Population structure and genetic diversity in Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae): Is there a correlation between genetic and geographic proximity?

Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae) is a minuscule insect species, which forms galls, is subsocial, and parthenogenetic. It is associated with Ficus benjamina L. (Moraceae) and has a pantropical occurrence. The paucity of genetic studies on the order Thysanoptera led us to use inter-simple sequence repeat molecular marker to assess intra- and inter-gall, as well as intra- and inter-site, genetic variability and population structure of G. uzeli. Analyses indicated low genetic variability, probably related to haplodiploidy, genetic drift, the galling habit, and the low dispersal ability of G. uzeli. Populations were highly structured, with higher variation within populations than among them. Geographic distance does not appear to affect structure and genetic diversity, the latter being influenced by G. uzeli’s bioecological traits, by numerous introductions during a short period, and by a possible recent, common ancestry. © FUNPEC-RP

New occurrence of B chromosomes in Partamonahelleri (Friese, 1900) (Hymenoptera, Meliponini)

Cytogenetic analyses of the stingless bee Partamona helleri collected in the state of Bahia, Northeast Brazil revealed the chromosome numbers n = 18 in the haploid males and 2n = 35 in the diploid females. All karyotypes displayed one large acrocentric B chromosome, which differs from the minute B chromosomes previously described in the populations from southeastern Brazil. Giemsa staining, C-banding and DAPI/CMA3 fluorochrome staining also revealed a remarkable interpopulational divergence regarding both the regular karyotype and the B chromosomes. The B chromosomes found in the samples from Jequié, Bahia, were entirely heterochromatic, while those found in Cravolândia, Bahia, displayed a euchromatic portion at the telomeric end of the long arm. CMA 3 labeling sites varied from seven to eight between the two localities in Bahia, due to the presence of an extra GC-rich block in the karyotype of the samples from Jequié. This is the first report of a large B chromosome in P. helleri and reveals the occurrence of a geographic differentiation within this species

Genetic analysis of Melipona quadrifasciata Lep. (Hymenoptera: Apidae, Meliponinae) with RAPD markers

Melipona quadrifasciata ("mandaçaia") can be subdivided into two subspecies: M. q. anthidioides and M. q. quadrifasciata. In the present study we used RAPD markers to estimate intercolonial genetic variation among 69 colonies of Melipona quadrifasciata. Ten workers per colony were analyzed. The intercolony genetic distances based on RAPD markers ranged from 29.5% (colonies collected in the State of São Paulo vs colonies from the State of Minas Gerais) to 34.2% (São Paulo vs Santa Catarina). These results indicate a high genetic similarity among the colonies analyzed.According to the genetic distances two different groups could be distinguished. The first containing the samples from Santa Catarina region and the second, samples from Paraná, São Paulo, Minas Gerais, and Espírito Santo. Based on the molecular analysis, bees belonging to the different subspecies M. q. quadrifasciata (from Santa Catarina) and M. q. anthidioides (from the other regions) were distinguished

Variation of fore wing shape in Melipona mandacaia Smith, 1863 (Hymenoptera, Meliponini) along its geographic range

Melipona mandacaia is a stingless bee species responsible for the pollination of many native plants in Brazil, South America. In spite of its ecological and economic importance, natural populations of M. mandacaia have been depleted because of deforestation. In order to evaluate the interpopulation morphometric structure of remaining populations, we carried out geometric morphometric studies based on fore wing shape in this native bee species. The grouping analysis by UPGMA revealed three distinct clusters and significant differences in fore wing size were observed (p<0.001) among populations. The three groups were also reflected in the first two principal components explaining about 60% of the total variation. These results indicate differentiation among populations, which can be regarded as unique management units. Therefore, efforts should be directed to the conservation of local populations of M. mandacaia to avoid the negative impacts of loss in pollination over plant species and environmental services

Cytogenetic and morphological diversity in populations of Astyanax fasciatus (Teleostei, Characidae) from Brazilian northeastern river basins

