Oaks

Sean Hoban, Emma Spence, and Patrick Thompson, The Morton Arboretum

The Morton Arboretum seeks to improve the conservation value and genetic representation in ex situ collections by developing guidance for sampling seed. One example regards IUCN Critically Endangered Quercus boyntonii (Boynton sand post oak), which is endemic to Alabama and only occurs on exposed sandstone outcrops.In situ threats include overcrowding by invasive species, off trail disturbance by humans, and the threat of wildfires. To help safeguard this species in case wild populations are lost, we compared genetic diversity of wild Quercus boyntonii populations to ex situ collections. We collected 246 individuals from 11 locations in the wild and 77 samples from 14 botanic gardens across the United States. We used microsatellite DNA markers to quantify genetic variation existing in the wild samples and calculate the proportion of genetic variation that exists in ex situ collections. This is a direct measure of the success of the collective efforts to build conservation collections. We found that current ex situ collections capture approximately 78% of overallgenetic diversity, and 100% of common alleles. We also used a resampling technique to determine how efficient this collection is, and we showed that a smallerex situcollection may be sufficient if it is carefully planned. The overall message is that ex situ collections of a taxon spread across a number of institutions can safeguard a species’ genetic diversity. This work is part of a large, multi-institution project in which genetic variation in ex situ collections of 10 species will be quantified. Our end goal is to provide advice to the garden community about how to establish and maintain ex situ tree collections, which includes initiatives to distribute germplasm collaboratively.

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

Emily Beckman, Sean Hoban, Matt Lobdell, and Murphy Westwood, The Morton Arboretum

Oaks are keystone species across the majority of forest and shrubland habitats in the United States, but many are threatened with extinction in the wild. Ongoing conservation efforts exist for some native U.S. oak species, but growing threats and limited resources necessitate prioritization and coordination. To that end, The Morton Arboretum, BGCI-US, and the U.S. Forest Service conducted a conservation gap analysis of native U.S. oaks. As part of the analysis, we completed an extensive global ex situ survey, which enabled us to estimate the genetic and ecological coverage of ex situ collections for at-risk native oaks. These results facilitate the prioritization of species, populations, and regions for further representation in ex situ collections. Such analyses also pave the way for coordination among collections and provide a model approach for assessing other genera and regions.

Date Recorded: 
Friday, May 3, 2019