Fossilized Seeds Tell Story Of Grape Diversification

The paper also describes a new species that provides the earliest evidence of Vitaceae in the Western Hemisphere. Scientists’ understanding of ancient fruits often comes from the seeds, which are more likely to fossilize than the soft tissue. The earliest known grape seed fossils were found in India and are 66 million years old—about when a huge asteroid hit the Earth, triggering a massive extinction that altered the course of life on the planet. “We always think about the animals, the dinosaurs, because they were the biggest things to be affected,” says Fabiany, “but the extinction event had a huge impact on plants too. The forest reset itself, in a way that changed the composition of the plants.” And the absence of dinosaurs might have helped that reset. Large animals alter their ecosystems, and the ramblings of dinosaurs may have made forests more open than they are today. Absent the huge reptiles, some tropical forests, including those in South America, became denser, forming an understory and a canopy, and providing an opportunity. “In the fossil record, we start to see more plants that use vines to climb up trees, like grapes, around this time,” Fabiany observes. Diversifying birds and mammals may have also aided grapes by spreading their seeds in the years following the mass extinction. The team studied nine species of fossil grapes from Colombia, Panama, and Perú, spanning from 60 to 19 million years old, including four species “new to science” described in this paper. At 60 million years old, Lithouva susmanii is the earliest known South American grape fossil, and among the world’s oldest from anywhere. This new species is also important because it supports the idea of a South American origin of the group in which the common grape vine Vitis evolved. Taken together, the new and extant species e lucidate previously unknown dispersal events for Vitaceae in the region, and a more dynamic biogeographic history than previously recognized, marked by multiple local/regional extinctions, including the extirpation of two major lineages from the Neotropics. “The fossil record tells us that grapes are a very resilient order. They’re a group that has suffered a lot of extinction in the Central and South American region, but they also managed to adapt and survive in other parts of the world,” says Fabiany. Such discoveries are instructive because, in Fabiany’s words “these little tiny, humble seeds can tell us so much about the evolution of the forest,” and they also reveal patterns about how biodiversity crises play out. The discoveries received international news coverage, which you can sample here.
July 12. 2024