tradeoffs in a free-living lizard across a variable landscape: consequences for individuals and populations.

PLoS One 2012 20;7(11):e49895. Epub 2012 Nov 20.

Department of Biology, Utah State University, Logan, Utah, United States of America.

Current life history theory suggests that the allocation of energetic resources between competing physiological needs should be dictated by an individual's longevity and pace of life. One key physiological pathway likely to contribute to the partitioning of resources is the vertebrate stress response. By increasing circulating glucocorticoids the stress response can exert a suite of physiological effects, such as altering immune function. We investigated the effects of stress physiology on individual immunity, reproduction and oxidative stress, across an urban landscape. We sampled populations in and around St. George, Utah, examining corticosterone in response to restraint stress, two innate immune measures, reproductive output, and the presence of both reactive oxygen metabolites and antioxidant binding capacity, in populations of common side-blotched lizards (Uta stansburiana) experiencing variable levels of environmental stress. Additionally, using capture-mark-recapture techniques, we examined the relationships between these physiological parameters and population-level differences. Our results reveal elevated physiological stress corresponds with suppressed immunity and increased oxidative stress. Interestingly, urban populations experiencing the most physiological stress also exhibited greater reproductive output and decreased survival relative to rural populations experiencing less physiological stress, demonstrating a tradeoff between reproduction and life maintenance processes. Our results suggest that environmental stress may augment life history strategy in this fast-paced species, and that shifts in life history strategy can in turn affect the population at large. Finally, the urban environment poses definite challenges for organisms, and while it appears that side-blotched lizards are adjusting physiologically, it is unknown what fitness costs these physiological adjustments accrue.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0049895PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502225PMC
May 2013
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