Selective Pressure Research Articles

The effect of quantitative wheat resistance on the aggressiveness of Fusarium graminearum.

Little is known about the selection pressures acting on plant pathogen populations, especially those applied by quantitative forms of resistance. Fusarium graminearum causes Fusarium Head Blight (FHB) in wheat, producing significant yield losses and mycotoxin contamination. Quantitative host resistance is the best method to control FHB. However, there needs to be more understanding of how disease resistance affects the evolution of plant pathogens. This study aimed to determine if the presence or absence of wheat resistance influenced the fitness components and genomic regions of F. graminearum. Thirty-one isolates from highly susceptible and 25 isolates from moderately resistant wheat lines were used. Isolate aggressiveness was measured by area under the disease progress curve (AUDPC), visually damaged kernels, and deoxynivalenol contamination. In vitro growth rate and spore production were also measured. Two whole-genome scans for selection were conducted with 333,297 SNPs. One scan looked for signatures of selection in the entire sample and the other scan was for divergent selection between the isolates from moderately resistant wheat and highly susceptible wheat. The population of isolates from highly susceptible wheat was primarily aggressive. Several regions of the F. graminearum genome with signatures for selection were identified. The moderately resistant wheat varieties used in this study did not select more aggressive isolates, suggesting that quantitative resistance is a durable method to control FHB.

Impacts of polymethyl methacrylate nanoplastics on nutrient removal, microbial community and antibiotic resistant genes in bioretention systems amended with biochar and pyrolusite

Increasing release of nanoplastics (NPs) into wastewater may pose a potential threat to nitrogen and phosphorous removals in ecological wastewater treatment systems. To better understand the responses of bioretention system (BRS) by NPs, a Conventional Sand BRS (CB-BRS) and two modified BRSs, Microbial Fuel Cell (MFC)-Biochar BRS (MB-BRS) and Pyrolusite-MFC-Biochar BRS (PMB-BRS) were established and the effects of 0.5 mg/L polymethyl methacrylate (PMMA) NPs on nutrient removal, microbial community structures, as well as key enzyme activities, functional genes, antibiotic resistance genes (ARGs) were comprehensively investigated within a 120-day exposure. We observed a significant decrease in total nitrogen (TN) and total phosphorous (TP) removals in BRSs. TN removal efficiencies gradually declined from 93.56 % to 54.23 % and the TP removal efficiencies declined from 88.29 % to 74.47 % in CB-BRS. By contrast, MB-BRS (TN:72.28 %; TP:81.58 %) and PMB-BRS (TN:80.76 %; TP:96.69 %) apparently overperformed CB-BRS. In conjunction with ecological-relevant functional prediction based on the FAPROTAX database, the Illumina high-throughput sequencing unveiled substantial selective pressure imposed by PMMA NPs, particularly leading to diminished denitrifying microbes. PMMA NPs adversely affected key nitrogen-transformation enzyme activities (URE, AMO, and NIR) and denitrification functional genes (nirK, nirS, and nosZ). Alarmingly, PMMA NPs stimulated ARGs (sulI and tetC) propagation in all BRSs. Notably, the introduction of pyrolusite and biochar mitigated the adverse effects through the formation of manganese cycle and prosperous electron transfer process and effectively retained ARGs after 120-day exposure. The findings provide unprecedented insights into the potential ecological threat posed by PMMA NPs and viable strategies to control this hidden danger.

A novel chemically defined medium for the biotechnological and biomedical exploitation of the cell factory Leishmania tarentolae

The development of media for cell culture is a major issue in the biopharmaceutical industry, for the production of therapeutics, immune-modulating molecules and protein antigens. Chemically defined media offer several advantages, as they are free of animal-derived components and guarantee high purity and a consistency in their composition. Microorganisms of the genus Leishmania represent a promising cellular platform for production of recombinant proteins, but their maintenance requires supplements of animal origin, such as hemin and fetal bovine serum. In the present study, three chemically defined media were assayed for culturing Leishmania tarentolae, using both a wild-type strain and a strain engineered to produce a viral antigen. Among the three media, Schneider's Drosophila Medium supplemented with Horseradish Peroxidase proved to be effective for the maintenance of L. tarentolae promastigotes, also allowing the heterologous protein production by the engineered strain. Finally, the engineered strain was maintained in culture up to the 12th week without antibiotic, revealing its capability to produce the recombinant protein in the absence of selective pressure.

