Historical Flow Research Articles

Genetic variation reveals complex population structuring of Tomicus piniperda L. (Coleoptera, Scolytidae) in the UK: Implications for management of this important pest

Abstract Tomicus piniperda is a common pest of pine trees responsible for significant economic damage. Although the impact of T. piniperda on forestry is likely to increase in the future due to climate change, little is known about its dispersal within the United Kingdom (UK) or between continental Europe and the UK. This study addressed these knowledge gaps using mitochondrial and microsatellite DNA markers. Mitochondrial DNA revealed high levels of genetic diversity as previously reported for this species across Europe. Nuclear DNA diversity revealed two geographically incoherent groups (Scotland, Wales, Belgium and the Netherlands vs. England and Switzerland). These genetic patterns likely reflect a combination of historical gene flow, anthropogenic introduction and restricted contemporary gene flow between the UK and Europe. Significant structure was found among UK samples suggesting T. piniperda might not disperse extensively between pine stands. This differs from widespread gene flow across continental Europe and may be due to the low percentage of land covered by forests in the UK in addition to the high fragmentation of its forest cover. Genetic variation was higher among the Scottish samples compared to those from more southern clines, suggesting the potential proximity of Scotland to a Pleistocene glacial refuge for T. piniperda.

Three hundred years of past and future changes for native fish species in the upper Danube River Basin—Historical flow alterations versus future climate change

AbstractAimRivers belong to the most threatened ecosystems on Earth. Historical anthropogenic alterations have, and future climate change will further affect rivers and the species therein. While many studies have projected climate change effects on species, little is known about the severity of these changes compared to historical alterations. Here, we used a unique 300‐year time series of hydrological and climate data to explore the vulnerability of 48 native fish species in the upper Danube River Basin to past and potential future environmental changes.LocationUpper Danube River Basins (Germany and Austria).MethodsWe applied a climate niche factor analysis and calculated species‐specific vulnerability estimates based on modelled and observed hydrological and climate data from 1800 to 2100. We compared the estimated species vulnerabilities between two historical time intervals (1800–1830 and 1900–1930) and a future time interval (2070–2100, including the two representative concentration pathways 4.5 and 8.5) to an observed reference time interval (1970–2000). In addition, we identified the main environmental drivers of species vulnerability and their change over the past 200 years and for the predicted 100 years in the future.ResultsOur results showed that (i) in the past, species vulnerability was mainly driven by changes in discharge, while (ii) future potential vulnerabilities would be due to temperature. Moreover, we found that (iii) future environmental conditions for riverine fish species driven by temperature would change at a similar magnitude as past hydrological changes, driven by anthropogenic river alterations. Future changes, projected for the RCP 4.5, would result in moderate species vulnerability, whereas for the RCP 8.5, the vulnerability for all species would substantially increase compared to the historical conditions.Main ConclusionAccounting for an extended timeline uncovers the extent of historical pressures and provides unprecedented opportunities to proactively plan conservation strategies that are necessary to address future challenges.

African bushpigs exhibit porous species boundaries and appeared in Madagascar concurrently with human arrival

Several African mammals exhibit a phylogeographic pattern where closely related taxa are split between West/Central and East/Southern Africa, but their evolutionary relationships and histories remain controversial. Bushpigs (Potamochoerus larvatus) and red river hogs (P. porcus) are recognised as separate species due to morphological distinctions, a perceived lack of interbreeding at contact, and putatively old divergence times, but historically, they were considered conspecific. Moreover, the presence of Malagasy bushpigs as the sole large terrestrial mammal shared with the African mainland raises intriguing questions about its origin and arrival in Madagascar. Analyses of 67 whole genomes revealed a genetic continuum between the two species, with putative signatures of historical gene flow, variable FST values, and a recent divergence time (<500,000 years). Thus, our study challenges key arguments for splitting Potamochoerus into two species and suggests their speciation might be incomplete. Our findings also indicate that Malagasy bushpigs diverged from southern African populations and underwent a limited bottleneck 1000-5000 years ago, concurrent with human arrival in Madagascar. These results shed light on the evolutionary history of an iconic and widespread African mammal and provide insight into the longstanding biogeographic puzzle surrounding the bushpig’s presence in Madagascar.

