Ex Situ Conservation

Dr. Johnny Randall, North Carolina Botanical Garden

The infamous Venus flytrap, Dionaea muscipula, found across North Carolina and into South Carolina, has been seen to be declining in recent years. It is currently under review for federal listing, is ranked G2 on NatureServe, and considered vulnerable by RedList. Threats to this charismatic plant include poaching, trampling, and changes in fire and hydrology. Dr. Randall of the North Carolina Botanical Garden is conducting a double-pronged conservation effort, collecting and banking seeds by maternal line, and doing genetic analysis across the populations. Results from the genetic data suggest four distinct clusters that closely match phylogeographic areas.

Contributing Author(s): 
Date Recorded: 
Wednesday, March 4, 2020

Wesley M. Knapp, North Carolina Natural Heritage Program

Preventing extinction is the lowest bar for conservation success we can set and the roll of ex situ conservation efforts in preventing extinction is becoming more significant. Continued work to document the extinct plants of North America north of Mexico has resulted in the discovery that up to 7 plants are extinct in the wild (EW). While these extinct plant taxa have no naturally occurring populations, they are still found in ex situ collections at botanical gardens. These collections may have issues in having full conservation value. Many collections were taken from few or single individuals and not necessarily intended to prevent the extinction of a species, but now represent the last known individuals. Some species reported as present in seed banks or botanical gardens are incorrectly identified. Additionally, botanical gardens having the last known individuals of a species are not necessarily aware of the significance of these collections. Evidence suggests a species has gone extinct while at a botanical garden because the specimen was destroyed before the significance of the collection was recognized. A prioritization of ex situ conservation efforts, using the best data is critical to prevent future extinction events. Single site global endemics or species of extremely narrow geographic distributions are the most susceptible to extinction. I will discuss a collaboration with NatureServe to identify global single site endemics that we hope will help prioritize seed banking and ex situ collections for these species following best practices to ensure quality/genetic diversity of collections. Additionally, an ongoing collaboration with the North Carolina Botanical Garden to prioritize the rarest plants in North Carolina for ex situ conservation efforts has already seen significant results.

Date Recorded: 
Wednesday, March 4, 2020

Dr. Sean Hoban, The Morton Arboretum, Taylor Callicrate, Species Conservation Toolkit Initiative, Chicago Zoological Society, Susan Deans, Plant Biology and Conservation Program, Northwestern University, Michael Dosmann, The Arnold Arboretum of Harvard University, Jeremie Fant, Chicago Botanic Garden, Oliver Gailing, University of Göttingen, Kayri Havens, Chicago Botanic Garden, Andrew Hipp, The Morton Arboretum, Priyanka Kadav, Michigan Technological University, Andrea Kramer, Chicago Botanic Garden, Matthew Lobdell, The Morton Arboretum, Tracy Magellan, Abby Meyer, Botanic Gardens Conservation International, Emma Spence, Center for Tree Science, The Morton Arboretum, Patrick Thompson, Auburn University Raakel Toppila, Seana Walsh, National Tropical Botanical Garden, Murphy Westwood, The Morton Arboretum, Jordan Wood, Illinois Natural History Survey, M. Patrick Griffith, Montgomery Botanical Center

Ex situ collections such as botanic gardens inspire and educate the public, provide material for scientific study, and produce material for ecological restoration. The challenge for an efficient and effective collection is safeguarding high genetic and ecological diversity in as few samples as possible, due to the relatively small resources available for conservation. A botanic garden might have resources to maintain a few to a few hundred plants of priority species in conservation collections, but not the thousands that seed banks can preserve. Providing scientifically grounded recommendations for the number of individuals that need to be conserved, and how to collect from the wild and manage collections over time, is a pressing need. Previous work using case studies and modeling of important biological traits has established the fact that some species must be sampled differently, and that widely used standard sample sizes might not be optimal practice for capturing the maximum diversity. We present here a comparative study of ex situ gene conservation in three southeastern oaks (Quercus georgiana, oglethorpensis and boyntonii) and two magnolias (M. pyramidata and asheii). Specifically, we use genetic datasets and resampling algorithms to: quantify how much genetic diversity has been captured in a global network of botanic garden collections currently, resample the wild population genetic datasets to determine how much genetic diversity could be captured by varying sample sizes, determine minimal sampling needed to capture 70% and 95% of the genetic diversity, and use a diminishing returns method to calculate optimal stopping points- when additional collection effort no longer provides sufficient gains. Between 62 and 72% of genetic diversity is currently safeguarded for the oaks, and about 80% is conserved for the magnolias. The recommended collection size depends on key decisions by curators about the type of genetic diversity that is valued, but may range from approximately 50 to 200 individuals. We hope that these findings motivate future seed collections from wild provenances for botanic garden collections and stimulate discussion on ex situ gene conservation goals and outcomes.

Date Recorded: 
Wednesday, March 4, 2020

Christina Carrero, The Morton Arboretum, Emily Coffey, Atlanta Botanical Garden, Patrick Griffith, Montgomery Botanical Center

A 2019 study by Griffith, et al. showed that gardens must collaborate to conserve genetic diversity, especially for exceptional species whose seeds cannot be properly seed banked. This process of capturing the genetic diversity of exceptional species in ex situ collections requires a tailored strategy for each species, emphasizing the need for a coordinated effort by botanic gardens. By working through networked consortia, botanic gardens can implement innovative solutions to safeguard these species in a changing world. We highlight a new initiative to conserve genetic diversity of exceptional species through a coordinated effort of gardens, using oak, magnolia, maple, and cycad consortia as case-studies. We outline the challenges and opportunities of conserving exceptional species within these distinct plant groups, providing solutions and recommendations that can guide collection efforts for other groups.The audience will gain a better understanding of exceptional plant species, conservation challenges, and innovative solutions. Participants will be provided with the tools and framework to join or create a consortium as a way to contribute to the conservation efforts of threatened exceptional plants. Our hope is that these presentations will gain new consortium members, growing a diverse, coordinated network of institutions and experts who will advance our goal in preventing the extinction of the world’s exceptional species. Ultimately, by working through networked consortia, the sum of our efforts is greater than its parts.

