There were several plausible hypotheses for how the butterflies might have evolved. They might have evolved in the Amazon, with the rising Andes fragmenting their populations. If that were true, the species would be closely related to one another.
But that is not what Dr. Pierce found. Instead, she and her colleagues found that the New World species shared a common ancestor that lived about 10 million years ago. But many New World species were more closely related to Old World butterflies than to their neighbors. Dr. Pierce and her colleagues concluded that five waves of butterflies came from Asia to the New World — just as Nabokov had speculated.
“By God, he got every one right,” Dr. Pierce said. “I couldn’t get over it — I was blown away.”
Dr. Pierce and her colleagues also investigated Nabokov’s idea that the butterflies had come over the Bering Strait. The land surrounding the strait was relatively warm 10 million years ago, and has been chilling steadily ever since. Dr. Pierce and her colleagues found that the first lineage of Polyommatus blues that made the journey could survive a temperature range that matched the Bering climate of 10 million years ago. The lineages that came later are more cold-hardy, each with a temperature range matching the falling temperatures.
In case you were wondering, yes, this is that Vladimir Nabokov. He is better known outside scientific circles as the proclaimed author of Lolita and other novels. Link -via The Loom
(Image credit: Vlad Dinca)