Genetic potential of a maize population from Southern Brazil for the modified convergent-divergent selection scheme

Maize (Zea mays L.) is a very important cereal to world-wide economy which is also true for Brazil, particularly in the South region. Grain yield and plant height have been chosen as important criteria by breeders and farmers from Santa Catarina State (SC), Brazil. The objective of this work was to estimate genetic-statistic parameters associated with genetic gain for grain yield and plant height, in the first cycle of convergent-divergent half-sib selection in a maize population (MPA1) cultivated by farmers within the municipality of Anchieta (SC). Three experiments were carried out in different small farms at Anchieta using low external agronomic inputs; each experiment represented independent samples of half-sib families, which were evaluated in randomized complete blocks with three replications per location. Significant differences among half-sib families were observed for both variables in all experiments. The expected responses to truncated selection of the 25% better families in each experiment were 5.1, 5.8 and 5.2% for reducing plant height and 3.9, 5.7 and 5.0% for increasing grain yield, respectively. The magnitudes of genetic-statistic parameters estimated evidenced that the composite population MPA1 exhibits enough genetic variability to be used in cyclical process of recurrent selection. There were evidences that the genetic structure of the base population MPA1, as indicated by its genetic variability, may lead to expressive changes in the traits under selection, even under low selection pressure.

Genetic Diversity and a PCR-Based Method for Xanthomonas axonopodis Detection in Passion Fruit

Xanthomonas axonopodis pv. passiflorae causes bacterial spot in passion fruit. It attacks the purple and yellow passion fruit as well as the sweet passion fruit. The diversity of 87 isolates of pv. passiflorae collected from across 22 fruit orchards in Brazil was evaluated using molecular profiles and statistical procedures, including an unweighted pair-group method with arithmetical averages-based dendrogram, analysis of molecular variance (AMOVA), and an assigning test that provides information on genetic structure at the population level. Isolates from another eight pathovars were included in the molecular analyses and all were shown to have a distinct repetitive sequence-based polymerase chain reaction profile. Amplified fragment length polymorphism technique revealed considerable diversity among isolates of pv. passiflorae, and AMOVA showed that most of the variance (49.4%) was due to differences between localities. Cluster analysis revealed that most genotypic clusters were homogeneous and that variance was associated primarily with geographic origin. The disease adversely affects fruit production and may kill infected plants. A method for rapid diagnosis of the pathogen, even before the disease symptoms become evident, has value for producers. Here, a set of primers (Xapas) was designed by exploiting a single-nucleotide polymorphism between the sequences of the intergenic 16S-23S rRNA spacer region of the pathovars. Xapas was shown to effectively detect all pv. passiflorae isolates and is recommended for disease diagnosis in passion fruit orchards.

Mitochondrial DNA Variability Among Eight Tikuna Villages: Evidence for an Intratribal Genetic Heterogeneity Pattern

To study the genetic structure of the Tikuna tribe, four major Native American mitochondrial DNA (mtDNA) founder haplogroups were analyzed in 187 Amerindians from eight Tikuna villages located in the Brazilian Amazon. The central position of these villages in the continent makes them relevant for attempts to reconstruct population movements in South America. In this geographic region, there is particular concern regarding the genetic structure of the Tikuna tribe, formerly designated ""enigmatic"" due to its remarkable degree of intratribal homogeneity and the scarcity of private protein variants. In spite of its large population size and geographic distribution, the Tikuna tribe presents marked genetic and linguistic isolation. All individuals presented indigenous mtDNA haplogroups. An intratribal genetic heterogeneity pattern characterized by two highly homogeneous Tikuna groups that differ considerably from each other was observed. Such a finding was unexpected, since the Tikuna tribe is characterized by a social system that favors intratribal exogamy and patrilocality that would lead to a higher female migration rate and homogenization of the mtDNA gene pool. Demographic explosions and religious events, which significantly changed the sizes and compositions of many Tikuna villages, may be reflected in the genetic results presented here. Am J Phys Anthropol 140:526-531,2009. (C) 2009 Wiley-Liss, Inc

Population structure and inbreeding effects on growth traits of Santa Ines sheep in Brazil

The aim of this study was to describe the population structure, inbreeding and to quantify their effect for different weights, of Santa Ines sheep. For this reason, 6490 data of production and 17,097 animals in the pedigree data set were utilized to evaluate birth weight (BW), weight at 60 days (W60) and weight at 180 days (W180). The genetic structure analysis of the population was realized by the software ENDOG (v.4.6.), resulting in some level of inbreeding for 21.72% of the animals in the pedigree data, being 41.02% the maximum value, and average of 10.74% for the inbred individuals. The population average inbreeding was 2.33% and the average relatedness was 0.73%. The effective number of ancestors was 156 animals and the effective number of founders was 211 individuals. A significant depressive effect of the inbreeding can be verified for all traits. The monitored parameters related with the genetic variability on this population must be constant in order to prevent the decrease in the genetic progress. The utilization of a program for directed mating in the present flock is an appropriate alternative to keep the level of inbreeding under control. (C) 2010 Elsevier B.V. All rights reserved.

