Range Of Species Research Articles

The Spatial Coupling of Fluid Pathways with Gas Hydrates and Shallow Gas Reservoirs: A Case Study in the Qiongdongnan Basin, South China Sea

Shallow gas reservoirs play a crucial role in the gas hydrate system. However, the factors influencing their distribution and their relationship with the gas hydrate system remain poorly understood. In this study, we utilize three-dimensional seismic data to show the fluid pathways and shallow gas reservoirs within the gas hydrate system in the Qiongdongnan Basin. From the deep to the shallow sections, four types of fluid pathways, including tectonic faults, polygonal faults, gas chimneys, and gas conduits, are accurately identified, indicating the strong spatial interconnection among them. The gas pipes are consistently found above the gas chimneys, which act as concentrated pathways for thermogenic gases from the deep sections to the shallow sections. Importantly, the distribution of the gas chimneys closely corresponds to the distribution of the Bottom Simulating Reflector (BSR) in the gas hydrate system. The distribution of the shallow gas reservoirs is significantly influenced by these fluid pathways, with four reservoirs located above tectonic faults and polygonal faults, while one reservoir is situated above a gas chimney. Furthermore, all four shallow gas reservoirs are situated below the BSR, and their distribution range exhibits minimal to no overlap with the distribution of the BSR. Our findings contribute to a better understanding of shallow gas reservoirs and the gas hydrate system, providing valuable insights for their future commercial development.

A Palearctic view of a bat fungal disease.

The fungal infection causing white-nose disease in hibernating bats in North America has resulted in dramatic population declines of affected species, since the introduction of the causative agent Pseudogymnoascus destructans. The fungus is native to the Palearctic, where it also infects several bat species, yet rarely causes severe pathology or the death of the host. Pseudogymnoascus destructans infects bats during hibernation by invading and digesting the skin tissue, resulting in the disruption of torpor patterns and consequent emaciation. Relations among pathogen, host, and environment are complex, and individuals, populations, and species respond to the fungal pathogen in different ways. For example, the Nearctic Myotis lucifugus responds to infection by mounting a robust immune response, leading to immunopathology often contributing to mortality. In contrast, the Palearctic M. myotis shows no significant immunological response to infection. This lack of a strong response, resulting from the long coevolution between the hosts and the pathogen in the pathogen's native range, likely contributes to survival in tolerant species. After more than 15years since the initial introduction of the fungus to North America, some of the affected populations are showing signs of recovery, suggesting that the fungus, hosts, or both are undergoing processes that may eventually lead to coexistence. The suggested or implemented management methods of the disease in North America have encompassed, for example, the use of probiotics and fungicides, vaccinations, and modifying the environmental conditions of the hibernation sites to limit the growth of the pathogen, intensity of infection, or the hosts' responses to it. Based on current knowledge from Eurasia, policy makers and conservation managers should refrain from disrupting the ongoing evolutionary processes and adopt a holistic approach to managing the epizootic.

Assessment of the global population size of the Mongolian gazelle Procapra gutturosa

Abstract The Mongolian gazelle Procapra gutturosa is a wild ungulate ubiquitous across the largest remaining temperate grasslands of Mongolia, Russia and China. The species is nomadic and ranges over long distances, resulting in widely fluctuating abundance in any given location. Therefore, a comprehensive and range-wide survey is required to accurately estimate its global population size, but challenges are posed by the expansive geographical distribution and the political boundaries across the species’ vast range. To obtain an estimate of the total population, we compiled data from recent range-wide surveys. During 2019–2020, we estimated the population size in Mongolia by conducting line transect distance surveys and total counts, and by deriving numerical predictions for unsurveyed areas through data analysis. The gazelle's population in Russia was surveyed in 2020 across its summer range using simultaneous counts, transect surveys and expert knowledge. The distance sampling surveys in Mongolia revealed that slightly more than half of the gazelles along the transects were detected. Our assessment of the gazelle population, although probably an underestimate, suggests there are c. 2.14 million individuals in Mongolia and c. 30,000 in Russia. These results confirm that the Mongolian gazelle is the most abundant nomadic ungulate in the open plains across its range. However, to obtain more accurate estimates across all range states and effectively monitor the gazelle's population status, it is essential to implement standardized survey protocols that correct for imperfect detection. At present, the management of the Mongolian gazelle is inadequate, as there is a lack of regular monitoring to identify any adverse population changes that could necessitate conservation interventions.

