California

Sula Vanderplank, San Diego Zoo Global

The cross-border seedbanking initiative affectionately known as ‘Baja Rare’ targets around 65 taxa that are documented to be rare, threatened or endangered both sides of the MX/US border.  Many of these plants are far better-known in the US than in Mexico and as a result, our program has had to start with significant reconnaissance and surveys to find the populations historically documented.  In four cases (Streptanthus campestris, Navarrettia peinsularis, Erythranthe purpurea and Acmispon haydonii), expert botanical participation has revealed mis-identifications which make each of these three plants significantly rarer than previously assumed.  This project has also revealed at least one new highly restricted endemic taxon and multiple taxa worth of further study.  The role of the expert botanist is essential.

Date Recorded: 
Friday, October 9, 2020

Billy Sale, Califonia Botanic Garden

California Botanic Garden (CalBG) is in the process of seed bulking three rare species of Atriplex from populations originating in southern California. Atriplex coronata var. notatior (G4T1), Atriplex parishii (G2G3) and Atriplex serenana var. davidsonii (G5T1). To better inform the project, propagation trials were performed prior to seed bulking in order to examine germination pretreatments. Gibberellic acid was identified as the most effective pretreatment for all three species and used to initiate seed bulking efforts. This project additionally sought to examine growth in four container sizes and three different soil types for seed production. Each species was planted in four container sizes (6 inch treepots, 6 inch squares, 3 gallons, and 4 inch trays) and three different soil types (restoration potting mix, restoration with lime, and restoration with additional peat moss), which were replicated in all pot sizes in order to see how seed production was impacted. Seed produced from each container was collected separately. Preliminary results and methods will be shared.

Date Recorded: 
Thursday, October 8, 2020

Tony Gurnoe, San Diego Botanic Garden

Baccharis vanessae, Encinitas baccharis, was originally described from a small population in Encinitas, California, just a couple of miles from the San Diego Botanic Garden (SDBG). The last individual to live within the garden was documented in 1997 and has not been observed since. The nearby type locality has also dwindled to just over two dozen individuals. Last year the team from the SDBG joined the efforts to conserve Encinitas baccharis by monitoring this population and collecting seeds from the few maternal lines available. Most of these seeds went into seed banks as part of the California Biodiversity Initiative and California Plant Rescue programs, but a cohort were also grown in SDBG’s nursery. This fall Baccharis vanessae will be reintroduced to the botanical garden with the goal of gaining a better understanding of how the species behaves in varying soil types and exposure scenarios. Meanwhile, SDBG staff continue to work with other populations, other institutions, and various other agencies toward the culmination of major in situ reinforcement and establishment of long-term management plans for Baccharis vanessae.

Contributing Author(s): 
Date Recorded: 
Friday, October 9, 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

Kristen Hasenstab-Lehman, C. Matt Guilliams, Santa Barbara Botanic Gardens

Dithyrea maritima (Davidson), or beach spectaclepod, is a dune specialist endemic to coastal dunes from central California, United States, to northwestern Baja California, Mexico. Individuals of this perennial herb spread by rhizomes, forming a diffuse colony of ramets, each terminating in rosette of 1 to several fleshy leaves, and a two-chambered fruit (silicle). It is listed on the California Native Plant Society Rare and Endangered Plant Inventory on list 1B.1 and was listed as Threatened under the California Endangered Species Act. Studied occurrences of the self-incompatible D. maritima have low seed set, though manual outcrosses boost seed production. Knowledge of the distribution of genotypes on the landscape is be a critical first step toward any number of recovery actions. In this study, we sample from approximately 30 individuals from each of eleven samplinglocations spanning the range of the taxon from Morro Bay, CA, USA to San Quintín, Baja CA, MX. We used double digestion RADseq to prepare libraries for high-throughput sequencing, assemble the dataset in ipyrad producing 5092 SNPs, and analyze population genomics of the species. We place the observed population genomic patterns into the context of regional biogeography, and conclude with recommendations for managing the species.

