Phylogeny of the bee genus Agapostemon (Hymenoptera: Halictidae)

Abstract

This thesis presents a phylogenetic reconstruction of the evolutionary relationships among the species of the halictid bee genus Agapostemon , with the goal of revising current classification to reflect evolutionary history, and of tracing the behavioural and geographic changes within this New World genus. Representatives of other genera belonging to the tribe Agapostemonini were included in the analysis to provide an external reference point for determining the ancestral conditions and rooting the Agapostemon clade. Variation in morphological features among taxa, particularly among Agapostemon species, provided the basis for the construction of a data set of 149 characters for cladistic analysis. Behavioural variation was included as a 150^th character.

Parsimony analysis in which all multistate characters were left unordered, and in which all characters were given equal weights, resulted in 18 equally most parsimonious trees, with a length of 1031 evolutionary steps. A strict consensus of these trees is highly resolved for Agapostemon species, and this topology was used for interpretation of behavioural and biogeographical histories. The relationships indicated by the result led to the description of a new subgenus within Agapostemon: Notagapostemon . (Abstract shortened by UMI.)