Comparing landscape characteristics to understand Malayan tapir (Tapirus indicus) conflicts: A case study in Negeri Sembilan

The IUCN Red List has listed the Malayan tapir (Tapirus indicus) as an endangered species in 2016, owing to its declining population trend. Human-caused forest degradation and encroachment on wildlife habitats drive this species to roam out of its natural range, resulting in human-tapir conflict (HTC). This study executes kernel density analysis on 78 HTC points recorded in Negeri Sembilan from 2013 to 2018 to determine the high and low HTC zones, and investigates the influence of five landscape variables on the occurrence of HTC. Values of five landscape variables in high and low HTC zones were extracted, and the significance of occurrence between these two zones was tested using an independent sample t-test. In terms of spatial distribution, Kuala Pilah and Jelebu covered high-conflict zones, while the lowest conflict zone was in Rembau. The t-test indicated that elevation (t = –3.551, p < 0.05) and slope (t = –2.012, p < 0.05) were significant between high and low conflict zones. Distance to the forest (t = 1.424, p > 0.05), distance to water (t = –0.106, p > 0.05), and distance to urban areas (t = –1.536, p > 0.05) were not significant for HTC. HTC tends to occur in low topographic areas, while tapirs outside of their natural habitat forage in close proximity to the forest and water bodies, but restrict their movement near human settlements. Hot Spot Analysis (Getis-Ord Gi*) on forest patches revealed an overlaping region between high HTC zones and low forest-patch contiguity, indicating that forest fragmentation may promote tapir conflicts. Hence, by systematically recording the conflict distribution in Negeri Sembilan, many actions could be taken into consideration to mitigate HTC in this state.

Molecular identification of the invasive subterranean termite Reticulitermes grassei (Blattodea: Rhinotermitidae) outside its known distribution: introduction routes and implications for pest management strategies.

Despite providing important ecosystem services, termites are also serious pests of wooden structures. Termites are highly adaptive organisms that cause concern as an invasive species. Predictions of the future spread of their distribution range due to factors such as climate change, urban growth, and global trade present new challenges to our capacity to protect our wood and wood-based materials and structures effectively. Reticulitermes grassei Clément, 1978 (Blattodea: Rhinotermitidae) is a subterranean termite native to the Iberian Peninsula and France, whose global distribution has widened over recent years. This article updates the distribution range of this species, confirming its identification in the Azores, Madeira, and Morocco through molecular analysis. The origin and consequences of these putative invasive populations are discussed in light of previously available data. The resulting network showed a highly structured base consisting of many haplotypes from the southern and southwestern Iberian Peninsula (Spain and Portugal), including those from Morocco (in natural landscapes) and Switzerland (in infrastructures). The more derived part of the network includes the haplotypes from southwest France, the northwest Iberian Peninsula, the United Kingdom, Azores, and Madeira, the last 3 being linked probably to human-mediated transportation events. The potential impacts of invasive subterranean termite populations expanding into new regions are concerning, especially in urban environments, and remain uncertain in natural areas. The challenges posed by these termites could be especially worrying in island ecosystems. Hence, it is crucial to implement early warning systems and monitoring programs in regions susceptible to subterranean termite invasions.

Evolution of multiple asymptotic grain face and volume distributions during grain growth- connection to the initial distribution and asymptotic stabilization of the topological event rates

There has long been a question concerning the existence of a single vs. multiple asymptotic grain size distributions in normal grain growth. The goal of this study has been to address this topic by investigating the underlying mechanisms by which grain face and volume distributions evolve from transient to asymptotic states during grain growth. This investigation employs 3D Monte Carlo simulations to quantify the topological mechanisms of this transition, i.e., grain separation, encounter and loss, and examine their mutual evolution with the distributions from a wide range of initial states towards their multiple final asymptotic states. In the initial transient growth stage, the topological event rates fluctuate markedly, seeking balance among themselves and with the face/volume distributions. In the asymptotic stage this balance is indicated by asymptotic behavior of the ratios of the rates, as well the mean face class 〈f〉, and normalized widths, CV, of the face and size distributions. It was found that a moderate range of initial distributions evolved through relatively short transient periods towards asymptotic states less spread from each other but with those same relative orders of width. Initial distributions much wider or narrower than these evolved through longer transient periods with trajectories crossing the paths of the more moderate ones, with the widest initial distributions becoming the narrowest and the initially narrowest becoming the widest. These behaviors are explained by their interactive evolution with the topological event rates.