Assessment of Genomic Diversity and Selective Pressures in Crossbred Dairy Cattle of Pakistan.

Improving the low productivity levels of native cattle breeds in smallholder farming systems is a pressing concern in Pakistan. Crossbreeding high milk-yielding holstein friesian (HF) breed with the adaptability and heat tolerance of Sahiwal cattle has resulted in offspring that are well-suited to local conditions and exhibit improved milk yield. The exploration of how desirable traits in crossbred dairy cattle are selected has not yet been investigated. This study aims to provide the first overview of the selective pressures on the genome of crossbred dairy cattle in Pakistan. A total of eighty-one crossbred, thirty-two HF and twenty-four Sahiwal cattle were genotyped, and additional SNP genotype data for HF and Sahiwal were collected from a public database to equate the sample size in each group. Within-breed selection signatures in crossbreds were investigated using the integrated haplotype score. Crossbreds were also compared to each of their parental breeds to discover between-population signatures of selection using two approaches: cross-population extended haplotype homozygosity and fixation index. We identified several overlapping genes associated with production, immunity, and adaptation traits, including U6, TMEM41B, B4GALT7, 5S_rRNA, RBM27, POU4F3, NSD1, PRELID1, RGS14, SLC34A1, TMED9, B4GALT7, OR2AK3, OR2T16, OR2T60, OR2L3, and CTNNA1. Our results suggest that regions responsible for milk traits have generally experienced stronger selective pressure than others.

Adaptive evolution of antioxidase-related genes in hypoxia-tolerant mammals.

To cope with the damage from oxidative stress caused by hypoxia, mammals have evolved a series of physiological and biochemical traits, including antioxidant ability. Although numerous research studies about the mechanisms of hypoxia evolution have been reported, the molecular mechanisms of antioxidase-related genes in mammals living in different environments are yet to be completely understood. In this study, we constructed a dataset comprising 7 antioxidase-related genes (CAT, SOD1, SOD2, SOD3, GPX1, GPX2, and GPX3) from 43 mammalian species to implement evolutionary analysis. The results showed that six genes (CAT, SOD1, SOD2, SOD3, GPX1, and GPX3) have undergone divergent evolution based on the free-ratio (M1) model. Furthermore, multi-ratio model analyses uncovered the divergent evolution between hypoxic and non-hypoxic lineages, as well as various hypoxic lineages. In addition, the branch-site model identified 9 positively selected branches in 6 genes (CAT, SOD1, SOD2, SOD3, GPX2, and GPX3) that contained 35 positively selected sites, among which 31 positively selected sites were identified in hypoxia-tolerant branches, accounting for 89% of the total number of positively selected sites. Interestingly, 65 parallel/convergent sites were identified in the 7 genes. In summary, antioxidase-related genes are subjected to different selective pressures among hypoxia-tolerant species living in different habitats. This study provides a valuable insight into the molecular evolution of antioxidase-related genes in hypoxia evolution in mammals.

Multivariate data analysis of process parameters affecting the growth and productivity of stable Chinese hamster ovary cell pools expressing SARS-CoV-2 spike protein as vaccine antigen in early process development.

The recent COVID-19 pandemic revealed an urgent need to develop robust cell culture platforms which can react rapidly to respond to this kind of global health issue. Chinese hamster ovary (CHO) stable pools can be a vital alternative to quickly provide gram amounts of recombinant proteins required for early-phase clinical assays. In this study, we analyze early process development data of recombinant trimeric spike protein Cumate-inducible manufacturing platform utilizing CHO stable pool as a preferred production host across three different stirred-tank bioreactor scales (0.75, 1, and 10 L). The impact of cell passage number as an indicator of cell age, methionine sulfoximine (MSX) concentration as a selection pressure, and cell seeding density was investigated using stable pools expressing three variants of concern. Multivariate data analysis with principal component analysis and batch-wise unfolding technique was applied to evaluate the effect of critical process parameters on production variability and a random forest (RF) model was developed to forecast protein production. In order to further improve process understanding, the RF model was analyzed with Shapley value dependency plots so as to determine what ranges of variables were most associated with increased protein production. Increasing longevity, controlling lactate build-up, and altering pH deadband are considered promising approaches to improve overall culture outcomes. The results also demonstrated that these pools are in general stable expressing similar level of spike proteins up to cell passage 11 (~31 cell generations). This enables to expand enough cells required to seed large volume of 200-2000 L bioreactor.

