Brachyptery and Phyletic Size Increase in Carabidae (Coleoptera)

Abstract

Phyletic body size increase is surveyed across taxa of Carabidae for which cladistic hypotheses of phylogenetic relationships are available. Patterns of body size evolution are assessed by regression analysis of body length on cladogram position for species-level taxa. Phyletic size increase is significantly more frequent in taxa containing brachypterous species than in taxa comprising exclusively macropterous species. Brachyptery and increase in body size occur principally in groups inhabiting stable, favorable habitats. Macropterous taxa characteristically inhabit less stable environments and do not exhibit phyletic size increase. Brachyptery may permit evolution of larger body size by removing the need for maintaining a thoracic flight apparatus. For island lineages, the historical constraint of small ancestral size of the colonizing species serves as one explanation for the observed patterns of size increase.