The seeds of invasion: a comparison of endophytic seed bacteria of Acacia longifolia between its native and invasive ranges

AbstractAcacia longifolia is an aggressive invader in Mediterranean-type ecosystems severely impacting biodiversity and ecosystem functions. The species’ invasiveness has been linked to its ability to thrive in nutrient poor soils, high seed production, and quick establishment after fire. In this study, we identify and compare the bacterial endophytes of A. longifolia seeds collected from populations in the species’ native (Australia) and invasive (Portugal) ranges. For this, we characterised the morphology (length, width, and weight) of seeds from two sites in each range and isolated and cultivated bacteria from seeds. DNA fingerprinting and cluster analyses revealed slightly higher, and distinct, bacterial diversity associated with seeds collected from native range populations in comparison to those collected from invasive populations. Sequencing of the 16S rDNA gene identified 119 bacterial isolates from 15 genera, with Curtobacterium strains being common in both ranges. Several differences in bacterial genera were found among ranges and sites: Dermacoccus, Frigoribacterium, Kocuria, Pantoea and Phyllobacterium taxa were each unique to seeds from the native populations, while Brevundimonas, Microbacterium, Rhizobium and Sphingomonas taxa were only found in the invasive seeds. The genus Paraburkholderia occurred in all invasive-range seeds but was not isolated from the native-range. Bacillus and Paenibacillus co-occurred in seeds collected from all invaded sites, but the simultaneous presence of both taxa was not found in native-range seeds. We propose that the bacterial endophytes present in invasive-range seeds may be important players for the invasiveness of A. longifolia, due to their role as plant growth promoters, providing extra capabilities helping acacia expansion.

Present and future situation of West Nile virus in the Afro‐Palaearctic pathogeographic system

West Nile virus (WNV) is a globally widespread arthropod‐borne virus that poses a significant public health concern. Mosquitoes transmit the virus in an enzootic cycle among birds, which act as reservoirs. Climate plays a crucial role in these outbreaks as mosquitoes are highly influenced by climatic conditions, and bird migrations are also affected by weather patterns. Consequently, changes in climate can potentially impact the occurrence of WNV outbreaks. We used biogeographic modelling based on machine learning algorithms and fuzzy logic to analyse and evaluate separately the risk of WNV outbreaks in two different biogeographic regions, the Afrotropical and the Western Palaearctic region. By employing fuzzy logic tools, we constructed a comprehensive risk model that integrates the Afro‐Palaearctic system as a unified operational unit for WNV spread. This innovative approach recognizes the Afro‐Palaearctic region as a pathogeographic system, characterized by biannual connections facilitated by billions of migratory bird reservoirs carrying the disease. Subsequently, we forecasted the effects of different climate change scenarios on the spread of WNV in the Afro‐Palaearctic system for the years 2040 and 2070. Our findings revealed an increasing epidemic and epizootic risk south of the Sahara. However, the area where an upsurge in risk was forecasted the most lies within Europe, with the anticipation of risk expansion into regions presently situated beyond the virus' distribution range, including central and northern Europe. Gaining insight into the risk within the Afro‐Palaearctic system is crucial for establishing coordinated and international One Health surveillance efforts. This becomes particularly relevant in the face of ongoing climate change, which disrupts the ecological equilibrium among vectors, reservoirs, and human populations. We show that the application of biogeographical tools to assess risk of infectious disease, i.e. pathogeography, is a promising approach for understanding distribution patterns of zoonotic diseases and for anticipating their future spread.

Detecting Pathogenic Phytophthora Species Using Volatile Organic Compounds.

