The finding upends long-held thinking that plants' speciation rates are tied to the first development of a new physical trait or mechanism. The research has been funded by the U.S. National Science Foundation (NSF iPlant initiative) and the German Science Foundation (DFG).
A circular layout of the BigPlantTree.
visualization tool: NSF iPlant Collaborative
Providence, RI [Brown University]/Heidelberg, Germany [Heidelberg Institute for Theoretical Studies]/New Haven, CT [Yale University] — Evolution has been successful for billions of years and produced a vast amount of successful new species, but we still do not understand the underlying mechanisms. Researchers from the U.S. and Germany have recently unraveled new parts of this process. They found that plants initially tinker with their configuration and performance prior to coming up with new, improved versions of themselves.
The issue at hand is when a grouping of plants with the same ancestor, called a clade, begins to spin off new species. Biologists laboring over assembling the tree of life have long assumed that rapid speciation occurred when a clade first developed a new physical trait or mechanism and had begun its own genetic branch. But the team, led by Brown post-doctoral researcher Stephen Smith, who is also affiliated to the Heidelberg Institute for Theoretical Studies (HITS), discovered that major lineages of flowering plants did not begin to rapidly spawn new species until they had reached a point of development at which speciation success and rate would be maximized. The results are published in the American Journal of Botany.
Evolution is not what we previously thought,” said Smith, who works in the laboratories of Brown biologist Casey Dunn and of HITS computer scientist Alexis Stamatakis. “It’s not as if you get a flower, and speciation (rapidly) occurs. There is a lag. Something else is happening. There is a phase of product development, so to speak.”
Research in this area is only possible with computational methods. “This is a nice example of how computer science and cyberinfrastructure initiatives can help to extend the limits of biological explorations” says Alexandros Stamatakis, group leader of the scientific computing group at HITS.
To tease out the latent speciation rate, Smith and co-workers computed the largest plant phylogeny (evolutionary tree) to date, involving 55,473 species of angiosperms (flowering plants), the genealogical line that represents roughly 90 percent of all plants worldwide. Reconstructing a tree of this size is also a technical milestone and a starting point for many other studies. The researchers looked at the genetic profiles for six major angiosperm clades, including grasses (Poaceae), orchids (Orchidaceae), sunflowers (Asteraceae), beans (Fabaceae), eudicots (Eudicotyledoneae) and monicots (Monocottyledoneae). Together, these branches make up 99 percent of flowering plants on Earth.
The common ancestor for the branches is Mesangiospermae, a clade that emerged more than 125 million years ago. Yet with Mesangiospermae and the clades that spun off it, the researchers were surprised to learn that the boom in speciation did not occur around the ancestral root; instead, the diversification came about some time later, although a precise time remains elusive.
“During the early evolution of these groups,” Smith said, “there is the development of features that we often recognize to identify these groups visually, but that they don’t begin to speciate rapidly until after the development of the features.”
Put another way, the authors write, “These findings are consistent with the view that radiations tend to be lit by a long ‘fuse,’ and also with the idea that an initial innovation enables subsequent experimentation and, eventually, the evolution of a combination of characteristics that drives a major radiation.”
Shifts in diversification aren`t often directly associated with the origin of the familiar group (orchids, sunflowers, etc.). There are many more shifts than one might imagine. The diversity patterns may be explained not just by a few major shifts, associated with the major groups, like flowering plants. Instead, the diversity of groups more likely reflects a composite of many individual, smaller bursts within clades. It wouldn´t be possible to see this very well in the context of small phylogenies
Smith believes some triggers for the speciation explosion could have been internal, such as building a better flower or learning how to grow faster and thus outcompete other plants. Or, the winning edge could have come from the arrival of pollinating insects or changes in climate. The team plans to further investigate these questions.
"Taken at face value, our analyses suggest that many bursts in speciation, spread quite evenly and hierarchically across the entire tree, are responsible for the evident success of the flowering plants," explains Jeremy Beaulieu (Yale). Michael Donoghue (Yale) adds: "The possibility of working with phylogenetic trees of this size opens up all sorts of new research questions, but also clearly highlights the need for new statistical and computational tools. This area is in its infancy."
The U.S. National Science Foundation (NSF iPlant initiative) and the German Science Foundation (DFG) funded the research. The computations to assemble the phylogeny were performed at Yale’s High Performance Computing Center and at the Texas Advanced Computing Center.
The tree can be browsed on-line at: http://portnoy.iplantcollaborative.org/ (select BigPlantTree) thanks to resources provided by the NSF iPlantCollaborative and the efforts by Karen Cranston at the National Evolutionary Synthesis Center.
Press Contact:Dr. Peter Saueressig
Platinum nanoparticles for selective treatment of liver cancer cells
15.02.2019 | ETH Zurich
New molecular blueprint advances our understanding of photosynthesis
15.02.2019 | DOE/Lawrence Berkeley National Laboratory
For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.
The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...
Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens
Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...
Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light
When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...
The so-called Abelian sandpile model has been studied by scientists for more than 30 years to better understand a physical phenomenon called self-organized...
Physicists from the University of Basel have developed a new method to examine the elasticity and binding properties of DNA molecules on a surface at extremely low temperatures. With a combination of cryo-force spectroscopy and computer simulations, they were able to show that DNA molecules behave like a chain of small coil springs. The researchers reported their findings in Nature Communications.
DNA is not only a popular research topic because it contains the blueprint for life – it can also be used to produce tiny components for technical applications.
11.02.2019 | Event News
30.01.2019 | Event News
16.01.2019 | Event News
15.02.2019 | Physics and Astronomy
15.02.2019 | Physics and Astronomy
15.02.2019 | Life Sciences