conservation efforts

Maria Teresa Gonzalez-Arnao, Pedro Isidro-Adolfo, Maria F. NetzahualcoyotlMata, Lourdes G. Iglesias Andreu, Jaime Martínez-Castillo, University of Veracruz, INBIOTECA, CICY, 

In this study we used six selected ISSR primers (T05, T06, C07, UBC823, UBC825, UBC848) to evaluate the genetic stability during cryopreservation of vanilla (V. planifolia) shoot-tips subjected to a Droplet-Vitrification (D-V) protocol using PVS2 solution for dehydration. We studied the impact of tissues culture and cryopreservation, assessing the effect of multiplication cycles of donor plantlets, with few (less than 4) and multiples (more than 12) subcultures, from which were isolated the shoot-tips to be cryopreserved. It was also assessed the effect of treatments, which allowed growth recovery after immersion in liquid nitrogen. To apply D-V procedure, shoot-tips were dissected of motherplantlets with few or multiple subcultures, and then preconditioned for 1 day on MS semisolid medium supplemented with 0.3M trehalose, loaded in a solution of 0.4M sucrose + 2M Glycerol and exposed to PVS2 solution for 30 min at room temperature prior to the ultra-rapid cooling in liquid nitrogen placed on droplets of PVS solution over aluminium cryoplates. The analysis of electrophoretic profiles of in vivo plants and in vitro plantlets with different subculture numbers revealed a total of 153 bands and 21.2% of polymorphism. UPGMA dendrogram based on Nei’s genetic distance demonstrated that plants with multiple subcultures induced the greatest genetic variation but kept a high (0.90) similarity index. The electrophoretic profiles of all successive steps of D-V protocol revealed a total of 199 bands and 34.2% polymorphism. Treatment with PVS2 promoted the greatest variation and continued declining the level (0.816) of similarity compared to that of the plantlets with multiples subcultures. Plantlets regenerated after cryopreservation kept the same level (0.819) of those treated with PVS2, indicating that liquid nitrogen immersion did not induce a further genetic variation. Our studies revealed that both, subculturing number and the composition of vitrification solution influenced genetic variability.

Date Recorded: 
Tuesday, July 23, 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

Manuel Luján, Jian Liu, Nathalie Nagalingum, California Academy of Sciences, Kunming Institute of Botany, Chinese Academy of Sciences

Rare plant species exhibit narrow geographic distribution and are often considered to have smaller populations and lower levels of genetic diversity compared to their more common relatives. The genus Cycas includes about 117 species, 32 of which are native to Australia and 20 occur only in the subtropical and tropical regions of Queensland. Most of the Queensland species of Cycas are known from only a handful of localities and their population characteristics remain to be investigated. Our main objective was to assess genetic diversity and population size of the rare species of Cycas and compare it them the more widely distributed species. We used RADseq to generate genomic data to estimate percentage of polymorphic loci (P), heterozygosity (Ho and He) and nucleotide diversity (π), and footage from unmanned aerial vehicles to estimate populations size. Our preliminary results suggest that rare species (C. terryana) have levels of genetic diversity that are comparable to more common species (C. ophiolitica and C. media). Population size of rare species (e. g. C. tuckeri) tend to be smaller than more common species (C. cairnsiana). Given that Cycas are long-lived plants, rare and small populations constituted by old plants, may be maintaining ancestral allelic variants from previously more widespread and common populations. Further study considering the populations demographic structure are needed to better understand this pattern and inform conservation efforts.

Date Recorded: 
Wednesday, September 11, 2019

Oliver A. Ryder, Director, Conservation Genetics, Kleberg Endowed Chair, San Diego Zoo Institute for Conservation Research

In January, 1975 genetics studies commenced at the San Diego with group of researchers who would become the core of CRES, the Center for Reproduction of Endangered Species – now the San Diego Zoo Institute for Conservation Research. Founded by Kurt Benirschke, MD, cell culture and chromosomal analyses were first established. In June of that year, the first postdoctoral fellow joined the team, Oliver Ryder. By the time that Dr. Benirschke left the employ of the Zoo (to join its Board of Trustees), the research disciplines had expanded to include reproductive sciences, endocrinology, behavior and virology. Ryder oversaw the continuing development of the Frozen Zoo® and projects in molecular evolution, systematics, hybridization, speciation, kinship analyses, and population genetics, each area evolving as new technologies became available. An historical overview, the continuing development of conservation genetics at ICR in the era of genomics, and the incorporation of advanced cellular technologies for genetic rescue into our Conservation Genetics toolkit will be presented.

Date Recorded: 
Tuesday, September 10, 2019

Alexander G. Linan, Porter P. Lowry II, Allison Miller, George E. Schatz, Jean-Claude Sevathian, Christine E. Edwards, Saint Louis University, Missouri Botanical Garden, Institut de Systématique, Évolution et Biodiversité (ISYEB), Centre National de la Recherche Scientifique/Muséum National d'Histoire Naturelle/École, Pratique des Hautes Études, Université Pierre et Marie Curie, Sorbonne Universités, Donald Danforth Plant Science Center

The ebony and persimmon genus (Diospyros) is a diverse group of largely tropical trees and shrubs, comprising >800 species, many of which are poorly known, and/or are of dire conservation concern. Some of the most endangered members of the genus are endemic to islands of the Western Indian Ocean. The Mascarene Islands, comprising the islands Reunion, Rodrigues, and Mauritius is located east of Madagascar, and harbor 14 endemic species of Diospyros. Most of the species diversity is endemic to Mauritius are of dire conservation concern with the majority of species listed as either Critically Endangered or Endangered by IUCN Red List assessments. Despite their conservation status, nothing is known about patterns of genetic diversity or whether these sympatrically distributed and closely related species represent distinct genetic units. In this study we conducted population level sampling on all extant species of endemic Mascarene Diospyros and genotyped samples using 2bRAD seq in order to: 1) clarify species limits within the group, 2) determine and compare levels of genetic diversity across species and, 3) assess patterns of genetic structure within species and prioritize populations for conservation efforts. We found the morphologically described species correspond to unique genetic units despite the presence of hybrids and provide recommendations for future/ongoing conservation efforts.

Date Recorded: 
Wednesday, September 11, 2019