Deciphering the microbial communities of alkaline hot spring in Panamik, Ladakh, India using a high-throughput sequencing approach.

Due to their distinctive physicochemical characteristics, hot springs are extremely important. The whole genome metagenomic sequencing technology can be utilized to analyze the diverse microbial community that thrives in this habitat due to the particular selection pressure that prevails there. The current investigation emphasizes on culture-independent metagenomic study of the Panamik hot spring and its nearby areas from Ladakh, India. Based on different diversity indices, sequence analysis of the soil reservoir showed higher species richness and diversity in comparison to water and sediment samples. The mineral content and various physicochemical pameters like temperature, pH had an impact on the composition of the microbial community of the geothermal springs. The phyla Proteobacteria, Cyanobacteria, Bacteroidetes, Actinobacter, Firmicutes, and Verrucomicrobia in bacterial domain dominate the thermos-alkaline spring at Panamik in different concentrations. Economically significant microbes from the genera Actinobacter, Thermosynechoccus, Candidatus Solibacter, Chthoniobacter, Synechoccus, Pseudomonas and Sphingomonas, were prevalent in hot spring. In the archaeal domain, the most dominant phylum and genera were Euryarchaeota and Thermococcus in all the samples. Further, the most abundant species were Methanosarcina barkeri, Nitrospumilus maritimus and Methanosarcina acetivorans. The present study which only examined one of the several thermal springs present in the Himalayan geothermal area, should be regarded as a preliminary investigation of the microbiota that live in the hot springs on these remote areas. These findings suggest that further investigations should be undertaken to characterize the ecosystems of the Panamik hot spring, which serve as a repository for unidentified microbial lineages.

When the solution becomes the problem: a review on antimicrobial resistance in dairy cattle.

Antibiotics' action, once a 'magic bullet', is now hindered by widespread microbial resistance, creating a global antimicrobial resistance (AMR) crisis. A primary driver of AMR is the selective pressure from antimicrobial use. Between 2000 and 2015, antibiotic consumption increased by 65%, reaching 34.8billion tons, 73% of which was used in animals. In the dairy cattle sector, antibiotics are crucial for treating diseases like mastitis, posing risks to humans, animals and potentially leading to environmental contamination. To address AMR, strategies like selective dry cow therapy, alternative treatments (nanoparticles, phages) and waste management innovations are emerging. However, most solutions are in development, emphasizing the urgent need for further research to tackle AMR in dairy farms.

Variation in resting respiration rate of Brook Trout among source populations: Implications for bioenergetic models

AbstractObjectiveOur objective was to compare wild and hatchery sourced Brook Trout Salvelinus fontinalis to determine the importance of source population on routine respiration rate (RRR), the major cost term in bioenergetic models.MethodsWe evaluated intraspecific variation in RRRs of one hatchery and four wild Brook Trout populations. Hatchery fish were obtained from the Bowden State Fish Hatchery in Elkins, West Virginia, and were the basis for the previously published bioenergetics model for the species. Wild fish were obtained from four headwater streams in West Virginia. Using intermittent respirometry, we measured and analyzed RRRs sequentially at 20, 16, and 12°C. Measures on hatchery fish were censored to restrict the dataset to similar sizes and temperatures as used with the wild populations. We used a suite of mixed effects models and one linear model to compare RRRs of hatchery fish with wild fish, as well as to determine whether wild populations differed.ResultWe found that the RRR of hatchery fish was double that of wild fish over the range of 12–20°C. Within the wild populations, the RRR of the Potomac drainage fish was lower than two of the three Ohio drainage populations despite all steams falling within 55 km of each other.ConclusionOur findings suggest that selective pressures at the hatchery, as well as factors that influence thermal regimes in wild populations, likely influence RRR in Brook Trout. More research is needed to identify correlates related to intraspecific variation in fish respiration rates. Most fish bioenergetics models are not based on, or calibrated to, the specific population to which they are applied. Therefore, we encourage greater efforts be expended to calibrate and validate such models in the future.

Bridging ecological assembly process and community stability upon bacterial invasions.

