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Tomas Hrbek has a knack for complexity.

You can see it in his eyes—complex optical organs firing energetic lightning bolts of excitement as he explains concepts of biodiversity.

You can hear it in his voice—complex blends of Czech and Portuguese accents honed during the height of intensive research, where ‘pele’ and ‘formiga’ sneak into euphonious English explanations.

And you can read it in his research—complex explorations of diverse ecosystems and dense datasets from deep within the Amazon Rainforest.

Luckily for Mico schneideri, complexity is in Tomas Hrbek’s DNA. In fact, it is complexity that allowed this new species of Amazonian primate to emerge from years of fieldwork and surveys. Mico schneideri, or Schneider’s marmoset, had been misidentified as an entirely different species for nearly three decades because of the scarcity of basic ecological and distributional data.

To understand this misidentification—and the complexity it took to describe Mico schneideri correctly—we travel nearly 5,000 miles from San Antonio to the forests of the ​​Juruena-Teles Pires mineral province in the state of Mato Grosso, Brazil. At the confluence of the Juruena and Teles Pires Rivers, this province lies directly within the “arc of deforestation,” the southern edge of the Amazon Rainforest rapidly being cleared for cattle ranching, small-scale subsistence farming, and logging. It’s here that Hrbek, Rodrigo Costa-Araújo, Ph.D., from the Museu Paraense Emílio Goeldi and the Federal University of Amazonas, and their team began a series of nearly a dozen trips deep into the rainforest’s canopies, cataloging visual and aural observations of what would soon be known as Schneider’s marmoset.

The goal? To “obtain new distribution records, specimens, and samples to overcome the previous scarcity of these materials and data in museums and in literature,” Hrbek and his team wrote in a 2021 article for Nature’s Scientific Reports. This fieldwork, called surveying, consisted of forest treks and up-stream canoeing to approximate, catalog, and geolocate call-and-response observations.

“We were not specifically looking for a new marmoset,” Hrbek admits. Rather, the team was looking to record an abundance of general data about Amazonian marmosets of the genus Mico, marmosets that are “little known endemics of this region and therefore a priority for research and conservation efforts.”

But with time in the field spent watching common behaviors, using and understanding vocalization techniques, and analyzing skins in museum collections, the team began to hone in on the fact that they weren’t observing Mico emiliae, or Snethlage’s marmoset, as Schneider’s marmoset had previously been classified. “It then became clear that in this particular area, there was something that didn’t match essentially anything else that had been seen before,” Hrbek says.

Hrbek works with �԰����� Coatney ’23 and Elizabeth Proctor ’22 in his lab.

Hrbek knew that the team could not solely rely on observational data to confirm its hunch. They turned to a set of surveys conducted over the course of the past century. Data from these surveys are spread out in institutions and museums across the world, from Brazil to Europe. This data helped inform an overview of both the taxonomic revisions and phylogenetic revisions of Mico. Through laboratory analysis of these revisions, the research team members confirmed their survey data, and Schneider’s marmoset emerged as a new species.

“The real biodiversity of the Amazon basin is significantly underestimated,” Hrbek says. Biodiversity is driven in part, he explains, by the dynamism of the geology of the Amazon basin. Geological disruptors have the potential to fragment species populations that were previously continuous, allowing them to diverge; they also have the potential to bring previously separated populations into contact with one another. As these species interact with one another, they have the potential to form hybrid groups carrying genes from two different sets of parental species. Over time, this hybrid group may become separated or isolated from its parent species due to the emergence of a behavioral or physical barrier. If the hybrid group survives this divergence and its population becomes stable, it may eventually be described as a new species. “Although this mechanism is underappreciated, it’s important for generating diversity in addition to the traditional mechanisms,” he adds.

Data collection allows analysis and statistics to inform research on the Araguaia dolphin. Inia araguaiaensis photo courtesy Gabriel Santos-Melo.

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All in a day’s work? Hrbek, the Cowles Distinguished Professor of Biology at �԰�����, is no stranger to new species. An ecologist and geneticist, Hrbek has more than two dozen new species discoveries to his name, ranging from a river dolphin in Brazil to a black uakari in Venezuela to a pupfish in Turkey. Hrbek has dedicated his career to exploring our world’s biodiversity and championing conservation efforts.

“There are 146 primate species and subspecies in Amazonia, representing 20% of the global primate diversity and comprising the most diverse primate fauna in the world,” Hrbek and his team wrote in the 2021 article. “Characterizing primate species diversity and distribution in the Amazonian arc of deforestation is a necessary first step ... which lends support to biodiversity conservation in this region before the entire biome reaches an environmental point of no return.”

Hrbek reframes this: “If we don’t know the species exists, how do we know we should protect it?”

Of course, a question like this begets complexity in its answer. Often, ecologists don’t know—can’t know—that a species exists because concrete, empirical data hasn’t yet been collected (hence Hrbek’s team’s surveys in the ​​Juruena-Teles Pires province). But for Hrbek, it’s about more than the raw data: It’s about the assumption that we, as humans and scientists, know so little about the world’s true biodiversity.

Hrbek uses data-driven approaches in his lab to analyze complexity in biodiversity.

“Conservation efforts are identified and conservation areas are designated based on known species in that ecological region. Decisions are made about adding or removing a particular area from a conservation effort when we think, or don’t think, a species exists somewhere else,” he says. “There are entire ecological communities composed of these ‘cryptic species,’ and if we don’t know they exist or concern ourselves with their conservation, we could wipe them out entirely.”

Hrbek’s research agenda is to see to it that this doesn’t happen—at least not more than it already has. As the arc of deforestation encroaches ever closer into the heart of the Amazon Rainforest, Hrbek has extended his focus to educating students and communities about the importance of conservation efforts and the effects on the lack thereof. He is a professor in the �԰����� First-Year Experience course “Climate: Changed,” where he encourages students to inquisitively explore and critically interpret the data fueling climate change arguments in order to draw their own evidence-based conclusions, rather than simply accepting existing conclusions at face value.

“As humans, we have a tendency to seek simple solutions. But there are no simple solutions for anything. Complexity is underappreciated; to become comfortable with complexity, to be able to function within it, means you can approach science with lenses of analysis, statistics, and predictions—from data-driven perspectives.”

If complexity makes good science, it makes Tomas Hrbek a good scientist. And it means the future of complex biodiversity is in good hands.

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