RESUMO
Abstract Introduction: Plant functional traits are widely used to predict community productivity. However, they are rarely used to predict the performance (in terms of growth diameter, growth height, survival, and integral response index) of woody species planted in degraded soils. Objective: To evaluate the relationship between the functional traits and the performance of 25 woody species planted in disturbed soils affected by oil extraction activities in Ecuadorian Amazon. Methods: Eighteen permanent sampling plots were established and five 6-month-old seedlings of each 25 species were randomly planted in each plot (125 individuals per plot), at a distance of 4×4 m. Eight quantitative functional traits (leaf size, specific leaf area, leaf nitrogen concentration, leaf phosphorus concentration, leaf minimum unit, leaf dry matter content, stem specific density and leaf tensile strength) were determined for each species. Results: The woody species with high performance shows greater leaf size, specific leaf area and Stem Specific Density than those showing low performance. Leaf nitrogen concentration and stem specific density had a direct relationship with the integral response index. The leaf size, leaf phosphorus concentration, leaf dry matter content and leaf tensile strength showed a negative relationship with the integral response index. Conclusions: Our study demonstrated that the performance of woody species o disturbed soils can be predicted satisfyingly by leaf and stem functional traits, presumably because these traits capture most of environmental and neighborhood conditions.
Resumen Introducción: Los rasgos funcionales de las plantas han sido ampliamente utilizados para predecir la productividad (en términos de crecimiento en diámetro, crecimiento en altura, sobrevivencia e índice de respuesta integral) de las comunidades vegetales. Sin embargo, rara vez han sido utilizados para predecir el desempeño de las especies leñosas plantadas en suelos degradados. Objetivo: Evaluar la relación entre el desempeño y los rasgos funcionales de 25 especies leñosas plantadas en suelos afectados por actividades de extracción de petróleo en la Amazonía ecuatoriana. Métodos: Se establecieron 18 parcelas permanentes de muestreo y en cada parcela se sembraron aleatoriamente cinco plántulas de 6 meses de las 25 especies (125 individuos por parcela), a una distancia de 4×4 m. Se determinaron ocho rasgos funcionales (área foliar, área foliar específica, concentración de nitrógeno foliar, concentración de fósforo foliar, unidad mínima foliar, contenido foliar de materia seca, densidad específica del fuste y fuerza tensil foliar) de cada especie. Resultados: Las especies leñosas con alto desempeño presentaron mayor área foliar, área foliar específica y densidad específica del fuste que las especies de bajo desempeño. La concentración de nitrógeno foliar y la densidad específica del fuste mostraron una relación directa. El área foliar, la concentración de fósforo foliar, el contenido de materia seca foliar y la fuerza tensil foliar presentaron una relación inversa con el Índice de Respuesta Integral. Conclusión: Se demostró que el desempeño de las especies leñosas plantadas en suelos alterados puede predecirse satisfactoriamente por rasgos funcionales de hoja y de tallo, debido posiblemente a que los rasgos influyen en el crecimiento y supervivencia de las especies, y reflejan la mayoría de las condiciones ambientales.
Assuntos
Árvores/crescimento & desenvolvimento , Poluição por Petróleo/análise , Ecossistema Amazônico , EquadorRESUMO
[This corrects the article DOI: 10.3389/fpls.2019.00092.].
