Portal de Periódicos da CAPES

Noah Whiteman

2022; Elsevier BV; Volume: 32; Issue: 24 Linguagem: Inglês

10.1016/j.cub.2022.11.001

1879-0445

Noah K. Whiteman,

Environmental DNA in Biodiversity Studies

Noah Whiteman is Professor of Integrative Biology and of Molecular and Cell Biology at the University of California, Berkeley. He studies the mechanistic basis of adaptations that arise from species interactions, particularly between host and parasite, and between plant and animal. He received a 2020 Guggenheim Fellowship and is an elected fellow of the Royal Entomological Society and the California Academy of Sciences. What turned you on to biology in the first place? It was partly innate and partly the influence of my parents. My father was an amazing naturalist and my mother encouraged me through reading and by listening to the knowledge I accumulated. I was one of those kids who just observed nature and tried to understand it, often by catching animals and bringing them home, alive, to show my family. My mother had what she called a ‘three-foot rule’ that meant I couldn’t come closer than three feet if I was holding an animal, and if I wanted a new ‘pet’ I had to read about it first by going to the library and finding books on the subject. I credit them both with fostering my innate curiosity about nature that was just insatiable. My biophilia was also undoubtedly influenced by the fact that, from about the age of 10 onwards, I lived in the middle of nowhere, at the edge of the vast Sax-Zim Bog in between Duluth and the Iron Range cities in Minnesota, within the southern limits of the Boreal forest. That bog is a huge relic peatland covered in rafts of sphagnum peat moss, studded with black spruce and tamarack trees, like the taiga, and below them, legions of carnivorous pitcher plants and tiny sundews. Prior to that we lived in Duluth, on the northern shore of Lake Superior. What I didn’t realize at the time was that the Sax-Zim Bog was also known as the ‘Arctic Riviera’ by birders because many different bird species from Canada, including great grey owls and northern hawk owls, would make their way down to the bog in the winter when rodent populations up north were waning. Because it was inland, temperatures went as low as minus 40 degrees, which is the same in Celsius as it is in Fahrenheit! Fall arrived early, snow fell in October, timberwolves left tracks in the winter snow, wood frogs sang in the spring, and boreal birds bred there in the summer. I took it all in — and for granted — because it was just the backyard to me. Now of course I see how lucky I truly was to have lived deep inside this remarkable biome. We hunted both white-tailed deer (with a bow) and ruffed and sharp-tailed grouse (with a shotgun) and ate the meat. I tried to tan the hide of the deer, but it didn’t really work out. It turns out that the word ‘tan’ comes from ‘tan-oak’, which really is all about tannins: these bind to proteins like the collagen in skin and are necessary to ‘tan’ the hide and make it soft! Instead, I just soaked the hide in salt. Still, I put that brittle thing up on my wall in my bedroom. I liked being surrounded by artifacts from nature, as well as nature itself. And what drew you to your specific field of research? My parents didn’t have college educations, and there were no scientists or academics on either side of my entire extended family. So, I was encouraged to be a veterinarian — I got lots of James Herriot books as gifts. The other option was to be a game warden or wildlife officer. I was not informed of other avenues because my family just didn’t know of them. At St John’s University, I was pre-medicine but took an entomology course from Professor James Poff. When he taught us about the dance language of the honey bees, I was hooked. His class forced me to grapple with a deep, dark secret — my love of insects. After that, as a senior, I decided to try to do an honor’s thesis after a friend told me I should (I had no idea what that was or entailed) — and I did. My project involved looking for signatures of character displacement in social wasp species across latitude in the US that Professor Poff had collected and kept in ‘Cornell’ drawers. He got the idea from a chapter on character displacement in a book on coevolution edited by Professor Doug Futuyma and Professor Montgomery (Monty) Slatkin. I liked the tedium of measuring thousands of wings and the feeling of becoming lost in data collection. It worked well with the serially obsessive part of my personality. I presented the work at a regional undergraduate conference in Minnesota and won an award for the best presentation — so the die was cast right then at St John’s. Little did I know that one day Doug would give a special lecture to my evolution course when I taught it for the first time at the University of Arizona or that Monty would be chair of the search committee at the University of California, Berkeley where I now hold a faculty position! If you think about character displacement as being the product of interspecific competition, it certainly does fall into the coevolution realm. So, I guess I’ve been studying reciprocal interactions and their outcomes on phenotypes since I was an undergraduate. If you had to choose