"This obsidian told us that early on, Paleoindians must have gone to the highlands," Rademaker told Live Science. There were no rivers or other geologic forces to carry the volcanic rock to the coast, and the closest volcanoes were in the Andes Mountains, roughly 100 miles (160 kilometers) away, said Rademaker, who is now a postdoctoral researcher at the University of Tübingen in Germany. There, they found tools made of obsidian, a volcanic rock. At that time, Rademaker and his colleagues were studying a 13,000-year-old Paleoindian fishing settlement on the coast of Peru called Quebrada Jaguay. The recent discovery of these high-altitude artifacts was made possible by work that started in the 1990s. Furthermore, in this dissertation I present evidence to fill a gap in our current knowledge base, by complementing the extensive research findings on the role of Andean uplift in shaping the evolution of plants in terrestrial ecosystems, with investigations on aquatic plants.In follow-up work, the team plans to look for more evidence of occupation, such as human remains. Together, these three projects advance our understanding of aquatic plants living in fast-flowing and standing-water aquatic ecosystems in the Neotropics. To investigate the impact of Andean uplift and drainage basin reconfiguration on river plant evolution, I use \textit evolved in South America. How did Andean uplift and drainage basin reconfiguration shaped the evolution of aquatic plants in rivers and wetlands across the Andes in northern South America? In this dissertation I aim to address this question and provide a novel perspective on the impact of landscape change on the evolution of the Neotropical flora, by using empirical data obtained from samples collected in the field from which I generate comprehensive genomic datasets and conduct phylogenetic, populations genetics, and biogeographical analyses. Aquatic plants are most diverse in the Neotropics. However, fossil and stratigraphic data show that the uplift of the Andes not only resulted in the development of high-elevation tropical ecosystems, but also in changes in drainage basin reconfiguration through time. All botanical investigations that have aimed to understand the role of landscape change on the evolution of the Neotropical flora have been restricted to terrestrial plants. The Andean Cordillera is deemed responsible for triggering explosive radiations and increasing diversification rates in Neotropical taxa. Given that northern South America is a geologically dynamic region consisting of a complex and heterogeneous landscape matrix, landscape change is viewed as a primary factor promoting species diversification. Northern South America is one of the most biodiverse regions on earth and understanding the causes and processes that have led to the assembly of this rich biota has been central to ecological and evolutionary investigations since Humboldt and Wallace.
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