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The biogeographic history of a species results from responses to past and current processes, and understanding those responses at both temporal scales is essential. We explored phylogeographic and current genetic variation structure in Ctenomys flamarioni —a subterranean rodent that inhabits a small region of the coastal plain of Brazil—and contrasted the roles of "present-day niche suitability" versus "historical climate stability" to understand current and past intraspecific genetic diversity. We used both mitochondrial DNA sequences (concatenated Cytb and D-loop , n = 78) and nuclear DNA (9 microsatellites loci, n = 154) molecular markers for individuals across the entire distribution of the species. We used phylogeographic trees, Bayesian clustering, and haplotype networks to explore genetic variation and diversity. We correlated genetic diversity with measures of current niche suitability and potential areas of Late Quaternary paleostability. Phylogeographic patterns confirmed low levels of genetic diversity structured at different hierarchical levels. We also found a weak but significant pattern of isolation by distance, indicating that geographical distance partially modulates genetic differences among populations. We also observed a positive correlation between genetic diversity and climate paleostability for microsatellites at local and regional scales. However, we found no significant association between genetic diversity and niche suitability for microsatellites at local or regional scales. We observed several signatures of bottleneck and population expansion at different geographic scales. Our results suggest that Quaternary climatic fluctuations—acting together with habitat suitability and other contemporary factors—played a fundamental role in elucidating the evolutionary history of the species—including patterns of historical dispersal, and current patterns of habitat occupation and genetic structure. In addition, based on our molecular and environmental data sets from the across the range of the species and considering the restricted endemism of C. flamarioni , we emphasize the urgency of conservation actions to protect this endangered species. [ABSTRACT FROM AUTHOR]

Dams are one of the main threats to Neotropical potamodromous fish, causing blockages of migratory routes and loss of breeding areas in an increasing number of drainage systems. In this scenario, current data argue that the maintenance of free-flowing tributaries along fragmented watersheds would be an important strategy to the migratory fish conservation, both in panmixia situations and in scenarios with different coexisting stocks, as already reported for Prochilodus lineatus. This study analyzed microsatellite loci and mitochondrial haplotypes in samples of P. lineatus obtained in different years along the Cinzas River basin, as well as in the Capivara Reservoir (largest Reservoir in the Paranapanema main channel, upper Paraná River) and in the Tibagi River, all connected by free stretches, aiming to investigate the contributions of the Cinzas River basin to the population dynamics of migratory fish in the Capivara reservoir region. Both markers detected high genetic diversity levels and indicated different genetic stocks of P. lineatus along the Cinzas River basin, suggesting some temporal genetic structuring, as well as the mixture of these stocks in the sample from the Capivara reservoir and from other points, corroborating the relationships among stocks in this reservoir and its tributaries. [ABSTRACT FROM AUTHOR]

Cnesterodon hypselurus is a small fish that has a restricted distribution in southern Brazil, including headwaters of the Tibagi and Itararé river basins (Upper Paraná River). This study reported C. hypselurus in a headwater of Cinzas River basin, where there were no previous records of this species, and employed microsatellite loci and mitochondrial haplotypes in a population genetic analysis. A total of 57 specimens was analyzed, including 30 from Cinzas River basin, 25 from Itararé River basin and two from Tibagi River basin. Results indicated low genetic diversity levels (HE = 0.334 and h = 0.246) for the sample from Cinzas River, suggesting reflections of a founder effect after the species had dispersed from one watershed to another, possibly by headwater captures. Since different populations were detected between the Cinzas and Itararé rivers (DEST = 0.248, P-value < 0.05) and other occurrence sites are still unknown in the Cinzas River basin, the data herein have great relevance and should be taken into account in future management and conservation actions, as well as in evolutionary studies of C. hypselurus. [ABSTRACT FROM AUTHOR]