a different field of biology, what would it be? I might answer an even broader question first — what field would I choose if not biology? I was one course short of a history minor in college and just loved every one I took whether it was on the French Revolution from Professor Linda Lierheimer or East Asian History from Professor Richard Bohr. There were parallels with studying organic evolution. Both fields are only studied with hindsight — they both seek to explain the past, just different realms — and both revolved around bellicosity. This question came to the fore of my mind as I worked on my recent book manuscript, which is about the intersection between human history and evolutionary history, in the form of our relationship with the toxins that plants and other organisms make. So, that’s a long way of saying, I think I’d be a historian if I weren’t an evolutionary biologist. I couldn’t study biology and not have evolution at the core of my research and teaching. Who were your key early influences? Well, besides my parents, it was a 7th and 9th grade science teacher, Ms. Terry Sundland and, later in high school, my environmental science teacher Mr. Chris Evavold. I wrote about the nitrogen cycle in my 10 gallon aquarium for a paper in Ms. Sundland’s class and she wrote on the margin “The mind of a scientist!”. Nobody had ever really said that to me before. Mr. Evavold encouraged me too, through his appreciation for natural history. Then in college it was all of the biology and chemistry faculty at St John’s University and the College of St. Benedict, and particularly Professor James Poff (entomology), Professor Charles Rodell (genetics), Professor Gordon Brown (ecology), Professor Stephen Saupe (botany), Professor and Sister Jeanne Marie Lust (introductory biology), Professor Kate Graham (organic chemistry), Professor and Abbot John Klassen (organic chemistry), and Professor and Sister Carleen Schomer (general chemistry). Each was an incredibly caring person who saw the best in me. I was earnest and bright, but anxious and uncertain of my future. Do you have a scientific hero? I have many — and I think this is important. There isn’t just one way to be an inspiration. Nor is there just one way to be a great scientist or to make great discoveries as a scientist. One is Professor Emeritus Doug Futuyma from SUNY Stony Brook, who is in my field, but was one of the first ‘out’ faculty members in evolutionary biology of whom I was aware. I invited him to give a guest lecture in the first evolution course I taught at University of Arizona while he was visiting for a research seminar, and he agreed. It was generous. Getting to know him a bit helped me see that I could try to achieve at the highest levels in science even though I am gay — I say ‘even though’ because it is clear that LGBTQIA+ people continue to be discriminated against and excluded from opportunities in STEM fields. White gay men are the least sanctioned by STEM, but I’ve felt the sting of it myself, although mostly in subtle ways. Another is Professor Emerita Elizabeth Bernays, from University of Arizona (and before that UC Berkeley), who provided a counterpoint to the Ehrlich and Raven ‘escape and radiate’ model of coevolution for understanding why herbivorous insects often specialize on particular sets of chemically similar host plants. Liz is a little bit of a rebel, albeit a quiet one — she stood against the intellectual and male-dominated tide in her field. To Liz, it was all about the fitness benefits of escaping a set of enemies cued in to chemicals from the host plants that their prey lived on. Liz also taught me that one can change course even in our somewhat constrained academic lives, and that this can bring with it great reward. After she retired, Liz received an MFA in creative writing and then began to write books. After her husband, Professor Reg Chapman died, Liz also met Linda and married her. The last heroic person to me I’ll mention is long gone and was written about by Alexander von Humboldt and Aimé Bonpland in their book describing their travels to South America. The man they described was an Indigenous Amazonian man, name unknown, who was responsible for making the curare, or arrow poison from plant toxins: “He was the chemist of the place. We found at his dwelling large earthen pots for boiling the vegetable juice, shallower vessels to favour the evaporation by a larger surface, and leaves of the plantain-tree rolled up in the shape of our filters, and used to filtrate the liquids, more or less loaded with fibrous matter. The greatest order and neatness prevailed in this hut, which was transformed into a chemical laboratory. The old Indian was known throughout the mission by the name of the poison-master (amo del curare). He had that self-sufficient air and tone of pedantry of which the pharmacopolists of Europe were formerly accused.” Here is what von Humboldt and Bonpland quoted him as saying: “I know,” said he, “that the whites have the secret of making soap, and manufacturing that black powder which has the defect of making a noise when used in killing animals. The curare, which we prepare from father to son, is superior to anything you can make down yonder (beyond sea). It is the juice of an herb