Low Levels Of Variation Research Articles

The population genetics of nonmigratory Allen's Hummingbird (Selasphorus sasin sedentarius) following a recent mainland colonization.

Allen's Hummingbird comprises two subspecies, one migratory (Selasphorus sasin sasin) and one nonmigratory (S. s. sedentarius). The nonmigratory subspecies, previously endemic to the California Channel Islands, apparently colonized the California mainland on the Palos Verdes Peninsula some time before 1970 and now breeds throughout coastal southern California. We sequenced and compared populations of mainland nonmigratory Allen's Hummingbird to Channel Island populations from Santa Catalina, San Clemente, and Santa Cruz Island. We found no evidence of founder effects on the mainland population. Values of nucleotide diversity on the mainland were higher than on the Channel Islands. There were low levels of divergence between the Channel Islands and the mainland, and Santa Cruz Island was the most genetically distinct. Ecological niche models showed that rainfall and temperature variables on the Channel Islands are similar in the Los Angeles basin and predicted continued expansion of nonmigratory Allen's Hummingbird north along the coast and inland. We also reviewed previous genetic studies of vertebrate species found on the Channel Islands and mainland and showed that broad conclusions regarding island–mainland patterns remain elusive. Challenges include the idiosyncratic nature of colonization itself as well as the lack of a comprehensive approach that incorporates similar markers and sampling strategies across taxa, which, within the context of a comparative study of island–mainland relationships, may lead to inconsistent results.

Novel standardized method for extracellular flux analysis of oxidative and glycolytic metabolism in peripheral blood mononuclear cells

Analyzing metabolism of peripheral blood mononuclear cells (PBMCs) provides key opportunities to study the pathophysiology of several diseases, such as type 2 diabetes, obesity and cancer. Extracellular flux (XF) assays provide dynamic metabolic analysis of living cells that can capture ex vivo cellular metabolic responses to biological stressors. To obtain reliable data from PBMCs from individuals, novel methods are needed that allow for standardization and take into account the non-adherent and highly dynamic nature of PBMCs. We developed a novel method for extracellular flux analysis of PBMCs, where we combined brightfield imaging with metabolic flux analysis and data integration in R. Multiple buffy coat donors were used to demonstrate assay linearity with low levels of variation. Our method allowed for accurate and precise estimation of XF assay parameters by reducing the standard score and standard score interquartile range of PBMC basal oxygen consumption rate and glycolytic rate. We applied our method to freshly isolated PBMCs from sixteen healthy subjects and demonstrated that our method reduced the coefficient of variation in group mean basal oxygen consumption rate and basal glycolytic rate, thereby decreasing the variation between PBMC donors. Our novel brightfield image procedure is a robust, sensitive and practical normalization method to reliably measure, compare and extrapolate XF assay data using PBMCs, thereby increasing the relevance for PBMCs as marker tissue in future clinical and biological studies, and enabling the use of primary blood cells instead of immortalized cell lines for immunometabolic experiments.

Description of Echolocation Call Parameters for Urban Bats in Vietnam as a Step Towards a More Integrated Acoustic Monitoring of Urban Wildlife in Southeast Asia

This study is the first step towards more systematic monitoring of urban bat fauna in Vietnam and other Southeast Asian countries by collecting bat echolocation call parameters in Ho Chi Minh and Tra Vinh cities. We captured urban bats and then recorded echolocation calls after releasing in a tent. Additional bat’s echolocation calls from the free-flying bats were recorded at the site where we captured bat. We used the obtained echolocation call parameters for a discriminant function analysis to test the accuracy of classifying these species based on their echolocation call parameters. Data from this pilot work revealed a low level of diversity for the studied bat assemblages. Additionally, the discriminant function analysis successfully classified bats to four bat species with an accuracy of >87.4%. On average, species assignments were correct for all calls from Taphozous melanopogon (100% success rate), for 70% of calls from Pipistrellus javanicus, for 80.8% of calls from Myotis hasseltii and 67.3% of calls from Scotophilus kuhlii. Our study comprises the first quantitative description of echolocation call parameters for urban bats of Vietnam. The success in classifying urban bats based on their echolocation call parameters provides a promising baseline for monitoring the effect of urbanization on bat assemblages in Vietnam and potentially also other Southeast Asian countries.