Understanding the link between microbial community stability and assembly processes is crucial in microbial ecology. Here, we investigated whether the impact of biotic disturbances would depend on the processes controlling community assembly. For that, we performed an experiment using soil microcosms in which microbial communities assembled through different processes were invaded by Escherichia coli. We show that the ecological assembly process of the resident community plays a significant role in invader-resident competition, invader survival, and compositional stability of the resident community. Specifically, the resident communities primarily assembled through stochastic processes were more susceptible to invader survival. Besides, E. coli invasion acts as a biotic selection pressure, leading to competition between the invader and resident taxa, suppressing the stochasticity in the resident community. Taken together, this study provides empirical evidence for the interpretation of microbial community assemblage on their (potential) ecosystem functions and services, such as the prevention of pathogen establishment and the pathogenic states of soil microbiomes.

Twelve newly assembled jasmine chloroplast genomes: unveiling genomic diversity, phylogenetic relationships and evolutionary patterns among Oleaceae and Jasminum species

BackgroundJasmine (Jasminum), renowned for its ornamental value and captivating fragrance, has given rise to numerous species and accessions. However, limited knowledge exists regarding the evolutionary relationships among various Jasminum species.ResultsIn the present study, we sequenced seven distinct Jasminum species, resulting in the assembly of twelve high-quality complete chloroplast (cp) genomes. Our findings revealed that the size of the 12 cp genomes ranged from 159 to 165 kb and encoded 134–135 genes, including 86–88 protein-coding genes, 38–40 tRNA genes, and 8 rRNA genes. J. nudiflorum exhibited a larger genome size compared to other species, mainly attributed to the elevated number of forward repeats (FRs). Despite the typically conservative nature of chloroplasts, variations in the presence or absence of accD have been observed within J. sambac. The calculation of nucleotide diversity (Pi) values for 19 cp genomes indicated that potential mutation hotspots were more likely to be located in LSC regions than in other regions, particularly in genes ycf2, rbcL, atpE, ndhK, and ndhC (Pi > 0.2). Ka/Ks values revealed strong selection pressure on the genes rps2, atpA, rpoA, rpoC1, and rpl33 when comparing J. sambac with the three most closely related species (J. auriculatum, J. multiflorum, and J. dichotomum). Additionally, SNP identification, along with the results of Structure, PCA, and phylogenetic tree analyses, divided the Jasminum cp genomes into six groups. Notably, J. polyanthum showed gene flow signals from both the G5 group (J. nudiflorum) and the G3 group (J. tortuosum and J. fluminense). Phylogenetic tree analysis reflected that most species from the same genus clustered together with robust support in Oleaceae, strongly supporting the monophyletic nature of cp genomes within the genus Jasminum.ConclusionOverall, this study provides comprehensive insights into the genomic composition, variation, and phylogenetic relationships among various Jasminum species. These findings enhance our understanding of the genetic diversity and evolutionary history of Jasminum.

Consistent pattern in scaling relationships of leaf dry mass versus area of woody species co-occurring in dry-hot and wet-hot habitats

The scaling relationships between leaf dry mass (LDM) and surface area (LA) can reflect the efficiency of light harvesting and photosynthesis, as well as the ability of plants to withstand biotic and abiotic stress. However, it remains little unknown whether plants alter the scaling relationships of LDM and LA, as along with leaf mass investment per unit area in common species growing in different habitats with high temperature and contrasting water availability. This study involved measuring LA, LDM, and leaf morphological traits (e.g., leaf thickness, dry mass per unit area, and density) in 14 woody species (10 tree species, 2 shrub species, and 2 liana species) that co-occur in wet-hot (WH) and dry-hot (DH) habitats in southwest China. Our results showed that the scaling exponents (α) of LDM vs. LA were consistently greater than 1.0 (indicating the increase in LA fails to keep pace with increasing LDM) for all 14 common species at both sites, irrespective of their growth forms. Furthermore, species exhibited a higher leaf mass investment per unit area and leaf density at the DH site compared to the WH site. These results suggest that the law of “diminishing returns” applies to the scaling relationships of LDM and LA in common species inhabiting both types of habitats. Additionally, plants at the DH site increased leaf mass and density investments, potentially reflecting an essential adaptation to strong selective pressure experienced by plant species in that habitat. This study provides new insights into the scaling relationships of LDM and LA in contrasting habitats, enriching our understanding of the plant life-history strategies and adaptations in response to climate change.