Artifactual Orthologs and the Need for Diligent Data Exploration in Complex Phylogenomic Datasets: A Museomic Case Study from the Andean Flora.

The Andes mountains of western South America are a globally important biodiversity hotspot, yet there is a paucity of resolved phylogenies for plant clades from this region. Filling an important gap in our understanding of the World's richest flora, we present the first phylogeny of Freziera (Pentaphylacaceae), an Andean-centered, cloud forest radiation. Our dataset was obtained via hybrid-enriched target sequence capture of Angiosperms353 universal loci for 50 of the ca. 75 spp., obtained almost entirely from herbarium specimens. We identify high phylogenomic complexity in Freziera, including the presence of data artifacts. Via by-eye observation of gene trees, detailed examination of warnings from recently improved assembly pipelines, and gene tree filtering, we identified that artifactual orthologs (i.e., the presence of only one copy of a multicopy gene due to differential assembly) were an important source of gene tree heterogeneity that had a negative impact on phylogenetic inference and support. These artifactual orthologs may be common in plant phylogenomic datasets, where multiple instances of genome duplication are common. After accounting for artifactual orthologs as source of gene tree error, we identified a significant, but nonspecific signal of introgression using Patterson's D and f4 statistics. Despite phylogenomic complexity, we were able to resolve Freziera into 9 well-supported subclades whose evolution has been shaped by multiple evolutionary processes, including incomplete lineage sorting, historical gene flow, and gene duplication. Our results highlight the complexities of plant phylogenomics, which are heightened in Andean radiations, and show the impact of filtering data processing artifacts and standard filtering approaches on phylogenetic inference.

Navigating datascapes: mapping testing practices within and across national and global contexts

ABSTRACT We draw upon Appadurai’s ‘scapes’ and Latour’s Actor Network Theory (ANT) to interrogate historical and spatial flows in relation to specific testing technologies. We reveal how testing systems, conceptualised as actor-networks, rearticulate colonial legacies of inequality which are intensified by new and emerging technologies. ANT helps trace social and relational interactions occurring in various national and global data spaces, and helps make sense of incessant transformations in education datascapes. Mapping actor-networks, and translations, help name and navigate neoliberal forces acting through colonial legacies via emerging educational datascapes. Our examination shows how educational technologies associated with standardised testing in northern and southern contexts – specifically, England, Singapore, Bangladesh and Australia – exacerbate structural inequalities. We consider how such technologies are actants and reflective of co-existing historical and temporal influences, and global cultural and spatial flows, allowing us to map the multiple ways in which educational technologies are manifested in an emerging education datascape.

Generalized Scaling and Model for Friction in Wall Turbulence.

We present a novel generalized scaling framework and predictive model for wall friction in turbulent flows. The scaling is derived from the dynamical equations, and total mean-flow kinetic energy and the velocity profile shape factor are used as surrogates for dynamical and boundary condition effects. Veracity of the present approach is assessed using data from the literature spanning unprecedented ranges of flow types, Reynolds numbers, accelerations, and history effects. Unlike previous models that solely apply to standard flows, the present framework reconciles nonstandard flows with standard flows and enables accurate estimates of wall friction in numerical simulations and experiments without resolving the viscous sublayer or using the law of the wall.

Identidades. Un acercamiento desde la semiótica de la cultura

The text examines the concept of identity from the semiotics of culture. Identity is not an immutable set of traits but is formed through constantly evolving semiotic processes. The territory and the geographical environment influence the configuration of the identity of individuals and communities. The temporal dimension is addressed through the idea of «explosion» in Lotman’s semiotic theory, which represents ruptures in the historical flow and unpredictability of history. The role of emotions that are culturally conditioned is highlighted. Cultural differences affect their expression. Individual and collective identities are interconnected. Individual consciousness is formed through external elements that we assume as our own. Finally, a «citizen identity» is advocated that transcends national and ethnic borders in a globalized world and that promotes integration and diversity in an interdependent global context.