The board work experience diversity and the performance of Russian companies

The goal of this study is to empirically assess the influence of the board of directors’ work experience diversity on the performance of Russian non-public companies. The board work experience diversity is measured by the diversity index proposed by the authors, as well as by the number of work experience types and categories. Russian boards are characterized by a low level of diversity, directors with work experience in the same company prevail, on the second and third places is the experience in other enterprises in the industry and the experience in the group of related companies. It has been established that there are no prevailing combinations of experience in industrial companies. A positive influence of the directors’ work experience diversity on the increase of companies’ return on capital from 2017 to 2019 was found. The analysis is based on the data from a 2018 survey of industrial managers conducted by the Higher School of Economics.

Land‐use history determines stand structure and tree diversity in vanilla agroforests of northeastern Madagascar

AbstractQuestionIn human‐modified tropical landscapes, agroforestry is considered a promising land use to reconcile biodiversity conservation with production goals. The role of agroforests regarding conservation may be strongly influenced by land‐use history; however, few studies have explicitly investigated this. We therefore tested the importance of land‐use history for habitat structure and tree diversity in vanilla agroforests situated in a human‐modified tropical landscape.LocationSmallholder mosaic landscape of northeastern Madagascar.MethodsWe studied tree stand structure, diversity and composition in vanilla agroforests of contrasting land‐use history, old‐growth forests, forest fragments and woody fallows after slash‐and‐burn agriculture, which all contribute to the smallholder mosaic landscape of northeastern Madagascar. The vanilla agroforests were either derived directly from forest or otherwise from woody fallows after slash‐and‐burn agriculture.ResultsLand‐use history strongly influenced tree species diversity and composition in vanilla agroforests and also affected stand structure. Forest‐derived agroforests maintained high levels of tree species diversity and differed in community composition from fallow‐derived agroforests, which had relatively low levels of tree diversity. Additionally, forest‐derived vanilla agroforests harboured a significantly higher percentage of endemic species than fallow‐derived agroforests, and forest‐derived agroforests also shared many species with old‐growth forests and forest fragments. Fallow‐derived vanilla agroforests harboured a lower percentage of endemic species than woody fallows.ConclusionConsidering the land‐use history of agroforests is important to unfold their full potential as elements in a multifunctional human‐modified landscape. Forest‐derived agroforests are an alternative to forest conversion through slash‐and‐burn agriculture and have the potential to sustain high levels of species diversity and important habitat structures. In contrast, fallow‐derived agroforests regain stand structure on degraded historically forested land and thereby have the potential to increase canopy cover and connectivity at the landscape scale.

Variability of Chloroplast DNA in Oxytropis Section Polyadena (Fabaceae) from Asian Russia: Population Analysis and Phylogenetic Relationships

Nucleotide polymorphism of the intergenic spacers psbA–trnH, trnL–trnF, and trnS–trnG of chloroplast DNA was analyzed in populations of six Oxytropis species of the section Polyadena from Asian Russia. A low level of nucleotide diversity (0.0001–0.0014) was found, except for two O. glandulosa populations (0.0036 and 0.0059). It was noted that the haplotype diversity varies from 0.133 to 0.911. It was established that high interspecific genetic distances and detected species-specific nucleotide substitutions and indels indicate a significant differentiation of the chloroplast genomes of O. muricata, O. microphylla, O. trichophysa, and O. glandulosa (lineages 2, 3). The species O. pseudoglandulosa, O. muricata, O. varlakovii, and O. glandulosa (lineage 1) form a weakly differentiated complex, which is probably caused by their relatively recent divergence.