Complete Chloroplast Genome of Alternanthera sessilis and Comparative Analysis with Its Congeneric Invasive Weed Alternanthera philoxeroides

Alternanthera sessilis is considered the closest relative to the invasive weed Alternanthera philoxeroides in China, making it an important native species for studying the invasive mechanisms and adaptations of A. philoxeroides. Chloroplasts play a crucial role in a plant’s environmental adaptation, with their genomes being pivotal in the evolution and adaptation of both invasive and related species. However, the chloroplast genome of A. sessilis has remained unknown until now. In this study, we sequenced and assembled the complete chloroplast genome of A. sessilis using high-throughput sequencing. The A. sessilis chloroplast genome is 151,935 base pairs long, comprising two inverted repeat regions, a large single copy region, and a small single copy region. This chloroplast genome contains 128 genes, including 8 rRNA-coding genes, 37 tRNA-coding genes, 4 pseudogenes, and 83 protein-coding genes. When compared to the chloroplast genome of the invasive weed A. philoxeroides and other Amaranthaceae species, we observed significant variations in the ccsA, ycf1, and ycf2 regions in the A. sessilis chloroplast genome. Moreover, two genes, ccsA and accD, were found to be undergoing rapid evolution due to positive selection pressure. The phylogenetic trees were constructed for the Amaranthaceae family, estimating the time of independent species formation between A. philoxeroides and A. sessilis to be approximately 3.5186–8.8242 million years ago. These findings provide a foundation for understanding the population variation within invasive species among the Alternanthera genus.

Selection maintains a nonadaptive floral polyphenism

Abstract Adaptive phenotypic plasticity evolves in response to the contrasting selection pressures that arise when organisms face environmental heterogeneity. Despite its importance for understanding how organisms successfully cope with environmental change, adaptive plasticity is often assumed but rarely demonstrated. We study here the adaptive nature of the extreme seasonal within-individual floral polyphenism exhibited by the crucifer Moricandia arvensis, a Mediterranean species that produces two different types of flowers depending on the season of the year. During spring, this species has large, cross-shaped, lilac flowers, while during summer, it develops small, rounded, white flowers. Although floral polyphenism was associated with increased plant fitness, selection moved floral traits away from their local optimum values during the harsh summer. This result strongly suggests that floral polyphenism is not adaptive in M. arvensis. The main factor selecting against floral polyphenism was pollinators, as they select for the same floral morph in all environments. Despite not being adaptive, floral polyphenism occurs throughout the entire distribution range of M. arvensis and has probably been present since the origin of the species. To solve this paradox, we explored the factors causing floral polyphenism, finding that floral polyphenism was triggered by summer flowering. Summer flowering was beneficial because it led to extra seed production and was favored by adaptive plasticity in leaf functional traits. Taken together, our study reveals a complex scenario in which nonadaptive floral polyphenism has been indirectly maintained over M. arvensis evolutionary history by selection operating to favor summer flowering. Our study provides thus strong evidence that nonadaptive plasticity may evolve as a byproduct of colonizing stressful environments.

A qualitative study on determinants of the use of malaria rapid diagnostic test and anti-malarial drug prescription practices by primary healthcare workers in Ebonyi state, Nigeria

BackgroundThe increased availability and use of malaria rapid diagnostic test (RDT) by primary healthcare (PHC) workers has made universal diagnostic testing before malaria treatment more feasible. However, to meaningfully resolve the problem of over-treatment with artemisinin-based combination therapy and the heightened risk of selection pressure and drug resistance, there should be appropriate response (non-prescription of anti-malarial drugs) following a negative RDT result by PHC workers. This study explored the determinants of the use of RDT and anti-malarial drug prescription practices by PHC workers in Ebonyi state, Nigeria.MethodsBetween March 2 and 10, 2020, three focus group discussions were conducted in English with 23 purposively-selected consenting PHC workers involved in the diagnosis and treatment of malaria. Data was analysed thematically as informed by the method by Braun and Clarke.ResultsThe determinants of the use of RDT for malaria diagnosis were systemic (RDT availability and patient load), provider related (confidence in RDT and the desire to make correct diagnosis, PHC worker’s knowledge and training, and fear to prick a patient), client related (fear of needle prick and refusal to receive RDT, and self-diagnosis of malaria, based on symptoms, and insistence on not receiving RDT), and RDT-related (the ease of conducting and interpreting RDT). The determinants of anti-malarial drug prescription practices were systemic (drug availability and cost) and drug related (effectiveness and side-effects of the drugs). The determinants of the prescription of anti-malarial drugs following negative RDT were provider related (the desire to make more money and limited confidence in RDT) and clients’ demand while unnecessary co-prescription of antibiotics with anti-malarial drugs following positive RDT was determined by the desire to make more money.ConclusionsThis evidence highlights many systemic, provider, client, and RDT/drug related determinants of PHC workers’ use of RDT and anti-malarial drug prescription practices that should provide tailored guidance for relevant health policy actions in Ebonyi state, Nigeria, and similar settings.

