Hybrid Species Research Articles

Unidirectional hybridization between American paddlefish Polyodon spathula (Walbaum, 1792) and sterlet Acipenser ruthenus (Linnaeus, 1758).

Interspecific hybridizations among sturgeon species are feasible and often bidirectional. The American paddlefish (Polyodon spathula) from Family Polyodontidae and sturgeon species from Family Acipenseridae were reported capable of hybridization, but viable hybrids have been described only in crosses with the American paddlefish as paternal parents. In the reciprocal cross, the hybrids were not viable however embryos start to develop and reach late gastrula and early neurula stages. The goal of this study was to examine the hybridization between the sterlet sturgeon (Acipenser ruthenus) and the American paddlefish. Hybrid and purebred crosses were produced by artificial fertilization. Viable hybrid offspring were harvested (three month old) and verified in the families produced by female sterlet crossing with male American paddlefish. In the reciprocal hybrid crosses with female American paddlefish and male sterlet, the embryos development did not pass over 120 h post fertilization, indicating the unidirectional hybridization between American paddlefish and sterlet. Chromosome counting showed for the same ploidy level of viable hybrid and parent species. Analysis of three microsatellite markers confirmed the unidirectional hybridization between the American paddlefish and the sterlet species. Overall, the inferred genetic cause suggests that unidirectional hybridization between American paddlefish and sterlet may be the case not only for these two species but likely also between American paddlefish and other sturgeon species.

Assessing the global distribution and conservation status of the Taxus genus: An overview

Taxus, commonly known as Yew, is a non-resinous evergreen tree renowned for its anti-cancer properties, attributed to the plant alkaloid Paclitaxel. This study draws upon secondary data sourced from reputable books, journals, and authenticated websites pertaining to the taxonomy of this significant flora. Taxus thrives in moist, humid, shady environments with slightly acidic soil, often flourishing beneath the canopies of species such as Abies, Fagus, Picea, and Quercus spp. The primary objective of this investigation was to evaluate the global status of the Taxus genus. Its distribution spans the northern hemisphere, with various regional common names associated with Taxus species. Through a comprehensive review, our findings reveal a total of 12 natural species and 2 hybrid species globally, including T. media Rehder and T. hunnewelliana Rehder. Notably, four Taxus species—T. chinensis Rehd., T. contorta Griff., T. globosa Schlect., and T. wallichiana Zucc—are endangered, while T. brevifolia Nuttall is categorized as near threatened according to the IUCN Red List. The updated Taxus genus database presented in this study serves as a valuable resource for diverse stakeholders, encompassing researchers, academicians, forest managers, herbal industry professionals, and policymakers. This information will help in formulating effective conservation strategies and sustainable utilization plans for this important genus.

Microbial contamination profile on esthetic elastomeric ligatures through the checkerboard DNA-DNA hybridization technique : Arandomized split-mouth study.

The aim of this study is to assess the microbial contamination of three different brands of esthetic elastomeric ligatures. Different brands of esthetic ligatures (Unistick Pearl [American Orthodontics, Sheboygan, WI, USA], Power Sticks Pearl [Ortho Technology, Tampa, FL, USA], and Ease [Obscure, 3M Unitek, Monrovia, CA, USA]) were randomly assigned to permanent canines of 25patients (aged 11-18years) undergoing corrective orthodontic treatment. After 30days, the ligatures were removed, processed, and the biofilm composition was analyzed by checkerboard DNA-DNA hybridization for 40bacterial species. The microbiological data were analyzed using anonparametric mixed model. The ligatures presented intense microbial contamination after 30days, but no statistically significant differences were observed among the three groups (p > 0.05). The levels of the evaluated individual species and proportions of the microbial complexes showed no statistically significant differences among the ligature groups (p > 0.05). Esthetic elastomeric ligatures became multicolonized by several bacterial species after 30days of exposure to the oral cavity. However, no relevant differences were observed among the biofilm composition formed on the different ligature brands.

Ancient tree genomes for old questions.

