Chromosome Evolution in the Genus Partamona (Apidae: Meliponini), with Comments on B Chromosome Origin.

The genus Partamona includes 33 species of stingless bees, of which 11 were studied cytogenetically. The main goal of this study was to propose a hypothesis about chromosomal evolution in Partamona by combining molecular and cytogenetic data. Cytogenetic analyses were performed on 3 Partamona species. In addition, the molecular phylogeny included mitochondrial sequences of 11 species. Although the diploid number was constant within the genus, 2n = 34, B chromosomes were reported in 7 species. Cytogenetic data showed karyotypic variations related to chromosome morphology and the amount and distribution of heterochromatin and repetitive DNA. The molecular phylogenetic reconstruction corroborated the monophyly of the genus and separated the 2 clades (A and B). This separation was also observed in the cytogenetic data, in which species within each clade shared most of the cytogenetic characteristics. Furthermore, our data suggested that the B chromosome in the genus Partamona likely originated from a common ancestor of the species that have it in clade B and, through interspecific hybridization, it appeared only in Partamona rustica from clade A. Based on the above, Partamona is an interesting genus for further investigations using molecular mapping of B chromosomes as well as for broadening phylogenetic data.

Molecular identification of three species of Oncideres (Coleoptera: Cerambycidae) using RAPD markers.

Twig girdlers have a short adult life and a long larval stage (up to one year in some species). This fact, together with lack of morphological traits to identify the species from the larval stage, poses obstacles for the taxonomic identification and characterization of the many twig girdlers found in the wild. To solve this matter, Random Amplified Polymorphic DNA (RAPD) molecular markers have been applied to identify some insect species and to determine species boundaries. The aim of this study was to identify three species of Oncideres using the RAPD technique. Adults and larvae of O. saga, O. ocularis and O. ulcerosa were collected in Minas Gerais, Brazil. Two RAPD primers were used (OPA-05 and OPB-13), which produced different electrophoretic profiles that were used to construct a UPGMA phenogram. Three groups identified in the analyses accurately separated the three species, based on individuals in two different stages of development (adults and larvae): I: O. saga, II: O. ulcerosa, and III: O. ocularis. Molecular markers, such as RAPD, are valuable tools that help taxonomists in species identification.

Phylogeography and Historical Biogeography of the Astyanax bimaculatus Species Complex (Teleostei: Characidae) in Coastal Southeastern South America.

Astyanax bimaculatus, a ubiquitous species in many Neotropical basins, is characterized by a complex taxonomy and are currently considered a species complex. The goal of this study was to analyze 31 populations (N = 136) of this species from southeastern Brazil using cytogenetic techniques: conventional staining, nucleolar organizer region (Ag-NOR), C-banding, and 18S and 5S recombinant DNA fluorescent in situ hybridization (FISH) probes; and molecular techniques: S72, RAG2, and COI. All populations were 2n = 50 (6m + 20sm +18st +6a); Ag-NORs were predominantly simple, C-banding revealed high variation levels within and among basins, and the FISH probes 18S and 5S were restricted to chromosome pairs 14 and 7, respectively. The S72 was uninformative for phylogenetic analyses, and RAG2 showed no variation among populations. The COI gene revealed three haplogroups. The most basal was composed of Pandeiros population (São Francisco Basin) that diverged in the Middle Miocene. The second was composed of A. altiparanae from the Upper Paraná Basin and Espírito Santo Stream (Paraíba do Sul Basin), whereas the third was composed of Astyanax lacustris from São Francisco and coastal basins. The second and third haplogroups diverged in the Pleistocene, indicating that diversification of the bimaculatus complex was driven by tectonic activity and sea-level fluctuations.