No abstract

It is widely recognized that different regions of a genome often have different evolutionary histories and that ignoring this variation when estimating phylogenies can be misleading. However, the extent to which this is also true for morphological data is still largely unknown. Discordance among morphological traits might plausibly arise due to either variable convergent selection pressures or else phenomena such as hemiplasy. Here we investigate patterns of discordance among 282 morphological characters, which we scored for 50 bee species particularly targeting corbiculate bees, a group that includes the well-known eusocial honeybees and bumblebees. As a starting point for selecting the most meaningful partitions in the data, we grouped characters as morphological modules, highly integrated trait complexes that as a result of developmental constraints or coordinated selection we expect to share an evolutionary history and trajectory. In order to assess conflict and coherence across and within these morphological modules, we used recently developed approaches for computing Bayesian phylogenetic information allied with model comparisons using Bayes factors. We found that despite considerable conflict among morphological complexes, accounting for among-character and among-partition rate variation with individual gamma distributions, rate multipliers, and linked branch lengths can lead to coherent phylogenetic inference using morphological data. We suggest that evaluating information content and dissonance among partitions is useful step in estimating phylogenies from morphological data, just as it is with molecular data. Furthermore, we argue that adopting emerging approaches for investigating dissonance in genomic datasets may provide new insights into the integration and evolution of anatomical complexes.

particularly with Apis mellifera Linnaeus, 1758 -the honeybee. This has long been a species with close proximity of mankind (the species of Apis are distributed all over the Old World), with economic interest because of honey production (pollination became a hotly debated topic more recently, e.g., Oldroyd, 2007; Cameron et al., 2010; Potts et al., AbstractPhylogenetic hypotheses and estimates of divergence times have already been used to investigate the evolution of social behavior in all lineages of bees. The interpretation of the number of origins of eusocial behavior and the timing of these events depends on reliable phylogenetic hypotheses for the clades in which these lineages are nested. Three to six independent origins of eusocial behavior are interpreted to have occurred in bee taxa that differentiated in the Late Cretaceous, or much later in the Paleogene. Only two groups of bees exhibit the behaviors that qualify their members to be considered obligate (i.e. 'fixed-caste') eusocial, the honey bees (Apini) and the stingless bees (Meliponini). The evolutionary history of corbiculate bees remains uncertain in many respects, but phylogenetic research has been paving the path for comprehensive comparative approaches likely to shed light on the origin of diversity of forms and behaviors of these bees. In total, corbiculate bees encompass about 1,000 species, roughly 5% of the described species diversity of bees. These bees are rather heterogeneous in terms of social organization, particularly stingless bees and orchid bees, which display a fascinating range of behavioral variation. Using phylogenetic tools, it has been possible to infer that caste polymorphism, division of labor and other traits of corbiculate bees probably started evolving over 80 million years ago. Phylogenetic hypotheses must be interpreted as more or less uncertain scenarios for studying the biological diversity, but when trusted they can provide powerful tools to investigate the evolution of social behaviors.