Molecular markers can be used to monitor genetic variability in cultivated fish stocks with the aim of developing better aquaculture techniques and increasing productivity. In view of the above, the objective of the present work was to evaluate the genetic variability in pirarucu broodstocks in fish farms in the southeast and northeast of the of Pará state, Brazil. The samples were genotyped using four microsatellite markers, and genetic diversity indices were calculated for each broodstock. A total of 16 alleles were identified from the four loci tested in the 33 pirarucu samples, with means of 3.00, 2.75, and 2.25 alleles per locus in broodstocks from Tucumã, Parauapebas, and Moju municipalities, respectively. The Parauapebas broodstock had the highest mean observed heterozygosity. In the broodstocks from Tucumã and Parauapebas, the markers AgCAm16 and AgCAm18 were not at Hardy-Weinberg equilibrium. This pilot study showed that there were considerable losses of genetic variability in pirarucu breeding centers in the municipalities of Tucumã, Parauapebas and Moju compared to the variability in the natural populations of this fish species. [ABSTRACT FROM AUTHOR]

Eugenia involucrata DC. is a forest species with high environmental and economic potential. The objective of this study was to quantify the genetic variability and analyzed the genetic structure of three natural fragments located in the central region of the Rio Grande do Sul state, Brazil. We used four microsatellite loci developed for the congener species Eugenia uniflora and using GenAlEx 6.5 software, parameters of genetic variability and its partition among and within fragments were estimated for each locus. We observed high levels of genetic variability (3.67 alleles per locus; HO = 0.815; HE = 0.625; FIS = −0.294), most of which (93%) were distributed within the fragments, suggesting that these individuals came from a single original population. Gene flow between fragments was high (2.35 to 4.56 migrants per generation), resulting in low genetic differentiation indexes (FST values ranging from 0.052 to 0.096). The fragments showed high genetic variability, distributed within the remnants themselves, and low genetic differentiation. Our results have repercussions for planning locally adapted germplasm collections for forest restoration programs, thereby avoiding the implantation of populations with an exogamous depression. [ABSTRACT FROM AUTHOR]

The genetics of human populations is the branch of Genetics that studies the dynamics of genes in natural populations, aiming at the elucidation of mechanisms that alter their genetic composition. Among the fundamentals of this science is the Hardy-Weinberg Equilibrium, which determines that gene frequencies remain unchanged and genotypic proportions reach a stable balance, obtaining the same constant relation with each other over time. To demonstrate this principle, it is necessary to admit that the studied population is not subject to evolutionary factors or to those that alter genotypic frequencies, increasing the homozygosity. More specifically, it is necessary to assume that the population obeys the following premises: random mating, infinite population, non-overlapping generations, in addition to the absence of mutation, selection and migration. More than recalling basic concepts of Genetics and Statistics, this article aims to describe the Bernstein Method for verifying the gene equilibrium for blood types. The research is concluded with a case study in the city of Engenheiro Coelho - SP, where the Hardy-Weinberg Equilibrium for blood types in the population is verified. [ABSTRACT FROM AUTHOR]

Samples of 168 maté trees (Ilex paraguariensis) from four natural populations of different states of Brazil (Rio Grande do Sul, Santa Catarina, Paraná and Mato Grosso do Sul) were analyzed for their variability in storage proteins seed, which were used to estimate the degree of differentiation among and within species, because are relatively stable during evolution. Data on band presence/absence from 80 different polypeptides were used to perform similarity coefficient of Jaccard. A high level of genetic variability was reported within sampled populations (SJ intra=0.374). Lower levels of diversity were observed between populations (SJ inter=0.308). Total genetic diversity of maté was Hsp=0.264 estimated by Shannon measure. Partition of that value disclosed that 95 % of the total diversity is within-population, and only 5% to between-populations. The phenogram based on King's distances indicates a certain degree of geographic differentiation. This represents the first study on storage protein variability in I. paraguariensis and guides the choice of the specimens to increment germoplasm banks and genetic improvement programs. [ABSTRACT FROM AUTHOR]

Brycon nattereri is an endangered Neotropical fish reported along conserved stretches of the upper Paraná, Tocantins and São Francisco rivers. Populations of this species have been very rare in some Paraná River sub basins. This study analyzes the genetic diversity and population structure of B. nattereri in a restricted area of occurrence recently identified in upper Paraná River basin. Seven microsatellite loci and 497 bp of D-Loop mitochondrial region were examined in 92 individuals from four points along the area of occurrence. Both molecular markers indicated a single population distributed along a stretch of the river approximately 80 km long. Although some of the data suggest an ancient bottleneck, current levels of genetic diversity (HE = 0.574 and h = 0.616) were similar to those of other species of the genus Brycon. The results suggest that the population of B. nattereri has been able to maintain satisfactory levels of genetic diversity, in spite of the small area of occurrence. These data have highlighted an important conservation area and action may prove essential to improve the quality of the environment, and especially the water and riparian plant life, if the area is to be managed and conserved efficiently. [ABSTRACT FROM AUTHOR]