RESUMO
Urochloa decumbens (Stapf) R. D. Webster is one of the most important African forage grasses in Brazilian beef production. Currently available genetic-genomic resources for this species are restricted mainly due to polyploidy and apomixis. Therefore, crucial genomic-molecular studies such as the construction of genetic maps and the mapping of quantitative trait loci (QTLs) are very challenging and consequently affect the advancement of molecular breeding. The objectives of this work were to (i) construct an integrated U. decumbens genetic map for a full-sibling progeny using GBS-based markers with allele dosage information, (ii) detect QTLs for spittlebug (Notozulia entreriana) resistance, and (iii) seek putative candidate genes involved in defense against biotic stresses. We used the Setaria viridis genome a reference to align GBS reads and selected 4,240 high-quality SNP markers with allele dosage information. Of these markers, 1,000 were distributed throughout nine homologous groups with a cumulative map length of 1,335.09 cM and an average marker density of 1.33 cM. We detected QTLs for resistance to spittlebug, an important pasture insect pest, that explained between 4.66 and 6.24% of the phenotypic variation. These QTLs are in regions containing putative candidate genes related to defense against biotic stresses. Because this is the first genetic map with SNP autotetraploid dosage data and QTL detection in U. decumbens, it will be useful for future evolutionary studies, genome assembly, and other QTL analyses in Urochloa spp. Moreover, the results might facilitate the isolation of spittlebug-related candidate genes and help clarify the mechanism of spittlebug resistance. These approaches will improve selection efficiency and accuracy in U. decumbens molecular breeding and shorten the breeding cycle.
RESUMO
In dairy farm animals, one the most important goal of the selection is the improvement of milk yield and composition. Several studies have demonstrated that the candidate genes of the kappa-casein (CSN3) and β - lactoglobulin (β-LG) are associated with milk yield, milk quality and health traits in dairy animals. Therefore the aim of this study was to detect polymorphisms in CSN3 and β-LG genes and its association with milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY in Girolando cattle. Totally, 138 bulls and 729 cows (n=867) were sampled. The genotypes of both genes were obtained by the PCR-RFLP method using HinfI and HaeIII enzymes for CSN3 and β-LG genes, respectively. Statistical results revealed two alleles A and B for both genes. The genotypes and alleles more frequents for CSN3 and β-LG genes were respectively: AA (0.7324) and A (0.8558), and AB (0.4827) and A (0.5017). The x2 test revealed that the two loci were at Hardy-Weinberg equilibrium (p<0.001). The allele substitution effects for the variants were not significant on 305MY and PTA for 305MY (p>0.05). The allele variants of β-LG and CSN3 might be more investigated before include them into future breeding schemes designed for Girolando dairy cattle with objective of improving milk traits as milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY.(AU)
Em rebanhos leiteiros, um dos objetivos mais importantes da seleção é a melhoria da produção e composição do leite. Vários estudos demonstraram que os genes candidatos da kappa-caseína (CSN3) e da β-lactoglobulina (β-LG) estão associados a produção de leite, qualidade do leite e características de saúde em animais leiteiros. Portanto, o objetivo deste estudo foi detectar polimorfismos nos genes CSN3 e β-LG e avaliar possíveis associaçoes desses polimorfismos com a produção de leite em até 305 dias (305MY) e a capacidade de transmissão prevista (PTA) de leite em bovinos da raça Girolando. No total, 138 touros e 729 vacas (n = 867) foram amostrados. A genotipagem foi realizada pelo método PCR-RFLP utilizando as enzimas HinfI e HaeIII para os genes CSN3 e β-LG, respectivamente. Os resultados estatísticos revelaram dois alelos A e B para ambos os genes. Os genotipos e alelos mais frequentes para os genes CSN3 e β-LG foram respectivamente: AA (0,7324) e A (0,8558) e AB (0,4827) e A (0,5017). O teste x2 revelou que os dois loci estavam em equilibrio de Hardy-Weinberg (p <0,001). Os efeitos de substituiçao alélica para as variantes nao foram significativos para as características 305 MY e PTA para 305MY (p> 0,05). Portanto, as variantes alélicas identificadas nos genes β-LG e CSN3 devem ser mais investigadas antes de serem incluidas nos programas de melhoramento desenhados para bovinos leiteiros Girolando objetivando melhorar as características do leite analisadas no presente estudo.(AU)
Assuntos
Caseínas/genética , Lactoglobulinas/genética , Leite/química , Polimorfismo de Nucleotídeo Único , Proteínas do Leite/análise , Técnicas de Genotipagem , Reação em Cadeia da PolimeraseRESUMO
In dairy farm animals, one the most important goal of the selection is the improvement of milk yield and composition. Several studies have demonstrated that the candidate genes of the kappa-casein (CSN3) and β - lactoglobulin (β-LG) are associated with milk yield, milk quality and health traits in dairy animals. Therefore the aim of this study was to detect polymorphisms in CSN3 and β-LG genes and its association with milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY in Girolando cattle. Totally, 138 bulls and 729 cows (n=867) were sampled. The genotypes of both genes were obtained by the PCR-RFLP method using HinfI and HaeIII enzymes for CSN3 and β-LG genes, respectively. Statistical results revealed two alleles A and B for both genes. The genotypes and alleles more frequents for CSN3 and β-LG genes were respectively: AA (0.7324) and A (0.8558), and AB (0.4827) and A (0.5017). The x2 test revealed that the two loci were at Hardy-Weinberg equilibrium (p0.05). The allele variants of β-LG and CSN3 might be more investigated before include them into future breeding schemes designed for Girolando dairy cattle with objective of improving milk traits as milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY.