There are several highly damaging Phytophthora species pathogenic to forest trees, many of which have been spread beyond their native range by the international trade of live plants and infested materials. Such introductions can be reduced through the development of better tools capable of the early, rapid, and high-throughput detection of contaminated plants. This study utilized a volatilomics approach (solid-phase microextraction coupled to gas chromatography-mass spectrometry) to differentiate between several Phytophthora species in culture and discriminate between healthy and Phytophthora-inoculated European beech and pedunculate oak trees. We tentatively identified 14 compounds that could differentiate eight Phytophthora species from each other in vitro. All of the Phytophthora species examined, except Phytophthora cambivora, uniquely produced at least one compound not observed in the other species; however, most detected compounds were shared between multiple species. Phytophthora polonica had the most unique compounds and was the least similar of all the species examined. The inoculated seedlings had qualitatively different volatile profiles and could be distinguished from the healthy controls by the presence of isokaurene, anisole, and a mix of three unknown compounds. This study supports the notion that volatiles are suitable for screening plant material, detecting tree pathogens, and differentiating between healthy and diseased material.

Estimating species distribution from camera trap by‐catch data, using jaguarundi (Herpailurus yagouaroundi) as an example

AbstractAimPlanning conservation action requires accurate estimates of abundance and distribution of the target species. For many mammals, particularly those inhabiting tropical forests, there are insufficient data to assess their conservation status. We present a framework for predicting species distribution using jaguarundi (Herpailurus yagouaroundi), a poorly known felid for which basic information on abundance and distribution is lacking.LocationMesoamerica and South America.Time PeriodFrom 2003 to 2021.Taxa Herpailurus yagouaroundi. MethodsWe combined camera‐trap data from multiple sites and used an occupancy modelling framework accounting for imperfect detection to identify habitat associations and predict the range‐wide distribution of jaguarundis.ResultsOur model predicted that the probability of jaguarundi occupancy is positively associated with rugged terrain, herbaceous cover, and human night‐time light intensity. Jaguarundi occupancy was predicted to be higher where precipitation was less seasonal, and at intermediate levels of diurnal temperature range. Our camera data also revealed additional detections of jaguarundis beyond the current International Union for Conservation of Nature (IUCN) range distribution, including the Andean foothills of Colombia and Bolivia.Main ConclusionOccupancy was predicted to be low throughout much of Amazonian lowlands, a vast area at the centre of jaguarundi known range. Further work is required to investigate whether this area represents sub‐optimal conditions for the species. Overall, we estimate a crude global jaguarundi population of 35,000 to 230,000 individuals, covering 4,453,406 km2 of Meso‐ and South America at the 0.5 probability level of occupancy. Our current framework allows for an initially detailed, well‐informed species distribution that should be challenged and refined with improved habitat layers and additional records of jaguarundi detection. We encourage similar studies of lesser‐known mammals, pooling existing by‐catch data from the growing bank of camera‐trap surveys around the world.

Endosymbiont diversity across native and invasive brown widow spider populations

The invasive brown widow spider, Latrodectus geometricus (Araneae: Theridiidae), has spread in multiple locations around the world and, along with it, brought associated organisms such as endosymbionts. We investigated endosymbiont diversity and prevalence across putative native and invasive populations of this spider, predicting lower endosymbiont diversity across the invasive range compared to the native range. First, we characterized the microbial community in the putative native (South Africa) and invasive (Israel and the United States) ranges via high throughput 16S sequencing of 103 adult females. All specimens were dominated by reads from only 1–3 amplicon sequence variants (ASV), and most individuals were infected with an apparently uniform strain of Rhabdochlamydia. We also found Rhabdochlamydia in spider eggs, indicating that it is a maternally-inherited endosymbiont. Relatively few other ASV were detected, but included two variant Rhabdochlamydia strains and several Wolbachia, Spiroplasma and Enterobacteriaceae strains. We then diagnostically screened 118 adult female spiders from native and invasive populations specifically for Rhabdochlamydia and Wolbachia. We found Rhabdochlamydia in 86% of individuals and represented in all populations, which suggests that it is a consistent and potentially important associate of L. geometricus. Wolbachia was found at lower overall prevalence (14%) and was represented in all countries, but not all populations. In addition, we found evidence for geographic variation in endosymbiont prevalence: spiders from Israel were more likely to carry Rhabdochlamydia than those from the US and South Africa, and Wolbachia was geographically clustered in both Israel and South Africa. Characterizing endosymbiont prevalence and diversity is a first step in understanding their function inside the host and may shed light on the process of spread and population variability in cosmopolitan invasive species.

