The bee family Apidae comprises nearly 6000 described species (~35% of the bees in the world), including a diverse array of social forms, including solitary and communal orchid bees (Euglossini), the primitively eusocial bumble bees (Bombini), the advanced eusocial honey bees (Apini), and the stingless bees (Meliponini). Understanding the evolutionary history of social behavior in apid bees requires a phylogeny at the tribal and generic levels. However, currently a clear understanding of the phylogeny of this group is lacking because different data sets provide highly conflicting results. Morphological data and the fossil record appear to suggest a single origin of advanced eusociality (reproductive division of labor, overlapping generations, and cooperative care of young), while multiple molecular studies have supported dual origins of advanced eusociality. This project will combine data from morphology, the fossil record, and large molecular data sets generated with novel 454 Lifesciences sequencing technology to resolve the conflicting results obtained by previous studies. The research will allow a re-assessment of the morphological data, and are-examination of apid fossils from Dominican, Baltic, and North American amber deposits. The combination of fossil data and DNA sequence data will allow application of relaxed-clock dating methods to estimate the antiquity of the apid bees and the antiquity of eusociality. The project will lead to a revised classification for the family and improved understanding of the evolutionary history of bees.
Bees are vital biodiversity components of the natural world and are critically important for pollination in human agrarian systems. These social insects are at risk in the biodiversity challenges facing the world, and the project will train more of the kinds of scientists needed to understand the extent of the risks as well as potential solutions for such challenges. The project will include traditionally underrepresented groups in the research, and partnerships with several universities and museums will provide a strong outreach to the general public. The project will facilitate education of systematists and provide basic knowledge for understanding a unique group of insects that are of great practical importance to human society.
Bees are the most important group of pollinating animals on earth. Bees arose over 120 million years ago and have since diversified into a bewildering 20,000 described species. They are enormously important economically as well. A recent study estimated the economic value of bee pollination to be €153 billion/year ($202 billion/year) on a worldwide basis. Both managed and wild bees contribute significantly to pollination of the fruits, nuts, berries, and stimulants (e.g, coffee) that make up an estimated 1/3 of the human diet. Our NSF-funded research project focused on developing phylogenies (family trees) for bees in the family Apidae. Apidae is the largest bee family with over 5000 described species, or nearly 1/4 of the described bee species on earth. Apidae includes bees familiar to everyone, including honey bees (Apini), bumblebees (Bombini), and carpenter bees (Xylocopini). However there are also many less well known kinds of bees, including long-horned bees (Eucerini), oil-collecting bees (Ctenoplectrini and Centridini), and many cleptoparasitic groups (e.g., Nomadinae). Apidae includes the major of bees that are managed for crop pollination, including honey bees (for virtually all crops) and bumblebees (for greenhouse tomatoes, squashes and pumpkins, and orchard fruits). Apidae are therefore of significant economic importance. Among the most interesting apid bees are the primitively and highly eusocial tribes in the so-called "corbiculate Apidae": honey bees (Apini), bumblebees (Bombini), stingless bees (Meliponini), and orchid bees (Euglossini). These highly social bees are models for understanding social organization in insects, including communication, division of labor, cooperative foraging, nest construction, nest defense, orientation, learning, and many other basic biological features. However, there has been controversy around the phylogeny of these highly social bees. According to some data sets, those based on anatomy, the honey bees and stingless bees are closely related to each other. According to this view, the advanced form of eusociality shared by both of these groups is shared because they are closely related. For example, the sophisticated forms of communication that are shared by honey bees and stingless bees are shared because they are closely related to one another. However, some previous studies, primarily based on molecular data, had suggested a different picture. According to those studies, honey bees and stingless bees were not viewed as closely related. This would imply that the similarities shared between these two groups evolved independently and converged on the same type of social system. We sought to resolve this issue using a robust phylogeny of the Apidae based on multiple nuclear genes. We sequenced seven genes for over 200 species of apid bees and we reconstructed the phylogeny using sophisticated methods that infer the evolutionary relationships from data sets of aligned DNA sequences. Our results very strongly supported the second view, that honey bees and stingless bees are not closely related. Instead, they appear to be distantly related and therefore similarities in their social behavior are most likely due to convergent evolution. This has important implications for the study of social behavior in bees and insects as a whole. We can how ask, for example, what ecological or evolutionary factors would have lead to the parallel development of very similar kinds of social systems in two distantly related groups? Why would similar modes of communication, colony defense, nest founding, division of labor have evolved twice? We also used our phylogenetic data, in combination with the bee fossil record, to estimate the timing of social evolution in apid bees. We found that sociality evolved early in apid bees (over 90 million years ago; during the age of dinosaurs) and that sociality has been maintained over a very long time period. This helps explain the complexity of social behavior in apid bees – they have apparently had a very long time to develop these complex societies. This project has provided training to four undergraduates (Kojun Kanda, Neha Botapati, Andrew Debevec and Christine Santiago), one of whom is of Hispanic descent (Christine Santiago), two female graduate students, (Sophie Cardinal and Margarita Lopez-Uribe), one of whom is of Hispanic descent (Margarita Lopez-Uribe), and three post-doctoral associates (Jason Gibbs, Sophie Cardinal, and Shannon Hedtke), two of whom are woman. Sophie Cardinal has obtained a full-time curatorial position at the Canadian National Collection, Ottawa, Canada and Jason Gibbs is currently has a post-doctoral position at Michigan State. Undergraduates Kojun Kanda and Andrew Debevec are both pursuing PhD degrees in major research universities.