Evolution may be less random than we thought.
Evolution has long been viewed as a relatively random process, in which species features are shaped by random mutations and environmental factors and thus largely unpredictable.
But an international team of scientists headed by researchers from Yale University And the Columbia University It was discovered that a particular plant lineage independently developed three types of similar leaves frequently in mountainous places scattered in the modern tropics.
The research revealed the first examples in plants of “repetitive radiation,” the repeated evolution of similar forms in different regions. This finding raises the possibility that evolution is not necessarily a random and predictable process.
The study was recently published in the journal Nature’s environment and evolution.
“The results show how evolution can in fact be predicted, with organisms growing together and natural selection to produce the same forms over and over under certain conditions,” said Michael Donoghue, professor emeritus of ecology and evolutionary biology from Yale University. “Perhaps evolutionary biology can become a much more predictive science than we once imagined.”
The research team examined the genetics and morphology of the Viburnum subspecies, a genus of flowering plants that began spreading in Central and South America from Mexico about 10 million years ago. Donoghue conducted research on this botanical group for his Ph.D. Thesis at Harvard 40 years ago. At the time, he advocated an alternative theory that the large hairy leaves and small, smooth leaves had evolved early in the group’s history and later migrated separately, scattered by birds, across the various mountain ranges.
However, new genetic analyzes presented in the study show that the two different leaf types evolved separately and simultaneously in each of the many mountainous regions.
“I came to the wrong conclusion because I was lacking relevant genomic data in the 1970s,” Donoghue said.
The team found that a very similar set of leaf types evolved in nine of the 11 regions studied. However, the full set of leaf species may not yet develop in places where the viburnum has migrated only recently. For example, the mountains of Bolivia lack the large, hairy-leaf species found in other, wetter areas with little sunlight in the cloud forests of Mexico, Central America, and northern South America.
“These plants arrived in Bolivia less than a million years ago, so we expect that the shape of the large, hairy leaves will eventually evolve in Bolivia as well,” Donoghue said.
Many examples of repetitive radiation have been found in animals, such as the anolis lizards of the Caribbean. In this case, the same group of body shapes, or “ectomorphs,” evolved independently on several different islands. With a botanical example in hand now, evolutionary biologists will attempt to discover the general conditions under which robust predictions about evolutionary trajectories can be made.
“This decades-long collaborative work has revealed a fascinating new system for studying evolutionary adaptation,” said Erica Edwards, professor of ecology and evolutionary biology at Yale University and co-author of the research. “Now that we have established this pattern, our next challenges are to better understand the functional significance of these leaf types and the underlying genetic structure that enables their recurring appearance.”
Reference: “Repeated radiation of a plant mass along a cloud forest archipelago” by Michael J. Cacho, Morgan K. Moglin, Jordan R. Gardner, Nora M. Heavi, Matisse Castorina, Ali Segovia Rivas, Wendy L. Clement, and Erica J. Edwards, July 18, 2022, Nature’s environment and evolution.
DOI: 10.1038 / s41559-022-01823-x