Long-Term Co-Circulation of Host-Specialist and Host-Generalist Lineages of Group B Streptococcus in Brazilian Dairy Cattle with Heterogeneous Antimicrobial Resistance Profiles

Group B Streptococcus (GBS) is a major cause of contagious bovine mastitis (CBM) in Brazil. The GBS population is composed of host-generalist and host-specialist lineages, which may differ in antimicrobial resistance (AMR) and zoonotic potential, and the surveillance of bovine GBS is crucial to developing effective CBM control and prevention measures. Here, we investigated bovine GBS isolates (n = 156) collected in Brazil between 1987 and 2021 using phenotypic testing and whole-genome sequencing to uncover the molecular epidemiology of bovine GBS. Clonal complex (CC) 61/67 was the predominant clade in the 20th century; however, it was replaced by CC91, with which it shares a most common recent ancestor, in the 21st century, despite the higher prevalence of AMR in CC61/67 than in CC91, and high selection pressure for AMR from indiscriminate antimicrobial use in the Brazilian dairy industry. CC103 also emerged as a dominant CC in the 21st century, and a considerable proportion of herds had two or more GBS strains, suggesting poor biosecurity and within-herd evolution due to the chronic nature of CBM problems. The majority of bovine GBS belonged to serotype Ia or III, which was strongly correlated with CCs. Ninety-three isolates were resistant to tetracycline (≥8 μg/mL; tetO = 57, tetM = 34 or both = 2) and forty-four were resistant to erythromycin (2.0 to >4 μg/mL; ermA = 1, ermB = 38, mechanism unidentified n = 5). Only three isolates were non-susceptible to penicillin (≥8.0 μg/mL), providing opportunities for improved antimicrobial stewardship through the use of narrow-spectrum antimicrobials for the treatment of dairy cattle. The common bovine GBS clades detected in this study have rarely been reported in humans, suggesting limited risk of interspecies transmission of GBS in Brazil. This study provides new data to support improvements to CBM and AMR control, bovine GBS vaccine design, and the management of public health risks posed by bovine GBS in Brazil.

What is driving the global decline of human fertility? Need for a multidisciplinary approach to the underlying mechanisms.

An intense period of human population expansion over the past 250 years is about to cease. Total fertility rates are falling dramatically all over the world such that highly industrialized nations, including China and the tiger economies of SE Asia, will see their populations decline significantly in the coming decades. The socioeconomic, geopolitical and environmental ramifications of this change are considerable and invite a multidisciplinary consideration of the underlying mechanisms. In the short-term, socioeconomic factors, particularly urbanization and delayed childbearing are powerful drivers of reduced fertility. In parallel, lifestyle factors such as obesity and the presence of numerous reproductive toxicants in the environment, including air-borne pollutants, nanoplastics and electromagnetic radiation, are seriously compromising reproductive health. In the longer term, it is hypothesized that the reduction in family size that accompanies the demographic transition will decrease selection pressure on high fertility genes leading to a progressive loss of human fecundity. Paradoxically, the uptake of assisted reproductive technologies at scale, may also contribute to such fecundity loss by encouraging the retention of poor fertility genotypes within the population. Since the decline in fertility rate that accompanies the demographic transition appears to be ubiquitous, the public health implications for our species are potentially devastating.

Life history correlations and trade-offs resulting from selection for dispersal in Tribolium castaneum.