Em rebanhos leiteiros, um dos objetivos mais importantes da seleção é a melhoria da produção e composição do leite. Vários estudos demonstraram que os genes candidatos da kappa-caseína (CSN3) e da β-lactoglobulina (β-LG) estão associados a produção de leite, qualidade do leite e características de saúde em animais leiteiros. Portanto, o objetivo deste estudo foi detectar polimorfismos nos genes CSN3 e β-LG e avaliar possíveis associaçoes desses polimorfismos com a produção de leite em até 305 dias (305MY) e a capacidade de transmissão prevista (PTA) de leite em bovinos da raça Girolando. No total, 138 touros e 729 vacas (n = 867) foram amostrados. A genotipagem foi realizada pelo método PCR-RFLP utilizando as enzimas HinfI e HaeIII para os genes CSN3 e β-LG, respectivamente. Os resultados estatísticos revelaram dois alelos A e B para ambos os genes. Os genotipos e alelos mais frequentes para os genes CSN3 e β-LG foram respectivamente: AA (0,7324) e A (0,8558) e AB (0,4827) e A (0,5017). O teste x2 revelou que os dois loci estavam em equilibrio de Hardy-Weinberg (p 0,05). Portanto, as variantes alélicas identificadas nos genes β-LG e CSN3 devem ser mais investigadas antes de serem incluidas nos programas de melhoramento desenhados para bovinos leiteiros Girolando objetivando melhorar as características do leite analisadas no presente estudo.
Assuntos
Caseínas/genética , Lactoglobulinas/genética , Leite/química , Polimorfismo de Nucleotídeo Único , Proteínas do Leite/análise , Reação em Cadeia da Polimerase , Técnicas de GenotipagemRESUMO
Information on the genetic control of the quality traits of soft wheat (Triticum aestivum) is essential for breeding. Our objective was to identify QTL associated with end-use quality. We developed 150 F4-derived lines from a cross of Pioneer 26R46 × SS550 and tested them in four environments. We measured flour yield (FY), softness equivalent (SE), test weight (TW), flour protein content (FP), alkaline water retention capacity (AWRC), and solvent retention capacity (SRC) of water (WA), lactic acid (LA), sucrose (SU), sodium carbonate (SO). Parents differed for nine traits, transgressive segregants were noted, and heritability was high (0.67 to 0.90) for all traits. We detected QTL distributed on eight genomic regions. The QTL with the greatest effects were located on chromosome 1A, 1B, and 6B with each affecting at least five of ten quality traits. Pioneer 26R46 is one of the best quality soft wheats. The large-effect QTL on 1A novel and accounted for much of the variation for AWRC (r2 = 0.26), SO (0.26) and SE (0.25), and FY (0.15) and may explain why Pioneer 26R46 has such superior quality. All alleles that increased a trait came from the parent with the highest trait value. This suggests that in any population that marker-assisted selection for these quality traits could be conducted by simply selecting for the alleles at key loci from the parent with the best phenotype without prior mapping.
