From Plant Press, Vol. 25, No. 4, October 2022.
By Jun Wen, Alicia Talavera and Greg Stull
Curator Jun Wen and her collaborators have been conducting extensive field work on the grape family Vitaceae, especially the grape genus Vitis. This summer Wen traveled throughout the southern US in early July with postdoctoral fellow Alicia Talavera, and to Mexico throughout August with Research Collaborator Greg Stull to collect Vitaceae and specimens of other plant groups significant for biogeographic studies of the Northern Hemisphere. The two trips in the USA and Mexico resulted in approximately 800 specimens representing one of the most important sets of Vitaceae collections from North America (including Mexico), many specimens of Northern Hemisphere intercontinental disjunct plants, and also economically important wild relatives of food and drug plants.
Grape hunting in the southern US: North America is one of the two major centers of diversity for the grape genus Vitis. It is home to approximately 30 of the 75 species in the genus. The wine grape Vitis vinifera is one of the earliest domesticated crops and is considered the most economically important fruit crop in the world. Despite the economic and evolutionary interests, the taxonomy of the grape genus remains controversial, largely due to extremely complex histories of hybridizations and morphological plasticity. Studies in the Wen lab incorporating evidence from the field, herbarium, and genome sequences are ongoing to unravel the complex evolutionary history of Vitis, especially several species complexes in North America, e.g., the Vitis cinerea complex, and the Vitis aestivalis complex. Talavera’s postdoctoral research focuses on clarifying the taxonomy and evolutionary diversification of North American Vitis and exploring phylogeographic patterns in this region. In order to expand the population sampling for Talavera’s postdoctoral research, Wen and Talavera conducted a field trip to the southern US, covering Virginia, North Carolina, Tennessee, Alabama, Florida, Mississippi, Louisiana, Arkansas, Missouri, Kentucky, Indiana, Ohio, and West Virginia.
Wen and Talavera collected approximately 300 specimens of Vitis, and many other taxa (e.g., Angelica, Ampelopsis, Arundinaria, Carya, Clematis, Cyrilla, Halesia, Juglans, Magnolia, Nekemias, Nyssa, Parthenocissus, Polymnia, Prunus, Sagittaria, Sabatia, Trepocarpus, and Wisteria). This southern US field trip was critical for Talavera’s Vitis studies and provided the opportunity for her to gain a broad understanding of species variations in natural populations. They collected in diverse types of habitats across the eastern deciduous forests in North America, including the mesophytic forests in the Appalachians, the southern mixed oak-pine forests, the coastal cypress-tupelo swamp forests, the Mississippi alluvial plain forests, and the rich oak-hickory forests in the Ozarks.
Overall, the trip was a great experience for Talavera, who came to the Smithsonian from southern Spain in January 2022. Talavera returned to Washington D.C. with a greater appreciation of the ecological and cultural diversity in the areas where grapes thrive. They look forward to their phylogenomic results from these collections and the insights into the evolutionary diversification history of North American Vitis and the drivers that have shaped the species diversity in this region.
Left: Jun Wen collecting Magnolia macrophylla in the mixed deciduous and pine forest of Alabama. (photo by Alicia Talavera)
Middle: Muscadine grape Vitis rotundifolia in Biloxi, Mississippi. (photo by Jun Wen)
Right: Alicia Talavera processing silica gel preserved DNA samples in our Grape Escape. (photo by Jun Wen)
Journey into tropical Mexico: Tropical Mexico remains the key to understanding the diversity and evolutionary diversification of Central American Vitaceae. This is particularly true for the taxonomically difficult genera Vitis and Cissus, which are in need of detailed study to clarify species boundaries and species numbers in the Americas. Tropical Mexico also represents one of the keys to better understanding the biogeographic history of the Northern Hemisphere, including the fragmentation of mesic forests across the North American continent during episodes of aridification and glaciation over the past 10 million years. With these research problems in mind, Wen and Stull conducted a major field trip to Mexico, in collaboration with Dr. Marcelo Pace from the Universidad Nacional Autónoma de México (UNAM). Joining them was one of Pace’s graduate students, Angelica Quintanar, who is starting her doctoral dissertation research on Vitaceae wood anatomy and the evolutionary adaptation of the wood characters. Quintanar’s collecting goal aligned perfectly with that of the others: to collect as many Vitaceae specimens as possible, including extra collections of stem and wood samples for subsequent anatomical work.
