Phylogenetic Systematics And The Evolution Of Nesting Behavior, Host-Plant Preference, And Cleptoparasitism In The Bee Family Megachilidae (Hymenoptera, Apoidea)
Members of the bee family Megachilidae exhibit fascinating behavior related to nesting, floral preference, and cleptoparasitic strategy. In order to explore the evolution of these behaviors, I assembled a large, multi-locus molecular data set for the bee family Megachilidae and used maximum likelihood-, Bayesian-, and maximum parsimony-based analytical methods to trace the evolutionary history of the family. I present the first molecular-based phylogenetic hypotheses of relationships within Megachilidae and use biogeographic analyses, ancestral state reconstructions, and divergence dating and diversification rate analyses to date the antiquity of Megachilidae and to explore patterns of diversification, nesting behavior and floral preferences in the family. I find that two ancient lineages of megachilid bees exhibit behavior and biology which reflect those of the earliest bees: they are solitary, restricted to deserts, build unlined nests, and are host-plant specialists. I suggest that the use of foreign material in nest construction allowed early megachilid bees to escape their ancestral desert habitat and colonize temperate, previously uninhabitable areas. In order to further examine phylogenetic relationships among tribes of the family Megachilidae, I develop a novel bootstrapping algorithm designed to balance the signal from combined molecular-morphological datasets; I use the results of all phylogenetic analyses to propose a new subfamilial- and tribal-level classification for Megachilidae and present a revised key to the tribes of Megachilidae. I also reconstruct the evolutionary history of the tribe Anthidiini and offer the first molecular-based phylogenetic hypothesis of the generic and suprageneric relationships within Anthidiini based on maximum likelihood and Bayesian phylogenetic analyses. I trace the evolutionary history of nesting behavior, the origins of cleptoparasitism, and the evolution of cleptoparasitic strategy in the megachilid tribe Anthidiini using Bayesian ancestral state reconstructions. Our results indicate three suprageneric clades within Anthidiini: the Trachusa group, the Anthidium group, and the Dianthidium group; each of these groups shows a distinct preference for either plant fibers or plant resins as a primary nest-building material. Our phylogeny supports two origins of cleptoparasitism in Anthidiini and also supports the hypothesis that cleptoparasitic lineages with hospicidal adults are an evolutionary intermediate between nest-building bees and cleptoparasitic lineages with hospicidal larvae.
bees; nesting behavior; cleptoparasitism; diversification; divergence dating; bee-host plant relationships
Danforth, Bryan Nicholas
Doyle, Jeffrey J; Lazzaro, Brian
Ph.D. of Entomology
Doctor of Philosophy
dissertation or thesis