Sequence and RFLP analysis of the ITS2 ribosomal DNA in two neotropical social bees, Melipona beecheii and Melipona yucatanica (Apidae, Meliponini)

Two stingless bees species of the genus Melipona, M. beecheii and M. yucatanica, are the only ones reported for the Yucatan Peninsula. The natural distribution of M. beecheii ranges from southern Mexico to Costa Rica, that of M. yucatanica from south Mexico to Guatemala. Colonies of both species occur in a variety of habitats and show adaptations to local conditions denoting the occurrence of ecotypes. The ITS2 of ribosomal DNA has been characterized in both species and its utility to discriminate among colonies has been investigated through RFLP experiments. The ITS2 region is unusually long, 1788 bp in M. beecheii and 1845 bp in M. yucatanica (including the 3 ' end of the 5.8S gene and partial 5 ' of the 28S gene). Mean nucleotide divergence between both ITS2 sequences is 16 % (excluding sites with insertions/deletions) and 20 % when the insertions/deletions are taken into account. The G+C content in both sequences is close to 53 %. The PCR-RFLP assay was performed with 12 restriction enzymes on colonies of M. beecheii from Mexico (Yucatan, Campeche and Chiapas) Costa Rica, El Salvador and Guatemala, and of M. yucatanica from Mexico (Yucatan) and Guatemala. The restriction patterns obtained allow to discriminating colonies of both species with different origins. Both kinds of data are thus useful for assessing intra and interspecific genetic variability and for developing appropriate conservation strategies for these species.