Reconstruction of a specific example of insect invasion waves: the cladistic analysis of Canthon (Coleoptera: Scarabaeidae) and related genera in North America

The invasion of the Mexican Transition Zone from South America during the Miocene and Plio-Pleistocene periods by neotropical lines is examined. Predictions regarding phylogenesis and ecological evolution are made. Firstly, the proposed Miocene invasion lineage(s) shared a common history and diversified in the biomes that evolved in North America during the Miocene and Pliocene. Second, those species which diversified from a common ancestor form a phylogenetically related group reflecting the history of the group in accordance with the history of the area and biomes which they occupy. Third, the species stemming from the proposed South American Plio-Pleistocene invasion evolved under a different set of ecological and biogeographic conditions and are distantly related in phylogenetic terms to members of the first invasions wave. Fourth, consequently, in a cladogram including species of both invasion waves, the Plio-Pleistocene elements branch at the base of the tree. Fifth, the branching sequence of the cladogram was not in concordance with the estimated age of appearance of the different biomes which the species occupy. These 5 predictions were supported by a species cladogram and it is concluded that the results of this analysis support the hypothesis of 2 waves of invasions of the Mexican Transition Zone by Neotropical elements from South America.