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Trace the evolution of 50,000 species over four billion years and you get the TimeTree of Life.
This computational informatic, assembled by Temple University professors using data from more than 2,000 studies, illustrates the grandeur of the evolution of life in a series of interlinked evolutionary trees that are mapped over time.
“People want to be able to see this tapestry of life,” said Sudhir Kumar, director of Temple’s Institute for Genomics and Evolutionary Medicine and member of the research team. “Data visualization is a really important part of the big data revolution.”
Scientifically, the Timetree proves that the rate of speciation, or development of new species, is constant throughout all of life, according to S. Blair Hedges, another team member and director of Temple’s Center for Biodiversity.
“It’s basically trees of organisms, calibrated to time,” he said. “This shows that speciation is completely separate from adaptation … It’s purely isolation and time. If you take any two species of plants or animals, keep them separate for two million years, you’re going to have a new species.” While it’s a long time to wait for a new type of dog, new species of microorganisms and lizards have been documented, Kumar said.
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But ultimately, the ongoing diversification of life is still unpredictable given ongoing changes to the environment and world at large. “What one cannot say is what species will become more diverse and which groups will not. Various calamities and environmental pressures lead to destruction of niches for some groups,” Kumar said. “The overall diversity of life on Earth will keep increasing, but which groups of animals and plants will go extinct?”
According to environmentalists at the World Wildlife Fund (WWF), half of the world’s wildlife has been lost in the past 40 years, in terms of overall animal populations. This loss has been caused by problems like climate change, over-exploitation of natural resources, and habitat loss.
Subsequently, many species are now nearing the edge of extinction, such as the Javan rhino (an estimated 35 remain), African Forest elephants (who saw 60 percent of their population extinguished from 2002 to 2013 and could go extinct within a decade) and the Vaquita, the world’s smallest porpoise and the rarest marine mammal in the world (fewer than 100 currently remain).
“Even if diversification rates have been constant over evolutionary time scales, rates of species loss have spiked during mass extinction events that reduced global diversity. Evidence today points to being in the sixth such event,” said Jon Hoekstra, vice president and chief scientist of WWF.
To Hedges, the TimeTree goes hand in hand with the work of conservation, because it provides a new way to look at how species are related. The research that went into creating the TimeTree of Life charts “global patterns of biodiversity for major groups like mammals and birds,” he said. “Knowing historical patterns allows us to see how geology and climate have impacted the evolution of species in the past,” he said. “Combined with distributions and land use by humans, all of this information can help predict the distribution and abundance of species in the future.”
This TimeTree represents years of collaboration between Hedges and Kumar. One turning point was the decision to represent the data as a spiral, so that it could be presented to the world on a single piece of paper. “There’s nothing magical about the spiral,” Hedges said, “but sometimes we understand things better when we see it.”