A Review on Some Ecological Aspects of Invasive Flora Based on Comparative Analysis of “Tehri” and “Pauri” Garhwal, Uttarakhand, India

The establishment of invasive plants in a particular area leads to significant ecological changes on the native species of that area, alters ecosystem services and is one of the major drivers of biodiversity loss. In recent years, invasion by alien plants in the hilly regions has posed a severe threat to the ecosystem of these areas. A review was made in this context to study the Invasive Alien Plant Species (IAPS) of “Tehri” and “Pauri” districts. Large number of invasive alien plants was identified under different genera and families from both the study areas. Based on the growth form of invasive plants, herbs contributed the maximum percentage. Asteraceae was found to be dominating over other families followed by Solanaceae. The native range indicated differences in nativity of invasive flora found in Tehri and Pauri with a large percentage of invasive plants coming from Asia (23%) and Tropical America (26%) and respectively. It was observed that invasive plants are invading higher elevation zones which parallels with the directional filtering theory. Due to higher proliferation rates outside their native range and absence of natural predators, it is quite difficult to control this increasing expansion of invasive plants which is a call for concern and needs immediate attention. Keywords: Invasive alien plant species (IAPS), Ecosystem services, Native species, Biodiversity, Directional filtering .

The Great Canadian (Electric) Road Trip: Evaluating EV Use in National Park Tourism

As part of its 2050 net zero emission commitment, Canada has a mandate to transition to electric vehicles (EVs) to decarbonize transportation. While the EV charging infrastructure is expanding in urban areas, the infrastructure for inter-city and nature-based tourism has not been assessed. This study combined four metrics of feasibility and convenience into an EV readiness index to evaluate 94 road trip itineraries associated with Canada’s iconic national parks. Index scores ranged from not possible (0) to equal to the travel experience of internal combustion vehicle (20). With the summer range, the average one-day route score was 19.2, as 82% of one-day itineraries could be completed without requiring additional charging. Multi-day routes scored lower (14.0), with 24% being highly inconvenient or impossible due to gaps between charging stations. With a reduced winter EV range, average index scores for one- and multi-day trips declined as charging needs increased (18.4 and 13.2, respectively). Across the 94 travel routes, EVs were estimated to produce only 17% of the carbon dioxide emissions of internal combustion vehicles (this was much lower in some provinces). The findings also highlight key regional differences in tourism EV readiness and where infrastructure is needed to provide equitable access to Canada’s national parks for tourists seeking to decarbonize their holiday travel.

Vortex-induced vibration of the variable cross-sectional cylinder cases in transverse direction at Re = 3900 using OpenFOAM

The one-degree-of-freedom (1-DOF) vortex-induced vibration in structures with varying cross-sectional shapes and incoming flows have been conducted using numerical simulation. The investigation centers on amplitude, frequency, spectrum, phase and fluid force coefficients. Additionally, the temporal and spatial characteristics as well as vortex dynamics mechanism are scrutinized, particularly during the cross-flow amplitude extremes. It can be indicated through studies that the cross-flow amplitudes in different incoming flows exhibit a distinctive distribution with three discernible branches. Frequency locking is found to amplify the dynamic response of the structure. Four tapered cylinder cases exhibit a delay in the location of the cross-flow amplitude extremes compared to two cylinder cases attributable to the influence of structural shear rate, which expands the upper branch. Superimposing incoming shear rate in the same direction as the structural shear rate not only enhances the cross-flow amplitude extremes but also broadens the range of forces and velocities distribution acting on the structure. Conversely, the imposition of incoming shear rate in the opposite direction to the structural shear rate leads to a contrary outcome. The incoming shear rate introduces secondary frequencies with higher energy in the spectrum characteristics of two cylinder cases, consequently promoting the amplification of the cross-flow amplitudes.