Date Recorded: 
Wednesday, September 11, 2019

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, 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

Dr. Stephanie Steele, San Diego Zoo Global 

The Torrey pine (Pinus torreyana) is a rare, iconic species that occurs naturally in only two locations in Southern California: in coastal San Diego County and on Santa Rosa Island. The species is of particular conservation concern due to prolonged drought which has increased susceptibility of trees to attack by the bark beetle Ips paraconfusus. The Ips beetle has posed a significant challenge for trees in the mainland population in recent years. While Torrey pines harbor a remarkably low level of genetic diversity, it is possible that genetic variation underlies resistance to beetles and thus determines, at least partially, which trees survive. To test this, we are using RNA-Seq to survey functional genetic diversity in Torrey pines that either succumb to mortality by bark beetles or remain asymptomatic. We aim to 1) characterize functional genetic diversity in the species, particularly in defense-related genes, 2) test for genetic differentiation between affected and asymptomatic trees, and 3) identify whether specific genetic variants are associated with survival. This work will offer insight into the adaptive potential of Torrey pines to respond to continued bark beetle outbreaks and will inform future restoration efforts for this iconic species.

Contributing Author(s): 
Date Recorded: 
Wednesday, September 11, 2019

Jill Hamilton, North Dakota State University

Species evolutionary potential is tightly linked to both the amount and distribution of genetic variation available through which natural selection may act. Rare species present particular challenges under rapidly changing conditions where the genetic consequences of rarity may limit species ability to adapt to ongoing change. Thus in a rapidly changing environment, maintenance of genetic variation within and across populations becomes an increasingly important target for species conservation. Here, I examine the role genetic rescue may play in the maintenance of a rare species' evolutionary potential. Exhibiting exceptionally low levels of genetic variation, endangered Torrey pine, one of the rarest pines in the world and endemic to California, may represent a candidate for genetic rescue. Restricted to just one island and one mainland population, preliminary evaluation of fitness traits in Torrey pine indicate F1 hybrids, representing a cross between mainland and island trees, are more fit relative to parental populations when grown in a common environment. This suggests that in the short-term, gene flow between populations may provide necessary genetic variation to persist in changing conditions. However, there remain gaps in our understanding of the long-term consequences of genetic rescue. Torrey pine, a poster child for rarity in forest trees, provides an ideal system for which to track the short and long-term consequences of genetic rescue.

Date Recorded: 
Wednesday, September 11, 2019

Kyle L. Gunther, Sula Vanderplank, Jon P. Rebman, Andres Orduño Cruz, & Lluvia Flores-Rentería, San Diego State University, San Diego Natural History Museum, San Diego Zoo Global, Centro de Investigaciones Biológicas del Noroeste

California and the Baja peninsula are home to high levels of floral abundance, diversity, and endemism. Much of this region is part of a biodiversity hotspot and therefore a conservation priority. The Mission Manzanita (Xylococcus bicolor) is endemic to this area, an ecologically and ethnobotanically important shrub, and the sole member of a monotypic genus within Ericaceae. Xylococcus bicolor is narrowly distributed from the middle of Baja California to the Los Angeles area, and has been predicted to experience up to 88% habitat loss due to climate change and development. However, little is known about its population structure, demographics, and genetic diversity, which may be useful information for conservation purposes. In order to fill this gap in knowledge, we are studying these aspects from a genetic perspective. Using a genome skimming technique to reveal thousands of single nucleotide polymorphisms, we are analyzing the population structure, genetic diversity, gene flow, and effective population sizes across the X. bicolor distribution. Preliminary results suggest the presence of intraspecific divergence and population structure, while niche models show loss of suitable habitat using climate change scenarios. We hope our study will provide useful information for land management and conservation decisions.

Date Recorded: 
Wednesday, September 11, 2019