Genetic diversity and relationship between wild and cultivated cowpea [Vigna unguiculata (L.) Walp.] as assessed by allozyme markers

Abstract In Cameroon, cowpea plays an important role in traditional agroecosystems. Genetic variation in wild and cultivated cowpea in Cameroon has not yet been documented. Allozyme markers because of their codominance and polymorphism are useful tools for studying genetic variation and disparity in plant species. The present study was undertaken to elucidate the relationship between wild and cultivated cowpea from Cameroon. Ten enzyme systems encoding nineteen isozyme loci were used on 62 cowpea germplasm (45 wild and 17 cultivated). A total of thirty-two alleles were found. One allele was only found in cultivated samples (Enp98 ). Eight alleles were specific only to wild plant (Amp2 98 , Amp3a 103 , Amp4 96 , Fdh104 , Idh2 95 , Pgi3 92 , Pgm2 95 and Sdh95 ). Twenty-three alleles were common to both wild and cultivated accessions. Amp2 10 2 (z = −4.633, p < 0.001) and Fle3 96 (z = −2.858, p < 0.010) were significantly more represented in cultivated compared to wild cowpea forms. The mean number of alleles per locus in wild (1.632 alleles/locus) cowpea were significantly higher (t = 2.805, p < 0.010) compared to cultivated (1.263 alleles/locus) cowpea. Also, the proportion of polymorphic loci (P = 52.63%) and average Nei’s genetic diversity (He = 0.126) were important in wild, compared to the cultivated plants: P = 26.31% and He = 0.063, respectively. The low level of diversity found in domesticated accessions compared to wild can be attributed to a major genetic bottleneck that probably happened during the domestication process. Cluster analysis revealed by UPGMA dendrogram separated the 62 accessions into three clusters. Although an admixture of both wild and cultivated accessions within the same cluster were found, the dendogram, however, highlighted a visible separation between wild and cultivated cowpea. Wild cowpea with many more private alleles indicates an untouched resource available for future breeding.

Increased rainfall variability and nitrogen deposition accelerate succession along a common sere

AbstractOngoing climate change is increasing rainfall variability in many parts of the world; in particular, the heaviest rainfall events are becoming heavier. In terrestrial ecosystems, nitrogen deposition is increasing as a result of emissions from fossil fuel burning and volatilization of nitrogen‐based fertilizers. These changes in the timing and rate of resource inputs can impact plant communities by altering competitive dynamics, succession, and community composition. In many systems, these are occurring alongside successional dynamics, making it difficult to tease apart mechanisms. Here, we resampled a nitrogen by rainfall variability manipulation experiment in a restored tallgrass prairie to examine the relative role of background community dynamics and treatment effects on plant diversity. During the treatment period, nitrogen addition and increased rainfall variability reduced diversity. Here, four and five years after the treatments were halted, we found similarly low levels of diversity across all treatments—an effect driven by dominance of a tall, fast‐growing, clonal forb, Solidago canadensis. The convergence of plots toward a low diversity state suggests that all experimental communities were gradually becoming dominated by S. canadensis, including in the absence of rainfall or nitrogen treatments. In contrast to short‐term findings from the same experiment, we conclude that our treatments accelerated succession toward a tall, clonal forb‐dominated community along an existing sere, but did not fundamentally alter longer‐term community composition—a result that was only apparent several years after the conclusion of the experiment. These findings reinforce the need to interpret the results from short‐term experimental manipulations within the context of long‐term successional change.