Population structure of the migratory fish Prochilodus lineatus (Characiformes) from rio Grande basin (Brazil), an area fragmented by dams

1. Prochilodus lineatus (Prochilodontidae, Characiformes) is a migratory species of great economic importance both in fisheries and aquaculture that is found throughout the Jacui, Paraiba do Sul, Parana, Paraguay and Uruguay river basins in South America. Earlier population studies of P. lineatus in the rio Grande basin (Parana basin) indicated the existence of a single population; however, the range of this species has been fragmented by the construction of several dams. Such dams modified the environmental conditions and could have constrained the reproductive migration of P. lineatus, possibly leading to changes in the population genetic structure. 2. In order to evaluate how genetic diversity is allocated in the rio Grande basin, 141 specimens of P. lineatus from eight collection sites were analysed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with 15 restriction enzymes. 3. Forty-six haplotypes were detected, and 70% of them are restricted. The mean genetic variability indexes (h = 0.7721 and pi = 1.6%) were similar to those found in natural populations with a large effective size. Fst and Exact Test values indicated a lack of structuring among the samples, and the model of isolation by distance was tested and rejected. 4. The haplotype network indicated that this population of P. lineatus has been maintained as a single variable stock with some differences in the genetic composition (haplotypes) between samples. Indications of population expansion were detected, and this finding was supported by neutrality tests and mismatch distribution analyses. 5. The present study focused on regions between dams to serve as a parameter for further evaluations of genetic variability and the putative impact of dams and repopulation programmes in natural populations of P. lineatus. Copyright (C) 2011 John Wiley & Sons, Ltd.

DIAGNOSTIC TECHNIQUES OF LOCAL INFLUENCE IN SPATIAL ANALYSIS OF SOYBEAN YIELD

Modeling of spatial dependence structure, concerning geoestatistics approach, is an indispensable tool for fixing parameters that define this structure, applied on interpolation of values in places that are not sampled, by kriging techniques. However, the estimation of parameters can be greatly affected by the presence of atypical observations on sampled data. Thus, this trial aimed at using diagnostics techniques of local influence in spatial linear Gaussians models, applied at geoestatistics in order to evaluate sensitivity of maximum likelihood estimators and restrict maximum likelihood to small perturbations in these data. So, studies with simulated and experimental data were performed. Those results, obtained from the study of real data, allowed us to conclude that the presence of atypical values among the sampled data can have a strong influence on thematic maps, changing, therefore, the spatial dependence. The application of diagnostics techniques of local influence should be part of any geoestatistic analysis, ensuring that the information from thematic maps has better quality and can be used with greater security by farmers.

Técnicas de diagnóstico de influência local na análise espacial da produtividade da soja

A modelagem da estrutura de dependência espacial pela abordagem da geoestatística é fundamental para a definição de parâmetros que definem esta estrutura, e que são utilizados na interpolação de valores em locais não amostrados pela técnica de krigagem. Entretanto, a estimação de parâmetros pode ser muito afetada pela presença de observações atípicas nos dados amostrados. O desenvolvimento deste trabalho teve por objetivo utilizar técnicas de diagnóstico de influência local em modelos espaciais lineares gaussianos, utilizados em geoestatística, para avaliar a sensibilidade dos estimadores de máxima verossimilhança e máxima verossimilhança restrita na presença de dados discrepantes. Estudos com dados experimentais mostraram que tanto a presença de valores atípicos como de valores considerados influentes, pela análise de diagnóstico, pode exercer forte influência nos mapas temáticos, alterando, assim, a estrutura de dependência espacial. As aplicações de técnicas de diagnóstico de influência local devem fazer parte de toda análise geoestatística a fim de garantir que as informações contidas nos mapas temáticos tenham maior qualidade e possam ser utilizadas com maior segurança pelo agricultor.

CHARACTERIZATION OF MICROSATELLITE LOCI IN HIMATANTHUS DRASTICUS (APOCYNACEAE), A MEDICINAL PLANT FROM THE BRAZILIAN SAVANNA

Premise of the study: We developed a new set of microsatellite markers for studying the genome of the janaguba tree, Himatanthus drasticus (Mart.) Plumel, which is used in folk medicine in northeastern Brazil. These novel markers are being used to evaluate the effect of harvesting on the genetic structure and diversity of natural populations of this species. Methods and Results: Microsatellite loci were isolated from an enriched H. drasticus genomic library. Nine primer pairs successfully amplified polymorphic microsatellite regions, with an average of 8.5 alleles per locus. The average values of observed and expected heterozygosity were 0.456 and 0.601, respectively. Conclusions: The microsatellite markers described here are valuable tools for population genetics studies of H. drasticus. The majority of the primers also amplified sequences in the genome of another species of the same genus. This new set of markers may be useful in designing a genetic conservation strategy and a sustainable management plan for the species.

