Stark contrasts in clade species diversity are reported across the tree of life and are especially conspicuous when observed in closely related lineages. The explanation for such disparity has often been attributed to the evolution of key innovations that facilitate colonization of new ecological niches. The factors underlying diversification in bees remain poorly explored. Bees are thought to have originated from apoid wasps during the Mid-Cretaceous, a period that coincides with the appearance of angiosperm eudicot pollen grains in the fossil record. The reliance of bees on angiosperm pollen and their fundamental role as angiosperm pollinators have contributed to the idea that both groups may have undergone simultaneous radiations. We demonstrate that one key innovation-the inclusion of foreign material in nest construction-underlies both a massive range expansion and a significant increase in the rate of diversification within the second largest bee family, Megachilidae. Basal clades within the family are restricted to deserts and exhibit plesiomorphic features rarely observed among modern bees, but prevalent among apoid wasps. Our results suggest that early bees inherited a suite of behavioural traits that acted as powerful evolutionary constraints. While the transition to pollen as a larval food source opened an enormous ecological niche for the early bees, the exploitation of this niche and the subsequent diversification of bees only became possible after bees had evolved adaptations to overcome these constraints.

The evolution of parasitic behavior may catalyze the exploitation of new ecological niches yet also binds the fate of a parasite to that of its host. It is thus not clear whether evolutionary transitions from free-living organism to parasite lead to increased or decreased rates of diversification. We explore the evolution of brood parasitism in long-tongued bees and find decreased rates of diversification in eight of 10 brood parasitic clades. We propose a pathway for the evolution of brood parasitic strategy and find that a strategy in which a closed host nest cell is parasitized and the host offspring is killed by the adult parasite represents an obligate first step in the appearance of a brood parasitic lineage; this ultimately evolves into a strategy in which an open host cell is parasitized and the host offspring is killed by a specialized larval instar. The transition to parasitizing open nest cells expanded the range of potential hosts for brood parasitic bees and played a fundamental role in the patterns of diversification seen in brood parasitic clades. We address the prevalence of brood parasitic lineages in certain families of bees and examine the evolution of brood parasitism in other groups of organisms.

Butterfly monitoring and Red List programs in Switzerland rely on a combination of observations and collection records to document changes in species distributions through time. While most butterflies can be identified using morphology, some taxa remain challenging, making it difficult to accurately map their distributions and develop appropriate conservation measures. In this paper, we explore the use of the DNA barcode (a fragment of the mitochondrial gene COI) as a tool for the identification of Swiss butterflies and forester moths (Rhopalocera and Zygaenidae). We present a national DNA barcode reference library including 868 sequences representing 217 out of 224 resident species, or 96.9% of Swiss fauna. DNA barcodes were diagnostic for nearly 90% of Swiss species. The remaining 10% represent cases of para- and polyphyly likely involving introgression or incomplete lineage sorting among closely related taxa. We demonstrate that integrative taxonomic methods incorporating a combination of morphological and genetic techniques result in a rate of species identification of over 96% in females and over 98% in males, higher than either morphology or DNA barcodes alone. We explore the use of the DNA barcode for exploring boundaries among taxa, understanding the geographical distribution of cryptic diversity and evaluating the status of purportedly endemic taxa. Finally, we discuss how DNA barcodes may be used to improve field practices and ultimately enhance conservation strategies.

The Palaearctic complex of anthidiine bees closely related to Pseudoanthidium scapulare has long been a source of unresolved taxonomic and systematic issues. Until now, the number of species in the complex and their geographical distributions were largely unclear, thus complicating the compilation of accurate species checklists and hindering conservation efforts. In order to address these issues, we use morphology and mitochondrial cytochrome c oxidase subunit I (COI) sequences, combined with a thorough examination of the relevant literature and type material, to delimit species within this complex, assign names to species and clarify geographical ranges. An unexpected result was that a certain number of morphologically distinct taxa exhibited low levels of genetic divergence at the COI locus, resulting in species paraphyly. A set of ultra-conserved elements (UCEs) was also sequenced in order to further investigate relationships among these taxa. One morphologically distinct species was also paraphyletic using UCE data, hinting at recent species divergences and genetic exchange at zones of contact between morphologically well-differentiated taxa. The results of our study reveal the presence of ten species in this complex, including a previously overlooked species for western continental Europe. A complete diagnosis of the males and females of these species is provided, as are maps detailing the geographic distributions of each. An illustrated identification key to the males and females of each species is presented. Two new species are described, Pseudoanthidium kaspareki sp. nov. and P. rozeni sp. nov. New synonymy is established for several species and Pseudoanthidium palestinicum and P. tropicum are raised to species level. The new combination, Icteranthidium floripetum comb. nov. is also established. Lectotypes are designated for the following species: Anthidium eversmanni, A. floripetum, A. frontale, A. karakalense, A. nanum and A. reptans. Previously unpublished lectotype designations are published here for A. sinuatum and A. tenellum.

The bee tribe Anthidiini (Hymenoptera: Megachilidae) is a large, cosmopolitan group of solitary bees that exhibit intriguing nesting behavior. We present the first molecular-based phylogenetic analysis of relationships within Anthidiini using model-based methods and a large, multi-locus dataset (five nuclear genes, 5081 base pairs), as well as a combined analysis using our molecular dataset in conjunction with a previously published morphological matrix. We discuss the evolution of nesting behavior in Anthidiini and the relationship between nesting material and female mandibular morphology. Following an examination of the morphological characters historically used to recognize anthidiine genera, we recommend the use of a molecular-based phylogenetic backbone to define taxonomic groups prior to the assignment of diagnostic morphological characters for these groups. Finally, our results reveal the paraphyly of numerous genera and have significant consequences for anthidiine classification. In order to promote a classification system based on stable, monophyletic clades, we hereby make the following changes to Michener's (2007) classification: The subgenera Afranthidium (Zosteranthidium) Michener and Griswold, 1994, Afranthidium (Branthidium) Pasteels, 1969 and Afranthidium (Immanthidium) Pasteels, 1969 are moved into the genus Pseudoanthidium, thus forming the new combinations Pseudoanthidium (Zosteranthidium), Pseudoanthidium (Branthidium), and Pseudoanthidium (Immanthidium). The genus Neanthidium Pasteels, 1969 is also moved into the genus Pseudoanthidium, thus forming the new combination Pseudoanthidium (Neanthidium). Based on morphological characters shared with our new definition of the genus Pseudoanthidium, the subgenus Afranthidium (Mesanthidiellum) Pasteels, 1969 and the genus Gnathanthidium Pasteels, 1969 are also moved into the genus Pseudoanthidium, thus forming the new combinations Pseudoanthidium (Mesanthidiellum) and Pseudoanthidium (Gnathanthidium).