Background: genetic improvement in Colombia is limited by the lack of phenotypical and genealogical information. Additionally, molecular markers are important tools for studying the genetic structure of populations. Objective: to determine the structure of a population of Holstein cows in Antioquia, Colombia. Methods: a population of 1,800 animals distributed over 178 herds in 11 municipalities of Antioquia (Colombia) was genotyped using PCR-RFLP for gene polymorphisms of bovine growth hormone, kappa casein, prolactin, and BoLA DRB3.2. Population structure parameters, such as all Wright's F-statistics, were calculated and Hardy Weinberg equilibrium was determined. Analysis of molecular variance was carried out and Nei distances were estimated to determine population differentiation. Results: the total population was in Hardy Weinberg equilibrium for the four genes; however, kappa casein gene was in disequilibrium in some of the populations. Genetic structure of populations shows little genetic differentiation between them. Furthermore, a trend for outcrossing was found in most populations; this may be due to incorporation of imported semen into Colombia's dairy farms. The most genetically distant populations were in Marinilla and Rionegro municipalities due to their technological level and geographic location, which places them outside the scope of artificial insemination programs with foreign semen. Conclusions: the genetic similitude between populations of Holstein cows in Antioquia is due to their geographic proximity; therefore, their management of genetic conditions is very similar. [ABSTRACT FROM AUTHOR]

We present here a review of the use of molecular markers and cytogenetic data, applied to the detection of plant biodiversity. We mentioned a few examples of application of these tools in the investigation of taxa belonging to the families of monocotyledonous Iridaceae and Poaceae, which are the subject of scientific research of the authors of this review. [ABSTRACT FROM AUTHOR]

The present study aimed at estimating genetic parameters and variability among and within provenances for silvicultural traits of Handroanthus vellosoi (Toledo) Mattos, in provenances and progenies test stands, located at the Luiz Antônio Experimental Station (São Paulo State, Brazil). The test was established in the compact family block design, with two provenances (allocated in the plots), six replicates and sub-linear plots of five plants, totalizing 35 progenies. Diameter at breast height (DBH), plant height, cylindrical volume, stem form and survival at 24 years of age were evaluated. Significant differences among the provenances were observed only to the trait stem form. The analysis of deviance showed significant differences among progenies for the joint analysis of the provenances (experimental population), suggesting that the population has high genetic variation and indicating the possibility of genetic improvement by selection of the best progenies. Heritability estimates in individual and family level ranged from low to moderate (26% for DBH, 32% for plant height, 24% for cylindrical volume, 27% for form and 36% for survival), confirming the possibility of genetic improvement by selection and that the provenances have potential to respond to the pressure of natural selection. [ABSTRACT FROM AUTHOR]

The shrimp industry has grown significantly over the past 10 years in Brazil, especially the farmed production of the exotic Pacific white shrimp, Litopenaeus vannamei. In 2004, this industry was marked by a productivity crisis, which stirred interest towards genetic improvement of shrimp stocks. Shrimp breeders importation was banned in Brazil by a govern Normative Instruction in 1997, as a sanitary precaution. Since then, broodstock replacement in hatcheries has been based on domestic stocks, raising concerns on the decline of genetic diversity and if the existing diversity would allow effective genetic improvement programs. In the present research, genetic parameters such as number of alleles, effective allele number, expected and observed heterozygosities, inbreeding coefficient, genetic differentiation index and deviation from Hardy- Weinberg equilibrium have estimated of two important commercial hatcheries in Northeast Brazil, genotyping 5 microsatellite loci. Effective allele number (3 to 10.5) and average observed and expected heterozygosities (0.480 and 0.680) were consistent with those reported for cultured and wild Penaeid populations. However, FIS positive values (0.381 for hatchery A and 0.249 for hatchery B) reflected a significant heterozygous deficiency within hatcheries (P<0.01). Nevertheless, we concluded that even after ten years of limited genetic input, it has been possible to maintain a high level of genetic variability, possibly due to the wide diverse origin of the founder broodstocks and the constant breeders exchange among hatcheries. [ABSTRACT FROM AUTHOR]