STREAMFLOW GENERATION OF RIVER NIGER BASIN KOGI USING MODIFIED THOMAS FIERRING MODEL

There is a concerted effort towards protection of environment as a result of incessant change of climate and its resultant effects on human live and property. Studies have shown that flooding is ranked the most devastating natural disaster in the world; and it is a common natural environmental hazard in various parts of Nigeria. In recent times, flooding has been reported to constitute a major challenge to about 1.5 billion people or 19% of the world population; whereas 70 million people globally exposed to flooding every year while over 800 million people are living in flood-prone areas. The 2022 destructive flooding in River Niger Basin Lokoja Nigeria has attracted attention of experts with a view to curtailing the future reoccurrence. Based on this rationale, this study aimed to determine the trend in the hydrometric dataset and to provide extensive time series analysis of the streamflow in the study area using Modified Thomas Fierring Model (MTFM). In order to achieve the objectives of the study, the dataset for 20 years was sourced from the NIWA (National Inland Waterway Authority) whereby the daily and monthly data was extensively analyzed and the (Thomas Fierring) T-F model the data for the “n” years was divided into 12 sections while the data of each month was re-aggressed to the previous month so that there were 12 linear regressions. Also, MTFM was used to predict the monthly flows from River Niger from 2000 to 2019 so as to compute 36 parameters (12) means (), standard deviations (), and Lag-1 autocorrelation coefficients (r1)). After the estimation of the parameters of the MTFM, the series of historical monthly flows for 20 years were generated. These series were compared with the recorded monthly flows of River Niger for the hydrological period of 20 years (2000-2019), with the use of basic statistical characteristics like mean, standard deviation, maximum, minimum, coefficient of variation, skewness and Kurtosis as shown in Table 1 and Figure 2. The findings revealed that monthly discharge time series of River Niger Basin from 2000 to 2019 are consistent with slightly variation in the trends after modified modified Thomas Fierring Model application; and the study further underscored the relevance of MTFM for analyzing streamflow of River Niger Basin Lokoja. Among others, the study recommended up-to-date hydrometric data of River Niger Basin for optimum control and management of streamflow in the study area; and concluded that up-to-date information in this direction will help future researcher to consolidate on the existing body of knowledge in the field.

CHALLENGES OF CHINA’S FOREIGN DIRECT INVESTMENT UNDER THE “BELT AND ROAD” INITIATIVE IN THE POST-PANDEMIC ERA

The evolution of China’s foreign direct investment (FDI) in countries along the “Belt and Road” represents a cornerstone of this ambitious initiative, with far-reaching implications for global economic dynamics. A comprehensive analysis of this phenomenon is indispensable, not only for fostering China’s economic expansion but also for elevating the “Belt and Road” initiative to unprecedented levels of success and influence. Our exhaustive research endeavor commences with a meticulous deconstruction of the multifaceted “Belt and Road” concept, delving deep into its historical roots, geopolitical significance, and economic ramifications. We then embark on a thorough exploration of the intricate challenges confronting China’s FDI across the diverse tapestry of participating nations and regions, encompassing political, economic, cultural, and environmental dimensions. This nuanced understanding serves as the foundation for developing tailored solutions and strategic recommendations designed to address these complex issues with precision and foresight. Our study aims to conduct an in-depth analysis and meticulous evaluation of the multifaceted risks associated with China’s FDI under the “Belt and Road” Initiative in the post-pandemic landscape, while concurrently formulating robust and effective countermeasures. We endeavor to shed light on the profound and transformative ways in which the global economic terrain, irrevocably reshaped by the COVID-19 pandemic, molds and influences China’s international investment strategies. This includes examining the pandemic’s impact on supply chains, market demands, and geopolitical relationships, all of which have significant bearing on FDI decisions and outcomes. Furthermore, we present a comprehensive array of meticulously crafted recommendations, not only to safeguard China’s economic interests but also to cultivate sustainable and mutually advantageous development in partner countries along the Belt and Road routes. These recommendations span various domains, including risk mitigation strategies, enhanced due diligence processes, and innovative financing models that align with post-pandemic realities. To execute this study with unparalleled rigor and precision, we employ a diverse and sophisticated array of cutting-edge research methodologies. Our analytical framework incorporates a meticulous examination of extensive statistical data pertaining to FDI distribution, enabling us to identify overarching trends, discern subtle patterns, and pinpoint specific effects with remarkable accuracy. This includes analyzing historical FDI flows, sector-specific investments, and regional variations to provide a comprehensive picture of China’s investment landscape. Furthermore, we leverage advanced econometric modeling techniques to conduct a granular and nuanced analysis of the impact exerted by a wide spectrum of risk factors on FDI performance. These models account for various economic indicators, political stability indices, and pandemic-related variables to provide a holistic view of the investment environment. This approach allows us to rigorously test and validate the efficacy of our proposed countermeasures, ensuring their practical applicability and potential for success. By adopting this multifaceted and interdisciplinary approach, we ensure a truly comprehensive and deeply nuanced understanding of the intricate and dynamic interplay of factors shaping China’s FDI landscape under the “Belt and Road” Initiative. Our methodology also incorporates qualitative analyses, including case studies of successful and challenging FDI projects, interviews with key stakeholders, and comparative analyses with other global investment initiatives, further enriching our insights and recommendations.

