Whereas it was thought that tropical climates were more favorable to speciation, a recent study by Canadian scientists at the University of British Columbia in Vancouver shows that species divergences occur more frequently in much colder areas of the planet. They compared pairs of “sister species”, which share the most recent common ancestor, across the Americas and discovered that, while species diverged some 3.4 million years ago as an average near the equator, temperate species split 1.7 million years ago, and none or the arctic species separated more than a million years ago. They concluded that warmer regions of the globe keep the species around longer, whereas harsher environments select them more quickly, driving them to both speciation and extinction.

Source: Science