Body volume modeling by linear features of the Irmen type cattle

The results of modeling the variability of the complex trait "body volume" by linear traits measured on a 10-point scale in accordance with the current instructions for cattle grading of dairy and dairy-beef breeds are presented. The object of research is the complex indicator "body volume" of Irmen type cattle. The exterior of the livestock was evaluated by experts on a collegial basis. The models obtained made it possible to identify a group of exterior features associated with the variability of the studied trait and to identify errors in the work of the evaluators. The tasks were solved using multiple linear, polynomial, power and logarithmic regression models. It was found that multiple linear regression models accurately describe the norm reaction of the body volume response. Residue distribution diagrams made it possible to control the quality of appraisers' assessment and adjust their further work. The logarithmic model was marked as closest to linear. The residues in most cases turned out to be close to zero, which was explained by the low level of variability of the traits used. It was revealed that the use of different levels of power orders in modeling the variability of the body volume in points can lead to the emergence of biologically inexplicable relationships with such linear features as the location of the front teats, the location of the rear teats, attachment of the anterior lobes and the position of the bottom of the udder. The construction of the scatter diagram revealed a high level of variation in the residues and led to the conclusion that it was inexpedient to introduce power series models into the practical work of livestock breeders. The insignificant contribution of the studied linear features to the variation of the complex feature under study is shown. High intra-group variance in the construction of second- and fourth-order polynomial models was reflected in the lowest values of the Fisher criterion.

Морфо-физиологические особенности дикорастущих образцов тимофеевки луговой (Phleum pratense L.)

The research was carried out in the field at the Central experimental base of the Federal Williams Re¬search Center. The object of research was 12 samples of wild-growing meadow timothy grass. Samples were sown according to the scheme of a standard collection nursery. All studies and observations were carried out on the herbage of the 2nd and 3rd year of life. Statistical processing of results of researches of meadow timothy indicates a low level of variation in the main morphological and physiological characte¬ristics. Only by the number of vegetative shoots have the coefficient of variation reach 35.8%. Samples 416 and 419 were distinguished by precocity, samples 406 and 419 by the height of plants during flower¬ing, sample 412 by the number of generative shoots, and sample 412 by the yield of air-dry mass. Sam¬ples 409 and 414 were distinguished by the length of the sultan, and the weight of seeds — 414 and 415. Nine reliable correlations were found at the significance level 05 and 01. However, all of them are related to the yield of the number of generative and vegetative shoots. Using the binomial equation, the experi¬mentally obtained variability of dry mass yield from the number of generative and vegetative shoots by 93.1% is described. The optimal productivity of meadow timothy grass stand for generative shoots in the area of 550–600 shoots, and vegetative ones — in the area of 320–350 shoots per square meter. Analysis of remoteness and kinship between samples showed the presence of 2 clusters (genetically different quality groups), which can be used for combinational ability selection and fixing of selection-valuable features and properties.

Multi locus sequence typing of clinical Burkholderia pseudomallei isolates from Malaysia.

BackgroundMelioidosis is a neglected tropical disease with rising global public health and clinical importance. Melioidosis is endemic in Southeast Asia and Northern Australia and is of increasing concern in Malaysia. Despite a number of reported studies from Malaysia, these reports are limited to certain parts of the country and do not provide a cohesive link between epidemiology of melioidosis cases and the nation-wide distribution of the causative agent Burkholderia pseudomallei.Methodology/principle findingsHere we report on the distribution of B. pseudomallei sequence types (STs) in Malaysia and how the STs are related to STs globally. We obtained 84 culture-confirmed B. pseudomallei from confirmed septicaemic melioidosis patients from all over Malaysia. Prior to performing Multi Locus Sequence Typing, the isolates were subjected to antimicrobial susceptibility testing and detection of the YLF/BTFC genes and BimA allele. Up to 90.5% of the isolates were sensitive to all antimicrobials tested while resistance was observed for antimicrobials typically administered during the eradication stage of treatment. YLF gene cluster and bimABp allele variant were detected in all the isolates. The epidemiological distribution patterns of the Malaysian B. pseudomallei isolates were analysed in silico using phylogenetic tools and compared to Southeast Asian and world-wide isolates. Genotyping of the 84 Malaysian B. pseudomallei isolates revealed 29 different STs of which 6 (7.1%) were novel. ST50 was identified as the group founder followed by subgroup founders ST376, ST211 and ST84. A low-level diversity is noted for the B. pseudomallei isolates described in this study while phylogenetic analysis associated the Malaysian STs to Southeast Asian isolates especially isolates from Thailand. Further analysis also showed a strong association that implicates agriculture and domestication activities as high-risk routes of infection.Conclusions/significanceIn conclusion, MLST analysis of B. pseudomallei clinical isolates from all states in Malaysia revealed low diversity and a close association to Southeast Asian isolates.