Contribution of hydraulic modeling and hydrology to flood prevention and design of engineering structures: Case study of a bridge over the Oued Ourika – Morocco

Located downstream of the Ourika watershed near the commune of Chouiter, the bridge studied is built over the Oued Ourika at the level of the N9 (national road linking Marrakech to Ouarzazat). The flood event of November 2014, reaching a peak flow of 347 m3/s, destabilized the bridge’s overall structure. Hence, the need to rebuild a new bridge, taking into account the magnitude of these extreme events. Hydraulic modeling involves creating mathematical and computer-based representations of hydraulic systems. Its purpose is to simulate water flow behavior and map flood-prone areas. Before initiating any hydraulic simulation, it is imperative to conduct a hydrological study to provide the input data for the hydraulic model. Precipitation records, evaporation rates, soil permeability, historical peak flow data, and site topography constitute, on the one hand, the product of the hydrological study and, on the other, the inputs for the hydraulic model. The hydraulic model is based on Saint-Vant equations to solve the conservation of mass and momentum equations. The aim of this work is to determine the critical water level at the bridge for a 100-year flood in order to optimize the height of the new bridge.

A Half-Century of Human Impact on Nan River Runoff and Sediment Load Supplied to the Chao Phraya River

The construction of large dams in the upper tributary basin of the Chao Phraya River (CPR) has been linked to a significant decrease in sediment load in the CPR system, estimated between 75–85%. This study, utilizing historical and recent river flow and sediment data from 1922 to 2019, examines the impact of three major dams constructed in the Nan River basin (the Sirikit, Naresuan, and Khwae Noi dams) on river runoff and sediment loads in the CPR. The investigation employed the Mann–Kendall (MK) test and the double mass curve (DMC) for analysis. Findings indicate that the Nan River is a major contributor to the CPR, accounting for around 40% of the runoff and 57% of the total sediment load (TSL). The Naresuan diversion dam’s water regulation was found to significantly reduce annual runoff and TSL downstream of the dam. Despite an initial increase in sediment load at the CPR headwater (C.2) post the construction of the Sirikit dam, attributed to expanded irrigation downstream and channel improvements in the lower Nan River, the operation of the three dams eventually led to a 31% reduction in sediment load at C.2 compared to pre-construction levels.

