genetic diversity

Trees Will Adapt, Migrate or Die

Barbara Crane, US Forest Service, National Forest System (SePPCon 2016)

Barbara Crane, USFS, describes special considerations for trees.  Because the are long-lived, they cannot respond quickly to multiple threats from pathogens, fire, drought and climate change. Rates of historic migration of 300 to 1200 ft/yr cannot keep up with the rate of changing climate. Understanding genetic variation related to environment and response to change is necessary to conserve forest diversity. For the USFS Southern Region, which is home to 140 tree species, we developed a Genetic Risk Assessment System and identified the top 10 species at risk from climate change. Barbara gives examples of actions with several species and emphasizes that collecting from southern edge of a species range may capture valuable unique genes.

This work was presented at the Southeast Partners in Plant Conservation (SePPCon) 2016 Meeting. Learn more about SePPCon here.

Date Recorded: 
Tuesday, November 1, 2016

Use of dry tissue for comparing ploidy among rare plant populations?

Given the reproductive difficulties that differences in plant ploidy may cause in the movement or mixture of plant populations, our group is considering incoporating analysis of plant ploidy into a grant evaluating

Seana Walsh, Dustin Wolkis, and Ken Wood, National Tropical Botanical Garden

Phyllostegia electra (Lamiaceae) is endemic to the mesic and wet forests of Kaua'i. It is listed as Critically Endangered on the IUCN Red List of Threatened Species and is a focal species for achieving conservation objectives outlined in the Hawai'i Strategy for Plant Conservation. With less than 50 known wild individuals among 15 subpopulations, P. electra is also a focal species of the University of Hawai'i's Plant Extinction Prevention Program. It is not, however, protected by the Endangered Species Act.

A grant from the Mohamed bin Zayed Species Conservation Fund is supporting NTBG staff to: 1) make conservation collections from wild populations, 2) conduct a genetic diversity study in collaboration with Chicago Botanic Garden (CBG), 3) outplant into protected and managed habitat, and 4) investigate optimal seed storage methods.

Eighteen remote field work trips have been undertaken since March 2017 to secure conservation collections and obtain leaf material for the genetic diversity study. Genetic marker (microsatellites) development was recently completed and silica-dried leaf material sent to CBG for DNA extraction. Since June 2017, 215 individuals have been outplanted into Kalalau Exclosure and NTBG Gardens and Preserves. Preliminary results of our investigation into optimal seed storage indicate that seeds do not tolerate exposure to liquid nitrogen without prior desiccation. We also found that germination was significantly higher in the 42% eRH frozen treatment compared to the 30% eRH frozen treatment. This work is directly contributing to the conservation of this rare taxon and we are using this multi-faceted project model in our approach to conserving other rare plant taxa as well.

Contributing Author(s): 
Date Recorded: 
Friday, May 3, 2019

Valerie Pence and Megan Philpott, Cincinnati Zoo & Botanical Garden

Crotalaria avonensis is a Florida endemic found in three populations and characterized by low seed production. In the late 1990s, CREW developed protocols for tissue culture propagation from field collected shoot cuttings as well as cryopreservation methods. In order to develop a genetically representative collection for conservation, in vitro lines were established from shoots collected at all three populations from 2008-2012. Plants were produced and sent to Bok Tower Garden for further growth and for use in an outplanting by Archbold Biological Station. The resulting collection of genotypes in culture at CREW provides an example of the challenges of a genetically diverse collection of an exceptional species. C. avonensis cultures require maintenance subculturing every 2-3 months. Only a low number of replicates could be maintained for each genotype, resulting in some loss of genotypes over time. Cryopreservation offered a solution to this challenge and over the course of 16 years, a number of lines were cryopreserved. In a study of lines stored for 5.5 Ð 16 years in liquid nitrogen, there was no change in average viability of the collection in storage, although specific survival differed by genotype. A cost estimation indicated that cryopreservation could decrease the cost of maintaining the collection over 20 years by at least 1/3. Genetic analysis of the collection and the wild populations is also underway in order to determine the genetic representation of the collection.

Contributing Author(s): 
Date Recorded: 
Friday, May 3, 2019

Christa Horn and Joyce Maschinski, San Diego Zoo Global and Center for Plant Conservation

The primary purpose of a conservation collection is to support species’ survival and reduce the extinction risk of globally and/or regionally rare species. A conservation collection is an ex situ (offsite) collection of seeds, plant tissues, or whole plants that has accurate records of provenance, maternal lines differentiated, and diverse genetic representation of a species’ wild populations. To be most useful for species survival in the wild, a conservation collection should have depth, meaning that it contains seeds, tissues or whole plants of at least 50 unrelated mother plants, and breadth, meaning it consists of accessions from multiple populations across the range of the species. Conservation collections of seeds should have tests of initial germination and viability, cultivation protocols developed, and periodic testing of long-term viability.

Contributing Author(s): 
Date Recorded: 
Friday, May 4, 2018

Jordan Wood, Jeremie Fant, Andrea Kramer and Kay Havens, Chicago Botanic Garden

Genetics becomes important whenever populations become small (<100). This includes loss o fgenetic diversity from drift, increased expression of deleterious genes due to inbreeding, and limiting local adaptation. Since many species of plants are able to be seed banked, it is possible to maintain numbers well above these critical genetic thresholds. However for exceptional species, which can only be maintained as living plants, or for critically endangered species where remaining individuals are already below these numbers, the need to consider the remaining genetic diversity becomes critical. Importantly, the management focus shifts from saving a population to preserving each genetically unique individual. When you have such small numbers, it is critical to know how each individual contributes to the overall genetic diversity remaining. We are working with National Tropical Botanic Gardens (Hawaiʻi) to develop a multi-institution species management and breeding plan for Ālula(Brighamia insignis)that will ultimately support its restoration to the wild. To do this we are working with scientists at the Chicago Zoological Society to modify management software that incorporates genetics and demography information to maintain the long-term health of their captive populations of animals over the long term. Through this case study, we hope to develop collections management practices for plants that preserve important genetic diversity while identifying genetically appropriate individuals to using in crosses and that can ultimately be used to create resilient populations that can be used in reintroductions.

Contributing Author(s): 
Date Recorded: 
Friday, May 4, 2018