Molecular cytogenetics provides insights into heterochromatin composition and karyotypic evolution in species of the Plebeia group (Apidae: Meliponini)

Abstract Background The Plebeia group, including Plebeia , Lestrimelitta , and Friesella , requires clearer taxonomic resolution. Plebeia is the polyphyletic: species in clade II are more closely related to Friesella and Lestrimelitta than to their congeners in clade I, which are more restricted to the Amazon biome, and Central and North America. Molecular cytogenetic studies in Meliponini have shown the important role of heterochromatin in karyotypic evolution and species diversification. In this study, we compared heterochromatic repetitive sequences in the Plebeia group to better understand its evolutionary patterns and diversification. Results For this, we hybridized a probe of highly and moderately repetitive DNA from the Friesella schrottkyi genome (here called FSch-C 0 t probe) onto the chromosomes of F. schrottkyi , Lestrimelitta limao , and some Plebeia species from clade II to investigate whether repetitive sequences constituting heterochromatin are shared among species. Additionally, we mapped the microsatellite (GA) n in four Plebeia species from clade II as a control experiment, as it typically shows general euchromatic hybridization patterns in stingless bees. The FSch-C 0 t probe labeled all heterochromatin in F. schrottkyi and was restricted to the centromeric heterochromatin in analyzed Plebeia species from clade II, indicating the sharing of repetitive sequences in part of the heterochromatin between these two genera. However, the FSch-C 0 t did not yield signals in the AT-rich regions of L. limao , which likely correspond to heterochromatin, suggesting a variation in the heterochromatic composition compared to that of F. schrottkyi and analyzed Plebeia species from clade II. In addition, FSch-C 0 t signals were detected in some terminal regions of the chromosomes in Plebeia spp. and L. limao , potentially corresponding to telomeric sequences. Microsatellite (GA) n was located on one of the chromosomal arms in the euchromatic regions of the four Plebeia taxa, following a trend reported for other Meliponini. Conclusion Our data reveal a dynamic evolution of heterochromatic composition in the Plebeia group, with hypotheses regarding its diversification discussed in light of available phylogenies.