Lifting the veil on the correction of double counting incidents in hybrid life cycle assessment

Life cycle assessment (LCA) and environmentally extended input–output analyses (EEIOA) are two techniques commonly used to assess environmental impacts of an activity/product. Their strengths and weaknesses are complementary, and they are thus regularly combined to obtain hybrid LCAs. A number of approaches in hybrid LCA exist, which leads to different results. One of the differences is the method used to ensure that mixed LCA and EEIOA data do not overlap, which is referred to as correction for double counting. This aspect of hybrid LCA is often ignored in reports of hybrid assessments and no comprehensive study has been carried out on it. This article strives to list, compare, and analyze the different existing methods for the correction of double counting. We first harmonize the definitions of the existing correction methods and express them in a common notation, before introducing a streamlined variant. We then compare their respective assumptions and limitations. We discuss the loss of specific information regarding the studied activity/product and the loss of coherent financial representation caused by some of the correction methods. This analysis clarifies which techniques are most applicable to different tasks, from hybridizing individual LCA processes to integrating complete databases. We finally conclude by giving recommendations for future hybrid analyses.     

The hybrid bacterial foraging algorithm based on many-objective optimizer

A new multi-objective optimized bacterial foraging algorithm - Hybrid Multi-Objective Optimized Bacterial Foraging Algorithm (HMOBFA) is presented in this article. The proposed algorithm combines the crossover-archives strategy and the life-cycle optimization strategy, look for the best method through research area. The crossover-archive strategy with an external archive and internal archive is assigned to different selection principles to focus on diversity and convergence separately. Additionally, according to the local landscape to satisfy population diversity and variability as well as avoiding redundant local searches, individuals can switch their states periodically throughout the colony lifecycle with the life-cycle optimization strategy. all of which may perform significantly well. The performance of the algorithm was examined with several standard criterion functions and compared with other classical multi-objective majorization methods. The examiner results show that the HMOBFA algorithm can achieve a significant enhancement in performance compare with other method and handles many-objective issues with solid complexity, convergence as well as diversity. The HMOBFA algorithm has been proven to be an excellent alternative to past methods for solving the improvement of many-objective problems.     

A biotechnology‐based male‐sterility system for hybrid seed production in tomato

Incorporating male sterility into hybrid seed production reduces its cost and ensures high varietal purity. Despite these advantages, male‐sterile lines have not been widely used to produce tomato (Solanum lycopersicum) hybrid seeds. We describe the development of a biotechnology‐based breeding platform that utilized genic male sterility to produce hybrid seeds. In this platform, we generated a novel male‐sterile tomato line by clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR‐associated protein 9 (Cas9)‐mediated mutagenesis of a stamen‐specific gene SlSTR1 and devised a transgenic maintainer by transforming male‐sterile plants with a fertility‐restoration gene linked to a seedling‐colour gene. Offspring of crosses between a hemizygous maintainer and the homozygous male‐sterile plant segregated into 50% non‐transgenic male‐sterile plants and 50% male‐fertile maintainer plants, which could be easily distinguished by seedling colour. This system has great practical potential for hybrid seed breeding and production as it overcomes the problems intrinsic to other male‐sterility systems and can be easily adapted for a range of tomato cultivars and diverse vegetable crops.     

Strong divergent selection at multiple loci in two closely related species of ragworts adapted to high and low elevations on Mount Etna

Recently diverged species present particularly informative systems for studying speciation and maintenance of genetic divergence in the face of gene flow. We investigated speciation in two closely related Senecio species, S. aethnensis and S. chrysanthemifolius, which grow at high and low elevations, respectively, on Mount Etna, Sicily and form a hybrid zone at intermediate elevations. We used a newly generated genome‐wide single nucleotide polymorphism (SNP) dataset from 192 individuals collected over 18 localities along an elevational gradient to reconstruct the likely history of speciation, identify highly differentiated SNPs, and estimate the strength of divergent selection. We found that speciation in this system involved heterogeneous and bidirectional gene flow along the genome, and species experienced marked population size changes in the past. Furthermore, we identified highly‐differentiated SNPs between the species, some of which are located in genes potentially involved in ecological differences between species (such as photosynthesis and UV response). We analysed the shape of these SNPs’ allele frequency clines along the elevational gradient. These clines show significantly variable coincidence and concordance, indicative of the presence of multifarious selective forces. Selection against hybrids is estimated to be very strong (0.16–0.78) and one of the highest reported in literature. The combination of strong cumulative selection across the genome and previously identified intrinsic incompatibilities probably work together to maintain the genetic and phenotypic differentiation between these species – pointing to the importance of considering both intrinsic and extrinsic factors when studying divergence and speciation.     