RESUMO
O objetivo dessa revisão é relatar os principais métodos de avaliação de carcaça e qualidade da carne através de predições in vivo e post-mortem. A avaliação de carcaça é um instrumento utilizado para caracterizar e classificar o produto final, melhorando sua qualidade, porém vários fatores influenciam na qualidade do produto final, dentre elas a raça, o sexo, a precocidade, a alimentação, o manejo pré-abate, o rigor mortis, maturação da carne, entre outros. Com isso foram desenvolvidos alguns métodos de avaliação e estes são divididos em características qualitativas da carcaça: conformação, maturidade, cor, textura, marmoreio, maciez e características quantitativas: comprimento, área de olho de lombo (AOL) e espessura de gordura subcutânea (EGS).(AU)
The objective of this review is to describe the main methods of carcass evaluation and meat quality through predictions in vivo and postmortem. The carcass evaluation is an instrument used to characterize and classify the final product, improving its quality, but several factors influence the final product quality, among them race, sex, precocity, feeding, pre-slaughter handling, the rigor mortis, the maturation of meat, among others. Therewith some methods that have been developed for assessment and these are divided into qualitative characteristics of the carcass: conformation, maturity, color, texture, marbling, meat tenderness and quantitative characteristics: length, loin eye area (REA) and fat thickness (EGS).(AU)
Assuntos
Animais , Carne/análise , Previsões/métodos , Qualidade dos Alimentos , Pesos e Medidas Corporais/veterinária , Matadouros/normasRESUMO
O objetivo dessa revisão é relatar os principais métodos de avaliação de carcaça e qualidade da carne através de predições in vivo e post-mortem. A avaliação de carcaça é um instrumento utilizado para caracterizar e classificar o produto final, melhorando sua qualidade, porém vários fatores influenciam na qualidade do produto final, dentre elas a raça, o sexo, a precocidade, a alimentação, o manejo pré-abate, o rigor mortis, maturação da carne, entre outros. Com isso foram desenvolvidos alguns métodos de avaliação e estes são divididos em características qualitativas da carcaça: conformação, maturidade, cor, textura, marmoreio, maciez e características quantitativas: comprimento, área de olho de lombo (AOL) e espessura de gordura subcutânea (EGS).
The objective of this review is to describe the main methods of carcass evaluation and meat quality through predictions in vivo and postmortem. The carcass evaluation is an instrument used to characterize and classify the final product, improving its quality, but several factors influence the final product quality, among them race, sex, precocity, feeding, pre-slaughter handling, the rigor mortis, the maturation of meat, among others. Therewith some methods that have been developed for assessment and these are divided into qualitative characteristics of the carcass: conformation, maturity, color, texture, marbling, meat tenderness and quantitative characteristics: length, loin eye area (REA) and fat thickness (EGS).
Assuntos
Animais , Carne/análise , Pesos e Medidas Corporais/veterinária , Previsões/métodos , Qualidade dos Alimentos , Matadouros/normasRESUMO
Beak shape in Darwin's ground finches (Geospiza) is emblematic of natural selection and adaptive radiation, yet our understanding of the genetic basis of beak shape variation, and thus the genetic target of natural selection, is still evolving. Here we reveal the genomic architecture of beak shape variation using genomewide comparisons of four closely related and hybridizing species across 13 islands subject to parallel natural selection. Pairwise contrasts among species were used to identify a large number of genomic loci that are consistently related to species differences across a complex landscape. These loci are associated with hundreds of genes that have enriched GO categories significantly associated with development. One genomic region of particular interest is a section of Chromosome 1A with many candidate genes and increased linkage. The distinct, pointed beak shape of the cactus finch is linked to an excess of intermediate frequency alleles and increased heterozygosity in significant SNPs, but not across the rest of the genome. Alleles associated with pointier beaks among species were associated with pointier-beaked populations within each species, thus establishing a common basis for natural selection, species divergence and adaptive radiation. The adaptive genomic landscape for Darwin's finches mirrors theoretical expectations based on morphological variation. The implication that a large number of genes are actively maintained to facilitate beak variation across parallel populations with documented interspecies admixture challenges our understanding of evolutionary processes in the wild.
