conservation genetics

Lauren Eserman, Atlanta Botanical Garden

Conradina glabra, or Apalachicola rosemary, is a federally listed endangered species that exists only on a small area of sandhill in Liberty County, Florida. Forestry practices in the last 100 years have resulted in declining populations of C. glabra. In the wild, plants produce very few seeds, but small plants that resemble seedlings are commonly found. Through a grant from the US Fish and Wildlife Service, we are using molecular genetic techniques to understand whether C. glabra is reproducing clonally or via sexual reproduction as well as what factors encourage seed germination. To address this question, we sampled plants from forty locations across Torreya State Park in a spatially explicit experimental design. A plant in the center of a large cluster of individuals was marked and samples were taken from plants in all four cardinal directions from the central plant at designated distances. From these samples, we generated RADseq data resulting in >10,000 SNPs from 564 individual plants. Analyses are still ongoing, but early results point to spatially structured genetic variation. Individuals share highly similar genotypes at distances < 1 meter; however, are genetically distinct at distances greater than 1 meter. These results suggest that Conradina glabra is perhaps clonal at very small geographic scales but is generally reproducing sexually across its range. Furthermore, we identify areas with unique genetic variation that is important for conservation. The results of this study are being communicated to land managers who are tasked with preserving this species on the ground.

Date Recorded: 
Friday, October 9, 2020

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

Jessica L. Allen, PhD, Southeastern Center for Conservation, Atlanta Botanical Garden

Dr. Allen outlines a conservation genomics approach to assessing genetic diversity between geographically separated populations of the Rock Gnome lichen, a Southern Appalachian endemic. Her results show that each locale sampled has a genetically distinct population. This suggests that the management plan for this lichen should include protecting all of the occurrences in order to preserve the greatest amount of genetic diversity within the species.

Date Recorded: 
Wednesday, March 4, 2020

Dr. Rebecca Hale, University of North Carolina, Asheville

Wayne Morgan, UNC Asheville Biology

Elise Powell, UNC Asheville Biology

Leila Beikmohamadi, Western Carolina University, Psychology

Mara Alexander, US Bureau of Land Management

Caroline Kennedy, UNC Asheville Biology

Jennifer Rhode Ward, UNC Asheville Biology

Pitchers of the purple pitcher plant, Sarracenia purpurea, are distinctly shorter and broader than those of other Sarracenia, which allows them to hold pools of rainwater. These phytotelma are subsequently colonized by a diverse invertebrate and microbial community, which appears to influence plant growth and reproductive effort. S. purpurea readily hybridizes with congeners to produce rosettes with morphologically intermediate pitchers, which are colonized by a similarly diverse, but less dense, community. Here, we tie together two aspects of our research investigating the ecology of hybrid pitcher plants. We show that morphology of hybrids is intermediate between that of their parent species, S. purpurea var. montana and S. jonesii (mountain sweet pitcher plant). We also show that phytotelma community diversity and number of colonists varies with pitcher morphology. Finally, we related these data to recent analyses that link phytotelma communities to plant growth and reproductive effort, and consider the implications for the conservation of cooccurring, rare pitcher plants.

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

Dr. Jeremie Fant, Chicago Botanical Garden

Many land managers are aware of the value of genetic data for making important decisions for the management of rare species. In the ever-expanding world of Genomics, practitioners now have access to more comprehensive and accurate data. However, the speed of change can make it hard to keep up to date with the technology and to appreciate what it offers, not to mention how to access this technology. After hosting a workshop on genomics tools in Hawai`i, it become clear that there can be a large gap between needs and access. After the workshop, we surveyed the needs of Land Managers working on the restoration of Lobeliod species – one of the most endangered taxonomic groups in Hawai`i. The aim of the survey was to 1) identify common needs, 2) clarify what genomics can offer (potential and limitations), and 3) develop ideas for the best ways of moving forward. This presentation will cover the lesson learned from this survey and hopefully help other land managers identify how they can too incorporate genomics into their management plans.

