New species might arise as a result of single rare events, rather than through the gradual accumulation of many small changes over time, according to a study of thousands of species and their evolutionary family trees. …
“What we've shown is that speciation is about happy accidents — rare events that happen in the environment that cause a species to speciate,” says Pagel. These events could include a mountain range being thrust up or a shift in climate, he says.
The team’s findings might stir things up in the world of evolutionary biology. “It really goes against the grain because most of us have this Darwinian view of speciation,” says Pagel. “What we’re saying is that to think about natural selection as the cause of speciation is perhaps wrong.”
It is difficult to imagine a more fundamental prediction of evolution. Natural selection is practically synonymous with evolution, and this research raises yet another contradiction to this long held prediction.