Dispersal is an important facet of the life history of many organisms and is therefore subject to selective pressure, but does not evolve in isolation. Across nature there are examples of dispersal syndromes, life history strategies in which suites of traits coevolve and covary with dispersal in combinations that serve to maximise fitness in a given ecological context. The red rust flour beetle, Tribolium castaneum, is a model organism and globally significant post-harvest pest which relies on dispersal to reach new patches of ephemeral habitat. Dispersal behaviour in Tribolium has a strong genetic basis. However, a robust understanding of the relationship between dispersal and other life history components, which could elucidate evolutionary processes and allow pest managers to control their spread and reduce the impact of infestation, is currently lacking. Here we use highly replicated lines of T. castaneum previously artificially selected for divergent small-scale dispersal propensity, to robustly test several important life history components: reproductive strategy, development time and longevity. As predicted, we find that a suite of important change as result of our selection on dispersal; high dispersal propensity is associated with a lower number of longer mating attempts by males, lower investment in early-life reproduction by females, slower development of later-laid offspring and longer female lifespan. These findings indicate that correlated intraspecific variation in dispersal and related traits may represent alternative life history strategies in T. castaneum. We therefore suggest that pest management efforts to mitigate the species' agro-economic impact should consider the eco-evolutionary dynamics within multiple life-histories. The benefits of doing so could be felt both through improved targetting of efforts to reduce spread, and also in forecasting of how the selection pressures applied through pest management are likely to affect pest evolution.

Features of bacterial and fungal communities in the rhizosphere of Gastrodia elata cultivated in greenhouse for early harvest.

Symbiotic microbes are essential for developing and growing Gastrodia elata, an achlorophyllous orchid of high medicinal value. Recently, the cultivation of G. elata in greenhouses has been adopted in Korea to produce mature tubers in a short time. However, no studies have been conducted on the microbial community structure of G. elata cultivated in greenhouse environments. Therefore, we analyzed the temporal features of bacterial and fungal communities in the rhizosphere of G. elata at the juvenile [JT; 2 months after sowing (MAS)], young (YT; 6 MAS), and mature (MT; 11 MAS) tuber stages using culture-dependent and high-throughput sequencing technology. The richness and diversity of the bacterial and fungal communities decreased with tuber growth of G. elata. The symbiotic fungi Mycena sp. and Armillaria sp. as well as tuber extract inhibited the growth of various soil-inhabiting fungal and bacterial strains, indicating that G. elata and its symbiotic fungi play important roles in the selection of rhizosphere microbes. Mortierella rishikesha was the most abundant fungal species in the rhizosphere. We also identified the microorganisms potentially beneficial for G. elata development during greenhouse cultivation. Tubers and symbiotic fungi actively exert selective pressure on rhizosphere microbes, influencing the diversity and abundance of bacterial and fungal communities as G. elata grows. This study is a first report on the temporal microbial community structure of G. elata cultivated in greenhouse. The results on the associated microbiome of G. elata will help understand their beneficial interactions with G. elata and contribute to improvement in cultivation.

Multiple herbicide-resistant kochia (Bassia scoparia) control in glufosinate-resistant canola

Multiple herbicide-resistant kochia [Bassia scoparia (L.) A.J. Scott] has grown in prevalence in the canola (Brassica napus L.) production region of North America. Glufosinate-resistant canola facilitates kochia management since glufosinate-resistant kochia is not known to occur. Field experiments were conducted from 2013 to 2015 in five environments near Lethbridge and Coalhurst, Alberta, to identify herbicide strategies targeting acetolactate synthase inhibitor-resistant kochia with and without glyphosate resistance in glufosinate-resistant canola. Sequential glufosinate treatments (500 g ai ha-1) postemergence caused excellent (≥90%) kochia control and biomass reduction across environments. Preplant (PP) carfentrazone + sulfentrazone (9 + 105 g ai ha-1) alone or followed by (fb) postemergence glufosinate (9 + 27 fb 500 or 9 + 105 fb 500 g ai ha-1) resulted in excellent kochia control in all environments tested. PP carfentrazone + sulfentrazone (9 + 53 g ai ha-1) alone, and a single postemergence treatment with glufosinate (500 or 590 g ai ha-1) alone or preceded by fall-applied ethalfluralin (1100 fb 500 g ai ha-1) with or without preplant carfentrazone (1100 fb 9 fb 500 g ai ha-1) caused ≥80% kochia control and biomass reduction in all environments tested. However, treatments containing preplant carfentrazone + sulfentrazone caused unacceptable canola injury or yield loss in at least one environment. In conclusion, single or sequential treatments of glufosinate postemergence managed multiple herbicide-resistant kochia effectively in canola. Layering fall-applied/preplant ethalfluralin and/or preplant carfentrazone with glufosinate postemergence may help alleviate resistance selection pressure placed on glufosinate in canola.