Влияние типа условий местопроизрастания и географического положения популяций на степень интрогрессивной гибридизации ели в Вологодской области

Приведены результаты оценки влияния типа условий местопроизрастания и географического положения на степень интрогрессивной гибридизации ели в Вологодской обл. Показано, что в ельниках кисличных доминируют особи с преобладанием признаков ели сибирской и равнозначными признаками сибирской и европейской елей. Результаты исследований подтверждают принципиальную схему интрогрессии ели на севере Русской равнины: встречаемость ели сибирской увеличивается с продвижением с юга на север и с запада на восток, а распространение ели европейской – в обратном направлении. The paper provides assessment results of how a site condition type and geographic location can influence the degree of introgressivehybridizationof spruce in the Vologda region (evidence from bilberry and wood sorrel spruce forests located in Kichmengsko-Gorodetsky, Totemsky and Cherepovetsky Districts). The study employed research methods proposed by L.F. Pravdin based on distinctive features put forward by I.A. Korenevto holistically assess the degree of introgressivehybridizationof Siberian and European spruce. Various types of site conditions in all of the populations in question show absence of substantial differences in mean values of the majority of morphometric cone parameters. Totemsky and Cherepovetsky populations turned out to be similar in mean sizes of cones. It was found that almost all morphometric cone parameters of the study populations in both types of forests in question vary approximately at the same level. However, Kichmengsko-Gorodetsky and Totemsky populations are characterized by a low level of variability in the length and width of seed scales in both types of forests, whereas in Cherepovetsky population variability of this feature is mean. The study shows that wood sorrel spruce forests are dominated by specimens with prevailing features of Siberian spruce and with equally weighted features of Siberian and European spruce. The results of the research proved that in the north of the Russian plain occurrence of the features of Siberian spruce increases when moving from the south to the north and from the west to the east. It was noted that in Totemsky population, located in the vicinity of the Sukhona river, the degree of hybridizationis higher than that in Kichmengsko-Gorodetsky population located next to it. It was concluded that the degree of hybridizationof European and Siberian spruce populations is connected to their geographic location and site conditions.It is recommendedto use the results of the study in selective seed farming. In Totemsky and adjacent north-eastern districts of the Vologda region when selecting superior trees preferences should be given to hybrid forms of spruce with equally weighted features of Siberian and European spruce. In Kichmengsko-Gorodetsky and Cherepovetsky districts it is essential that specimens of hybrid spruce with prevailing features of Siberian spruce and hybrid spruce with equally weighted features of Siberian and European spruce be selected.

Genomic analysis of SARS-CoV-2 reveals local viral evolution in Ghana.

