Phylogenetics and evolution of potato virus V: another potyvirus that originated in the Andes

Potato virus V (PVV) causes a disease of potato (Solanum tubersosum) in South and Central America, Europe and the Middle East. We report here the complete genomic sequences of 42 new PVV isolates from the potato’s Andean domestication centre in Peru, and of eight historical or recent isolates from Europe. When the principal open reading frames (ORFs) of these genomic sequences together with those of nine previously published genomic sequences were analysed, only two from Peru and one from Iran were found to be recombinant. The phylogeny of the 56 non-recombinant ORF sequences showed that the PVV population has two major phylogroups, one of which forms three minor phylogroups (A1-A3) of isolates, all of which are only found in the Andean region of South America (Peru and Colombia), and the other forms two minor phylogroups, a basal one of Andean isolates (A4) that is paraphyletic to a crown cluster containing all the isolates found outside South America (World). This suggests that PVV originated in the Andean region with only one minor phylogroup spreading elsewhere in the world. In minor phylogroups A3 and A4, there were subclades on long branches containing isolates from S. phureja evolving more rapidly than the others, and these interfered with dating calculations. Although no temporal signal was directly detected among the dated non-recombinant sequences, PVV and potato virus Y (PVY) are from the same potyvirus lineage and are ecologically similar, so “sub-tree dating” was done using a single maximum-likelihood phylogeny of PVV and PVY sequences, and PVY’s well-supported 157 CE “time to most common recent ancestor” was extrapolated to date that of PVV as 29 BCE. Thus the independent historical coincidences supporting the datings of the PVV and PVY phylogenies are the same; PVV arose at least 2,000 years ago in the Andes, and was taken to Europe during the Columbian Exchange, where it diversified around 1853 CE soon after the European potato late blight pandemic. PVV is likely to be more widespread than currently realised, and of biosecurity relevance for world regions that have not yet recorded its presence.

Non-uniform tropical forest responses to the ‘Columbian Exchange’ in the Neotropics and Asia-Pacific

It has been suggested that Iberian arrival in the Americas in 1492 and subsequent dramatic depopulation led to forest regrowth that had global impacts on atmospheric CO2 concentrations and surface temperatures. Despite tropical forests representing the most important terrestrial carbon stock globally, systematic examination of historical afforestation in these habitats in the Neotropics is lacking. Additionally, there has been no assessment of similar depopulation–afforestation dynamics in other parts of the global tropics that were incorporated into the Spanish Empire. Here, we compile and semi-quantitatively analyse pollen records from the regions claimed by the Spanish in the Atlantic and Pacific to provide pan-tropical insights into European colonial impacts on forest dynamics. Our results suggest that periods of afforestation over the past millennium varied across space and time and depended on social, economic and biogeographic contexts. We argue that this reveals the unequal and divergent origins of the Anthropocene as a socio-political and biophysical process, highlighting the need for higher-resolution, targeted analyses to fully elucidate pre-colonial and colonial era human–tropical landscape interactions.

The Failed Globalization of Psychedelic Drugs in the Early Modern World

This article reassesses what has been called ‘the puzzle of distribution’: why did some drugs rapidly emerge as global consumer goods in the era of the Columbian Exchange, whereas others remained restricted to regional centres of usage? I argue here that the early modern concept of transplantation allows us to approach the puzzle of distribution from a novel perspective. Early modern intoxicants were not disaggregated, free-floating commodities. Their consumption and trade took place within a larger constellation of social codes, cultural practices, ecologies, and built environments. Psychedelic compounds such as peyote and ayahuasca serve here as case studies for examining how the globalization of drugs involved far more than the transport of the substances themselves. Despite their centrality to numerous societies throughout the pre-Columbian Americas, the larger ‘assemblage’ of material cultures, cultural assumptions, and religious meanings that accrued around these substances made it difficult for them to follow the same paths as commodified drugs like cacao or tobacco.

Maize on the Move: The Diffusion of a Tropical Cultivar across Europe

This article examines the transfer and reception of maize into Europe in the wake of the Columbian Exchange. Treating maize as a plant – and reviewing familiar historical sources through the lens of the plant’s likes and dislikes, its requirements and inherent traits – provides us with a novel source of information about how maize might have moved through European spaces, even in cases where the traditional historical record is silent. This article will make use of such data, employing current genetic research to interpret art and textual sources. I will show that all maize originally transported to Europe hailed from one slim gene pool. I will argue that the unique characteristics of those seeds impacted on the way maize fit into European ecosystems, and consequently into European cultures.

Africa and the Americas in the Columbian Exchange: an Interview with Judith Carney

Africa and the Americas in the Columbian Exchange: an Interview with Judith Carney

Potato Virus A Isolates from Three Continents: Their Biological Properties, Phylogenetics, and Prehistory

Forty-seven potato virus A (PVA) isolates from Europe, Australia, and South America’s Andean region were subjected to high-throughput sequencing, and 46 complete genomes from Europe (n = 9), Australia (n = 2), and the Andes (n = 35) obtained. These and 17 other genomes gave alignments of 63 open reading frames 9,180 nucleotides long; 9 were recombinants. The nonrecombinants formed three tightly clustered, almost equidistant phylogroups; A comprised 14 Peruvian potato isolates; W comprised 37 from potato in Peru, Argentina, and elsewhere in the world; and T contained three from tamarillo in New Zealand. When five isolates were inoculated to a potato cultivar differential, three strain groups (= pathotypes) unrelated to phylogenetic groupings were recognized. No temporal signal was detected among the dated nonrecombinant sequences, but PVA and potato virus Y (PVY) are from related lineages and ecologically similar; therefore, “relative dating” was obtained using a single maximum-likelihood phylogeny of PVA and PVY sequences and PVY’s well-supported 157 CE “time to most common recent ancestor”. The PVA datings obtained were supported by several independent historical coincidences. The PVA and PVY populations apparently arose in the Andes approximately 18 centuries ago, and were taken to Europe during the Columbian Exchange, radiating there after the mid-19th century potato late blight pandemic. PVA’s phylogroup A population diverged more recently in the Andean region, probably after new cultivars were bred locally using newly introduced Solanum tuberosum subsp. tuberosum as a parent. Such cultivars became widely grown, and apparently generated the A × W phylogroup recombinants. Phylogroup A, and its interphylogroup recombinants, might pose a biosecurity risk.