Origin of calcite cements in the Permian Lucaogou Formation tight reservoirs, Jimsar sag, Junggar basin, NW China: Constraints from geochemistry

Understanding the diagenetic evolution of carbonate cementation in hydrocarbon reservoirs is critical to better reconstruct the history of fluid flow during petroleum accumulation. The extensive occurrence of carbonate cements within the lower Permian Lucaogou Formation tight reservoirs is regarded as a major diagenetic factor that causes strong hydrocarbon reservoir heterogeneities. Petrographic and geochemical analyses, including optical microscopy fitted with cathodoluminescence, scanning electron microscopy, carbon and oxygen stable isotopes, in situ rare earth element, as well as fluid inclusion microthermometry, were carried out to decipher the origin of calcite cementation and understand its control on reservoirs quality. Petrography shows that the precipitating cements mostly consist of pore-filling blocky/mosaic calcite, with a dull orange luminescence color. Chondrite-normalized rare earth element (REE) patterns and C–O isotopic compositions of these calcite cements exhibit strongly negative Eu and Tb anomalies, enrichment in light REE, positive carbon (δ13CPDB = 0.58‰–7.45‰) and negative oxygen (δ18OPDB = −11.38‰ to −8.61‰) isotopic values, similar to the dolostone and micritized peloidal grains, suggesting that the calcite-precipitating fluids were derived from dissolution of lacustrine depositional carbonates. The relative timing of calcite precipitation in reservoirs was constrained based on the thermal-burial history of the study region and precipitation temperatures obtained from fluid inclusions. The results show that this cementation episode mainly occurred during the Late Triassic to Early Jurassic, which was synchronous with the tectonic uplift event. Moreover, homogenization temperatures of fluid inclusions and geochemical signatures of the calcite cement are similar to those of the fracture-fillings, suggesting that these two calcite phases may be genetically related and form coevally within one fluid flow system. It can be interpreted as a response to the compressional tectonic deformation given by the collision of the Qiangtang Block with the Eurasia Plate. This tectonic deformation event is regarded as the driver for calcite precipitation during the early burial stage, resulting in a considerable reduction of reservoir quality. Calcite cementation is pervasive and may play a main role in halting hydrocarbon migration through some of the permeable pathways in reservoirs.

Alpine Extremophytes in Evolutionary Turmoil: Complex Diversification Patterns and Demographic Responses of a Halophilic Grass in a Central Asian Biodiversity Hotspot.

Diversification and demographic responses are key processes shaping species evolutionary history. Yet we still lack a full understanding of ecological mechanisms that shape genetic diversity at different spatial scales upon rapid environmental changes. In this study, we examined genetic differentiation in an extremophilic grass Puccinellia pamirica and factors affecting its population dynamics among the occupied hypersaline alpine wetlands on the arid Pamir Plateau in Central Asia. Using genomic data, we found evidence of fine-scale population structure and gene flow among the localities established across the high-elevation plateau as well as fingerprints of historical demographic expansion. We showed that an increase in the effective population size could coincide with the Last Glacial Period, which was followed by the species demographic decline during the Holocene. Geographic distance plays a vital role in shaping the spatial genetic structure of P. pamirica alongside with isolation-by-environment and habitat fragmentation. Our results highlight a complex history of divergence and gene flow in this species-poor alpine region during the Late Quaternary. We demonstrate that regional climate specificity and a shortage of nonclimate data largely impede predictions of future range changes of the alpine extremophile using ecological niche modeling. This study emphasizes the importance of fine-scale environmental heterogeneity for population dynamics and species distribution shifts.

Major patterns in the introgression history of Heliconius butterflies

Gene flow between species, although usually deleterious, is an important evolutionary process that can facilitate adaptation and lead to species diversification. It also makes estimation of species relationships difficult. Here, we use the full-likelihood multispecies coalescent (MSC) approach to estimate species phylogeny and major introgression events in Heliconius butterflies from whole-genome sequence data. We obtain a robust estimate of species branching order among major clades in the genus, including the ‘melpomene-silvaniform’ group, which shows extensive historical and ongoing gene flow. We obtain chromosome-level estimates of key parameters in the species phylogeny, including species divergence times, present-day and ancestral population sizes, as well as the direction, timing, and intensity of gene flow. Our analysis leads to a phylogeny with introgression events that differ from those obtained in previous studies. We find that Heliconius aoede most likely represents the earliest-branching lineage of the genus and that ‘silvaniform’ species are paraphyletic within the melpomene-silvaniform group. Our phylogeny provides new, parsimonious histories for the origins of key traits in Heliconius, including pollen feeding and an inversion involved in wing pattern mimicry. Our results demonstrate the power and feasibility of the full-likelihood MSC approach for estimating species phylogeny and key population parameters despite extensive gene flow. The methods used here should be useful for analysis of other difficult species groups with high rates of introgression.