The confirmed case fatality rate for the coronavirus disease 2019 (COVID-19) in Ghana has dropped from a peak of 2% in March to be consistently below 1% since May 2020. Globally, case fatality rates have been linked to the strains/clades of circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within a specific country. Here we present 46 whole genomes of SARS-CoV-2 circulating in Ghana, from two separate sequencing batches: 15 isolates from the early epidemic (March 12–April 1 2020) and 31 from later time-points ( 25–27 May 2020). Sequencing was carried out on an Illumina MiSeq system following an amplicon-based enrichment for SARS-CoV-2 cDNA. After genome assembly and quality control processes, phylogenetic analysis showed that the first batch of 15 genomes clustered into five clades: 19A, 19B, 20A, 20B, and 20C, whereas the second batch of 31 genomes clustered to only three clades 19B, 20A, and 20B. The imported cases (6/46) mapped to circulating viruses in their countries of origin, namely, India, Hungary, Norway, the United Kingdom, and the United States of America. All genomes mapped to the original Wuhan strain with high similarity (99.5–99.8%). All imported strains mapped to the European superclade A, whereas 5/9 locally infected individuals harbored the B4 clade, from the East Asian superclade B. Ghana appears to have 19B and 20B as the two largest circulating clades based on our sequence analyses. In line with global reports, the D614G linked viruses seem to be predominating. Comparison of Ghanaian SARS-CoV-2 genomes with global genomes indicates that Ghanaian strains have not diverged significantly from circulating strains commonly imported into Africa. The low level of diversity in our genomes may indicate lower levels of transmission, even for D614G viruses, which is consistent with the relatively low levels of infection reported in Ghana.

Karakteristik Kondisi Mangrove di Desa Taddan Kabupaten Sampang

Mangroves are intertidal plants found along tropical and non-tropical coastlines which is flooded by tides in brackish areas. Mangroves ecosystems have experienced a very large decrease in area especially in Madura region. This research was conducted in Taddan Village, Camplong District, Sampang. The objectives of this research were to identify mangrove vegetation, mangrove area and mangrove characteristics. The area of mangroves in the research location was 48 ha. There were 7 types of mangroves found, e.g Rhizophora apiculata, Rhizophora stylosa, Rhizophora mucronata, Sonneratia alba, Sonneratia caseolaris, Avicennia marina and Avicennia alba. The type of substrate in the mangrove research location was mainly mud. The distribution pattern of mangroves at the research location tends to spread in groups, with a low level of mangrove diversity. The uniformity index value is balanced, or in other words, there are individuals who dominate. The average sediment depth is 24.7 cm, the average salinity is 36.7 ppt, the average water pH is 5.3, the average DO is 5.9 mg / l, the average water temperature is 31, 70C, the average soil pH is 6.4. Further analysis concluded that environmental parameters in the area was unsuitable for marine tourism.

Analisis Kelimpahan Dan Keanekaragaman Perifiton Rawa Bangkau Kabupaten Hulu Sungai Selatan Kalimantan Selatan

Periphyton group are biota communities that be able adapt and grow well in lentic waters. Their habits are adhere to a permanent location. Aquatic vegetation in Bangkau can influenced the periphyton abundance and diversity as natural food in the food chain. The purpose of this study was to analyzed abundance and diversity of Periphyton from different aquatic vegetation. The research was conducted in three stations by purposive sampling. The method used was quantitative explored. The data that has been taken were epiphythic periphyton samples. Periphyton sampling procedures, preservation, and analysis were carried out based on Indonesian National Standard methods. Bangkau’s peatland had the highest abundance of phytoplankton-periphyton (9982 sel/liter) in inlet, but low at middle station (778 sel/liter). Zooplankton-periphyton (553 sel/liter) in middle station was the highest abundance whereas in outlet station (153 sel/liter) was the lowest. Bacillariophyceae had predominant and always attendanced Oscillatoria, Closterium, Planktonella, Diatom, meanwhile zooplankton-periphyton dominated Ciliophora in all stations and sampling. Diversity index of phytoplankton-periphyton in inlet station (1,55) was the highest and in inlet (0,77) was the lowest. Zooplankton-periphyton in middle (1,76) and outlet (0,94) was different based on Shannon wiener’s Index. The abundance index of Bangkau were mesotrophic categorized for phytoplankton-periphyton and oligotrophic for zooplankton-periphyton. Due to the low level of species diversity (H’≤ 3) showed moderate stability and for the water quality conditions was moderate polluted.