Molecular and epidemiological characterization of Staphylococcus aureus causing bovine mastitis in China

BackgroundStaphylococcus aureus is one of the most prevalent pathogens in bovine mastitis, which leads to substantial financial losses for the dairy industry. ResultsIn this study, S. aureus (n = 72) was isolated from 18 dairy farms in 15 provinces across China in 2021. The identification of these isolates at the species level was achieved by employing 16S rRNA sequencing. An isothermal amplification method for auxiliary detection of S. aureus was established, which can be employed not only for laboratory detection but also for point-of-care testing (POCT). Molecular characteristics of S. aureus mastitis in Chinese dairy cows were determined through MLST and spa typing. Finally, methicillin-resistant Staphylococcus aureus (MRSA) and MRSA resistance genes were detected using MIC and PCR amplification techniques. 72 isolates were identified as 12 sequence types (STs) and 7 clonal complexes (CC). ST1/CC1 was the dominant prevalent accounting for 33.3 % of the total, and exhibiting a wide distribution range. In terms of spa types, t114 was the dominant type, accounting for 31.9 % of the total, followed by t529 as the second major type. Four S. aureus strains were classified as MRSA according to their levels of oxacillin resistance (MIC ≥4 μg/mL). Among these four MRSA strains, one of them was found to be mecA positive. However, the presence of drug-resistance genes mecA and mecC was not detected in the remaining three MRSA strains, indicating the possible existence of new resistance genes. ConclusionsOur study investigated the prevalence of S. aureus mastitis in dairy cows in China, while also examined the molecular characteristics and MRSA strains. This information will help with the clinical monitoring, prevention, and control of S. aureus mastitis in dairy cattle.

First Observation of Electron Rolling‐Pin Distribution in Jupiter's Magnetosphere

AbstractThe electron rolling‐pin distribution, showing electron pitch angles primarily at 0°, 90°, and 180°, has been widely studied in the Earth's magnetosphere, but has never been reported in other planetary environments. Here, by utilizing the Jupiter Near‐polar Orbiter (Juno) measurements, we report for the first time the electron rolling‐pin distribution in Jupiter's magnetosphere. We reveal the energy range of such distribution and find it appears only above 19.5 keV, falling well into the suprathermal energy range. Moreover, we quantitively reproduce the formation processes of such distribution by using an analytical model. Gratifyingly, the distribution derived from the analytical model agrees well with the Juno observations, indicating such distribution is formed by the combination of global‐scale Fermi acceleration and local‐scale betatron acceleration. These results, demonstrating that the electron rolling‐pin distribution exists beyond the Earth, can improve our knowledge of electron dynamics in planetary magnetosphere.

Fatigue life estimation of nickel-based single crystal superalloy with different inclined film cooling holes: Initial damage quantification and coupling of damage-fracture mechanics models

Quantitative assessment of the initial damage state of a structure and fatigue life prediction on this basis, especially when it is sensitive to manufacturing quality, is crucial for both engineering application and material science. Traditional solutions based on fracture or damage mechanics either require precise constitutive relationships and cumbersome physical mechanism models or simply ignore the initial damage state. This study developed a novel equivalent initial flaw size (EIFS) quantitative evaluation method for film cooling holes in Nickel-based single crystal superalloy turbine blades to address the strong correlation between the initial damage in and fatigue life of the material. The temperature and stress field differences at the edges of holes with different inclination angles were simulated using a solid-liquid-gas three-phase level-set model and considered to represent the same initial damage. Next, the coupled damage–fracture mechanics model was used to achieve equivalent crack insertion, crack propagation, and fatigue life prediction based on the EIFS. The results indicate that this method can provide a highly robust EIFS distribution interval and that the crack geometry correction factor and EIFS distribution range are weakly correlated with the loading conditions (with an error within 2 %). The EIFS-based fatigue life predictions demonstrated a notable degree of accuracy, with the majority of the predicted and experimental fatigue lives falling within a three-fold dispersion band and all predictions remaining confined within a five-fold dispersion band of the actual lifetime. These results represent a substantial advancement in accuracy compared to traditional damage mechanics predictions. Therefore, this study provides a powerful approach for evaluating the fatigue life of turbine blades considering the initial damage state and can be widely applied to guide drilling process optimization and blade fatigue analysis.

