In December of 2022, Sean Hoban (tree conservation biologist at the Morton Arboretum in Lisle, Illinois) traveled to Montreal, Canada to attend the United Nations Biodiversity Conference, also referred to as COP15 (the 15th Conference of the Parties). The conference brought together the Parties to the UN Convention on Biodiversity (CBD), which was opened to signatures in 1992. As of 2023, the CBD has been ratified by 192 countries, though not by the United States. The CBD has three stated goals: the conservation of biodiversity, the sustainable use of its components, and the fair and equitable sharing of benefits arising from genetic resources.
Hoban attended COP15 as a scientific advisor, advocating for the consideration of genetic diversity. While the concept of biodiversity is most often associated with a great number and variation of species, genetic diversity refers to variation within species. A species with high genetic diversity displays a wide variety of inherited traits—which is a fundamental, though often overlooked, basis for the resilience of biodiversity. A notable outcome of the Convention was the adoption of the Kunming-Montreal Global Biodiversity Framework (GBF). The GBF contains several goals, notably the “30 by 30” target, which is a global initiative to designate 30% of the earth’s land and oceans as protected areas by 2030. Additionally, there were major advances to conserving genetic diversity.
ARNOLDIA: First, tell us about your journey to the Morton Arboretum. How long have you been there? Did public gardens factor in your research before this?
SH: I’ve been at the Morton for seven years. I have worked on trees and tree genetics since my Ph.D. My dissertation research was on butternut (Juglans cinerea), a tree threatened by an exotic fungus, and trying to understand the genetic impact of this disease, as well as the genetic impact of hybridization. The situation is actually very similar to American chestnut: hybrids may help save the species, but to some degree we also want to save the native gene pool of the species, so there’s some trade-off there.
My postdoctoral appointments turned in the direction of policy and public impact. My first postdoc was focused on translating genetic knowledge to non-geneticists—people in policy, people in government agencies. It was actually in Europe, so I was working with some European agencies—hosting workshops, developing tools and reading material—to connect genetic scientists to conservationists, protected-area managers, and people who are setting policy.
My second postdoc was what really propelled me towards the garden world. That was when I started to work on the genetic implications of how we sample seed for ex situ collections. It was actually a competitive proposal that I wrote for an NSF-funded postdoc: I had this idea that we could use simulations to create a species on a computer, and then apply different sampling strategies to that simulated species to test out how well any sampling design would work, in simulations that could account for species with varied biology or geography. And that’s been a major core of my work for almost ten years now. During that postdoc, I was invited to a couple botanic gardens to talk about the seed sampling work. I was invited to what was then Rancho Santa Ana Botanic Garden (in Claremont, California; now the California Botanic Garden). I think that was my first visit to a research site of a botanical garden. And then I was invited to Kew, where I collaborated with researchers on ash (Fraxinus) seed collections, and to the US National Seed Bank, to better understand how their seed bank works and to start some collaborations. Visiting thosethree places made me realize that there is this alternative research pathway—previously, I was focused on either working as a geneticist for the Forest Service or trying to get into academia. The new collaborations I made in that year opened me up to the garden world.
Some species are experiencing phenological mismatches due to their migration, while others will not be able to move and therefore will have to adapt.
You put genetic diversity on the table in a big way at COP15. How did that go? Do you feel like genetic diversity is on the table in the way it needs to be? Is there a change happening in the dynamic around the global biodiversity framework?
SH: I think genetic diversity is increasingly a consideration among conservationists, including in the COP15 discussions. Over the past decade, we’ve developed a shared understanding that species are either moving or adapting already: some species are experiencing phenological mismatches due to their migration, while others will not be able to move and therefore will have to adapt. In the media and getting into the policy conversation, there is acknowledgement that trees, including those in agricultural production, are really affected by climate change, and an awareness that genetic diversity can help alleviate some of those impacts. News stories of coral die-offs, with research showing how genetic diversity can help rescue those populations, has contributed to this awareness as well.
With broader recognition of climate change and the importance of genetic diversity in species survival, we see conservationists starting to implement genetic rescue, where they are moving individuals among populations. The Forest Service is starting to experiment with how far we will have to move seeds for reforestation. I think in conservation practice it’s becoming a more familiar topic, and that bubbles up to the policy level.
At COP15, genetic diversity was a topic of discussion, though it was not as prominent as the discussions on species and ecosystems. The COP15 process was broader than biodiversity—it was also about sustainable use, financing and resources to protect biodiversity, and sharing the benefits of biodiversity equitably. But in terms of biodiversity per se, it’s still largely about species and ecosystems, the 30 by 30 commitments in particular, which are important and valuable. A lot of the time was discussing definitions of “protected area,” priorities for protection, and rates of extinction, which is hard to measure. We need something more measurable. With genetic diversity, we can ask, how do we measure threat change to species and their abundance? And from there, we can explore whether there’s a percentage of genetic diversity that we can measure that’s as easy to communicate to the public as 30 by 30.
