Researchers at the zoology department at the University of British Columbia have discovered that contrary to common belief, species do not evolve faster in warmer climates.
Analysis of birds and mammals across the Americas revealed that new species emerge more frequently in temperate regions than in tropical ones.
Researchers came to this conclusion after analyzing the DNA of 618 mammal and bird species in the Americas over the last few million years.
For the study, Jason Weir and Dolph Schluter at the University of British Columbia examined pairs of ‘sister species’, which share an immediate common ancestor.
The picture shows a male masked tityra (Tityra semifasciata), one of the tropical species included in the study, at a nesting hole in a snag. It diverged from its sister species the black-tailed Tityra about 4 million years ago.
The researchers found that speciation (the process in which one species splits into two) is faster in temperate zones than in the tropics.
Analysis shows that new species actually evolve faster as one move towards the poles. It would take one species in the tropics three to four million years to evolve into two distinct species, whereas at 60 degrees latitude, it could take as little as one million years.
Thus cooler temperatures increases speciation, but that does not necessarily mean more species. This is because the higher speciation rate is neutralized by a higher extinction rate.
In comparison, even though there is a lower speciation rate in the tropics, the stable environment contributes to an equally low extinction rate. As a result, more species survive. This explains why there are more species in warmer climates.
Researchers speculate that the abrupt climatic changes in temperate regions over the past hundreds of thousands of years may have caused more rapid evolution than the relatively stable climate of tropical regions.
Thus, temperate zone like Canada is hotbed of evolution, not tropical areas like Amazon as conventionally known.
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Image courtsey: NewScientist (Image courtesy of Jason Weir)