genetic representation

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

Kim McCue, Shannon Felberg and Steve Blackwell
Desert Botanic Garden

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