which kills silently, without any one knowing whence the stroke comes.” The reason that this long-dead Indigenous man is so heroic to me is that he represents how, in many respects, science as a way of knowing clearly arose in so many cultures. The transmission of this knowledge that flowed across the generations led to many modern medicines (probably 50% of them) that we now take for granted. Which historical scientist would you like to meet and what would you ask them? Well, I’d like to meet that Indigenous man and ask him all the questions. I’d also like to meet Charles Darwin and Alfred Russell Wallace of course, and get their reaction to the advances in the field of evolution since their death, and particularly in the last 30 years. But more than anybody else, I’d like to meet Leonardo da Vinci and ask him to conceive of new ideas we could use to help tackle the global crises of our time — anthropogenic climate change and biodiversity loss. Do you have a favorite paper or science book? This is such a difficult question to answer. But if I had to pick one I would pick Caro-Beth Stewart, James W. Schilling, and Allan C. Wilson’s paper “Adaptive evolution in the stomach lysozymes of foregut fermenters” (Nature 330, 401–404). The reason is that it was published in 1987 — when I was just 11 years old — and in the still very early days of evolutionary genetics. They discovered that two types of mammals that independently evolved foregut fermentation ruminants like cows on the one and leaf-eating langur monkeys on the other, both evolved lysozymes that were secreted in the stomach and were resistant to the low pH. The two lysozymes evolved many of the same amino-acid changing substitutions in response to the diet shift. There are so many elegant things about this paper, the use of the species tree vs. the protein tree, the divining of signatures of Darwinian positive selection by using convergence as a screen, and the remarkable biology underlying the lysozyme. Later work would show that the lysozymes in the foregut were used to access the bacteria that were growing on the fermenting leaves and that RNAses had duplicated in these lineages too. This allowed the animals access to the RNA present in the bacterial cells, a rich nutritional substrate for obvious reasons. In addition, this lysozyme sequence dataset for primates was built upon over the years and served as the single most important one for the development of divergence-based tests for positive selection, like phylogenetic analysis by maximum likelihood (PAML). What’s your favorite experiment? I’ll just consider my own work. My favorite experiment was the one in which we found that the homozygous triple mutant ‘monarch flies’ we made using CRISPR–Cas9 genome editing were fully resistant to 30 mM concentrations of the cardiac glycoside heart poisons found in the milkweed host plants of the monarch butterfly. What is your favorite or least favorite conference? My favorite one is the Plant-Herbivore Gordon Research Conference. I generally have a hard time at large conferences. I get overwhelmed easily in large social settings and like interacting in very small groups. Some of this I attribute to being alone for most of my childhood in the quiet wilderness of northeastern Minnesota. What is your greatest research ambition? My greatest research ambition is to be filled with gratitude when I am old (if I am fortunate to live to be old) as I look through a list of the names of the junior researchers I have helped mentor. In what ways do inclusion and diversity influence your work and the scientific community in general? It shapes all that I do and how I think about science, my place in it, and why I choose to do the things I do for my work. When you are minoritized, you learn the rules of the majority and how to operate, if you can. For me, I’m gay and can shape-shift — not everybody knows that I am gay when they look at me or interact with me of course. For many others, they cannot hide certain aspects of their identities that are discriminated against. It is sad that this is even something that one has to consider (to hide, not hide, be unable to hide, etc.). When one challenges the norms, sometimes just by occupying a position or a space or by saying the unsayable, one risks being sanctioned, and in the academy these sanctions often emerge in subtle ways. I don’t think most discrimination is subconscious — I think it is operationalized fully consciously in cryptic and subtle ways. The worldwide system of higher education is largely patterned from a particular European-derived patriarchal structure. Academia is also a guild of course, built on an apprenticeship system. It is the family business for many. It has thrived under the colonial model wherein specimens, artifacts, knowledge, and the property of others was just stolen and brought back to the mothership. Such a system is fortified against change. Yet, many do have the genuine desire to change it, including some white, straight, cis men and women. I have seen a positive shift since I started as an academic, but the old guard, defending the fortress, remains powerful. This is a challenge. There is a lot of friction being generated right now, mostly between more junior and more senior