I was pleased to see that it came up, though, and it seemed that policymakers are understanding that this is a really important component of biodiversity that had previously been overlooked, one that is important for global adaptation of societies and nature.
So genetic diversity is on the docket for policymakers, though the concept may still be elusive for the public.
SH: It’s definitely harder to communicate the science around this, to visualize genetic diversity, to boil it down to simple concepts. We need to say that “whether a species occurs across a large area or in distinct habitats, there often are local adaptations, and these need to be protected.” So just thinking about this in terms of the resilience provided by adaptations to different habitats, which will help the species survive whatever changes come. So one science communication approach is to talk about the resiliency it provides. Another approach involves talking about how these genetic distinctions, which have evolved over millions of years, are essentially irreplaceable, in the same way that species are irreplaceable. The loss of genetic diversity is a distinct piece of nature being lost, even where species-level extinction is avoided.
This notion is especially inspiring—cultivating a sense of wonder and appreciation for genetic diversity at the local level, understanding that each of these variations are irreplaceable treasures. And it feels like that’s a place where gardens and arboreta can be effective, by highlighting that micro-diversity.’
SH: Absolutely! I think botanic gardens can highlight this very effectively, because we already show different forms that are exciting to people, whether they’re cultivars or different varieties or from different locations. We often have accessions that come from different parts of the world. So when you start to show phenology, you can see phenological differences in the same species. There are so many ways to actually see genetic variation in botanic-garden plants.
It must be challenging to navigate spaces like COP15, engaging with policymakers, government bodies and NGOs, and addressing the complexities of these networks that operate at very different scales and have very different professional idioms. What’s it like to navigate these as a scientist? What have you had to develop in terms of your skill set and practice to engage at these different levels?
SH: It was the most stretching I’ve done outside my skill set. Moving into COP15 and talking with negotiators from various countries was a really different, difficult world. The people who attend COP15 include scientists, NGOs, Indigenous representatives, and others. But the primary cohort is people from ministries of the environment or similar agencies who are representing their governments. And this meant there was a whole new set of terminology and acronyms to learn, as well as a huge adjustment of the level at which I speak, and the speed with which people want answers—and by the same token, the slowness with which the whole process proceeds. Policymakers need answers very fast and in a nice, easy-to-read form. So there are slow processes and very fast processes, sprints and marathons.
Which prompts another question: what effect has it had on your lab group? Does it change what’s possible for junior members of your lab in terms of training, skill-building, and networking?
SH: I think it will. The past couple of years was just me getting my footing in this world, and now I’m starting to translate that to my lab group, to people at the arboretum, people at other gardens and U.S. agencies. Now that a few of us are comfortable in this experience, we can start to bring more people into it, whether by attending these meetings, participating in webinars or training sessions, or contributing to some of the science-communications efforts. I think there’s a lot of opportunities for early-career people to now take part in these activities and learn a lot from them. I think compiling case studies of plants where we have clear instances of genetically distinct populations, or really small populations that are losing genetic diversity—early-career people can be involved in all of that.
We need to think about those species that are ready for restoration now.
Beyond shaping visitor experience into more of an encounter with biodiversity and genetic diversity, how should gardens be thinking about genetic diversity in collection development?
SH: Gardens have made amazing efforts to get plant species into collections. I think there are probably at least three things that gardens need to emphasize with respect to genetic diversity. There is a need to focus more on wild genetic diversity, instead of sourcing plant material from other gardens or from nurseries. Supporting, or at least receiving material from, new seed-collecting and plant-exploration expeditions, taking advantage of these opportunities to get new genetically valuable material into collections, is terrifically important. We could also retool propagation protocols to make sure that seeds survive. All this will take some hard decisions around de-accessioning material that is not wild-collected or lacks provenance information. And then, thinking about how we propagate plants over time, especially for shorter-lived plants. There’s not as much urgency for an oak that lives for two hundred years. But for those species with ten, twenty-year life spans, well, when these reach the end of their life span, do we go back to the wild populations to get more genetic diversity? Or do we do what zoos do, and try and mate individuals among botanic gardens?
And then of course, gardens need to share data. More and more gardens are participating in Botanic Garden Conservation International’s data-sharing efforts, but there’s a lot of progress to be made there, because the data is important not only for identifying species to protect, but for finding gaps in species ranges that haven’t been protected.
And then—ultimately—building on a colleague’s idea, I’ve recently been saying that botanic gardens are a waypoint on the path to restoration. We need to think about those species that are ready for restoration now, where habitat has been restored, so that we can get some of those species and their genes back into the wild.
Any final takeaways?
SH: I think sometimes there’s skepticism about whether politicians care about science and whether some of them distrust science, etc. But my experience at COP15 suggests that most policymakers truly care about science. Just like the rest of us, they were working 12- to 14-hour days through that whole two-weeks of COP15, talking to scientists, and really doing their best. I was happy to see how peer-reviewed results and community consensus in science were really important.
This interview has been edited for length and clarity.
Sean Hoban is the tree conservation biologist for the Morton Arboretum, where he works to understand, document, and address threats to species of Quercus, Juglans, Populus, and Pinus.