Collaborative research: closing the GAP: the history of river connections with the formation of the isthmus of panama and its impact on the evolution of plants in rivers

The National Science Foundation's Division of Earth Sciences awarded $200,000 under the Geosciences program (CFDA 47.050) to the New York Botanical Garden for a collaborative research project spanning October 1, 2025, through September 30, 2028. This Project Grant supports fundamental research examining the evolutionary history of riverweeds (Podostemaceae), a specialized plant group inhabiting tropical and subtropical river systems, to elucidate the role of river connectivity in the formation of the Isthmus of Panama and its impact on plant evolution in freshwater systems. The research integrates paleobotanical analysis, genomic data from living plant specimens, and geological modeling to reconstruct the timing and patterns of riverine plant migration across the Isthmus during its closure.

The primary deliverable is peer-reviewed scientific research that shifts focus from terrestrial to freshwater perspectives on biotic migration during the Isthmus formation, providing a novel understanding of river system evolution and plant adaptation. Secondary products include training and professional development of American scientists in collaborative international research partnerships and multilingual scientific engagement, advancing workforce capacity within the geosciences research community. The research outcomes will contribute foundational knowledge to the integrated Earth system sciences while strengthening institutional pathways for future U.S. scientific research.

Abstract

One of the most important events in the history of life in the americas was when north and south america became connected by a land bridge?the isthmus of panama?which occurred between 15 million years ago and the present day. This connection allowed plants and animals to move between the two continents. Scientists have studied land plants to better understand when this event happened, but we still do not know how rivers played a role in how the land bridge formed. This project will study a special group of plants that live in tropical and subtropical rivers rapids and waterfalls, called riverweeds. Using information from both plant fossils and the DNA of living plants, we will study how these plants moved and evolved as the land bridge. Combining information about plants with geologic data, we hope to understand when rivers began to connect, and how these changes affected the plants living in them. This project will help science grow by training american scientists to work together with scientists in other countries and in various languages. The project will also help train new partners, strengthening the pathways for future american scientific research. This project will provide a novel lens on biotic migration during the rise of the isthmus of panama by leveraging the tight link between podostemaceae plants and river evolution, adding a new element to the story of the isthmus closure, and shifting the focus from terrestrial to unexplored freshwater systems. The traditional approach in plant evolution research is to interpret biological data using geological models. In this project, however, genomic data will be used to infer the timing and pattern of riverine plant migration across the isthmus, which will then be coupled with geological and fossil data to build a wholistic model of river connectivity across the isthmus of panama. The project will use a recently developed method for the integration of distributional and genomic data to refine the resulting models of past landscape change. This interdisciplinary approach will not only clarify the tempo and mode of riverine connectivity across the isthmus but will also fill critical gaps in our understanding of tropical biodiversity assembly in freshwater ecosystems. The project also includes opportunities for training for students ranging from high school to postdoctoral scholars. This project is CO-funded by the systematics & biodiversity science and life through environment and time programs. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are not planned for this award.