One research group from the University of Nebraska–Lincoln covered 66 million years of North America’s fossil record seeking an answer to how mammalian diversity and ecological shifts can tell about modern conservation strategies.
Sometimes it’s the present that’s best understood by looking toward history. A new University of Nebraska–Lincoln study did just that: digging into the fossil record from the last 66 million years to learn about ebb and flow in mammalian ecosystems and species diversity across North America.
The research was led by Alex Shupinski, who earned her doctorate in May, and co-authored by Kate Lyons, associate professor in the School of Biological Sciences. It provides an overview of how diversity changed with species over the first 65 million years of the Cenozoic—until humans’ arrival—and how climate and other environmental aspects, such as changing landscapes, impacted animal life on the continent.
Their findings, published in Proceedings of the Royal Society B, open a window onto how mammals recovered following the last mass extinction—the deletion of non-avian dinosaurs. Results of biodiversity changes across time
“Beginning 66 million years ago, we sweep from completely subtropical environment across North America to grasslands to a frozen savanna and finally reaching the Ice Age,” Shupinski said. “So that shows how species changed through time through so many ecological, environmental and climatic changes, and allows one to compare across these events and at different spatial scales.”
These researchers gridded the Cenozoic era fossil record at a resolution of a million years and measured changes in three indices of functional diversity, which quantify changes in community structures with mammalian traits at both the local and continental scale.
Most of the Cenozoic had the local and continental estimates differing, but surprisingly, in the first 10 Myr of this era—inmediately after the extinction of non-avian dinosaurs—there is an increase in all measures of functional diversity at the two different local and continental scales.
“That was cool to see, that for most of the Cenozoic, functional diversity was decoupled across time and spatial scales, except this one time,” Shupinski said. “For 10 million years, all the measures are changing in the same way. Then at 56 million years ago, we get this massive immigration of mammals into North America from other continents, and at that point, we see a divergence of functional diversity.
“Communities are changing at different times, at different rates, and in different directions,” she said. “We might see locally, the diversity of roles increasing, but continentally, they’re decreasing.”
Environmental Influence and Future Implications
Still, as Lyons commented, some of these changes among mammalian species can be attributed to environmental changes at the time, “such as cooling and warming periods or when heavily forested areas were usurped by grasslands,” but these large-scale environmental changes did not rise to the level of disruption caused by the mass extinction of dinosaurs.
“That is why this may probably be a way to pinpoint areas of the globe or communities that are under particular stress,” Lyons said. “We may be entering a sixth mass extinction event, and if so, we might expect to see communities that are on the vanguard of that extinction respond in a similar way, based on the patterns we see after the extinction of the non-avian dinosaurs.”
What informs today’s biodiversity crises with respect to conservation paleobiology is the long-term record of past change in ecosystems. In this sense, the paper gives a comprehensive review of the history of mammals, portending what lies ahead.
“If we’re looking at the modern, and we see a similar response in functional diversity of modern community structures, it may be a conservation tool, as we can highlight some of these communities that are experiencing the most disturbance, and are at highest risk of change and disturbance in their ecological services and function,” said Shupinski.
It has definitely added five more paragraphs to the story of the blog post. The trajectories of mammals’ evolution over timescales so large would mean understanding their resilience and adaptability in front of environmental challenges. However, as the paper does point out, mammalian communities responded drastically to the climatic shift from the warmth during the early Cenozoic to glacial periods of the Ice Age. These were the shifts setting a stage to shape not just the diversity of species but also helped to dictate what functional roles they would play within their ecosystems. For example, in times of warmth, species adapted to dense forest would do very well indeed, but in the cooler climate times, those adapted to more open grasslands could come to ecological dominance. It also noted that functional diversity changes should be considered at both local and continental levels. Dynamics over millions of years offer an insight into how mammalian communities might vary their response to environmental pressures across spatial scales. It could give the ability to understand how current and future environmental changes—human-driven—might affect biodiversity everywhere on Earth.
The findings have key implications for conservation efforts, says Kate Lyons. Scientists can learn from past reactions to environmental perturbations to understand the species and ecosystems that may be vulnerable now to such disturbances. Basically, that does what the essential tenet of deep-time ecological data does to merge with contemporary conservation strategies preparedness can be gained for the protection of biodiversity in a world full of changes.
Looking ahead, the research suggests that this climate change and habitat loss could spur shifts in functional diversity akin to those seen in deep time. By recognizing these patterns, conservationists can zero in on efforts where they really matter: not just saving individual species but the intricate networks of interactions underpinning ecosystem stability.
By doing so, it is the expectation of researchers to lighten up a framework within which to appreciate, and hopefully mitigate, the ecological challenges of the present and future by tracing mammalian evolution in North America over the past 66 million years. These broad perspectives can be observed as useful for the integration of paleontological insight into modern-day ecological science to deepen biodiversity appreciation and guide effective conservation practice globally.
It also pushes forward the connectivity of ecological communities over deep geological time scales, underlining the fact that changes currently underway in one region of the world may have consequences whose effects will echo across continents.
Understanding how mammalian diversity has responded to past environmental changes is critical for gaining insights into ecosystem resilience and vulnerability under stress. This knowledge is of extreme importance for the development of conservation strategies that, on one hand, save single species and, on the other hand, preserve the complex web of ecological interactions supporting biodiversity. Knowing lessons from deep-time studies of ecology can reduce these threats, make appropriate management decisions in the face of unprecedented climate change and human impacts now upon us, and ensure that planetary natural heritage is preserved for future generations.
Reference: “Unique functional diversity during early Cenozoic mammal radiation of North America” by Alex B. Shupinski, Peter J. Wagner, Felisa A. Smith and S. Kathleen Lyons, 1 June 2024, Proceedings B.
DOI: 10.1098/rspb.2024.0778
The study was funded by the U.S. National Science Foundation.
Additional authors on the study are Peter Wagner, professor of Earth and atmospheric sciences at Nebraska, and Felisa Smith of the University of New Mexico, Albuquerque.
Source: https://scitechdaily.com/
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