Assuntos
Bico/anatomia & histologia , Tentilhões/genética , Seleção Genética , Adaptação Biológica/genética , Alelos , Animais , Equador , Ligação Genética , Loci Gênicos , Genética Populacional , Hibridização Genética , Ilhas , Desequilíbrio de Ligação , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: Sugarcane (Saccharum spp.) is predominantly an autopolyploid plant with a variable ploidy level, frequent aneuploidy and a large genome that hampers investigation of its organization. Genetic architecture studies are important for identifying genomic regions associated with traits of interest. However, due to the genetic complexity of sugarcane, the practical applications of genomic tools have been notably delayed in this crop, in contrast to other crops that have already advanced to marker-assisted selection (MAS) and genomic selection. High-throughput next-generation sequencing (NGS) technologies have opened new opportunities for discovering molecular markers, especially single nucleotide polymorphisms (SNPs) and insertion-deletion (indels), at the genome-wide level. The objectives of this study were to (i) establish a pipeline for identifying variants from genotyping-by-sequencing (GBS) data in sugarcane, (ii) construct an integrated genetic map with GBS-based markers plus target region amplification polymorphisms and microsatellites, (iii) detect QTLs related to yield component traits, and (iv) perform annotation of the sequences that originated the associated markers with mapped QTLs to search putative candidate genes. RESULTS: We used four pseudo-references to align the GBS reads. Depending on the reference, from 3,433 to 15,906 high-quality markers were discovered, and half of them segregated as single-dose markers (SDMs) on average. In addition to 7,049 non-redundant SDMs from GBS, 629 gel-based markers were used in a subsequent linkage analysis. Of 7,678 SDMs, 993 were mapped. These markers were distributed throughout 223 linkage groups, which were clustered in 18 homo(eo)logous groups (HGs), with a cumulative map length of 3,682.04 cM and an average marker density of 3.70 cM. We performed QTL mapping of four traits and found seven QTLs. Our results suggest the presence of a stable QTL across locations. Furthermore, QTLs to soluble solid content (BRIX) and fiber content (FIB) traits had markers linked to putative candidate genes. CONCLUSIONS: This study is the first to report the use of GBS for large-scale variant discovery and genotyping of a mapping population in sugarcane, providing several insights regarding the use of NGS data in a polyploid, non-model species. The use of GBS generated a large number of markers and still enabled ploidy and allelic dosage estimation. Moreover, we were able to identify seven QTLs, two of which had great potential for validation and future use for molecular breeding in sugarcane.
Assuntos
Mapeamento Cromossômico/métodos , Genes de Plantas/genética , Ligação Genética , Técnicas de Genotipagem , Locos de Características Quantitativas/genética , Saccharum/genética , Análise de Sequência de DNA , Alelos , Mineração de Dados , Dosagem de Genes , Marcadores Genéticos/genética , Anotação de Sequência Molecular , Polimorfismo Genético , Saccharum/crescimento & desenvolvimentoRESUMO
Background In the present study populations, representing different rounds of recombination were used for the analysis of phenotypic effects associated with the sdw1/denso locus. Other studies have mostly focused only on one type of population. Many different QTLs mapped at the same position as the sdw1/denso locus may indicate a pleiotropy of this gene or a tight linkage between genes conditioning quantitative traits. To date, results of studies have not unequivocally proven either of these two phenomena. Results Both breeding and molecular mapping experiments were undertaken to examine 200 single seed descent (SSD) and 60 doubled haploid (DH) lines obtained from the Maresi (with a semi-dwarfing gene) and Pomo cross combination. They were evaluated for the type of juvenile growth habit and certain agronomic traits were measured after harvesting. The estimates of mean values, standard errors and significance of effects were analyzed. In terms of the analyzed characteristics, the greatest variability was obtained for genotypes with the prostrate growth habit. Microsatellite markers (SSR) were also used to identify co-segregation with the sdw1/denso locus and Bmag0013, Bmag0877, Bmag0306b markers were linked the closest. A partial linkage map of chromosome 3H with the sdw1/denso semi-dwarfing gene was constructed and QTLs were identified. Conclusions Our experiments confirmed the impact of the semi-dwarfing gene on plant height, heading and flowering date both in SSD and DH populations, which may indicate pleiotropy. Moreover, a partial linkage between sdw1/denso locus and grain weight per spike and 1000-grain weight was found in the SSD population.
