The study shows that the orchid family emerged in the Northern Hemisphere and evolved alongside the dinosaurs for 20 million years.

Orchids are one of the most species-rich families of flowering plants, rivaled only by the daisy family (Asteraceae). Photo: Lepinthes cassiola. Credit: Oscar Perez, RBGQ

In a new study published I The New PhytologistScientists from the Royal Botanic Gardens, Kew, along with partners from Latin America, Asia and Australia, are presenting an updated family tree of orchids, tracing their origins to the Northern Hemisphere around 85 million years ago. . Not only does the study shed new light on their complex and fascinating evolutionary history, but the study authors hope their findings will help inform future orchid conservation planning.

gave The family, Orchidaceae, is often hailed by scientists as one of the greatest evolutionary miracles in the plant world. Not only are these flowering plants found on every continent except Antarctica and in nearly every habitat, including north of the Arctic Circle, but they are also incredibly diverse, with an estimated 29,500 species—including birds. are nearly three times the recognized number of species. Globally

It is generally accepted that orchids originated around 90 million years ago or more, but earlier they were thought to have emerged on the continent of Gondwana, in what is now Australia. However, the new study indicates that their common ancestor may have originated in the Northern Hemisphere, on the Laurasia subcontinent, before spreading further across the globe.

Scientists at RBG Kew have come to the conclusion that they evolved by assembling the most densely sampled orchid tree of life ever discovered. This new family tree includes about 40 percent of all accepted orchid genera and about seven percent of known species diversity.

The tree was reconstructed by combining a variety of DNA sequence data obtained from the orchid family. New, ‘high-throughput’ gene capture data developed at RBG Kew as part of the Plant and Fungal Tree of Life (PaFToL) project were central to this work. The resolution of the tree was further increased by combining the results with previously published DNA sequences of several orchid species.

This DNA ‘barcoding’ sequence reflects decades of efforts to establish family relationships between different branches of the orchid’s evolutionary tree. Combined with geographic distribution information, this wealth of data led to a new orchid tree of life that also shows how orchid species diversity is distributed globally.

“Generating ‘gene capture’ data from this type of species in the laboratory would not have been possible without its geographical and historical breadth,” says Dr Natalia Przylomska, University of Portsmouth lecturer and research associate at RBG Kew’s Herbarium. Collection accessible for research.”

“I had the privilege of extracting DNA from field specimens recently collected by a number of field botanists involved in this research, going back to botanists such as AC Maingay and EL Ekman, who in the 19th century exploring the tropics and neotropics of the Old World. and the 20th century.”

Orchids are one of the most species-rich flowering plant families (only rivaled by the daisy family, Asteraceae) but also one of the most endangered. The biggest threats to orchids today include deforestation, and climate change, which may cause extinctions or declines in their ranges and population sizes.

As RBGQ’s State of the World’s Plants and Fungi 2023 report notes, 45 percent of the world’s known plants are threatened with extinction, and this number is even higher within the orchid family, which An estimated 56 percent of species are threatened

A better understanding of the individual branches of the orchid family tree and how they all connect will help scientists discover and describe new orchid biodiversity. In particular, they hope to achieve this in parts of the world where biodiversity loss is unfortunately accelerating.

One way to help conserve orchids is to understand better patterns of speciation, according to a new report. In this case, it may indicate which ecosystems have above-average levels of orchid diversity as well as the highest evolutionary potential to host new orchid diversity.

Dr. Oscar Perez, Research Leader—Integrated Monograph at RBGQ, says, “Our study is the first globally to reveal which ecoregions have the highest orchid evolutionary potential and species richness. That is, ecoregions that in very recent times (ie, the last 2-3 million years) have served as cradles of unprecedented species diversity, resulting in remarkably high levels of orchid species diversity. Happened.”

“We believe that such areas may have the potential to carry even greater diversity in the near future, as long as their native ecosystems are preserved. Thus, our study provides a rich sample of species.” The information generated can inform policies about prioritizing ecosystems for their conservation.”

Unfortunately, orchids are becoming extinct at an alarming rate compared to the time it took about 5 million years. This indicates that they will not return from extinction in human times, even without a precise estimate of the number of orchid species that have become extinct.

Professor Alexander Antonelli, director of science at RBG Kew and senior author of the study, says: “Orchids are not only extraordinary jewels of nature, but also hold untold mysteries about life on Earth: how species evolve. , adaptation and movement. The future is critical to protecting the complex interactions they play in ecosystems and ensuring that these stories can one day be revealed by scientists.”

The new study is the first step in scientists’ goal of creating a complete orchid tree of life that includes all known species. The authors also aim to establish the orchid family as the model of choice to understand how speciation and extinction occurred in different ecosystems around the world. Additionally, it will help to understand how Deforestation and illegal trade may affect the distribution of this species diversity in the near future.

More information:
Oscar A. Perez-Escobar et al., Origin and Species of Orchids, The New Phytologist (2024). DOI: 10.1111/nph.19580

Reference: Study shows orchid family emerged in northern hemisphere and flourished alongside dinosaurs for 20 million years (22 Feb 2024) https://phys.org/news/2024-02-orchid-family-emerged -northern-hemisphere.html

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