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

Shawn C. McCourt, Sally M. Chambers, and Bruce K. Holst, Marie Selby Botanical Gardens

The genus Harrisia (Cactaceae) comprises 20 narrowly endemic species of night-blooming cacti with two widely separated geographic ranges, including South America south of Amazonia, as well as the West Indies and southern Florida. Commonly known as aboriginal prickly-apple, H. aboriginum is a sprawling, multi–stemmed, columnar cactus endemic to ancient native American shell mounds, as well as coastal berms, coastal grasslands, and maritime hammocks in four counties along the southwest coast of Florida. This federally-listed species is in steep decline, primarily due to the development of beachfront property, invasive species dominance, and the erosion of coastal barrier islands. Some populations have disappeared entirely. Researchers at MSBG have been conducting an inventory of extant populations, assessing the health of each population, and determining what genetic variation (if any) occurs across the species’ geographic range. When possible, a small portion of seed has been collected for seed banking and to grow plants for the augmentation of shrinking populations and introduction to ecologically suitable sites situated above projected rises in sea level. To date, we have visited nine sites and collected detailed demographic data for 89 plants. Spines were collected from all 89 plants for DNA extraction and the testing and developing of microsatellite loci. Seeds from seven fruits were collected from three sites. Data presented represent the preliminary findings of our work, which has a focus on the importance of maintaining genetic diversity in ex situ collections for the purpose of rare plant conservation.

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

Joe Davitt, Institute for Conservation Research, San Diego Zoo Global

Maintaining a plant species’ genetic diversity can contribute to adaptive potential, prevent inbreeding effects, and potentially preserve traits such as drought tolerance and disease resistance, all of which are critical in a changing climate. Seed collections are often the best method of conserving the genetic diversity of rare plant populations ex-situ, however most seed collections are made with no available genetic data from the target species. Ideally, this genetic data would give us a clear picture of which populations are the most critical to conserve and how genetically structured a species’ populations are in relationship to one another, but this can be a time consuming and costly process. Seed collection protocols, such as those published by the Center for Plant Conservation, can inform our general best practices, but as seed collectors we must also infer best practice on a species by species basis. The life history and reproductive biology of the target species, as well as our sampling methods can greatly impact the effectiveness of seed collections to capture the entire target populations’ genetic diversity. Taking all available information about a species into consideration, we can infer the best seed collection methods to ensure genetic conservation.

Contributing Author(s): 
Date Recorded: 
Tuesday, September 10, 2019

Christy Powell, San Diego Zoo Global

San Diego Zoo Global's Christy Powell opens the 2019 Plant Genetics Conservation workshop at San Diego Zoo Global with a welcome to participants, some background on San Diego Zoo Global, and an inspirational story about a fern that has benefitted from conservation efforts.

Contributing Author(s): 
Date Recorded: 
Tuesday, September 10, 2019

Christy Powell, Brian Dorsey, San Diego Zoo Global, Huntington Botanical Garden

As the most endangered group of plants on the planet, cycads (Cycadales) face a number of threats to their continued existence. Efforts to preserve these iconic plants (in situ reserves and ex situ collections) could benefit greatly from a better understanding of population genetic dynamics and recent demographic history. We have shown that within the genus Dioon most species likely diverged between 30-80 kya. This very recent divergence along with long generation times suggests the possibility of shared polymorphisms across species and potentially incomplete speciation between accepted taxa. Conversely, the distribution of populations and the pollination/dispersal system suggests that migration rates may be quite low. Determining the relative influence of these processes will better inform conservation efforts. Given the nearly 50 Gb genomes of this group, we are using a hybrid of two RADseq methods to produce high coverage/highly multiplexed reduced representation data sets to assess connectivity, historical demography, and genetic diversity. While data for Dioon is still coming in, we have a pilot study using the same technique to assess the genetic diversity among Encephalartos latifrons plants held in botanical gardens in the USA, which we plan to extend to include wild populations with similar goals.

Contributing Author(s): 
Date Recorded: 
Tuesday, September 10, 2019