Microsatellite markers or SSR (Simple Sequence Repeats) have proved to be an excellent tool for cultivar identification, pedigree analysis and the evaluation of genetic distance among organisms. Soybean cultivars have been characterized mainly by morphological and biochemical traits. However, these traits have not been sufficient to characterize the large number of cultivars eligible to receive protection under the Brazilian Cultivar Protection Act. In order to define new soybean cultivar markers, the alleles of twelve SSR loci of 186 Brazilian soybean cultivars were studied by estimating the variation in their size range and their respective frequencies. On average, 5.3 alleles per locus were detected, with a mean genetic diversity of 0.64 ± 0.12. These loci were used to distinguish morphologically similar groups, presenting a mean similarity coefficient of 0.46; their use allowed to determine 184 profiles for the 186 cultivars. A dendrogram based on the SSR loci profiles showed good agreement with the cultivar pedigree information.

African-derived mitochondrial DNA (mtDNA) have been described in South American and Caribbean native cattle populations, which could have been introduced into America from Iberia or by direct importation from Africa. However, the similarity among described haplotypes is not known. We examined mtDNA variation in Guadeloupe Creole and Spanish cattle in an attempt to identify African-derived mtDNA haplotypes and compare them with those previously described. Eleven haplotypes clustered into the European taurine haplogroup (T3), two haplotypes into the African taurine (T1) haplogroup, and three haplotypes into the African-derived American haplogroup (AA). The AA1 and Eucons haplotypes were the most frequently observed. The presence of the AA haplogroup in Spanish cattle confirms historical records and genetic evidence of Iberian cattle as the main source of American native cattle origin. The possible origin of African-derived mitochondrial haplotypes in Iberian and Creole cattle is discussed, and the accumulated evidence does not support a founder effect from African ancestral cattle by direct importations. The presence of taurine AA and T3 haplotypes in Brazilian Nellore may indicate introgression by local European-derived cattle. Data presented in this work will contribute to the understanding of the origin of Guadeloupe Creole cattle.

In a population of the social bee Meh'pona subnitida of about 200 hives, from Mossor6, Northeastern Brazil, 54 hives were sampled and studied electrophoretically as far as the alleles Est-3 s, Est-3 M and Est-3 P were concerned. Males are produced by eggs laid by workers (no more than 4 in the same day) and by the queen. It was estimated that 61.2 ~ of the drones are sons of the queen and 38.8 are sons of the workers. With these values the effective number (Ne) was estimated in 395.80 which is 24~o higher than in a model in which all males are sons of the queen.

Pimelodus maculatus populations from the Tietê and Paranapanema rivers were sampled and had their genetic structure analyzed by using RAPD markers, with the aim of contributing to future conservation studies. The proportion of polymorphic loci was greater than 50% in the populations of both rivers. Genetic diversity data showed that, in spite of its nine hydroelectric plants, the Tietê river population was genetically homogeneous, whereas the Paranapanema river population was structured. This might be due to the presence of high waterfalls distributed all along its course. These data may serve as indicators for future conservation studies on the Tietê and Paranapanema rivers.

Stingless bees from 14 hives of Plebeia droryana were analysed for the MDH isozymic polymorphic system, which is controlled by four alleles, MDHI-I,and MDHl-4. The hives came from four different localities in Brazil and at least 15 drones were tested from each one, to estimate the proportion of them that are sons of the queen or of workers; the obtained values were 83.8% (range IOOYc to 43%) and 16.2% (range 0% to 57%), respectively. It is suggested that male-producing workers evolved from the need to preserve xo-heteroalleles.