Left: Jun Wen, Marcelo Pace and Angelica Quintanar collecting Ampelocissus erdvenbergiana near Valladolid, Yucatán. (photo by Greg Stull)
Middle: Greg Stull pressing specimens near Jalcomulco, Veracruz (photo by Angelica Quintanar)
Right: Jun Wen collecting in a remnant cloud forest near San Cristóbal de las Casas in Chiapas. (photo by Angelica Quintanar)
Prior to going to the field, Wen and Stull spent a few days working in the National Herbarium MEXU in UNAM, and were kindly welcomed by Dr. Susana Magallón Puebla, the director of the UNAM Institute of Biology, and by Dr. Gerardo Salazar, the director of MEXU. The MEXU herbarium is truly a gem and is the largest herbarium in Latin America. Recently it has been fully digitized, making more than 1.3 million specimens at MEXU online to the scientific community and the public. While at UNAM, Wen gave a well-received seminar on “Collections-based systematics in the age of genomics and informatics” in the Institute of Biology. Salazar and Dr. Lidia Cabrera also gave Wen and Stull a terrific tour of the National Biodiversity Pavilion, a new museum that was recently opened to showcase Mexico’s mega-biodiversity using collections, the tree-of-life theme, stories of scientists connecting with the public, and the behind-the-scenes labs (still under construction). The creation of the museum was inspired in part by visits to the Smithsonian’s Natural History Museum by Carlos Slim, the Mexican philanthropist who funded the Biodiversity Pavilion project.
Over the course of about 20 days in the field, the team made over 500 plant collections mostly emphasizing the entire southern half of Mexico and also in central to northeastern Mexico, driving approximately 3,800 miles across the states of Puebla, San Luis Potosi, Tamaulipas, Veracruz, Campeche, Tabasco, Yucatan, Chiapas, Oaxaca, Morelos, and Mexico. In distance this is roughly equivalent to taking the long route between Key West, Florida, and Vancouver, British Columbia. The resulting collections included about 150 accessions of Vitaceae and 350 accessions of plants that are important for further understanding Northern Hemisphere biogeography.
Left: Abundant lianas in humid forest of Reserva de la Biósfera de Los Tuxtlas, Veracruz. (photo by Greg Stull)
Right: Stem cross-section of the liana, Cissus erosa, northeast of Ciudad Valles, San Luis Potosí. Angelica Quintanar and Marcelo Pace are studying wood anatomy of Vitaceae so a large collection of Vitaceae wood was made during the trip. (photo by Jun Wen)
Wen and Stull both have research interests in studying Northern Hemisphere biogeography. Wen has a long history of studying disjuncts across the Northern Hemisphere, particularly genera disjunct between North America and Asia, and a number of the specimens collected are relevant for this pattern (e.g., Bocconia, Dendropanax, Saurauia). Stull is especially interested in exploring the evolutionary patterns and processes of plant disjunctions between the eastern United States and the montane zones in Mexico, an underexplored biogeographic pattern that includes more than 90 species or closely related species disjunct between these regions. One of the most iconic examples of this disjunction, Liquidambar styraciflua, was collected at several locations in Puebla and Veracruz. Other noteworthy collections include the root parasite Bdallophytum (Cytinaceae), the liana genus Dichapetalum (Dichapetalaceae), and Petenaea, a previously unplaced genus now treated as its own family, Petenaeaceae. The latter collection was made by graduate student Quintanar, who started her first botanical collection number of her career during this trip.
Reflecting on the field trips to Mexico, it was well noted that the lowland habitats across southern Mexico have changed drastically with the loss of primary forests in the last 35 years. The team had a difficult time relocating populations of the Mexican Ampelocissus (Vitaceae) along the Gulf coast. The New World Ampelocissus is a small lineage of 5-6 species that often occur in primary seasonally dry tropical forests. This lineage of Ampelocissus is sister to the economically important genus Vitis, and the locals in Puebla have been making wine from the fruits. We had a taste of the Ampelocissus wine bought from a small village store in Puebla at our farewell party with our UNAM friends on the eve of our departure; it was sweet, tasting like the muscadine wine from southeastern US. We hope that the rapid economic growth in Mexico will also go along with serious conservation efforts and strong public education programs about the tropical forests and the natural treasures in these vulnerable forests.
Left: Jun Wen discussing the ethnobotanical use of Ampelocissus acapulcensis with local villager Mr. Andres near Jolalpan in Puebla. (photo by Angelica Quintanar)
Right: Marcelo Pace pressing specimens near Xicotepec de Juárez, Puebla. (photo by Jun Wen)
Work is now underway to sequence and morphologically examine the collected Vitaceae specimens, facilitating phylogenomic and taxonomic studies that should lead to the recognition of several new species of Vitis and Cissus and clarify the early diversification of the grape genus. The disjuncts collected also lay an important foundation for future work by Stull and Wen, in collaboration with botanists at UNAM, that will unravel one of the last major puzzles in Northern Hemisphere biogeography: what is the evolutionary history behind the eastern US-Mesoamerican cloud forest floristic disjunction?
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