Assuntos
Hordeum/genética , Pleiotropia Genética , Recombinação Genética , Sementes/genética , Produção Agrícola , Genes de Plantas , Repetições de Microssatélites , Locos de Características Quantitativas , HaploidiaRESUMO
Brassica mustard species represent one of the most important oilseed crops in India, nevertheless, their genetic diversity is barely known. A better understanding on this topic is essential for the proper utilization of genotypes in breeding programmes. We evaluated the genetic diversity among 44 Indian mustard Brassica juncea genotypes including varieties/purelines from different agro-climatic zones of India and few exotic genotypes Australia, Poland and China. For this, we used A and B genome specific SSR markers and phenotypic data on 12 yield and yield contributing traits. Out of the 143 primers tested, 134 reported polymorphism and a total of 355 alleles were amplified. Dendrograms based on Jaccards similarity coefficients and Manhattan dissimilarity coefficients were generated based on an average linkage algorithm UPGMA using marker data and phenotypic data. Genotypes were grouped into four clusters based on genetic distances. Both the clustering patterns based on Jaccards similarity and Manhattan dissimilarity coefficients, independently, discriminated the genotypes effectively as per their pedigree and origin. PCoA revealed that, the grouping of genotypes based on SSR marker data is more convincing than phenotypic data, however, the correlation between phenotypic and genetic distance matrices was observed to be very low r=0.11. Hence, for diversity studies reliability on molecular markers is worth proving and SSR markers are the stronger tools than quantitative traits in discriminating B. juncea genotypes.
Las especies de mostaza del género Brassica representan uno de los cultivos de semillas oleaginosas más importantes en India, sin embargo, su diversidad genética es poco conocida. Para la utilización de genotipos en programas de cultivos resulta esencial un mayor conocimiento sobre este tema. Debido a ello, se evaluó la diversidad genética entre 44 genotipos de mostaza de la India Brassica juncea incluyendo variedades y líneas puras de diferentes zonas agro-climáticas de la India y algunos genotipos exóticos Australia, Polonia y China. Para ello, se utilizaron marcadores SSR específicos del genoma A y B y datos fenotípicos del rendimiento de 12 cosechas y sus características. De los 143 primers evaluados, 134 reportaron polimorfismo y un total de 355 alelos fueron amplificados. Se generaron dendrogramas a partir de los coeficientes de similitud de Jaccard y de disimilitud Manhattan, basados en un algoritmo de vinculación promedio UPGMA. Se utilizaron datos de marcadores genéticos y datos fenotípicos. Los genotipos se agruparon en cuatro grupos basados en las distancias genéticas. Ambos patrones de agrupamiento, tanto los basados en los coeficientes de similitud de Jaccard como los basados en los de disimilitud Manhattan, separaron independientemente los genotipos por su genealogía y origen, de una manera efectiva. El PCoA reveló que la agrupación de genotipos basada en datos de marcadores SSR, es más convincente que los datos fenotípicos, sin embargo, se observó que la correlación entre las matrices de distancia fenotípica y genética resultó muy baja r=0.11. Por lo tanto, para estudios de diversidad basados en marcadores moleculares es necesario realizar más pruebas. Los marcadores SSR constituyen herramientas más eficientes para discriminar entre genotipos de B. juncea, que las características cuantitativas.
