From Plant Press, Vol. 26, No. 3, July 2023.
By Gary A. Krupnick
The Smithsonian’s Department of Botany and the United States Botanic Garden (USBG) convened the 20th Smithsonian Botanical Symposium, “New Horizons in the Study of Neotropical Floras,” at the National Museum of Natural History (NMNH) in Washington, D.C., on May 19, 2023. The hybrid event brought together five engaging speakers who presented their research to both in-person and virtual audiences from around the world. The invited speakers included scientists specializing in the natural history, geographic diversity, evolution, and conservation of plants in the Neotropics. The origins, evolution, and even species composition of the Neotropical flora are far from understood and are the subject of active research in the face of ongoing habitat loss and climate change.
Eric Schuettpelz, NMNH Chair of Botany, welcomed the audience to the symposium by highlighting the mission of the Smithsonian as well as the immense collections housed in the museum and especially the U.S. National Herbarium. Susan Pell, USBG Executive Director, also provided opening remarks and gave an orientation to the USBG, including its history, a description of the living collections, current online and in-person programming, and their scientific and conservation partnerships.
Laurence Dorr, NMNH Department of Botany, then presented the José Cuatrecasas Medal for Excellence in Tropical Botany to Rafaela Campostrini Forzza, an accomplished scientist, science administrator, and educator. While Forzza was unable to attend in person, she accepted the award through a recorded video which was shared with the audience. In the recording she described how her work on Neotropical plants has focused on research, collections, conservation, and collaborations with local communities and policy makers. She expressed her thanks and gratitude to those who share her passion, colleagues who have inspired and supported her research, communities that have welcomed her into their homes and landscapes, and the plants and animals that have inspired her with their beauty and resilience.
Left: Eric Schuettpelz moderates the 20th Smithsonian Botanical Symposium.
Right: Laurence Dorr presents the 20th José Cuatrecasas Medal for Excellence in Tropical Botany to Rafaela Campostrini Forzza. (photos by Ken Wurdack)
The first presentation of the symposium was delivered by W. John Kress from the Smithsonian’s National Museum of Natural History. His talk, "The complexity of nature: A coevolutionary mosaic of plants and animals in the Neotropics,” explored the ecology and evolution of tropical plants and the animals they interact with, focusing specifically on heliconias and hummingbirds. He also described a DNA barcoding study examining the interactions between Costa Rican Zingiberales and their herbivorous beetles, showing a complex interaction involving specialists and generalists. He then shifted to hummingbirds and showed videos of bird bills fitting precisely in the shape of Heliconia flowers.
Kress described in detail a study system in the Eastern Caribbean—two species of Heliconia and one species of hummingbird. What he found was a complex sexual specialization of pollinators. The hummingbird, Anthracothorax jugularis, is sexually dimorphic with males having large bodies and straight bills feeding exclusively on Heliconia caribaea, and females being smaller with curved bills feeding exclusively on H. bihai. In addition to sexual and trait dimorphism, Kress also found behavioral dimorphism, with females as trapliners and males as territorial defenders using the Heliconia in their territory as bait for females. The study site of Dominica is where these two Heliconia species come together, but the study system becomes much more complex as you look north where only H. caribaea is found or south where only H. bihai is found—in those regions, the plants become compatible with both male and female hummingbirds and the plant size changes as well. Kress then presented an hypothesis of the speciation events that gave rise to the Caribbean Heliconia species. He concluded his talk with mention of the Anthropocene and the impacts of altered habitats and invasive species.
The second speaker of the day was M. Alejandra Jaramillo from Universidad Militar Nueva Granada in Colombia, who spoke about, “Piper evolution and ecology: A peppery tale from the understory.” She presented three “tales”: species descriptions, tropical diversity in the mountains, and a witch tale. She began with a focus on the Emerald Forest, Serrania de las Quinchas in Boyaca, Colombia and the genus Piper, a group with 2,000 species. She described the natural history of P. quinchasense with its peltate leaves, the high-elevation P. alwynii, and P. piluliferum, P. globosurachis, and P. nudilimbum, each with globulous inflorescences. She spoke about the phylogenetic classification of Piper, once having 11 Neotropical groups but now with additional smaller groups that have been identified using new samples, new sequences, and teamwork.