Contributing Author(s): 
Date Recorded: 
Wednesday, March 4, 2020

Josette Tin, Taylor La Val, Sean Lahmeyer, John Trager, Raquel Folgado*, The Huntington Library, Art Collections and Botanical Gardens, San Marino, CA., United States, *Speaker

Succulent plants are significant to the horticultural industry, and they are also sources for food, fibers, medicines, and cosmetics. The main threats for the wild population of these often emblematic plants are human activities, such as over-collection in the wild. The Huntington Desert Garden holds one of the largest ex-situ collections of succulent plants. Besides the traditional propagation methods for the field collections and the cryopreservation of seeds, in vitro repositories have been created to assure the preservation of the clonal type plants, which often have historic and botanical value. Experiments of droplet-vitrification based techniques have been used to cryopreserve clonal accessions of aloes and agaves. Apical shoot tips of 1 mm size from 5-week- old in vitro plantlets (aloe or agave) were exposed to loading solution for 20 min at room temperature, dehydrated with Plant Vitrification Solution 2 (PVS2) for different times (from 0 to 90 min) at 0 °C, transferred to aluminum foil strips and directly plunged into liquid nitrogen. For re-warming, aluminum strips were rinsed in unloading solution for 20 min at room temperature. Explants were transferred to regeneration media and kept in the dark for one week. In additional experiments, shoot-tips excised from donor plants pretreated onto a sucrose- enriched medium for two weeks were also submitted to cryoprocedure. The pretreatment with sucrose- supplemented medium improved the regeneration of both aloe and agave cryopreserved explants. The optimized protocols that have been developed for Aloe fievetii and Agave sobria spp frailensis (70 % and 90 % of plants recovered after cryopreservation, respectively) are being tested for other Aloe and Agave species. Regenerated plants were acclimated to ex vitro conditions.

Date Recorded: 
Thursday, July 25, 2019

Megan Philpott, Valerie PenceL*, Cincinnati Zoo & Botanical Garden, United States *Speaker

Threats to global plant biodiversity compel the need for ex situ collections of species worldwide. However, the subset of species known as exceptional plants are often overlooked. These species produce few or no seeds or produce recalcitrant seeds. The Center for Conservation and Research of Endangered Wildlife (CREW) at the Cincinnati Zoo & Botanical Garden maintains a liquid nitrogen bank of exceptional plant seeds and tissues known as the CryoBioBank®. CREW has partnered with the Lyon Arboretum in Honolulu to develop cryopreservation protocols for 21 endangered exceptional Hawaiian plant species and bank them in the CryoBioBank®. To date, micropropagation protocols to produce target tissues have been tested in 13 species, and cryopreservation protocols have been tested in 7 species. As an example, in Cyrtandra gracilis, micropropagation on medium containing 2mg/L of the auxin indole-3-acetic acid and 0.1mg/L of the cytokinin 6-benzylaminopurine induces shoot organogenesis on excised leaves. These leaves were dissected into leaf bud segments and compared with shoot tips for survival after liquid nitrogen storage. Cryopreservation of shoot tips using droplet vitrification (DV) with PVS2 yielded 0% survival, while leaf bud segments yielded 20% survival. DV using PVS3 increased survival in these leaf buds to 60%. Cryopreservation of leaf bud segments immediately after bud primordia formed yielded 25% survival compared to 50% survival if the buds were left to develop into shoots before cryopreservation. Shoot tips from another species, Melicope mucronulata, have been banked in the CryoBioBank® using the DV method following an experimental survival rate of 57% after 2 days of pre- culture on a 0.3M mannitol medium instead of one day on 0.3M mannitol and one day on 0.5M mannitol medium. This project will result in the long-term protection of many endangered exceptional Hawaiian species that would otherwise be unbankable using conventional methods. (Supported by IMLS grant #MG-30-17-0055-17).

Contributing Author(s): 
Date Recorded: 
Thursday, July 25, 2019

Jeremie Fant, Chicago Botanic Garden

This talk highlights the Chicago Botanic Garden’s work on adapting zoo conservation approaches for exceptional plant species. Challenges in ex situ conservation include genetic issues that arise from limited numbers of individuals and founders, and husbandry and hybridization issues encountered during the growing out of collections. A significant advantage in plant conservation is that seeds can be collected for a vast majority of plants. One example is the CBG's Dixon Tallgrass Prairie Seedbank, which has more than 1,700 species and 10,000 accessions. 

Although banking options are more restricted in animal conservation, other approaches used by the zoo community can be adapted to improve success rates in ex situ plant conservation programs. One such approach is pedigree analysis, which shifts focus from high numbers of individuals to equal numbers of founders. The CBG is testing pedigree analysis on several species, as illustrated by work done with Brighamia insignis. The steps include tracking founders by creating a pedigree of collections, calculating relatedness between all individuals, and making management decisions. This method enables researchers to identify genetically valuable individuals across collections, use life span of a species in collections to determine the sample size needed to maintain a collection, and identify crosses needed to increase diversity and improve collection robustness.

One of the next steps planned by the CBG is to identify collection plants less valuable for maintaining genetic diversity, and use them to test restoration techniques. The ultimate goal is to use ex situ collections for restoration of rare species in the field.

Contributing Author(s): 
Date Recorded: 
Thursday, May 2, 2019