Study: Cenozoic seeds of Vitaceae reveal a deep history of extinction and dispersal in the Neotropics
The ancestor of Vitoid grapes that gave rise to commercial grapes likely originated in the New World, in the tropical belt of the Americas and the Caribbean, 60 million years ago, according to a study co-authored by a University of Michigan researcher.
Researchers discovered fossilized seeds representing nine separate species of grape ranging in age from about 20 million to 60 million years old in Panama, Colombia and Peru. The oldest of these fossilized seeds came from plants related to the current subfamily Vitoideae, the same subfamily to which commercial grapes belong, says U-M paleobotanist Mónica Carvalho, co-author of the study published in Nature Plants.
"In excavating the fossil record in the New World tropics, we found seeds that are related to the grape family that date back to 60 million years ago. That led us to revise the fossil record of grapes in the New World. The oldest seed we found is closely related to the large group that gave rise to commercial grapes, to the subfamily Vitoideae," said Carvalho, assistant professor of earth and environmental sciences and an assistant curator at the U-M Museum of Paleontology.
"We have this rich but previously poorly known fossil record for grapes in the New World, and what we're seeing is this family has a complex history of extinction and dispersal in the New World. Various groups of this family, such as the genus Leea and species of tribe Cayrateae only live today in Southeast Asia and the Indo-Pacific, but their fossils indicate that they lived in the New World for a very long time before becoming regionally extinct."
Approximately 66 million years ago, at the end of the Cretaceous Period, an asteroid hit Earth. The event that famously caused the extinction of dinosaurs also "pretty much wiped out a lot of the preexisting forests that were living in the tropical latitudes of the New World," Carvalho says.
New rainforests grew in the destroyed landscape and prompted the diversification of many modern plant and animal groups. Carvalho and lead author Fabiany Herrera, a paleobotanist at the Field Museum of Natural History in Chicago, examined the fossil record from this time period to understand the evolution of modern rainforests.
"Within these early neotropical rainforests, we find the earliest record of Vitoideae, telling us that the lineage of grapes dates back to the origin of the first neotropical rainforests," Carvalho said.
Herrera says the discovery is important "because it shows that after the extinction of the dinosaurs, grapes really started to spread across the world."
The family of grapes has an extensive fossil record that predates the Cretaceous extinction event, Carvalho says. The oldest grapes go back to the age of dinosaurs, and were found in India. Seeds from these plants may have been borne by animals to the New World.
"The diversification of birds and mammals following the end-Cretaceous extinction could have aided in the dispersal of their seeds," Herrera said.
Carvalho says their study fleshes out the history of grapes in the Americas and Caribbean.
"There was a very large gap in the fossil record of grapes, after the extinction of dinosaurs. By about 50 million years ago, we see fossil grapes in North America and Europe," she said. "At the time, when the planet was warmer, grapes had a wider distribution in high, northern latitudes, but we didn't really know much about the history of this group in tropical latitudes. That's where our work comes in."