Biometry, Distribution and Genetic Characterization of Blue Jack Mackerel Trachurus picturatus (Bowdich, 1825), a Rare Pelagic Fish Species in the Adriatic Sea

The blue jack mackerel Trachurus picturatus (Bowdich, 1825) specimens (N = 155) were collected during the MEDITS survey, done along the eastern side, precisely, of the Croatian fishing ground in July 2018. Biometrical analysis of ten morphometric and five meristic characters, as well as genetic analysis proved that the collected specimens were blue jack mackerel. The total length (TL) and weight (W) of all observed specimens ranged from 9.2 to 33.7 cm (12.15 ± 2.95 cm) and from 5.79 to 384.94 g (17.64 ± 39.42 g), respectively. All calculated length–length relationships were linear (r > 0.923). Sex was determined only on two larger specimens (28 cm < TL < 32.8 cm), which were females. In the length–weight relationship, positive allometry was established (b = 3.1789). Based on 37 partial cytochrome b sequences, the overall haplotype diversity (h) of 0.812 ± 0.048 and nucleotide diversity (π) of 0.0064 ± 0.0007 indicated high levels of haplotype and low nucleotide diversity. The obtained sequences were compared to previously published research within the Northeast Atlantic Ocean and the Mediterranean Sea, confirming the absence of genetic structure among these populations.

Assessing Volatiles in Three Chinese Dwarf Cherry Cultivars during Veraison and Maturation Using Headspace-Solid Phase Microextraction with Gas Chromatography-Mass Spectrometry.

Chinese dwarf cherry is a native shrub in northwest China with a rich and unique fruit aroma. This study aims to determine the changes in volatile profiles during the maturation period, which provides a theoretical basis for the optimal harvest times and the breeding of aroma-rich varieties. The variation in the production of 164 volatile compounds from three Chinese dwarf cherry cultivars, namely, “Jing’ou 1”, “Jing’ou 2”, and “Jing’ou 3”, were investigated by headspace-solid phase microextraction (HS-SPME)-GC–MS. These volatiles mainly constituted alcohols, carbonyls, esters, terpenoids, and hydrocarbons. Their maturation process could be divided into three stages, namely prophase, metaphase, and anaphase. Prophase contained an abundance of hydrocarbons and carbonyls, primarily benzaldehyde being dominant among all volatiles. During metaphase, volatiles remained at a low level of abundance and diversity. Anaphase coincided with full maturation and was associated with esters and terpenoids; in particular, “Jing’ou 3” presented more compound diversity and a high level of acetate esters. The periods including the week prior to veraison and the week during maturation were particularly critical in volatile formation in Chinese dwarf cherries. This study reveals that the low level or lack of hexanal might be one of the distinctive characteristics separating Chinese dwarf cherries from other Cerasus or Rosaceae fruits.

A Framework for Scalable Bilevel Optimization: Identifying and Utilizing the Interactions Between Upper-Level and Lower-Level Variables

When solving bilevel optimization problems (BOPs) by evolutionary algorithms (EAs), it is necessary to obtain the lower-level optimal solution for each upper-level solution, which gives rise to a large number of lower-level fitness evaluations, especially for large-scale BOPs. It is interesting to note that some upper-level variables may not interact with some lower-level variables. Under this condition, if the value(s) of one/several upper-level variables change(s), we only need to focus on the optimization of the interacting lower-level variables, thus reducing the dimension of the search space and saving the number of lower-level fitness evaluations. This article proposes a new framework (called GO) to identify and utilize the interactions between upper-level and lower-level variables for scalable BOPs. GO includes two phases: 1) the grouping phase and 2) the optimization phase. In the grouping phase, after identifying the interactions between upper-level and lower-level variables, they are divided into three types of subgroups (denoted as types I–III), which contain only upper-level variables, only lower-level variables, and both upper-level and lower-level variables, respectively. In the optimization phase, if type-I and type-II subgroups only include one variable, a multistart sequential quadratic programming is designed; otherwise, a single-level EA is applied. In addition, a criterion is proposed to judge whether a type-II subgroup has multiple optima. If multiple optima exist, by incorporating the information of the upper level, we design new objective function and degree of constraint violation to locate the optimistic solution. As for type-III subgroups, they are optimized by a bilevel EA (BLEA). The effectiveness of GO is demonstrated on a set of scalable test problems by applying it to five representative BLEAs. Moreover, GO is applied to the resource pricing in mobile edge computing.

