Family Apidae

(3 subfamilies, 33 tribes, 170 genera, ~5130 species)

Apidae is used here in the expanded sense of Roig-Alsina & Michener (1993) and Michener (2000). Two groups of bees previously regarded as distinct families (Ctenoplectridae and Anthophoridae) are now included within the Apidae (Michener 2000) because these groups either made another group paraphyletic or were made paraphyletic by the corbiculate bees. Apidae consists of a diverse assemblage of some of the better known bee groups, including the carpenter bees (subfamily Xylocopinae), the cleptoparasitic (cuckoo) bees (subfamily Nomadinae), the long-horned bees (tribe Eucerini), the corbiculate bees (orchid bees [Euglossini], bumble bees [Bombini], stingless bees [Meliponini], and honey bees [Apini]), and many other less well known groups. Apidae includes bees with diverse nesting habits and includes several eusocial lineages, such as the tribe Allodapini and the eusocial corbiculate groups. Many apid groups show narrow host-plant associations including some genera within the Eucerini, Centridini, Anthophorini, Ctenoplectrini, and Emphorini (see Sipes & Wolf 2001). Apidae is united by 10 synapomorphies in the study of Roig-Alsina & Michener (1993). Among the more convincing synapomorphies is the presence of four (or more) ovarioles/ovary in Apidae. All other bee families have three ovarioles/ovary (Michener 2000). Michener (1979) reviewed the biogeographic history of the Apidae and hypothesized that they had a South American origin.

Among the most challenging phylogenetic questions in the apid bees are the phylogenetic affinities of the cleptoparasitic groups. Cleptoparasitic lineages have seemingly arisen multiple times in the Apidae from pollen-collecting ancestors. The major cleptoparasitic group is the subfamily Nomadinae (Alexander 1990, Roig-Alsina 1991), but even the limits of this subfamily are not clear (Michener 2000) because three tribes have been variously included and excluded from the Nomadinae (Osirini, Protepeolini, and Isepeolini; see section on Phylogenetic Relationships Among the Bee Families). We cannot be sure of the number of independent cleptoparasitic origins without a better understanding of higher-level apid phylogeny.

Additionally, while much phylogenetic work has been done on the corbiculate bees, molecular and morphological studies do not converge on the same overall tree topology and much controversy still surrounds the phylogenetic relationships among the corbiculate tribes (see section on Corbiculate Studies).

Because the apid bees are among the most charismatic and thoroughly studied of all bee families, a number of molecular systematic studies have already been done on the family. These studies have primarily involved the genes EF-1alpha, opsin, nuclear and mitochondrial ribosomal genes, and mitochondrial protein-coding genes (such as cytB and COI/COII). The studies involving xylocopine and allodapine bees, however, used the F1 copy of EF-1alpha. Most other data sets within bees have used the F2 copy (e.g., Danforth et al. 2004).

Related Studies

Xylocopine studies:

Leys et al. 2000, 2002

Allodapine studies:
Reyes et al. 1999
Bull et al. 2003
Schwarz et al. 2003, 2004.
More on Michael Schwarz’s research can be found at his web site

Emphorine studies:
Sipes & Wolf (2001) analyzed phylogenetic relationships among the species within the genus Diadasia, a primarily oligolectic genus endemic to the arid western US and Mexico. More information on Sedonia Sipes’ research can be found at:
http://www.science.siu.edu/plant_biology/Faculty/sipes/index.html

Corbiculate studies:
Cameron & Mardulyn 2001 (and many others; see Ascher et al. 2001 for a review of the literature). More information on Sydney Cameron’s research can be found at:
http://www.life.uiuc.edu/scameron/

Bombus studies:
Pedersen 1996, 2002
Kawakita et al. 2003, 2004
Cameron & Williams 2003
See also: http://www.nhm.ac.uk/entomology/bombus/index.html
This is an excellent overview of Bombus taxonomy, biodiversity, and biogeography by Paul Williams at the Natural History Museum, London.

Excel spreadsheets:
Genbank numbers for the numerous corbiculate bee sequences available in Genbank
(not yet available)