Major patterns in the introgression history of Heliconius butterflies.

Gene flow between species, although usually deleterious, is an important evolutionary process that can facilitate adaptation and lead to species diversification. It also makes estimation of species relationships difficult. Here, we use the full-likelihood multispecies coalescent (MSC) approach to estimate species phylogeny and major introgression events in Heliconius butterflies from whole-genome sequence data. We obtain a robust estimate of species branching order among major clades in the genus, including the 'melpomene-silvaniform' group, which shows extensive historical and ongoing gene flow. We obtain chromosome-level estimates of key parameters in the species phylogeny, including species divergence times, present-day and ancestral population sizes, as well as the direction, timing, and intensity of gene flow. Our analysis leads to a phylogeny with introgression events that differ from those obtained in previous studies. We find that Heliconius aoede most likely represents the earliest-branching lineage of the genus and that 'silvaniform' species are paraphyletic within the melpomene-silvaniform group. Our phylogeny provides new, parsimonious histories for the origins of key traits in Heliconius, including pollen feeding and an inversion involved in wing pattern mimicry. Our results demonstrate the power and feasibility of the full-likelihood MSC approach for estimating species phylogeny and key population parameters despite extensive gene flow. The methods used here should be useful for analysis of other difficult species groups with high rates of introgression.

How Effective Is Inter-Basin Transfer to Manage Temporal Variation Of “Too Much” And “Too Little” Water Conditions for Irrigation in a Himalayan Basin?

Better irrigation facilities leading to “more crop per drop” are today’s needs. This study examines how the overall water balance of Sunkoshi, Marin, and Bagmati Basins will be altered by implementing the Sunkoshi-Marin Diversion Project (SMDP) to fulfill the unmet demands of the Bagmati Irrigation Project (BIP) in the Bagmati Basin via the Marin Basin in Nepal. The specific objectives are to: i) quantify “too much” and “too little” water peculiar to the study basin based on historical data; ii) evaluate water availability, irrigation water requirement, and deficits with and without SMDP; and iii) provide evidence-based recommendations on the effectiveness of the SMDP considering hydropower generation, irrigation and low- and high-flow conditions. Thirty years of historical daily flow data (two gauging stations) and precipitation data (15 stations) were obtained from the Department of Hydrology and Meteorology. Other spatial input data were acquired from relevant authorized sources. Water availability has been estimated using flow at the diversion sites while the irrigation requirements have been calculated based on secondary information. Results show that additional water is not at all required for Marin and Bagmati Basins in the monsoon season. Rather, the diverted water increases the flood hazard. Moreover, the contribution of hydropower from SMDP to the national energy demand is insignificant in the monsoon. However, the SMDP was found to play an important role in meeting the irrigation deficits during the dry season. Its contribution to hydropower production in the lean period is also commendable. However, the proposed irrigation requirement of the BIP cannot be met even after the implementation of the SMDP. More importantly, there is a high probability of the intended diversion flow not being available in the Sunkoshi River (donor) which could have severe consequences downstream. Therefore, additional options for conjunctive use need to be explored.