Africanized honey bees more efficiently convert protein diets into hemolymph protein than do Carniolan bees (Apis mellifera carnica)

The superiority of Africanized over European honey bees in tropical and subtropical regions of the New World is both well documented and poorly understood. As part of an effort to try to understand the process by which the displacement of European bees occurred, we examined the ability of these two types of bees and of hybrids between the two to convert natural and artificial diets into usable protein. Newly emerged bees from colonies of tropically adapted Africanized and temperate-origin Carniolan bees and first-generation hybrids between the two were caged and fed artificial and natural protein diets for six days to determine whether there were differences in their ability to use these diets. The Africanized bees developed significantly higher protein levels in the hemolymph than did the Carniolan bees. The difference was 31% when the bees were fed bee bread (37.5 and 28.56 mu g protein/mu L hemolymph, respectively). The hybrids developed protein levels intermediate between the two parental types. These were approximately 10 times the levels found in bees fed with sucrose alone. Superior food conversion efficiency of the Africanized bees may be one of the reasons for their superiority both in the wild and for beekeeping in tropical and subtropical Latin America.

Effects of polymorphisms of LHR and FSHR genes on sexual precocity in a Bos taurus x Bos indicus beef composite population

The purpose of the present research was to investigate the effects of polymorphisms of luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) genes, evaluated by polymerase chain reaction-restriction fragment length polymorphism in European-Zebu composite beef heifers from six different breed compositions. The polymorphism site analysis from digestion with HhaI and AluI restriction endonucleases allowed the genotype identification for LHR (TT, CT and CC) and FSHR (GG, CG and CC) genes. A high frequency of heterozygous animals was recorded in all breed compositions for both genes, except in two compositions for LHR. The probability of pregnancy (PP) at first breeding was used to evaluate the polymorphism effect on sexual precocity. The PP was analyzed as a binary trait, with a value of 1 (success) assigned to heifers that were diagnosed pregnant by rectal palpation and a value of 0 (failure) assigned to those that were not pregnant at that time. Heterozygous heifers showed a higher pregnancy rate (67 and 66% for LHR and FSHR genes, respectively), but no significant effects were observed for the genes studied (P=0.9188 and 0.8831 for LHR and FSHR, respectively) on the PP. These results do not justify the inclusion of LHR and FSHR restriction fragment length polymorphism markers in selection programs for sexual precocity in beef heifers. Nevertheless, these markers make possible the genotype characterization and may be used in additional studies to evaluate the genetic structure in other bovine populations.

Unsuccessful attacks dominate a drone-preying wasp's hunting performance near stingless bee nests

Bee males (drones) of stingless bees tend to congregate near entrances of conspecific nests, where they wait for virgin queens that initiate their nuptial flight. We observed that the Neotropical solitary wasp Trachypus boharti (Hymenoptera, Cabronidae) specifically preys on males of the stingless bee Scaptotrigona postica (Hymenoptera, Apidae); these wasps captured up to 50 males per day near the entrance of a single hive. Over 90% of the wasp attacks were unsuccessful; such erroneous attacks often involved conspecific wasps and worker bees. After the capture of non-male prey, wasps almost immediately released these individuals unharmed and continued hunting. A simple behavioral experiment showed that at short distances wasps were not specifically attracted to S. postica males nor were they repelled by workers of the same species. Likely, short-range prey detection near the bees' nest is achieved mainly by vision whereas close-range prey recognition is based principally on chemical and/or mechanical cues. We argue that the dependence on the wasp's visual perception during attack and the crowded and dynamic hunting conditions caused wasps to make many preying attempts that failed. Two wasp-density-related factors, wasp-prey distance and wasp-wasp encounters, may account for the fact that the highest male capture and unsuccessful wasp bee encounter rates occurred at intermediate wasp numbers.

