Groundbreaking, evolutionary plant study by MSU biological sciences faculty reverses previous hypotheses

Contact: Sarah Nicholas

Studio portrait of Ryan Folk
Ryan A. Folk (Photo by Beth Wynn)

STARKVILLE, Miss.—New research from a Mississippi State University biological sciences faculty member reveals the evolutionary history of plant diversification is completely different than decades-old theories.

In a groundbreaking study featured this month in “Nature Communications,” a natural sciences journal publishing research advances of significance, Ryan A. Folk, assistant professor of biological sciences, found that, for the past 15 million years, cooling climate patterns have led to dynamic and evolving plant communities in temperate areas like the southeastern U.S. On the other hand, in relatively tropical climates, plants have evolved at a slower rate, an opposite finding of previous research studies.

Considered one of the largest investigations of this type to date, the study’s co-first author studied rosids—a large subgroup of more than 90,000 flowering plants—to understand global patterns of species diversification and its relationship to climate. He used a dataset of relationships for nearly 20,000 species with DNA data and nearly 3 million occurrence records for plants.

The paper, titled “Recent accelerated diversification in rosids occurred outside the tropics,” was accomplished in collaboration with a team of researchers from the University of Florida, Aarhus University in Denmark, and the Chinese Academy of Sciences.

“That the tropics are filled with biological diversity is common knowledge,” said Folk, who also is curator of the MSU Department of Biological Sciences’ herbarium. “It has long been thought that the tropics are so much more diverse because of continued high rates of evolution of new species in these areas. But in this paper, covering a massive group containing nearly a quarter of all green plant species, we show that it is the temperate areas of the earth that have the most dynamic evolutionary patterns right now.”

He continued, “The paper showcases the power of harnessing massive datasets to provide totally different perspectives and upset what we thought we knew about classic hypotheses. This work excited me because it was not simply a new finding but exactly opposite of my gut instinct. No one was really predicting this before huge data resources became available to perform these types of studies.”

“Everyone knows about the diversity of tropical rainforests. You would assume all the action in evolution is happening in them. But we found out that it is really the temperate regions of the earth—really our own back yards—where a lot of the recent action is taking place. That is not to say that tropical areas aren’t interesting. Instead they are like ‘museums’ of ancient diversity that tell us more about the early origins of plants on Earth,” he said.

The oldest communities of plants on Earth are distributed across the global tropics, according to Folk, but the diversity of tropical regions is not due to evolutionary mechanisms, but rather that tropical plant communities have “simply failed to go extinct so to speak. By contrast, temperate areas such as our own Mississippi are where the recent action has taken place in evolution.”

Folk said future studies will be critical for identifying and refining drivers of the high diversity of rosids and how these key members of present-day plant communities may respond during future, rapid climate warming.

A native of Akron, Ohio, Folk’s lab at MSU uses genomic and bioinformatic techniques to document the origins of plant diversity from evolutionary and ecological perspectives using a variety of plant groups and habitats. His work is based in MSU’s herbarium, housing approximately 35,000 vascular plant specimens from around the world with an emphasis on the southeastern U.S.

An MSU faculty member since 2019, Folk received his Ph.D. in evolution, ecology and organismal biology from Ohio State University in 2015. He received his bachelor’s degree in biology from the University of Akron in 2010.

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