Jaramillo then discussed how diversity is distributed along a gradient in the mountains. She described a biogeographic study involving three altitudinal zones: 500-1,100 m, 1,300-1,600 m, and >2,000 m. She found that species richness is a good proxy for phylogenetic diversity and functional diversity, with the lowlands being more diverse than the uplands. She addressed questions about how communities are assembled, the roles of morphology and physiology, and how climate change affects diversity in tropical mountain systems. She wrapped up her talk with a story about witches’ broom and a tri-trophic interaction among plants, herbivores, and bacteria. When phytoplasma bacteria infect a plant’s phloem, symptoms include the production of multiple small leaves or the modification of floral organs into leafy tissues. She addressed how prevalent phytoplasmas are in nature, their role in maintaining populations, and the impacts of climate change and deforestation. She concluded with a tribute to female tropical botanists.
Gregory W. Stull from the Smithsonian’s National Museum of Natural History then spoke on, “Plant migrations and the assembly of the Neotropical flora: insights from the Mesoamerican-eastern North American biogeographic disjunction pattern.” Stull focused his talk on the strong but understudied floristic connections of Mesoamerica with the mesic forests of eastern North America, how Mesoamerica represents a refuge for boreotropical lineages, and the disjunction that exists between these two regions. He described the boreotropical flora as a thermophilic forest that grew across the northern hemisphere from around 66 to 34 million years ago (the end of the Eocene) during a period of global warming. As the climate cooled from the Oligocene onward, the boreotropical forests started to deteriorate and were replaced by more distinctly temperate and deciduous forests. Stull explained how the montane regions of Mesoamerica represent an important refuge for the boreotropical flora. He described lines of evidence for this refuge which include Mesoamerican lineages that have boreotropical fossil records and how the oldest fossil evidence of North American taxa comes from boreotropical forests.
Stull described the disjunction pattern between eastern North American and Mesoamerica as coming in two forms: within-species disjunctions and closely-related lineage disjunctions. Stull explained that this study system has the potential to answer questions about species responses to climate change, speciation dynamics, and discovery of undocumented biodiversity. Stull suggested that this disjunction pattern originated about 15 million years ago after the Mid-Miocene Climatic Optimum, making it a relatively young disjunction pattern. While the eastern North American populations occur at lower elevations and are more geographically continuous, the Mesoamerican populations are at higher elevations (above 1,000 m) and are more spatially fragmented. This has implications for speciation events and population genetic diversity in cloud forests. Stull addressed topics ranging from the number of taxa that show a disjunction pattern (over 100 examples), insights and limitations from the fossil record (a general North-to-South migration pattern of these lineages from eastern North America to Mesoamerican highlands), and insights from molecular data (similar migration patterns as those revealed in the fossil record). Stull concluded by talking about future directions and ways that this study system might explain how plants respond to climate change.
Alejandra Vasco from the Botanical Research Institute of Texas spoke next about, “Accelerating lineage discovery to document Neotropical fern diversity.” Vasco says that with more than 1,450 known fern species, Colombia’s fern diversity is unparalleled elsewhere in the Americas, and yet, fern diversity in Colombia remains poorly known. Vasco spoke about the Ferns of Colombia project, which aims to improve our understanding of how many ferns exist in Colombia, where the ferns occur, how many of them are threatened with extinction, how to train the next generation of fern botanists, and the importance of spreading the love for ferns and nature. She talked about two recent large expeditions and four smaller expeditions that resulted in 1,300 new collections and thousands of photographs. Some collections were of species that hadn’t been collected for 150 years while others were new records for Colombia.
Vasco spoke about a web portal that her team developed that unifies the taxonomic resources for the ferns of Colombia. Her project is also producing genomic resources though the banking of silica-dried tissue and the generation of target-capture sequence data for all Colombian fern species. Another goal is to accelerate the pace of taxonomy and lineage discovery, and thus, she spoke about leveraging taxonomic and genomic resources, training students, and developing collaborations. Vasco described a strategy employing next-generation lineage discovery in three focal groups—Elaphoglossum, Pleopeltis, and Pityrogramma. This strategy will uncover cryptic diversity, such as polyploids and hybrids. She finished her talk with a discussion about IUCN conservation assessments and about community outreach using a curated iNaturalist project and a project that combines art with science (art exhibitions and YouTube videos).
