The Plant Press

Analyzing tree data to prevent extinctions

From Plant Press, Vol. 23, No. 2, April 2020.

Sara Oldfield, Co-Chair IUCN SSC Global Tree Specialist Group

This year biodiversity and climate change will be in the headlines as politicians take stock of progress towards global targets and make plans for increasing concerted action. Tree species are of fundamental importance both as elements of biodiversity and in adaptation and mitigation measures addressing climate change. One way botanists around the world are contributing their expertise to support scaled-up environmental action is through the Global Tree Assessment (GTA). This is a global effort to assess the risk of extinction faced by each and every tree species by the end of 2020. The goal is to pull together all existing data on the conservation status of tree species and add conservation assessments to the IUCN Red List of Threatened Species for all previously unassessed tree species. This is a huge collaborative effort, managed and coordinated by Botanic Gardens Conservation International (BGCI) and the IUCN Global Tree Specialist Group (GTSG) working together with many national and local institutions and individuals. The Smithsonian Institution is contributing significantly to this global initiative which will be used to prioritize and significantly increase conservation efforts to ensure that no tree species goes extinct.

Talisia furfuracea (Sapindaceae) is endemic to the Guiana Shield. This species is being evaluated for its conservation status as part of the Global Tree Assessment. (photo by Pedro Acevedo-Rodríguez)

An initial task in the GTA was to produce the first global checklist of the world's tree species. This in itself was no easy feat given that plant habit is not routinely recorded in taxonomic checklists. The list of around 60,000 tree species with accepted names and country level distribution took two years to produce by consulting a range of plant databases, over 500 scientific references, and working with around 80 tree experts. The list is maintained online by BGCI as the GlobalTreeSearch database at https://www.bgci.org/resources/bgci-databases/globaltreesearch/. It remains a dynamic resource reflecting taxonomic and nomenclatural changes and is a baseline for monitoring progress towards the GTA. GlobalTreeSearch has also been connected to the World Flora Online, which is being developed as the open-access, web-based compendium of all the world’s plant species.

Evaluating the conservation status of tree species for the GTA follows the guidelines for applying the IUCN Red List Categories and Criteria. Each species is assessed by considering information on its area of distribution, population size and trend, habitat, uses, and threatening factors. Herbarium specimens and collection data continue to be of primary value in carrying out conservation assessments. Wherever possible these are combined with field knowledge of botanical experts. Often there is limited information on individual tree species and further fieldwork would greatly enhance our knowledge. Nevertheless, we need to use what information is currently available rather than waiting and, at the same time, identify those species which are poorly known and in need of further research. Concerns about loss of particular areas of forest and similar indirect information can form part of the species assessment process.

Physical distancing telework testimonial

From Plant Press, Vol. 23, No. 2, April 2020.

By Erika Gardner

As someone who cares for the wellbeing and maintenance of the collection, as a part of the Core Collection Management team, I have been preoccupied with the following task while telecommuting. It pains me to not be physically in the collection but I am diligently working from home, updating transcriptions in the database, modifying and updating protocols which were last updated in 2016, and mounting unforsaken Poaceae specimens from home.

About 9 months ago I moved out of the heart of DC to the Maryland suburbs. We have a yard now and it is our first spring in this new house! In between work breaks I have been out exploring our modest plot. I have decided that since I am the “land manager” I have the liberty to collect and press the flora from my backyard. So far I have collected a native violet, Viola sororia and a non-native Vinca minor (escaped from my neighbor’s yard into mine). I have a Trillium sp. on the verge of flowering! I can’t wait to see it in flower to figure out what species it could be. I am using a children’s mini plant press that I purchased from the National Gallery of Art as a stocking stuffer. Glad I bought this in December because I am getting a lot of use out of it while in quarantine.

Having moved from California five years ago, core collections manager Erika Gardner is collecting local flora and familiarizing herself with the names and distinctive characteristics of east coast native plants, resourcefully using a miniature plant press to press specimens in her neighborhood and utilizing the digital records to verify correct identification. Here she is pressing a native Viola sororia and a non-native Vinca minor. (photos by E. Gardner)

Botanical research in the age of COVID-19

From Plant Press, Vol. 23, No. 2, April 2020.

