The Bermuda cedar is a mighty symbol of our island’s culture, history and natural heritage, and some of the brightest minds in the fields of conservation and genomics have come together to answer these questions: Did a pure Bermuda cedar survive the blight? And, if it did, how can we best preserve the species for future generations?
The only way to answer these questions definitively is by generating the world’s first reference genome and genetic test for the Bermuda cedar, and BioQuest cofounders Dr Carika Weldon and Jean-Pierre Rouja are heading up the research team that is in the process of achieving this. “We have already created a reference genome of a tree,” says Dr Weldon. The tree they used was the one planted at Government House in 1942 by then UK Prime Minister Winston Churchill, so they knew it was pre-blight and therefore there was a high chance of it being pure. They have also tested 32 other trees, including the cedar in St. Mark’s Church graveyard, which also has a high chance of being pure, as well as others they know are not Bermuda cedars.
In addition to the Bermuda cedar, there are the Darrell’s and Virginia cedars, many (but not all) of which were imported after the blight that devastated the island’s cedar forests between 1946 and 1953. A lot of these have cross-pollinated with Bermuda cedars, however, creating hybrid trees. “This is probably the biggest question because we don’t actually know when the hybridisation started because those other cedars may have been on-island even before the blight,” explains Dr Weldon. “The consensus in the community, in terms of those who are focused on cedar trees, is that there may already have been hybrids before the blight as well, but we don’t know for certain and we don’t know the extent. That’s why using that tree that Winston Churchill planted is a good guess, but he might have planted a hybrid as well. We don’t know.”
The only way they can know for sure is to test pure Virginia and Darrell’s cedars in their native habitat, get a genetic sequence for them both, and then compare these to the reference genomes of the Bermuda-based trees they have tested. This, however, costs money. Funding this whole “conservation challenge” are grants and donations through BioQuest’s partnership with Wise Ancestors and its crowd-funding platform. Wise Ancestors is a US-based non-profit organisation, which describes itself as “committed to advancing decentralised genomic research codeveloped with indigenous peoples and local communities for biodiversity conservation.”
Part of their model ties genomic research with benefit-sharing and to this end, the Bermuda cedar conservation challenge includes an apprenticeship element paired with a tradition-bearer. The apprentice is Sierra Pacheco who is part of the CariGenetics team. She was chosen, says Dr Weldon, because of her “love for biodiversity as well as genome.” CariGenetics, which was founded in 2022 by Dr Weldon, is conducting all the genetic research for this project. The tradition-bearer had to be someone who “intimately knew the cedar trees enough to be able to teach someone else,” and the man for that job was Myles Darrell, head of natural heritage at the Bermuda National Trust. “He’s the knowledge-bearer, the tradition-bearer of this tree, so he passed that on to her. That was the first phase, and her job was to receive it and understand it,” says Dr Weldon.
The second phase was the genetic testing and in that situation the tradition-bearer was Dr Weldon. “Myles was able to help when they were sampling, to identify which trees they probably should and shouldn’t be using. That was key to that second phase,” she says. Darrell can do this because there are some discernible characteristics that differentiate the three types of cedar. These include foliage colour, texture and growth habit. Bermuda cedars, for example, have a more blue-green tone to their foliage. The shape of the Virginia cedar is more upright and columnar, especially when young, and Darrell’s cedars tend to grow more quickly and can become taller and more robust in the trunk. None of these traits is reliable enough to use for conservation decisions, however, because these species, and their hybrids, can overlap in appearance: “Genetic mapping is the only accurate way to confirm which trees are truly Bermuda cedar,” Darrell says. “It allows us to identify and preserve authentic Bermudian lineages, protect biodiversity and ensure that what we’re restoring is the right tree, not a hybrid or an introduced species. This scientific clarity will guide replanting, seed collection and long-term restoration strategies.”
“We at BioQuest are now knowledgeable on all these different elements of the tree, and now we’re in a position where we can train others how to sample the tree, how to extract DNA from the tree,” continues Dr Weldon. Further down the line, once they have the reference genome for a pure Bermuda cedar, the apprentice will then be able to pass knowledge back to the tradition-bearer who can use that knowledge to make the best decisions regarding their propagation and conservation: “It’s not a one-way street,” she points out, “which is really exciting.”
How, exactly, do you extract DNA from a tree? The most efficient way to extract it is from their leaves, and the newer the leaf, the fresher the DNA. The best time for sampling is before the peak summer heat, which can negatively impact the sample’s integrity. Unlike blood samples, plant samples have to be pulverised into a powder because of the protective wall they have around their cells. Before being crushed, the samples have first to be frozen using liquid nitrogen. “This was a whole new world for us,” laughs Dr Weldon. “Liquid nitrogen is not readily available in Bermuda.” Once that process is complete, the DNA sequencing can begin. In the case of the Government House cedar tree, they were able to assemble the reference genome and confirm that it is around four times bigger than a human genome.
Managing all of the fieldwork and sample collection, as well as producing the film that will go along with this project, is Jean-Pierre Rouja, who specialises in developing conservation technology. He explains how the ultimate goal is changing as the project evolves. “When we first started this project,” he says, “the end game in my mind, initially, was, ok, let’s identify the pure Bermuda cedar and then let’s propagate it and let’s get it back out into the environment in a big way.” This was because the Bermuda cedar is better adapted to the island’s physical environment and environmental conditions, such as limestone and hurricane force winds. He has since learned, however, that “it may not be the best idea to put large scale reforestation of a pure Bermuda cedar back into the environment.” One of the main reasons for this is the fact that the scale which caused the blight, or “infestation” (as eminent entomologist Dr Walwyn Hughes advises is the correct term for it), could reemerge. “Until we have sequenced and identified what is determined to be a pure Bermuda cedar and identified and ground-truthed how many actually remain in the environment, and how and why they survived, whilst cross-referencing this with historical and traditional knowledge, we should perhaps pause pure Bermuda cedar propagation plans until we fully understand the risks and implications,” warns Rouja. “The dream of creating massive forests of pure Bermuda cedar might actually give the scale that is possibly still in the environment venue to reboot the infestation and actually be counter-productive to our long-term protection and conservation efforts.”
Dr Weldon also points out that “in biodiversity, the diversity genetically of a population is a measure of its health.” She explains that hybrids are interesting, and she would like to build up a better understanding of their genetic makeup as well, for example, what percentage of Darrell’s, Virginia and Bermuda they are, and how that translates into their appearance, smell and behaviour. Testing these trees is expensive and time-consuming, and another aspect of this project Rouja is working on is the development of an “affordable handheld field test kit” that can be taken into the field and used to instantly discover whether or not a tree is pure. And, if not, what percentage is pure. Once discovered, the pure Bermuda cedars could then be given extra protection measures.
The scientific research into Bermuda’s cedars is groundbreaking, not just because of the positive long-term impact it will have on the species and our environment but also because such advanced testing is being done in Bermuda, by Bermudians. “Through what Carika’s started with the lab here, we’re able to do locally now what was unheard of for any kind of budget five years ago,” Rouja explains. “The fact we’re able to do it locally and with a young team as well, who have long futures ahead of them. At the very least, we’re opening up this space to leveraging genomics for conservation.”
If you wish to support local botanical conservation genomics research you are invited to learn more and/or donate to BioQuest by Clicking Here. Outside of Bermuda, donations can be made directly on the Wise Ancestors Platform for which they can receive a US tax credit.