Amaranthus palmeri S. Watson reproduction system: Implications for distribution and management strategies

AbstractAmaranthus palmeri S. Watson is one of the most troublesome weed species worldwide, and is considered one of the most devastating weeds in agricultural fields in the United States. Recently, A. palmeri populations have spread beyond their native range, into the Mediterranean region, and have been reported in several European countries. Resistance to 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS) and acetolactate synthase (ALS) inhibitors have been found in European populations, exacerbating the management problems with this species in the Mediterranean region. While the biology, ecology, herbicide resistance mechanisms, and agricultural significance of A. palmeri have been studied, there remains a need to discuss how A. palmeri's unique reproductive traits influence its ability to adapt to various environments, especially as an invasive species spreading into new habitats. We review how the genetic and genomic characteristics of A. palmeri interact with aspects of its reproductive biology, including its breeding system, and alter its ability to hybridize and develop herbicide resistance. Finally, we discuss the breeding system of A. palmeri in the context of weed management, and explore different approaches such as irradiated pollens, genetic manipulations, and RNA interference (RNAi).

Molecular-Phylogenetic Characterization of Xanthomonas hortorum pv. pelargonii Strains Causing Leaf Spot of Geraniums in Iran.

Bacterial blight and leaf spot of geraniums is a destructive disease of cultivated Pelargonium species around the world. During 2020-2021, surveys were conducted in seven geranium-growing provinces of Iran to monitor the status of bacterial blight and leaf spot disease. The disease was observed in six surveyed provinces varying in the extent of occurrence and severity. Twenty-two Gram-negative pale-yellow bacterial strains resembling members of Xanthomonas were isolated from symptomatic leaves and stems. Pathogenicity and host range assays showed that the bacterial strains were pathogenic on Pelargonium grandiflorum, P. graveolens, P. peltatum, and P. zonale. All strains were positive for PCR test using the primer pair XcpM1/XcpM2 which is specific for Xanthomonas hortorum pv. pelargonii. Phylogenetic analysis using the sequences of gyrB and lepA genes showed that the 22 strains clustered in a clade among the sequences of X. hortorum pv. pelargonii strains retrieved from the GenBank, while distinct from the other pathovars of X. hortorum. BOX-PCR-based fingerprinting using BOX-A1R primer revealed that the strains isolated in this study were grouped into two clusters while no distinct correlation was observed between the host/area of isolation and BOX-PCR fingerprinting. None of the strains obtained in this study nor reference strain of the pathogen did produce bacteriocin against each other. Results obtained in this study shed light on the geographic distribution, taxonomic status and host range of the bacterial blight and leaf spot pathogen of geraniums in Iran, paving the path of further research on disease management.

Nematodes in Trichomycterus nigromaculatus (Pisces: Trichomycteridae) from the Río Gaira, Sierra Nevada de Santa Marta, Colombia

Objective. To determine the prevalence of helminth infection in Trichomycterus nigromaculatus captured in environments defined from the physicochemistry of the Gaira River, in Minca, Sierra Nevada de Santa Marta, Colombia. Material and Methods. We collected 476 specimens of T. nigromaculatus covering both climatic periods of the area, which were dissected to analyze the visceral cavity. Isolated parasites were fixed in 10% formalin for subsequent clarification. The specimens were identified by observation of adult stages under a stereoscopic microscope after clarification. Results. Specimens were found exclusively from the genus Spirocamallanus (Nematoda), the species Spirocamallanus sp. parasitic prevalence ranged from 0% in August to 28.57% in April with an abundance of 1.09 worms/host. Environmental parameters such as dissolved oxygen (Mean:5.65 mg. L-1, Max:7.5 mg. L-1, Min:4.41 mg. L-1); pH (Mean:7.2, Max: 9.3, Min: 5.7) and conductivity (Mean:72.82 µs.cm-1, Max: 123.7 µs.cm-1, Min: 40 µs.cm-1) presented statistically significant differences, the environment is eutrophicated. Conclusions. Spirocamallanus sp. were described in the areas of presence of the parasitic association in T. nigromaculatus, which constitutes a new record for the Colombian Caribbean and an extension of the geographic distribution and host range of the nematode.