Insights into the heterochromatin evolution in the genus Melipona (Apidae: Meliponini)

The species of the four Melipona subgenera can be subdivided into two cytogenetic groups: species belonging to Group I are characterized by having low heterochromatin content in their karyotypes (  50%). To study the patterns of heterochromatin accumulation in this genus, we isolated moderate to highly repetitive sequences in M. (Michmelia) mondury (Mmon probe) and M. (Melikerria) fasciculata (Mfas probe) obtained based on the renaturation kinetics of C0t − 1 DNA and used these fragments as probes to hybridize in thirteen species belonging to the four Melipona subgenera. The Mmon probe marked all chromosomes in all Michmelia species and additionally the secondary constriction of M. (Eomelipona) puncticollis. The Mfas probe showed positive markings only within Melikerria. These results indicate the independence of the heterochromatin growth between Michmelia and Melikerria. Absence of markings in the regular set of chromosomes in M. (Melikerria) quinquefasciata and positive markings in the Bs, with the Mfas probe, suggests an interspecific origin of these chromosomes. We also hypothesize about the possible scenario that led to the heterochromatin growth in the genus Melipona.