CONTRASTING PHYLOGEOGRAPHIC PATTERNS IN MITOCHONDRIAL DNA AND MICROSATELLITES: EVIDENCE OF FEMALE PHILOPATRY AND MALE-BIASED GENE FLOW AMONG REGIONAL POPULATIONS OF THE BLUE-AND-YELLOW MACAW (PSITTACIFORMES: ARA ARARAUNA) IN BRAZIL

Comparing the patterns of population differentiation among genetic markers with different modes of inheritance call provide insights into patterns of sex-biased dispersal and gene flow. The blue-and-yellow Macaw (Ara ararauna) is a Neotropical parrot with a broad geographic distribution ill South America. However, little is known about the natural history and current status Of remaining wild populations, including levels of genetic variability. The progressive decline and possible fragmentation of populations may endanger this species in the near future. We analyzed mitochondrial DNA (mtDNA) control-region sequences and six microsatellite 106 Of Blue-and-yellow Macaws sampled throughout their geographic range ill Brazil to describe population genetic Structure, to make inferences about historical demography and dispersal behavior, and to provide insight for conservation efforts. Analyses of population genetic structure based on mtDNA showed evidence of two major populations ill western and eastern Brazil that share a few low-frequency haplotypes. This phylogeographic pattern seems to have originated by the historical isolation of Blue-and-yellow Macaw populations similar to 374,000 years ago and has been maintained by restricted gene flow and female philopatry. By contrast, variation ill biparentally inherited microsatellites was not structured geographically, Male-biased dispersal and female philopatry best explain the different patterns observed in these two markers. Because females disperse less than males, the two regional populations with well-differentiated mtDNA haplogroups should be considered two different management units for conservation purposes. Received 4 November 2007 accepted 10 December 2008.

Phylogeography and historical demography of the neotropical stingless bee Melipona quadrifasciata (Hymenoptera, Apidae): incongruence between morphology and mitochondrial DNA

The stingless bees are among the most abundant and ecologically important social invertebrates in tropical communities. The Neotropical stingless bee Melipona quadrifasciata has two subspecies: M. quadrifasciata quadrifasciata and M. quadrifasciata anthidioides. The main difference between subspecies are the yellow metassomal stripes, which are continuous in M. q. quadrifasciata and discontinuous in M. q. anthidioides. Recently, two populations were described with continuous stripes and inhabiting clearly disjunct areas in relation to M. q. quadrifasciata. We sequenced 852 bp of the mtDNA COI gene from 145 colonies from 56 localities, and for the first time performed a detailed phylogeographic study of a neotropical stingless bee. Phylogenetic analyses revealed the existence of two clades exhibiting a south to north distribution: southern populations comprise the subspecies M. q. quadrifasciata, and northern populations are composed of M. q. anthidioides and two disjunct populations with continuous stripes. The divergence time of these two phylogroups was estimated between 0.233 and 0.840 million years ago in the Pleistocene, a period of climatic changes and geomorphological alterations in the Neotropical region. No evidence of genetic structure in relation to the tergal stripes was found, indicating that the morphological trait regarding the pattern of stripes on tergites is not an accurate diagnostic for the subspecies of M. quadrifasciata.

Land planarians (Platyhelminthes) as a model organism for fine-scale phylogeographic studies: understanding patterns of biodiversity in the Brazilian Atlantic Forest hotspot

The Brazilian Atlantic Forest is one of the richest biodiversity hotspots of the world. Paleoclimatic models have predicted two large stability regions in its northern and central parts, whereas southern regions might have suffered strong instability during Pleistocene glaciations. Molecular phylogeographic and endemism studies show, nevertheless, contradictory results: although some results validate these predictions, other data suggest that paleoclimatic models fail to predict stable rainforest areas in the south. Most studies, however, have surveyed species with relatively high dispersal rates whereas taxa with lower dispersion capabilities should be better predictors of habitat stability. Here, we have used two land planarian species as model organisms to analyse the patterns and levels of nucleotide diversity on a locality within the Southern Atlantic Forest. We find that both species harbour high levels of genetic variability without exhibiting the molecular footprint of recent colonization or population expansions, suggesting a long-term stability scenario. The results reflect, therefore, that paleoclimatic models may fail to detect refugia in the Southern Atlantic Forest, and that model organisms with low dispersal capability can improve the resolution of these models.

A new variety of the weed Borreria densiflora DC. (Rubiaceae)

The weed, known commonly as vassourinha de botao (buttonweed), is present in several crops in northern and north-eastern Brazil. Its occurrence is common in sugarcane and soybean crops in the states of Goias, Tocantins, and Maranhao. However, there is no published information in the literature about its taxonomic classification. Thus, this research aimed to classify taxonomically this species in order to develop a classification key based on the morphological characteristics among varieties of Borreria densiflora DC., as well as to illustrate it and provide a palynological basis to classify this species as a new variety For the classification process, data from the literature, morphological characteristics, and palynological evidence were considered. In this article, we describe a new variety, B. densiflora DC. var. latifolia E.L. Cabral & Martins. The new variety possesses a terrestrial habitat and it is a simple perennial weed species. These results show the importance of an accurate identification, as well as an understanding of the evolutionary changes inherent to weeds (like intraspecific variability), breeding system, genetic potential, and ecological studies. Those factors are essential to the beginning of a long-term weed management strategy.