Most foundational work on the evolution and migration of plant species relies on genomic data from contemporary samples. Ancient plant samples can give us access to allele sequences and distributions on the landscape dating back to the mid Holocene or earlier (Gugerli etal.,2005). Nuclear DNA from ancient wood, however, has been mostly inaccessible until now. In a From the Cover article in this issue of Molecular Ecology, Wagner etal. (2023) present the first resequenced nuclear genomes from ancient oak wood, including two samples dated to the 15th century and one that dates to more than 3500 years ago. These ancient tree genomes open the possibility for investigating species adaptation, migration, divergence, and hybridisation in the deep past. They pave the way for what we hope will be a new era in the use of paleogenomics to study Holocene tree histories.

Synthesis, antioxidant and structural properties of modified ebselen derivatives and conjugates.

Ebselen is a drug in clinical trials for several diseases and degenerative conditions where oxidative stress is implicated. A series of novel ebselen analogues was synthesized, including hydroxy-, alkoxy- and aminomethylene derivatives, as well as hybrid species where the ebselen selenium atom is shared with other potent antioxidant structures, such as cyclic selenenyl sulfide, cyclic seleninate ester and spirodioxyselenurane moieties. Conjugates of ebselen with cholesterol, prednisolone and the radical inhibitor BHT were also prepared. The products were tested for antioxidant activity in an NMR-based assay by measuring the rate of consumption of benzyl thiol or the production of dibenzyl disulfide in the presence of hydrogen peroxide when catalyzed by the ebselen analogues. Activities ranged from 12 to 0.12 times that of ebselen. The oxidation of the 2-hydroxymethylene derivative of ebselen was faster than thiolysis in the initial step and the overall rate was further accelerated under basic conditions. The corresponding selenenyl sulfide analogue underwent very slow disproportionation under neutral conditions that was enhanced by the presence of a base catalyst. During investigation of possible fluxional behaviour of a bis-amide analogue, an unusual tetraphenyphosphonium salt of a tricoordinate selenium pincer anion was discovered with exceptionally potent catalytic activity, 130 times that of ebselen. In addition to rate measurements, X-ray crystallography and DFT computational methods were also employed to gain further structural and mechanistic insights.

From microcosm to macrocosm: adaptive radiation of Darwin’s finches

Abstract In this Perspective we show the value of studying living organisms in the field to understand their history. Darwin’s finches are an iconic example of the early stages of speciation in a young adaptive radiation that produced 18 species in little more than a million years. The question they pose is how and why so many species originated and diversified rapidly. A long-term study of four species of finches on the small island of Daphne Major, combined with genomic investigations, provide some answers in terms of extrinsic and intrinsic factors. Beak size and shape, as well as body size, are key heritable features involved in both ecological and reproductive isolation, and their evolution by natural selection was caused by competitor species during prolonged droughts. Introgressive hybridization of related species is rare but recurring, apparently widespread, increases genetic variation, and does not incur a fitness cost. Hybridization can produce a new species. We use a phylogeny based on whole genome sequences of the four finches to infer morphological transitions in their radiation. Several lines of evidence indicate that some species are missing from the early phase of the radiation due to extinction. Combining these results, we re-cast the classical allopatry-then-sympatry theory of adaptive radiation as a competition-selection-hybridization process that generates a diversity of species.

Mapping of schistosome hybrids of the haematobium group in West and Central Africa.

Hybridization of parasitic species is an emerging health problem in the evolutionary profile of infectious disease, particularly within trematodes of the genus Schistosoma. Because the consequences of this hybridization are still relatively unknown, further studies are needed to clarify the epidemiology of the disease and the biology of hybrid schistosomes. In this article, we provide a detailed review of published results on schistosome hybrids of the haematobium group. Using a mapping approach, this review describes studies that have investigated hybridization in human (S. haematobium, S. guineensis, and S. intercalatum) and animal (S. bovis and S. curassoni) schistosome species in West Africa (Niger, Mali, Senegal, Côte d'Ivoire, Benin, Nigeria) and in Central Africa (Cameroon, Gabon, Democratic Republic of Congo), as well as their limitations linked to the underestimation of their distribution in Africa. This review provides information on studies that have highlighted hybrid species of the haematobium group and the regions where they have been found, notably in West and Central Africa.

