At the end of a 1945 paper on the group, he mused on how they had evolved. He speculated that they originated in Asia, moved over the Bering Strait, and moved south all the way to Chile.
Allowing himself a few literary flourishes, Nabokov invited his readers to imagine “a modern taxonomist straddling a Wellsian time machine.” Going back millions of years, he would end up at a time when only Asian forms of the butterflies existed. Then, moving forward again, the taxonomist would see five waves of butterflies arriving in the New World.
Nabokov conceded that the thought of butterflies making a trip from Siberia to Alaska and then all the way down into South America might sound far-fetched. But it made more sense to him than an unknown land bridge spanning the Pacific. “I find it easier to give a friendly little push to some of the forms and hang my distributional horseshoes on the nail of Nome rather than postulate transoceanic land-bridges in other parts of the world,” he wrote.
Tuesday, January 25, 2011
"The nail of Nome"
Gene sequencing retroactively corroborates Nabokov's controversial thesis about the evolution of the Polyommatus blues (the piece is by Carl Zimmer for the New York Times):