By Julia Beros

Life does not exist alone. It’s 12:30PM and the only indication of my coworkers is how slow shared documents begin loading in my remote desktop. During this time of great uncertainty, misinformation, and vulnerability, it can be a challenge to normalize and re-create the habitual, it can even be an insult to the desire to be more “useful.” But developing faith in our shared and now virtual community necessitates that we keep on keepin’ on. The speed at which the Smithsonian Institution reacted to the velocity of COVID-19’s approach in preparing ourselves to transition from a day-to-day routine working physically with specimens and collections to exclusively accessing them remotely and continuing research in the face of unknown challenges is not only impressive but admirable to see our passions overcome the immediate fight or flight reactionary instinct. It is clear as well, that as we log in from our various homes to access the collections, that the continued efforts of digitization at the Smithsonian are a true asset to research and maintaining continuity with the ever-changing infrastructure of our world.

Members of the Department of Botany meet over Zoom on March 30, 2020, for a departmental afternoon tea. All were welcome to participate, including researchers, collection staff, administrators, fellows, and associates. The National Museum of Natural History in Washington, DC, remains temporarily closed to support the effort to contain the spread of COVID-19.

Like much of the world right now, the conveyor belt, photographing specimens and creating up to 4,000 images a day, has paused, and so have the dedicated contractors who facilitate the process. In this moment of reflection we can see everything that the team accomplished thus far: of a projected 5 million botanical specimens, 2.83 million have been imaged and or recorded in the database (not including those digitized by the Botany IT team previous to the installation of the conveyor belt, or historic photographs and other media), making them available through the online catalog. With the effort of Open Access the information of our specimen image collections is not only digitally safeguarded, but it is accessible by the public for free to look at, use, and download. Nearing our last phase of imaging, the team had just begun digitizing the Poaceae (grasses). Previously about 24,000 bamboo specimens along with the type collections, were digitized, leaving an estimated 500,000 unimaged grasses of which we have already made headway with over 100,000 specimens. At our respective homes, the team continues working on a backlog of specimen data (as we are still inundated with the roses and mustards), checking for completeness and accuracy, uploading to the database, and making the data searchable to expedite access to the collections.

Prunus is a model clade for investigating tropical-to-temperate transitions

From Plant Press, Vol. 23, No. 2, April 2020.

By Richie Hodel

For over a century, biologists have observed a latitudinal gradient in species diversity in many clades across the Tree of Life, with greater species richness near the equator. However, we lack consensus about the cause of this biogeographic pattern and several hypotheses have been proposed. The tropical conservatism hypothesis (TCH) is one explanation for the observed latitudinal gradient; the TCH states that the relatively high biodiversity of the tropics is explained primarily by the geographic extent of tropical taxa during the past ~55 million years and the subsequent evolutionary conservation of environmental niches.

Recent large-scale phylogenetic studies using over 10,000 angiosperm species identified general trends describing how the latitudinal species gradient affects plant diversity. Notably, few lineages transitioned from tropical environments to temperate ones, which may be explained by the difficulty of acquiring the substantial adaptations necessary to tolerate the cooler conditions in temperate zones. One of the goals of my postdoctoral work at the National Museum of Natural History (NMNH) is to use the genus Prunus (Rosaceae) to test the TCH.

Prunus contains approximately 250-400 evergreen and deciduous species occurring throughout the temperate regions of the northern hemisphere and in the tropics and subtropics. Phylogenetic studies of Prunus have used several chloroplast and nuclear loci and produced key insights, but many questions remain. The phylogenetic position of Prunus within Rosaceae is uncertain, and phylogenetic relationships within Prunus are not yet fully resolved. Discord among chloroplast, nuclear, and morphological phylogenies suggests ancient polyploidy and/or hybridization may have impacted the evolutionary history of Prunus, and more data are needed to resolve the phylogeny (see figure below).

Cytonuclear discord in Prunus: the plastid phylogeny (left) infers a monophyletic racemose group, but the nuclear phylogeny (right) yields a paraphyletic racemose group. ‘A’ represents taxa in the Prunus-Amygdalus group, ‘B’ shows taxa in the Cerasus group, and ‘C’ depicts the polypoid racemose Prunus, which includes Laurocerasus, Padus, Pygeum, and Maddenia. The question mark shows the location on the phylogeny where ancient allopolyploidy may have occurred, leading to uncertain phylogenetic relationships in the racemose Prunus. Figure modified from Chin et al. 2014 and Zhao et al. 2016.