In the present work, morphometric and cytogenetic analyses were carried out in populations of the fish Astyanax fasciatus (Characidae) from Contas and Recôncavo Sul River basins (State of Bahia, Brazil), providing new data on the genetic structure of this species along the region. Based on morphologic measurements, we observed that populations from the same hydrographic basin were more similar to each other (Contas and Preto do Costa Rivers), and remarkably divergent from Recôncavo Sul (Mineiro Stream), as indicated by clustering analysis. Cytogenetic data revealed a same diploid number for all populations (2n = 48), but distinct karyotype formulae (8M+24SM+12ST+4A, FN = 92 in Contas River, 8M+24SM+10ST+6A, FN = 90 in Preto do Costa River, and 8M+18SM+16ST+6A, FN = 90 in Mineiro Stream). Ag-NORs were identified at telomeres on a subtelocentric chromosome pair, although multiple ribosomal sites have been detected in some specimens from Contas River. These results show that A. fasciatus populations from northeastern river basins are well differentiated and present peculiar cytogenetic features when compared to populations from other regions. Therefore, the apparent chromosomal plasticity of this species, likely to represent a complex of cryptic forms, is corroborated. Finally, we demonstrated that morphological features can be successfully used to support other sources of genetic information

Genetic Diversity of Melipona mandacaia SMITH 1863 (Hymenoptera, Apidae), an Endemic Bee Species from Brazilian Caatinga, Using ISSR

In order to evaluate the genetic diversity and structure of Melipona mandacaia, we analyzed 104 colonies collected in 12 localities in Bahia state, northeastern Brazil, using ISSR-PCR. A total of 109 bands were obtained with a significant polymorphism of 72.47%. Estimates of genetic diversity indicated low values of heterozygosity (He and HB values were 0.2616 and 0.2573, resp.). These reduced values have been reported in other studies in stingless bees and maybe justified by dispersion process in the origin of new nests. AMOVA revealed that the higher percentage of variation is within localities (70.39%). The ΦST and θB values were, respectively, 0.2961 and 0.3289, thereby indicating a moderate population structuring. The correlation between genetic and geographic distances (r=0.4542; P<0.01) suggests isolation by distance. Our study contributes to describing the genetic diversity of endemic organisms from Caatinga and may help future efforts to preserve this threatened biome

Geographic distribution and spatial differentiation in the color pattern of abdominal stripes of the Neotropical stingless bee Melipona quadrifasciata (Hymenoptera: Apidae)

Melipona quadrifasciata Lepeletier, 1836, regionally known as "mandaçaia", has been traditionally divided in two distinct subspecies: M. quadrifasciata anthidioides and M. quadrifasciata quadrifasciata. The main difference between the subspecies refers to the yellow metasomal stripes which are continuous in M. q. quadrifasciata and discontinuous in M. q. anthidioides. This study investigated the geographic differentiation in the metasomal stripes and characterized the restriction sites in the mtDNA of both chromatic types. Specimens from 198 localities were examined, and the variation observed in the pattern of stripes was grouped into distinct classes. The distribution pattern found in the present work agrees with the previously reported pattern: M. q. quadrifasciata inhabits the southern portion of the distribution, from Misiones, Argentina, southeastern Paraguay and Rio Grande do Sul to southern São Paulo, and M. q. anthidioides ranges from northeastern São Paulo to the northern Diamantina Plateau, Bahia, and westwards to the central portion of the Goiás state. It is documented for the first time the occurrence of two populations with continuous stripes inhabiting disjunct areas in relation to M. q. quadrifasciata - one in northern Minas Gerais and another in northeastern Bahia and Sergipe. The data of RFLP showed two restriction patterns, one present in M. q. quadrifasciata, and another in M. q. anthidioides and in populations with continuous metasomal stripes from northern Minas Gerais and northeastern Bahia and Sergipe. The observed patterns of geographic differentiation of M. quadrifasciata suggests the occurrence of repeated events of geographical isolation, followed by range expansion, that occurred probably during the cycles of climatic changes in the Pleistocene