USE OF THE rpl32-trnL REGION OF THE CHLOROPLAST GENOME IN THE MOLECULAR TAXONOMY OF HERACLEUM SPECIES

In recent decades, the invasion of alien plant species has acquired the status of one of the greatest threats to biodiversity. Invasive plants can not only displace native species but also transform ecosystems, which leads to more global negative consequences. An additional danger is the hybridization of invasive species with closely related native plants, which can contribute to the emergence of more aggressive invasive forms. The territory of Ukraine is also actively colonized by alien plants, among which the group of giant borschts (Heracleum, Apiaceae) attracts special attention. In addition to the impact on ecosystems, these plants are dangerous for people, because they can cause photochemical burns when in contact with the skin. For one of the species of this group, namely H. mantegazzianum Sommier & Levier, the possibility of hybridization with the aboriginal European species H. sphondylium L. However, both parental species and potential hybrid forms from the territory of Ukraine remain unexplored using molecular genetic methods. In this work, for the first time, we amplified and sequenced the spacer region of the chloroplast genome between the rpl32 and trnL genes for samples of H. mantegazzianum and H. sphondylium. The obtained sequences were compared with each other and with rpl32-trnL sequences available in the GenBank database for other species of the genus Heracleum. Phylogenetic analysis showed that the use of the rpl32-trnL region allows dividing all species of the genus into two main groups, one of which includes H. mantegazzianum and H. sphondylium Thus, the rpl32-trnL site can be successfully used for molecular identification of Ukrainian representatives of the genus Heracleum, as well as for determining the direction of hybridization for potential hybrid forms between the invasive species H. mantegazzianum and the native representative of the Ukrainian flora H. sphondylium. Key words: bioinformatic analysis, genetic polymorphism, molecular markers, molecular genomics, rpl32-trnL intergenic spacer, interspecific hybridization, Heracleum, Apiaceae.

Limited gene flow in adjacent valleys and genetic introgression in a mountain hybrid zone between <i>Aconitum</i> (Ranunculaceae) species

The number of polyploid plants in angiosperms is estimated at about 30-80%, depending on the study, but hybridization between diploids and tetraploids is not a common phenomenon. In this study, our aim was to determine the extent of hybridization and introgression between <i>Aconitum</i> species in a mountainous hybrid zone in the Tatra Mountains (Western Carpathians). We hypothesized that topography would affect their populations’ genetic structure. For this purpose, inter simple sequence repeat (ISSR) molecular markers and chloroplast DNA (cpDNA, region <i>trn</i>L(UAG)–<i>ndh</i>F) sequencing were used. The results revealed that diploid and tetraploid <i>Aconitum</i> species had specific cpDNA haplotypes, while the spontaneous hybrid species harbored a cpDNA haplotype typical for tetraploids. Bayesian STRUCTURE analysis showed that introgression occurred between diploid and tetraploid species above the tree line, where a spontaneous hybrid, a putative triploid <i>A. ×berdaui</i>, originated, probably via the triploid bridge mechanism. Molecular analysis of variance, principal coordinate analysis, and neighbor-net clustering revealed different genetic profiles of the diploids between neighboring mountain valleys. Hence, mountain topography, ridges, and valleys can form an effective geographical barrier, preventing gene flow over longer distances. Introgression happens near or above the tree line, where the hybridization zone is formed. In the introgressants, however, no morphological alterations were discernible.

