A Method for Studying Dinosaurs Can Also Help Fight the Spread of the Flu
Dinosaurs and influenza would seem to have nothing in common, but a powerful new method of analyzing biogeographical data can be applied to both — helping to solve mysteries about long-extinct animals, while also preventing flu's spread.
Non-avian dinosaurs and flu viruses would appear to share few, if any, characteristics. After all, one group consisted of large animals that went extinct millions of years ago, while the other includes pathogenic particles that are unfortunately still very much with us.
The evolutionary histories of dinosaurs and viruses have more in common than one might expect. And a new method for studying the animals is already being recruited in the fight against influenza and additional viruses that can infect humans and other species. The groundbreaking technique is described in the journal Nature Ecology & Evolution.
The breakthrough involves projecting shifting rates of evolutionary change onto the surface of a sphere, instead of on a flat plane. This allows biogeographical data to be analyzed within an Earth-resembling model that captures speed, direction, and distance moved over short to long periods of time.
"As long as a group of organisms can be placed in a phylogenetic tree, which describes how species are related to each other, or a single species of interest can be placed in the context of its close relationships within a phylogenetic tree, and has geographical data — longitudes and latitudes of where the organisms have occurred on the Earth — the method we develop can reconstruct where the organisms’ ancestors existed on the globe," co-author Andrew Meade of the University of Reading told Seeker.
On the dinosaur side of the research, the technique has already revealed new insights concerning the origin and dispersal of dinosaurs.
Meade, lead author Ciara O'Donovan, and senior author Chris Venditti plugged extensive information on dinosaurs and their fossil record into their model. The data came from the Paleobiology Database, an online resource curated by numerous scientists around the world.
The information shows that dinosaurs first evolved in what is now South America at close to the beginning of the Mesozoic Era, which lasted in its entirety from about 252–66 million years ago.
"Prior to the dinosaurs’ origination there was an extreme extinction event," O'Donovan told Seeker. "This happened 252 million years ago, at the Permian-Triassic boundary and is the largest extinction event to have occurred in Earth’s history."
"This decimated the majority of life on Earth and therefore may well have provided the dinosaurs with a blank canvas to colonize," she added. "This fairly ‘empty Earth’ would have been totally open and up for grabs, and the dinosaurs were able to spread across the globe quickly, taking every ecological opportunity in their path."
Pangea — the single, giant landmass that later broke up to form the continents — was additionally whole when the dinosaurs originated about 231 million years ago. This meant that there were few, if any, geographical barriers preventing the dinosaurs' movement.
O'Donovan and her team suspect that the dinosaurs must have had some beneficial biological predisposition, enabling them to take advantage of the "blank canvas" they found themselves on. This aided their moving, dispersing, and colonizing new habitats. The remains of dinosaurs have remarkably been found on every continent, from what are now the polar regions to nearly every place in between.
The researchers tracked the movements through evolutionary time of the four major groups of dinosaurs — Ornithischians, Sauropods, Theropods, and birds — as well as certain individual species, like Tyrannosaurus rex.
At the start of their research, the scientists thought that each of the four dinosaur groups would exhibit different dispersal patterns. They especially thought that would be the case for birds.
The researchers determined, however, that all of the animals shared a rapid initial expansion whereby the dinosaurs speciated quickly and moved over great distances. This was followed by a continual and gradual slow-down as the animals approached the critical Cretaceous-Tertiary boundary 66 million years ago.
Venditti explained: "As time went on, dinosaurs both moved less, and fewer new species were produced. The less they could move, the more likely it would have been that any speciation that did occur would be by specialization in the environment the dinosaurs were already living in."
"The idea that the dinosaurs were running out of space fits here," he continued. "The lack of space explains why the dinosaurs were less able to speciate to replace species that were going extinct. And species may have been going extinct owing to becoming specialized and therefore being vulnerable to changes within the environment."
The new information supports the conclusions of a prior University of Reading study that was published in 2016 in the journal Proceedings of the National Academy of Sciences. It found that 50 million years before the asteroid impact that occurred in the Yucatan peninsula 66 million years ago, dinosaurs were already in decline.
Nevertheless, the ancestors of today's birds survived.
"Where avian ancestors were not able to move to new environments owing to the lack of space by that time, they specialized to take advantage of a type of space previously unoccupied by dinosaurs — aerial space," O'Donovan said. "They were able to do this because they had feathered wings. In doing this, they would have been able to explore ecological opportunities that were previously inaccessible and would have been able to evade competition with their relatives on the ground."
It is possible that birds benefitted from the die-off in the same way that non-avian dinosaurs did after the Permian-Triassic extinction event.
The researchers suspect that birds might have changed their movements to take advantage of the ecosystem voids. The ancestors of mammals are thought to have done the same. The new model created for the study only goes up to 66 million years ago, however, so the geographical signatures for birds and mammals since then have not been determined yet.
The model can be applied to anything for which a certain amount of ancestral history is known. On a small scale, and considering the current popular technologies related to DNA, it could reveal the geographical signature of an individual family over time.
Meade said that the technique could also "be useful in the case of viruses, or perhaps plants linked to agriculture or invasive species if we wish to know where a certain virus originated, or how quickly a plant has spread or a species has invaded non-native environments."
The model could also show far more than the history of one particular human family.
"It is also possible to represent human cultures in a phylogenetic tree by using similarities and differences in language," Meade explained. "This means it would be possible to study the expansion of humans across the planet using our approach."
Chris Organ of Montana State University did not participate in the new study, but wrote a opinion article published in the same journal.
In it, Organ mentions that no such models can yet be 100 percent accurate.
"When studying fossils, there is limited exposure of fossil-bearing rocks and these don't capture a continuous sample of species across time," Organ told Seeker.
"Moreover, these rocks are not evenly distributed geographically today. These and other factors affect paleontological inferences."
Nevertheless, the data is as accurate as possible, and he is excited by the model's future possibilities. He especially looks forward to the research method's application to epidemiology, which is already being investigated by University of Auckland professor Alexei Drummond and others.
"This kind of method could be used to better understand how viruses evolve as they spread across the globe," Organ said, "and that might help us identify pathways that facilitate the spread or evolution of viruses."
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