academics in the area of DEIBJ and this is the source of the heat that can be used to create something new. It won’t happen overnight; change is gradual in the academy. Do you feel a push towards more applied science? How does that affect your own work? I felt this mostly as a PhD student for whatever reason. Probably because I studied feather lice on the heads of Galápagos hawks then — it doesn’t get any more esoteric than that! But even then I tried to think about how my work might be used to influence conservation strategies in the Galápagos. My sense now is that all scientific work is of inherent value if it is conducted in an ethical and rigorous manner. Lately though, the death of my father in 2017 pushed me in new research directions. To read more about that, you should read my book that will be published in 2023. Do you believe that there is a need for more crosstalk between biological disciplines? Yes, I usually am most comfortable at the interstices between disciplines, and I’ve always been this way. It is hard to navigate because one is always an outsider, but this is both where there is the most to learn, and the most to contribute professionally. This is because many fundamental elements of biological systems have been ‘described’ whether through observational or experimental work on mechanism. What remains to be understood are the emergent phenomena, like human consciousness for example, and the interactions between levels of organization that create something that is greater than the sum of their parts — like positive sign epistasis, to take the simplest possible example. Any strong views on social media and science? Yes, I use Twitter as the main way of finding out about new papers. The hive mind, if you follow the right people, can really help bring things to the surface and winnow things down (in a biased way of course). I don’t think Twitter is really useful for any kind of serious dialogue though. Which aspect of science, your field or in general, do you wish the general public knew more about? That everybody is a scientist in their heart — it is simply part of the human condition and wasn’t invented by any particular culture. Yes, the culture and epistemology of our modern scientific enterprise is a different thing from this altogether, and is one manifestation of this innate human bauplan, I think. My sense is that the difference between these two things gets confused. I wish generally that the public understood how evolution worked, because once one does, the biosphere and the fact that each of us is here to begin with will do more to inspire than one can imagine. What do you think are the big questions to be answered next in your field and what do you think are the biggest problems science as a whole is facing today? Ensuring the thriving of both humanity on the one hand and the biosphere of which we are a part and have shaped on the other are the principal challenges of our time. Breaking this down a bit is that in my view the biodiversity crisis is right now more acute than the climate crisis, although they are of course intertwined, and both are existential from a human point of view. The over-harvesting of wild animals, over-conversion of natural biomes to agricultural lands, the suppression of Indigenous sovereignty, and the rampant spillover of pathogens to humans are all problems that can be reversed in the short, medium, and long term. Climate change can be mitigated too before we reach tipping points that will generate unbelievably catastrophic feedback mechanisms that will make life miserable for most of us, but particularly for those in the Global South. In my field of evolution, I think the big questions revolve around the most fundamental ones — how and why can a single cell turn into a redwood, a human, or a dragonfly. We still don’t really know. Nor how or why all multicellular organisms maintain the same inheritance and variant reshuffling mechanisms like meiosis and recombination. At the same time, there do seem to be common mechanisms at the root of these problems. The two revolve around the origin and maintenance of the germline eukaryotic genome since its single origin over one billion years ago, the nature of the different levels of organization that are acted upon by evolution, and the dialectic between all of these levels and the environment, sensu lato. In biology, I think the biggest problem we face as a field is the lack of knowledge of natural history — without a detailed understanding of the nature of the “endless forms, most beautiful and wonderful” (as Darwin wrote) out there, we can only look through the glass darkly. Model organisms, as amazing as they are, do not tell us much about the most interesting aspect of evolution — the origin of novelty — which helps define diversity, and the problem of evolution itself. So, circling back, the biggest societal crisis of our time right now, biodiversity loss, is also linked to the biggest crisis in our field, loss of knowledge of biodiversity — and by this I mean a lack of training in this area coupled with the loss of populations and species. If one doesn’t comprehend what one is losing, it is hard to appreciate how it is being lost and why it might be of value, intrinsically and pragmatically.