Hybridization and invasive species in a threatened freshwater fish community under environmental pressures: Morphometric and molecular evidence

Abstract Mediterranean freshwater systems are under threat owing to increased drought driven by climate change, intensive human land uses and non‐native species. This is causing increased fish hybridization in isolated watercourses. The genetic and morphological characteristics of hybrids of sympatric native and non‐native fish species were studied in four streams of the Mediterranean Guadalquivir basin (south‐west Spain). Fish morphology was analysed using geometric morphometrics, and molecular determination of parenthood was inferred through one mitochondrial gene (cytb) and one nuclear gene (Beta‐actin) for all hybrids and a subset of pure parental specimens. Molecular analyses confirmed hybrids between the native Squalius alburnoides and non‐native Alburnus alburnus in a stream with continuous flow. Haplotype analyses suggested that they originated from backcrossing of hybrid offspring. Intergeneric crosses between native species S. alburnoides and Pseudochondrostoma willkommii, and S. alburnoides and Iberochondrostoma lemmingii were detected in streams under reduced connectivity scenarios. Morphometrics revealed that hybrid phenotypes were similar to S. alburnoides. In some cases, molecular markers uncovered hybridization events that were neither detected in the field nor by morphometric analyses, potentially supporting a backcrossing/introgression scenario. Hybridization is likely to be increasing in Mediterranean rivers where S. alburnoides are present owing to increased fragmentation caused by summer drought exacerbated by climate change and human land uses and pressures. This can become a problem for these endemic vulnerable species if genetic diversity is lost, morphological homogenization occurs and hybrids cannot be easily detected in the field. The potential risks could be addressed by monitoring and eradication of non‐native species and segregation from natives. To avoid native–native crosses, habitat quality and desiccation risk could be tackled by improved water quality and riparian reforestation to provide shade and reduce evapotranspiration. This would need increased coordination and intervention between the institutions that share conservation responsibilities in the area.

Nicop Anchored Porous Ti3C2tx Support with 3D Interconnected Structure for Advanced Hydrogen Evolution Reaction Electrocatalysts

MXene have gained much attention as promising electrocatalysts for noble metal-free hydrogen evolutrion reaction (HER) electrocatalysts owing to their high electrical conductivity, hydrophilic surfaces, abundant functional groups, and rational design for hybridization with other materials. In this study, a novel porous monolayered-Ti3C2TX@NiCoP (P-Ti3C2Tx@NiCoP) nanostructure was developed with 3D interconnected structure to significantly improve charge transfer capability and electrocatalytic activity. A strategic approach of modifying pristine Ti3C2Tx monolayers and combining them with other active cocatalysts. Specifically, the H2O2-utilized oxidation and HF etching process formed a highly microporous structure with a maximized surface area of monolayered MXenes as the support. A subsequent solvothermal process followed by phosphidation enabled successful anchoring of highly HER-active NiCoP nanoclusters onto abundantly exposed terminal edges of the P-Ti3C2Tx support. The structural porosity of the P-Ti3C2Tx nanoflakes played an important role in creating additional room for embedding catalytically active species while stably imparting high electrical conductivity to accelerate charge transfer to NiCoP nanoclusters. Moreover, inspired by the pH dependent change of structural arrangement of the Ti3C2Tx, we successfully induced 3D-interconnetecd structure by modulating surface electrostatic forces among Ti3C2Tx monolayers. Of note, the 3D-interconnected structure would shift charge transfer behavior from intermolecular to intramolecular aspects and this would contribute to enhanced charge transfer kinetics. With structural modification of support material and effective hybridization of active species, P-Ti3C2Tx@NiCoP showed highly enhanced HER activity with significantly lower overpoential of 115 and 101 mV at a current density of -10 mA cm-2 in 0.5 M H2SO4 and 1.0 M KOH, respectively, along with showing long-term stability over 60 h. As such, our approach of designing structurally modified-Ti3C2Tx and hybridization with other electrocatalytically active species would function as a solid platform for implementing Ti3C2Tx-based hetero-nanostructures to achieve state-of-the-art performance in next-generation energy conversion applications.

Cytological analysis of the diploid-like inheritance of newly synthesized allotetraploid wheat.