Comparative post-hatching ontogeny of Pseudoplatystoma reticulatum (Eigenmann & Eigenmann 1889) and Leiarius marmoratus (Gill, 1870) and their hybrid

Ontogenetic studies of the eggs and larvae of fish can provide information on the initial life history and biology of a species, are important for taxonomic and evolutionary studies, and for cultivation in captivity. The aim of this study was to analyze and describe the main morphological differences in the larval ontogeny of Pseudoplatystoma reticulatum, Leiarius marmoratus, and its hybrid (♀ P. reticulatum × ♂ L. marmoratus), as well as to identify characteristics that can identify the species and their hybrid at the larvae and juvenile stages. 205 L. marmoratus, 210 P. reticulatum, and 205 hybrid specimens were analyzed, all of which were obtained through induced reproduction. Analyses were performed from hatching to 30 days post-hatching. 19 morphometric and 5 meristic characteristics were evaluated, in addition to chromatophore shape and distribution. The specimens were classified into two life periods: Larval (stages: yolk sac, pre-flexion, flexion, and post-flexion) and Juvenile. Newly hatched larvae were transparent, poorly developed, and had a scarcity of chromatophores. During the early stages of larval development, the three groups showed similarities in appearance and proportional dimensions. However, at both the end of the post-flexion stage and at the juvenile period when individuals were approximately 2 cm long, it was possible to differentiate between hybrids and their parental species by their morphometric, meristic, and pigment characteristics. The hybrid, despite occupying an intermediate position in relationship to its parents, exhibited a shape and size more similar to P. reticulatum, its maternal parent.     

Comparative analysis of root sprouting and its vigour in temperate herbs: anatomical correlates and environmental predictors

Background and AimsRoot sprouting (RS), i.e. the ability to form adventitious buds on roots, is an important form of clonal growth in a number of species, and serves as both a survival strategy and a means of spatial expansion, particularly in plants growing in severely and recurrently disturbed habitats. Occurrence and/or success of plants in severely and recurrently disturbed habitats are determined by two components, namely the ability to produce adventitious buds on roots and the vigour of their production. As mechanisms behind different magnitudes of RS remain unclear, our study investigates: (1) whether the presence or absence of specific tissues in roots can promote or limit RS; and (2) whether there is some relationship between RS ability, RS vigour and species niche.MethodsWe studied RS ability together with RS vigour in 182 Central European herbaceous species under controlled experimental conditions. We used phylogenetic logistic regressions to model the presence of RS, RS vigour, the relationship between RS and anatomical traits and the relationship between RS and parameters of species niches.Key ResultsA quarter of herbs examined were able to produce adventitious buds on roots. They were characterized by their preference for open dry habitats, the presence of secondary root thickening and the occurrence of sclerified cortical cells in roots. Root sprouting vigour was not associated with any specific anatomical pattern, but was correlated with the environmental niches of different species, indicating that preferred disturbed and dry habitats might represent a selection pressure for more vigorous root sprouters than undisturbed and wet habitats.ConclusionsOur study shows that sprouting from roots is quite common in temperate dicotyledonous herbs. Two components of RS – ability and vigour – should be considered separately in future studies. We would also like to focus more attention on RS in herbs from other regions as well as on external forces and internal mechanisms regulating evolution and the functions of RS in both disturbed and undisturbed habitats.     

Vigour-related traits and immunity in hybrids of evolutionary divergent cyprinoid species: advantages of hybrid heterosis?

Hybrid advantage, described as the superiority of hybrids in some traits over their parents and termed the “heterosis effect,” is widely documented in the case of reciprocal crosses of parental species (i.e., hybrids representing the F1 generation). In fish, high survival, fast growth and better health status have been widely documented in F1 hybrids. Nonetheless, the effects of interspecific hybridization on vigour, physiology and immunity-related traits in fish are largely unknown, especially concerning native systems of coexisting parental and hybrid genomes in the same habitat. The present study examined the potential physiological and immune aspects of hybrid heterosis by comparing condition status (measured especially by indexes), haematological profile, glucose concentration and selected parameters of non-specific and specific immunity between the evolutionarily divergent non-congeneric cyprinoid species Abramis brama and Rutilus rutilus and their hybrids representing the F1 generation, all of them caught in nature. Clear differences were documented for vigour-related, physiological and immune parameters between the two divergent species. Hybrids generally tended to express intermediate characters of the measured traits, likely generated by the evolutionary divergence of the hybridizing species; nonetheless, for some traits, hybrids exhibited a character that was more similar to one parental species than to the other. This was interpreted as the heterozygote advantage for F1 hybrids. It is suggested that a maternally inherited genetic background may potentially influence the expression of some branches of non-specific immunity or other aspects related to the fish health status.