“People think of extreme environments like mountains and deserts as dead ends or not that important for the evolution of species, but that’s not true. They’re kind of the engine of new species,” says Michael Harvey at the University of Texas at El Paso.
Harvey and his colleagues put together genetic data of 1287 species of tropical songbirds to determine patterns in their diversity and evolution. From this, the researchers calculated the rates at which species formed in different geographical regions. They found higher rates of speciation in more extreme environments like parts of the central and southern Andes and Patagonia.
“This was sort of like the ultimate litmus test of this new idea that people have been starting to talk about. It establishes that this is the new paradigm, that species are forming at lower rates in these tropical places even though they have so many species currently,” says Harvey.
The researchers suggest that tropical hotspots are incredibly diverse because a large number of species accumulate in those areas over time rather than many new species forming there.
“I think this is perhaps the strongest evidence yet of this pattern that speciation rate is higher where there are fewer species,” says Chris Venditti at the University of Reading, UK. Now researchers have to figure out why, he says. “We want to know what is going on underneath the bonnet here.”
Journal reference: Science, DOI: 10.1126/science.abf0830
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