Polyploidization is a process which is related to species hybridization and whole genome duplication. It is widespread among angiosperm evolution and is essential for speciation and diversification. Allopolyploidization is mainly derived from interspecific hybridization and is believed to pose chromosome imbalances and genome instability caused by meiotic irregularity. However, the self-compatible allopolyploid in wild nature is cytogenetically and genetically stable. Whether this stabilization form was achieved in initial generation or a consequence of long term of evolution was largely unknown. Here, we synthesized a series of nascent allotetraploid wheat derived from three diploid genomes of A, S*, and D. The chromosome numbers of the majority of the progeny derived from these newly formed allotetraploid wheat plants were found to be relatively consistent, with each genome containing 14 chromosomes. In meiosis, bivalent was the majority of the chromosome configuration in metaphase I which supports the stable chromosome number inheritance in the nascent allotetraploid. These findings suggest that diploidization occurred in the newly formed synthetic allotetraploid wheat. However, we still detected aneuploids in a proportion of newly formed allotetraploid wheat, and meiosis of these materials present more irregular chromosome behavior than the euploid. We found that centromere pairing and centromere clustering in meiosis was affected in the aneuploids, which suggest that aneuploidy may trigger the irregular interactions of centromere in early meiosis which may take participate in promoting meiosis stabilization in newly formed allotetraploid wheat.

Western Palearctic Water Frogs’ (<i>Pelophylax esculentus</i> complex) Body Condition in Mixed Population Systems in Serbia Follow Levels of Habitat Suitability

Body condition is an important indicator in many ecological studies since it is expected that individuals and populations perform better in habitats more suitable for species. A wide range of metrics have been proposed as condition indices. In this study, we estimated the phenotypic condition of water frog species using the residual condition index. The study was carried out in three localities adjacent to nature preserves in South Banat, Serbia and with different levels of preserved natural features and anthropogenic pressure. Selected localities are typical habitats of water frogs with two parental and their hemiclonal hybrid species present. The localities were scored for suitability of the aquatic and terrestrial habitats. Statistical significance of residual condition index patterns from a multiway ANOVA was obtained for locality but not for species and sex. The lowest condition index was observed in frogs sampled from a locality maintained by human activity and with the lowest habitat suitability. Furthermore, the highest body condition index was obtained on the locality with the highest habitat suitability. One of the parental species, P. ridibundus had the highest overall body condition index while the hybrid species (P. esculentus) had the lowest. None of the three species from the complex had the highest body condition in all three localities, nor the worst.

Replacement of Carbon Black with Coppiced Biochar in Guayule Rubber Composites Improves Tensile Properties

Natural rubber, sourced from Hevea brasiliensis trees mainly in southeast Asia, is a critically important resource for transportation, national security, and medical products, among other uses. The guayule shrub is a domestic alternative source of natural rubber that is emerging with advantages over Hevea since it is well-suited for many medical and consumer applications. Biochar is a sustainable form of carbon made from biomass that is a potential replacement for petroleum-sourced carbon black, the most common filler for rubber composites. The coppiced-wood species hybrid poplar (Populus × canadensis) and Paulownia elongata are both rapidly growing hardwoods that have shown promise as feedstocks for biochar that can be used as fillers in common rubber composites such as Hevea natural rubber, styrene-butadiene, and polybutadiene. In this work, poplar and paulownia biochars were used to partially replace carbon black as filler in guayule rubber composites. Guayule composites with up to 60% of the carbon black replaced with poplar or paulownia biochar had higher tensile strength, elongation, and toughness compared to the 100% carbon black-filled control. These composites would be excellent candidates for rubber applications such as gloves, belts, hoses, and seals, while reducing dependence on fossil fuels and Hevea natural rubber.

PHENOLOGY AND INHERITANCE OF MORPHOLOGICAL HARACTERS IN INTERSPECIFIC HYBRID PLANTS OF COTTON AND THIN-FIBER COTTON VARIETIES (IN CLIMATE CONDITIONS OF SIRDARYA REGION)

