Phylogenomic systematics, comparative morphology and biogeography of bees (Hymenoptera: Anthophila)

Abstract

Bees comprise approximately 20,000 extant valid species, which are interpreted to derive from an evolutionary diversification process begun in the Cretaceous about 120 million years ago. This evolutionary radiation is reflected in a remarkable morphological as well as behavioral disparity of bees. These hymenopteran insects are a very intriguing model for comparative investigations associating morphological diversity and the tempo and mode of their macroevolutionary history. In order for a proper understanding of bee evolution to happen, a robust phylogenetic framework is essential. Despite the inestimable efforts made in recent decades to advance in the understanding of bee phylogeny, crucial questions could not be properly addressed, and the placement of various taxa is dubious as a result of either a lack of substantial effort to solve these problems of due to persistent difficulties in this kind of research. In this proposal, the phylogenetic relationships among major lineages of bees (Hymenoptera: Apoidea: Anthophila) will be investigated using a combination of comparative morphological work and phylogenomic data from Ultraconserved Elements (UCEs). For the morphological component, special attention will be given to internal skeletal structures, which will require refined studies using light microscopical investigations combined with stereomicroscopy, which will be allied to scanning electron microscopy (SEM) and micro-CT imaging. UCEs are a class of molecular markers increasingly used for phylogenomics ad yielding very promising results, in particular for Hymenoptera. Four specific goals are proposed: (a) reevaluate the monophyly of taxa treated as tribes, subfamilies and families of bees; (b) evaluate the placement of the root node of bees. as well as the position of the bee clade in relation to other Apoidea; (c) evaluate the utility and information content of internal skeletal morphological character complexes for higher level bee phylogeny; (d) infer divergence times for most bee clades and use these data to better explain bee diversification in time and space. (AU)