An international team of scientists has created the tree of life for almost 8,000 (about 60%) genera of flowering plants (angiosperms). This achievement sheds new light on the evolutionary history of flowering plants and their rise to ecological dominance on Earth.
Time-calibrated phylogenetic tree for angiosperms based on 353 nuclear genes; all 64 orders, all 416 families and 58% (7,923) of genera are represented. Image credit: Zuntini et al., doi: 10.1038/s41586-024-07324-0.
Flowering plants account for about 90% of all known plant life on land and are found virtually everywhere on the planet — from the steamiest tropics to the rocky outcrops of the Antarctic Peninsula.
These plants originated more than 140 million years ago after which they rapidly overtook other vascular plants including their closest living relatives — the gymnosperms (nonflowering plants that have naked seeds, such as cycads, conifers and ginkgo).
Our understanding of how flowering plants came to dominate the scene soon after their origin has baffled scientists for generations, including Charles Darwin.
For new research, the authors used 1.8 billion letters of genetic code from more than 9,500 species covering almost 8,000 known flowering plant genera (ca. 60%). More than 800 of these species have never had their DNA sequenced before.
“Analyzing this unprecedented amount of data to decode the information hidden in millions of DNA sequences was a huge challenge,” said Dr. Alexandre Zuntini, a researcher at Royal Botanic Gardens, Kew.
“But it also offered the unique opportunity to reevaluate and extend our knowledge of the plant tree of life, opening a new window to explore the complexity of plant evolution.”
“Flowering plants feed, clothe and greet us whenever we walk into the woods,” said Professor Stephen Smith, an evolutionary biologist at the University of Michigan.
“The construction of a flowering plant tree of life has been a significant challenge and goal for the field of evolutionary biology for more than a century.”
“This project moves us closer to that goal by providing a massive dataset for most of the genera of flowering plants and offering one strategy to complete this goal.”
“One of the biggest challenges faced by the team was the unexpected complexity underlying many of the gene regions, where different genes tell different evolutionary histories.”
“Procedures had to be developed to examine these patterns on a scale that hadn’t been done before.”
The flowering plant tree of life, much like our own family tree, enables scientists to understand how different species are related to each other.
The tree of life is uncovered by comparing DNA sequences between different species to identify changes (mutations) that accumulate over time like a molecular fossil record.
For the research, new genomic techniques were developed to magnetically capture hundreds of genes and hundreds of thousands of letters of genetic code from every sample, orders of magnitude more than earlier methods.
A key advantage of the team’s approach is that it enables a wide diversity of plant material, old and new, to be sequenced, even when the DNA is badly damaged.
The vast treasure troves of dried plant material in the world’s herbarium collections, which comprise nearly 400 million scientific specimens of plants, can now be studied genetically.
“In many ways this novel approach has allowed us to collaborate with the botanists of the past by tapping into the wealth of data locked up in historic herbarium specimens, some of which were collected as far back as the early 19th century,” said Dr. William Baker, a researcher at the Royal Botanic Gardens, Kew.
“Our illustrious predecessors, such as Charles Darwin or Joseph Hooker, could not have anticipated how important these specimens would be in genomic research today.”
“DNA was not even discovered in their lifetimes. Our work shows just how important these incredible botanical museums are to groundbreaking studies of life on Earth.”
“Who knows what other undiscovered science opportunities lie within them?”
The team’s results appear in the journal Nature.
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A.R. Zuntini et al. Phylogenomics and the rise of the angiosperms. Nature, published online March 15, 2024; doi: 10.1038/s41586-024-07324-0