Cotton Gossypium L. in the soil and climatic conditions of the Syr Darya is a cultural tetraploid from the family of G.Barbados L. The phenology of flowering in varieties belonging to the genus has been studied. According to it, of the selected research objects, the varieties Surkhan-18, Termez-202 and Surkhan-103 have a high possibility of continuing genetic and breeding processes in the conditions of the Syrdarya region and using these varieties to create hybrid organisms.It is important to study the morphological characteristics of the hybrids obtained on the basis of cross-breeding of different types of cotton, and to scientifically substantiate aspects such as the order in which the laws are passed. Because each variety has its own morpho-biological characteristics, and in most cases, morpho-biological characteristics (type of branching, leaf shape, shape and color of pods, the presence of anthocyanin spots on the petals, color of pollen, etc.) are taken into account when evaluating the variety. Also, on the basis of phenotypic analysis of the hybrids obtained by hybridization of varieties and species that are sharply different from each other in terms of morphological characteristics, it is possible to make a clear conclusion about the manifestation of morphological characteristics of one or another variety in hybrid plants. In order to successfully carry out breeding and create new hybrid plants that incorporate the best characteristics of the initial varieties, it is necessary to know the laws of passing morphological characteristics from one generation to the next, along with the valuable economic characteristics of cotton.

A simple method for Eucalyptus species discrimination: FTIR spectroscopy and machine learning

Wood sample classification is crucial in forestry, woodworking, and conservation efforts. It involves categorizing wood species based on physical characteristics like grain patterns, color, texture, and density. However, there are scientific gaps that hinder its effectiveness. One challenge is the difficulty in differentiating wood species with similar characteristics. To address this, we propose using FTIR spectroscopy and machine learning algorithms. In our study, we focused on the accurate classification of Corymbia citriodora (CIT), Eucalyptus grandis (GRA), and the hybrid species GG100 (GG). We evaluated bark and sapwood samples to determine the best for such a purpose. Using FTIR spectroscopy and Quadratic Discriminant Analysis with only seven PCs, we achieved 100% accuracy in bark sample classification. This approach offers advantages because FTIR spectroscopy captures unique chemical fingerprints, providing rapid and non-destructive analysis of wood samples. Machine learning algorithms learn from these spectral patterns for accurate species prediction. Notably, bark samples, easily obtained without tree damage, showed excellent classification results. By incorporating FTIR spectroscopy and machine learning, we can overcome the challenges of inter-species similarities and intra-species variations. This improves reliability and accuracy, supporting and ensuring high-quality wood products. Integrating FTIR spectroscopy and machine learning presents a promising solution for enhancing wood sample classification. Further research can expand species classification and improve wood identification processes.

Distinguish Dianthus species or varieties based on chloroplast genomes.

Most plants belonging to the widely distributed genus Dianthus are used for gardening. Interspecific hybridization of different Dianthus species leads to blurred genetic backgrounds. To obtain more genomic resources and understand the phylogenetic relationships among Dianthus species, the chloroplast genomes of 12 Dianthus species, including nine Dianthus gratianopolitanus varieties, were analyzed. The chloroplast genomes of these 12 species exhibited similar sizes (149,474-149,735 bp), with Dianthus caryophyllus having a chloroplast genome size of 149,604 bp marked by a significant contraction in inverted repeats. In the chloroplast genome of Dianthus, we identified 124-126 annotated genes, including 83-84 protein-coding genes. Notably, D. caryophyllus had 83 protein-coding genes but lacked rpl2. The repeat sequences of the chloroplast genome were consistent among species, and variations in the sequence were limited and not prominent. However, notable gene replacements were observed in the boundary region. Phylogenetic analysis of Dianthus indicated that D. caryophyllus and D. gratianopolitanus were most closely related, suggesting that the degree of variation within nine Dianthus varieties was no less than the variation observed between species. These differences provide a theoretical foundation for a more comprehensive understanding of the diversity within Dianthus species.

