The grapevine is known for its economic impact, especially for wine production, but its evolutionary history has also captured the attention of the scientific community. In a recent study, a research team consisting of Aixa Tosal (Universitat de Barcelona), Alba Vicente (Institut Català de Paleontologia Miquel Crusafont), and Thomas Denk (Museum of Natural History Stockholm) has described a new fossil species of the grapevine family, Nekemias mucronata, based on plant remains found in Cervera, in the Segarra region. The discovery helps fill a gap in the knowledge about the evolution and distribution of this plant group during the Cenozoic.

In botany, a tribe is a taxonomic classification intermediate between family and genus, used to organize families that contain many species, such as the Vitaceae family. This family is divided into five tribes, including Viteae, which groups about 200 species, including the grapevine (Vitis vinifera). The published study focuses on another tribe, Ampelopsideae, which is much smaller and consists of 47 species, among which is the new Nekemias mucronata.

The leaves of Nekemias mucronata have an interesting characteristic shared with some modern species of the same family: they are compound leaves, formed by several leaflets joined by a common axis. Through the study of nearly a hundred fossil specimens, the research team has been able to detail the foliar traits of the new species, recognizing common patterns among the apical and lateral leaflets. According to Alba Vicente, ‘Beatriu de Pinós’ researcher at the Institut Català de Paleontologia Miquel Crusafont, "this analysis has allowed us to distinguish Nekemias mucronata from other fossil species of the same family found in Eurasia, helping to better understand the dispersion routes of these plants during the Cenozoic."

The study also analyzes the paleobiogeographic distribution of the tribe Ampelopsideae. “Until now, the oldest record of the Vitaceae family dates back to the Late Cretaceous, with remains found in India,” explains Thomas Denk, researcher of the Museum of Natural History Stockholm. However, during the Eocene (about 40 million years ago), the lineages Ampelopsis and Nekemias were already present in Europe and Central Asia. Based on fossil information, the research team has proposed two possible dispersion routes to explain how these plants reached North America and other regions of the northern hemisphere.

One of the proposed routes suggests that these species dispersed from Central Asia to Europe and then to North America via the North Atlantic land bridge, a terrestrial dispersion route that connected continental landmasses millions of years ago. The other hypothesis proposes that the dispersion occurred through the Bering Strait, a route used by various plant and animal species at that time. According to Aixa Tosal, researcher at the Universitat de Barcelona, "our results show that this dispersion occurred about 20 million years earlier than previously thought, which compels us to reconsider the traditional models of dispersion across the northern hemisphere for this family."

In addition to dispersion routes, the study also explores the possible causes influencing the distribution of two fossil species of Ampelopsideae, Nekemias mucronata and Ampelopsis hibschii, which inhabited Eurasia from the late Eocene to the Neogene. The research team has determined that the distribution of these species was not strictly controlled by climatic factors, as previously thought. This suggests that other factors, such as land connections between continents and the adaptability of these plants to various biomes, may have played a crucial role in their expansion.

Despite the new findings, the team emphasizes that many questions remain unanswered about the early phases of dispersion of the Vitaceae family, especially between the Late Cretaceous and the Paleogene. With this work, it is hoped that further research will continue to unravel the evolution of this plant family and how they expanded across different continents between 66 and 41 million years ago.

Imatge principal: Lateral leaflets of Nekemias mucronata stored at the Museu de Ciències Naturals de Barcelona.

Article original:

• Tosal, A., Vicente, A., & Denk, T. (2024). Cenozoic Ampelopsis and Nekemias leaves (Vitaceae, Ampelopsideae) from Eurasia: Paleobiogeographic and paleoclimatic implications. Journal of Systematics and Evolution. https://doi.org/10.1111/jse.13126