AI tool reveals climate shifts may have fueled bursts of bird evolution

University of Michigan researchers have discovered that major evolutionary bursts among birds in the group Passeriformes, commonly known as passerines, coincided with significant climate shifts throughout Earth’s history. Using an advanced AI tool called Skelevision, the team analyzed thousands of bird specimens to uncover patterns in body shape evolution that align with periods of environmental change. The study, published in Nature Ecology & Evolution, suggests that evolutionary radiations, periods of rapid diversification, are often linked to climatic transitions. Researchers examined more than 2,000 species and collected over 170,000 individual skeletal measurements. These data were gathered using Skelevision, an AI-driven system developed through a collaboration between the University of Michigan and New York University. The tool allows for precise measurement of multiple bones across the avian skeleton by capturing images against a calibrated grid, enabling high-speed digitization of museum specimens. By scanning nearly 15,000 individual specimens, mostly from the U-M Museum of Zoology, the team was able to track how body shapes within the passerine lineage changed over millions of years. Lead author Jake Berv, a postdoctoral fellow at the U-M School for Environment and Sustainability, noted that the results support evolutionary theory, which posits that diversification tends to occur in pulses rather than continuously. According to the research, these bursts of evolution appear to be driven by factors such as new ecological opportunities or geographic expansion into novel environments. The statistical method used to analyze the data, named bifrost, enabled the researchers to assess the entire skeleton of each species simultaneously. This approach helped them reconstruct the evolutionary trajectory of body shape across the approximately 45-million-year history of passerines. Berv explained that the complexity of avian anatomy means that each bone is interconnected, making it essential to consider the whole organism when studying evolutionary changes. The findings revealed two key periods of evolutionary activity. One major burst of body-shape evolution occurred around 35 million years ago, during the Eocene, Oligocene transition, a period marked by intense global cooling. Another notable shift took place about 15 million years ago, when the pace of evolution slowed, coinciding with another significant geological event. These observations suggest that climate fluctuations may have played a crucial role in shaping the diversity of modern birds. Senior author Brian Weeks emphasized that the study has altered his understanding of how ecosystems function. He described the process of analyzing the vast dataset as both challenging and enlightening, highlighting the importance of integrating technology with traditional biological methods to gain deeper insights into evolutionary processes. As the research continues, scientists hope to expand their analyses to include additional bird families and explore whether similar patterns exist in other vertebrate groups. The work underscores the potential of AI tools in advancing our knowledge of evolutionary biology while reinforcing the link between environmental change and the dynamics of life on Earth.