Predominance of Burkholderia cenocepacia lineages causing onion sour skin in the semi‐arid region of north‐east Brazil

AbstractBurkholderia cepacia was originally described as the causal agent of onion sour skin. However, this bacterium is now recognized as a complex of 22 closely related species, commonly referred to as the B. cepacia complex (BCC). Only a few taxonomic studies have been undertaken with the aim of understanding the diversity of species associated with onion sour skin. In this study, we used a polyphasic analysis including rep‐PCR assay, biochemical and pathological profiles, and multilocus sequence analysis (MLSA) to characterize the BCC species associated with onion sour skin in the semi‐arid region of north‐east Brazil. Phylogenetic analysis of the recA of strains representing the genetic variability, as determined by rep‐PCR, grouped the strains into four clades. Clades I and II represent B. cenocepacia lineages IIB and IIIA, respectively, while the strains in Clades III and IV clustered more closely to Clades I and II than to strains of any other BCC species. MLSA confirmed the existence of the four clades with a 1.00 posterior probability. A distance matrix indicated a low level of divergence among the strains of the four clades found in the MLSA, proving that B. cenocepacia lineages IIIA, IIIB, and a new lineage of B. cenocepacia are associated with onion sour skin in the semi‐arid region of north‐east Brazil. Also, surprisingly, no strain was identified as B. cepacia, indicating that this species probably does not play a role in this disease in this region.

Genetic diversity and inter-relationships of fruit bio-chemicals and antioxidant activity in Iranian wild blackberry species

Blackberries are a rich source of bio-chemicals such as anthocyanins and polyphenolic antioxidants. The evaluation of the extent of variation among wild genetic resources can provide useful information for the establishment of effective conservation strategies and future breeding programs. In this study, variations and inter-relationship of berry weight, total phenol (TP), total soluble solids (TSS), titratable acidity (TA), ascorbic acid (AA), anthocyanin and antioxidant activity were estimated in their values among 57 accessions belonging to 4 different Rubus spp. native to Iran. The experiments were performed during two consecutive years (2014 and 2015). Combine analysis showed that there is no significant difference between the data of 2 years in all measured traits. High or very high levels of variations were detected in berry weight (0.14–1.30 g), antioxidant activity (40.21–88.08%), anthocyanin (80.74–145.09 mg/100 g), TSS (7.9–17.8 °Brix), TA (0.36–0.83%) and AA (9.56–20.92 mg/100 g). This is while TP showed very low levels of variation (109.5–129.1 mg/100 g). Correlation analysis showed that antioxidant activity correlated highly and positively with all of the measured characteristics including ascorbic acid (r = 0.927), anthocyanin (r = 0.752), total phenol (r = 0.681), TSS (r = 0.473) and berry weight (r = 0.541) except for TA. Cluster analysis based on all measured characteristics showed a partial differentiation between the accessions based on their species and, to lesser extent, according to their origin within the main clusters. Based on the bi-plot of the first two PCAs, genotypes and traits classified into four quadrants. This grouping was in agreement with that of cluster analysis, considering the fact that almost all of accessions in quadrants II and III (with a few exceptions) were same to those in the first clade of cluster analysis and the genotypes grouped in quadrants I and IV, represents the accessions of clade 2 in cluster analysis. The projection of the traits vectors in PCA were also fully in accordance to that of correlation analysis in almost all of studied traits. Results showed that a rich source of variations is available considering berry weight, fruit bio-chemical and antioxidant activity in the Iranian wild Rubus species, which needs immediate conservation and worth to be utilized in commercial breeding programs.