Résumé
Global biodiversity peaks in the tropical forests of the Andes, a striking
geological feature that has likely been instrumental in generating
biodiversity by providing opportunities for both vicariant and ecological
speciation. However, the role of these mountains in the diversification of
insects, which dominate biodiversity, has been poorly explored using
phylogenetic methods. Here we study the role of the Andes in the evolution
of a diverse Neotropical insect group, the clearwing butterflies. We used
dated species-level phylogenies to investigate the time-course of
speciation and to infer ancestral elevation ranges for two diverse genera.
We show that both genera likely originated at middle elevations in the
Andes in the Middle Miocene, contrasting with most published results in
vertebrates that point to a lowland origin. Although we detected a
signature of vicariance caused by the uplift of the Andes at the
Miocene-Pliocene boundary, most sister species were parapatric without any
obvious vicariant barrier. Combined with an overall decelerating
speciation rate, these results suggest an important role for ecological
speciation and adaptive radiation, rather than simple vicariance.