The final invited speaker of the day was Paola Pedraza-Peñalosa from the New York Botanical Garden who spoke on “Documenting the flora of a diversity hotspot: Las Orquideas National Park, Colombia.” The Las Orquideas National Park sits at the confluency of two important diversity hotspots–the tropical Andes and the Chocó biogeographic regions. Pedraza shared her main objectives: to catalogue the park’s vascular flora, to increase botanical knowledge of its priority areas, to enhance data accessibility, and to develop tools for conservation. She described the sharp gradient of altitude found within the park, with the Chocó rainforest at 300–1,000 m, the premontane forest at 1,000–2,000 m, and the montane forest at 2,000–3,100 m. Since most historical collections have been along accessible areas, she described the need to explore more remote locations. She described six large expeditions which had a goal of collecting plant groups that are either hard to identify in the field, hard to collect, very labor intensive, or very diverse such as ferns and orchids.
The expeditions described by Pedraza led to the discovery of a rare new ecosystem in the park: the first known paramo (3,100–3,400 m) at the locality. Overall, three years of field work and herbarium work uncovered a flora of 176 families, 756 genera, and 2,476 species of vascular plants. More species are yet to be documented, however, since Pedraza’s team was unable to explore at elevations below 800 m, and the team had a difficult time collecting tall trees and epiphytes and identifying difficult taxonomic groups. Among the most prominent plant families in Las Orquideas are the Orchidaceae, Rubiaceae, Melastomataceae, and Ericaceae. Unlike the Amazon, only 5-10% of the taxa are large woody species, while 50% are non-woody plants or epiphytes. Over 50% of the genera are monospecific, and thus the flora has many unique lineages. Pedraza’s group has since produced a dynamic electronic checklist, gifted Colombian herbarium specimens to many herbaria around the world, and made plant identification guides for school children and park visitors.
The final session of the Symposium was a panel discussion with all five speakers and the moderator Susan Pell (USBG). Questions from the in-person and virtual audiences and the moderator included: where do you see hope in Neotropical plant conservation and plants abilities to survive in their changing climate?; is there a future of using drones to assist in collecting in tropical areas?; why does the Andean flora consist of 50% monospecific genera?; can you describe the power and value of sharing your research in public forums like art exhibits?; and, what are the next areas that need to be explored in the Neototropics? To hear the fascinating responses to these questions by all five speakers, a video of the panel discussion is available on YouTube.
The talks ended with Kirk Johnson, NMNH Sant Director, delivering concluding remarks. Johnson emphasized that museums play an important role in research with its collections, scientists, scholars, students, and their role in communication. He warned that, “if we don't work to save the Amazon basin and the biodiversity and the surrounding areas, we're going to lose the planet.” Johnson highlighted how museums need to come together to combine efforts to tackle these challenges. He spoke about some of his paleobotanical research and gave recognition to successful activities and accomplishments happening at NMNH, such as the complete digitization of the US National Herbarium.
The Symposium concluded with evening events at the U.S. Botanic Garden’s Conservatory, including a closing reception and a poster session.
Elsa Peters Ruiz de Chávez (left photo) and Daniela Canelón and Santos Miguel Niño (right photo) present posters during the closing reception and poster session at the US Botanic Garden. (photo by Ken Wurdack)
An optional field trip before the symposium allowed attendees the opportunity to partake in two behind-the-scenes tours of the Joseph F. Cullman 3rd Library of Natural History, an event hosted by Smithsonian Libraries. Located at NMNH, the library featured a wide selection of stunning books highlighting historic publications in the study of Neotropical flora. Leslie Overstreet, Curator of Natural History Rare Books, presented such books as Hans Sloane’s A Voyage to the Islands Madera, Barbados, Nieves, S. Christophers and Jamaica (1707), Nicolai Josephi Jacquin’s Selectarum Stirpium Americanarum Historia (1763), and set number one of Botanica Magnifica (2008), a five-volume, double-elephant folio-sized work of two hundred fifty photographic images of plants by photographer Jonathan Singer and botanists John Kress and Marc Hachadourian.
The symposium attracted an audience of 260 attendees, with roughly half in-person and half online. Those who viewed the proceedings virtually watched from 22 countries from around the world. All speaker presentations, opening remarks, the presentation of the José Cuatrecasas Medal, and the roundtable panel discussions were recorded and are available for viewing on NMNH’s Natural History for Scientists YouTube page.
The 21st Smithsonian Botanical Symposium is tentatively scheduled to take place at the National Museum of Natural History and the U.S. Botanic Garden on Friday, May 17, 2024. The topic is still to be determined. Check the Department of Botany’s website for updates.
Video playlist of the 20th Smithsonian Botanical Symposium
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