Assuntos
Brassica/genética , Variação Genética/genética , Biomarcadores , Brassica/classificação , Primers do DNA/genética , Genótipo , Índia , Repetições de Microssatélites , Fenótipo , Técnica de Amplificação ao Acaso de DNA Polimórfico , Reprodutibilidade dos TestesRESUMO
Phenotypic integration is essential to the understanding of organismal evolution as a whole. In this study, a phylogenetic framework is used to assess phenotypic integration among the floral parts of a group of Neotropical lianas. Flowers consist of plant reproductive organs (carpels and stamens), usually surrounded by attractive whorls (petals and sepals). Thus, flower parts might be involved in different functions and developmental constraints, leading to conflicting selective forces. We found that Bignonieae flowers have very similar patterns of variance/covariance among traits and that such patterns are uncorrelated with the phylogenetic relationships between species. However, in spite of pattern stasis, our results also indicate that diversification of floral morphology in this group has occurred throughout the evolution of magnitudes of correlation among traits. Thus, we suggest that stabilizing selection has played an important role in phenotypic integration, resulting in the long-term stasis of covariance patterns underlying flower diversification during the ca. 50 Myr of evolution of Bignonieae. This is the first report of long-term stasis in the phenotypic integration of angiosperms, suggesting that patterns of floral morphology can be recognizable as specific attributes of distinct botanical families.
Assuntos
Bignoniaceae/anatomia & histologia , Filogenia , Bignoniaceae/classificação , Flores/anatomia & histologia , Flores/classificação , Fenótipo , Seleção GenéticaRESUMO
Zaprionus indianus is a dipteran (Drosophilidae) with a wide distribution throughout the tropics and temperate Palearctic and Nearctic regions. There have been proposals to reclassify the genus Zaprionus as a subgenus or group of the genus Drosophila because various molecular markers have indicated a close relationship between Zaprionus species and the immigrans-Hirtodrosophila radiation within Drosophila. These markers, together with alloenzymes and quantitative traits, have been used to describe the probable scenario for the expansion of Zaprionus indianus from its center of dispersal (Africa) to regions of Asia (ancient dispersal) and the Americas (recent dispersal). The introduction of Z. indianus into Brazil was first reported in 1999 and the current consensus is that the introduced flies came from high-latitude African populations through the importation of fruit. Once in Brazil, Z. indianus spread rapidly throughout the Southeast and then to the rest of the country, in association with highway-based fruit commerce. These and other aspects of the evolutionary biology of Z. indianus are addressed in this review, including a description of a probable route for this species' dispersal during its recent expansion.
RESUMO
To characterize the genetic variability among species and populations of South American wild rice, eleven populations of Oryza glumaepatula, seven of O. grandiglumis, four of O. latifolia and one of O. alta, from Brazil and Argentina, were evaluated. A greenhouse experiment was conducted in completely randomized blocks with 23 treatments. Twenty morphoagronomic traits were assessed. Univariate analyses were performed with 16 quantitative traits with the partitioning of populations within species. Significant differences (p<0.001) between species were observed for all the traits as well as among populations within the species. The most variable was O. glumaepatula followed by O. latifolia. Multivariate discriminant canonical and cluster analyses confirmed the separation of the highly diverse O. glumaepatula populations from the tetraploid species, and the high genetic variation among O. latifolia populations. Morphological differences among the three tetraploid species seemed to be enough to ascribe them at least the condition of species in statu nascendi.
Visando caracterizar a diversidade genética entre espécies e populações de arroz selvagem da América do Sul, foram avaliadas 11 populações de Oryza glumaepatula, sete de O. grandiglumis, quatro de O. latifolia e uma população de O. alta, originárias do Brasil e Argentina. Foi conduzido um experimento em casa-de-vegetação em blocos ao acaso com 23 tratamentos. Vinte caracteres agro-morfológicos foram avaliados. Análises univariadas foram realizadas para 16 caracteres quantitativos, desdobrando-se o efeito de populações dentro de espécies. Diferenças significativas (p<0,001) entre espécies foram observadas para todos os caracteres bem como entre populações dentro de espécies. A mais variável foi O. glumaepatula seguida de O. latifolia. Análises de agrupamento e discriminante canônica confirmaram a separação das populações de O. glumaepatula das espécies tetraplóides, e a grande variação genética entre populações de O. latifolia. Diferenças morfológicas entre as três espécies tetraplóides parecem suficientes para classificá-las como espécies pelo menos na condição statu nascendi.