Hybrids of monocots in the flora of Ukraine: Preliminary synopsis

Monocots include ca. 74 000–85 000 species. It is one of the most species rich, ecologically and economically important groups of plants. At the same time, monocots are a key component of ecosystems and have utilitarian significance. In agriculture the majority of the biomass produced comes from monocots. Many plants from this group are used as ornamentals or medicinal plants. This work is devoted to the study of the nomenclature of monocot hybrids in the flora of Ukraine. In general, there are many unsolved problems in the nomenclature of hybrids. Numerous names require clarification. The aim of this study is to compile a list of intergeneric and interspecific hybrids of monocots in the flora of Ukraine. This list includes wild hybrids, as well as cultivated ones that grow spontaneously in the wild. The list of hybrids is compiled mainly on the basis of literary sources. The names of taxa and nothotaxa are indicated according to IPNI. Formulas of the hybrids, basionyms and synonyms are given for the hybrids. The list of monocots' hybrids in the flora of Ukraine offered here includes 87 hybrids. There are many hybrids in the following families: Cyperaceae (20), Orchidaceae (25), Poaceae (22) and Potamogetonaceae (8). In other families there are not many hybrids: Amaryllidaceae (1), Araceae (2), Asparagaceae (1), Commelinaceae (1), Iridaceae (1), Juncaceae (4), Liliaceae (1), Typhaceae (1). There were a number of difficulties during the preparation of this article: 1) there is not enough information, the hybridization of plant species is poorly studied in Ukraine, 2) it is difficult to draw a clear line between hybrids and species of hybridogenic origin, 3) disputed status of parental taxa (i.e. different researchers consider parental taxa in different ranks). Therefore, this list should be considered preliminary.

Long-Term Effect of Wood Ash and Wastewater Sludge Fertilization on Tree Growth in Short-Rotation Forest Plantations on Abandoned Agricultural Land: A Case Study

Short-rotation forest plantations on former agricultural land capture CO2, provide bioeconomic materials, and mitigate climate change. This study aimed to enhance our understanding of the long-term effects of wood ash and wastewater sludge fertilization on various tree species (birch, hybrid aspen, grey alder, black alder, and hybrid alder) in short-rotation forestry plantations on abandoned agricultural land where tree growth measurements were taken over an 11-year period. After 11 years, the highest aboveground biomass (AGB) was observed for hybrid aspen clone No. 4 under wastewater sludge treatment (109.0 t ha−1), birch under wood ash treatment (34.3 t ha−1), black alder under wastewater sludge treatment (33.6 t ha−1), grey alder under wastewater sludge treatment (40.9 t ha−1), hybrid alder under control conditions (36.2 t ha−1), and hybrid aspen clone No. 28 under wood ash treatment (37.2 t ha−1). The average survival rate was 73% in control plots, 81% under wastewater sludge treatment, and 78% under wood ash treatment. Short-term positive impacts on tree growth were observed, effects that were not consistent over the long term. The impact of these treatments on tree growth varied between species, and the effects tended to diminish over time, which must be considered before fertilization.

Evaluating hybrid speciation and swamping in wild carnivores with a decision-tree approach.

Hybridization is an important evolutionary force with a principal role in the origin of new species, known as hybrid speciation. However, ongoing hybridization can create hybrid swamping, in which parental genomes are completely lost. This can become a biodiversity threat if it involves species that have adapted to certain environmental conditions and occur nowhere else. Because conservation scientists commonly have a negative attitude toward hybrids, it is important to improve understanding of the influence of interspecific gene flow on the persistence of species. We reviewed the literature on species hybridization to build a list of all known cases in the order Carnivora. To examine the relative impact, we also noted level of introgression, whether fertile offspring were produced, and whether there was mention of negative or positive evolutionary effects (hybrid speciation and swamping). To evaluate the conservation implications of hybrids, we developed a decision-making tree with which to determine which actions should be taken to manage hybrid species. We found 53 hybrids involving 68 unique taxa, which is roughly 23% of all carnivore species. They mainly involved monophyletic (83%) and sympatric species (75%). For 2 species, the outcome of the assessment was to eliminate or restrict the hybrids: Ethiopian wolf (Canis simensis) and Scottish wildcat (Felis silvestris silvestris). Both species hybridize with their domestic conspecifics. For all other cases, we suggest hybrids be protected in the same manner as native species. We found no evidence of genomic extinction in Carnivora. To the contrary, some species appear to be of hybrid origin, such as the Asiatic black bear (Ursus thibetanus) and African golden wolf (Canis lupaster). Other positive outcomes of hybridization are novel genetic diversity, adaptation to extreme environments, and increased reproductive fitness. These outcomes are particularly valuable for counterbalancing genetic drift and enabling adaptive introgression in a human-dominated world.