Estimating time and space in the evolution of the Lepidoptera

Abstract

Several aspects of estimating what happened when and where in the evolution of the Lepidoptera are discussed. Because of their scarcity and often poor preservation, fossils are not very helpful, but at least they demonstrate that, in the Oligocene some taxa of butterflies, perhaps at tribal level or higher, did occur in the Northern as well as in the Southern Hemisphere. The concept of a molecular clock is seen as a most needed test for vicariance explanations of disjunct distributions. Special emphasis is laid on the importance of calibration of the clock. The use of geological vicariance events as calibration points is rejected, because of circularity when vicariance explanations are to be tested. Fossils as calibration points should ideally be replaced by the minimum age of an apomorphous character state demonstrated by the fossil rather than a supposed identity on the basis of overall similarity. Some conditions that directed the evolution of Lepidoptera (called constraints here) are discussed for their possible use as calibration points. Estimation of the evolution in space through time (palaeobiogeography) as found in recent literature is discussed, the often supposed role (of the break-up) of Gondwana in the evolution of the butterflies is challenged, and an alternative hypothesis is given. R. de Jong, National Museum of Natural History, P.O. Box 9517, 2300 RA Leiden, The Netherlands. E-mail: jong@naturalis.nnm.nl