THE TROPICS AS A MUSEUM OF BIOLOGICAL DIVERSITY - ANALYSIS OF THE NEW-WORLD AVIFAUNA

The tropics have variously been argued to represent a cradle of divers ity, a museum of diversity, or some combination of the two. Few broad scale data have been available to examine these mechanisms. For the av ifauna of the New World, the tropics appear, at least, to act as a mus eum. The mean age of tribes is test at the equator and declines toward s the Poles, whether or not the mean is weighted by the number of spec ies in the tribe. The decline is asymmetrical, being much more severe in the northern hemisphere. The pattern results predominantly from a p rogressive loss of older tribes towards higher northern latitudes. Som e mechanisms that might generate these patterns are discussed.