How does one species become many?

Evolutionary biologists have long suspected that the diversification of a single species into multiple descendent species – that is, an “adaptive radiation” – is the result of each species adapting to a different environment. Yet formal tests of this hypothesis have been elusive owing to the difficulty of firmly establishing the relationship between species traits and evolutionary “fitness” for a group of related species that recently diverged from a common ancestral species.

A global team of biologists led by McGill University have compiled nearly two decades of field data – representing the study of more than 3,400 Darwin’s finches in the Galápagos Islands – to identify the relationship between beak traits and the longevity of individual finches from four different species.

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