Exploring multi-stability in three-dimensional viscoelastic flow around a free stagnation point

Fluid elements passing near a stagnation point experience finite strain rates over long persistence times, and thus accumulate large strains. By the numerical optimization of a microfluidic 6-arm cross-slot geometry, recent works have harnessed this flow type as a tool for performing uniaxial and biaxial extensional rheometry (Haward et al., 2023 [5,6]). Here we use the microfluidic ‘Optimized-shape Uniaxial and Biaxial Extensional Rheometer’ (OUBER) geometry to probe an elastic flow instability which is sensitive to the alignment of the extensional flow. A three-dimensional symmetry-breaking instability occurring for flow of a dilute polymer solution in the OUBER geometry is studied experimentally by leveraging tomographic particle image velocimetry. Above a critical Weissenberg number, flow in uniaxial extension undergoes a supercritical pitchfork bifurcation to a multi-stable state. However, for biaxial extension (which is simply the kinematic inverse of uniaxial extension) the instability is strongly suppressed. In uniaxial extension, the multiple stable states align in an apparently random orientation as flow joining from four neighbouring inlet channels passes to one of the two opposing outlets; thus forming a mirrored asymmetry about the stagnation point. We relate the suppression of the instability in biaxial extension to the kinematic history of flow under the context of breaking the time-reversibility assumption.

The 1870s Saskatchewan River avulsion: Ice jam or open water flood? A probabilistic approach for cold climate river avulsions

AbstractCold climate rivers can experience avulsions due to both open water and ice jam flooding; however, most existing models for evaluating avulsions only consider open water flows. We present a novel approach for determining site‐specific probabilities of avulsion cause (open water vs. ice jam flooding) by combining historical flow data, channel cross‐sections and known avulsion history for the study area. The approach is applied to the Cumberland Marshes region of the Saskatchewan River in Central Canada, which experienced an avulsion in the mid‐1870s that some researchers have suggested may have been triggered by an ice jam. For the study area, overbank flooding was found to occur much more frequently due to ice jams than open‐water floods. Based on an average avulsion return period of 660 years in the study area, the probability of historical avulsions being caused by ice jam flooding was estimated to range from 61% and 80%, using a range of annual ice jam probabilities between 0.1 and 0.5. Results from the study suggest ice jam flooding as the most likely cause of the 1870s avulsion, which is also supported by historical evidence. The developed methodology is relatively simple to apply and could be easily implemented at other cold‐climate sites to evaluate avulsion risks.

Speciation and conservation genetic assessment of two endangered cycad species

AbstractUnderstanding the driving forces of speciation is a central question in evolutionary biology. Cycas bifida (Dyer) K. D. Hill and Cycas micholitzii Dyer are two morphologically similar Cycas (Cycadaceae) species with deeply pectinate megasporophylls and dichotomously divided leaflets. Geographically, they are isolated by the Red River Fault Zone (RRFZ), which acts as a biogeographical barrier for many Cycas species. In this study, we investigated the divergence, genetic diversity, genetic structure, and demographic history of C. bifida and C. micholitzii to uncover the speciation mechanisms for the two endangered species. Results revealed high historical gene flow but low contemporary gene flow between the two species, with a deep divergence occurring in the Late Miocene. The long‐term geographical isolation and ecological niche differentiation were identified as important factors in driving the divergence of the two species, supported by significant isolation by distance testing, barrier analysis, and niche consistency detection. Geographical isolation by the RRFZ played a pivotal role in facilitating their divergence by constraining gene flow. Conservation genetic analyses indicated high genetic diversity within both species, coupled with disparate responses to Pleistocene climate fluctuations: C. micholitzii experienced population expansion, while C. bifida displayed a mild bottleneck effect. To ensure the protection and long‐term sustainability of two threatened species, relevant conservation guidelines were proposed based on the assessment of their genetic diversity and structure. This study furnishes valuable insights into the mechanisms underpinning species divergence and delivers actionable recommendations for cycad conservation.

Comparative phylogeography of two codistributed species of the genus Herichthys (Actinopterygii: Cichliformes: Cichlidae) in northeastern Mexico

Phylogeographic patterns of freshwater fishes in coastal regions are highly susceptible to eustatic sea level changes associated with Pleistocene glaciations. In this context, the Plain Coastal Gulf in northeastern Mexico represents an ideal study area due to its low elevation. Herein, we compare the phylogeographic structures of two cichlid species of the genus Herichthys Baird et Girard, 1854 widely distributed in the Pánuco–Tamesí system in northeastern Mexico using two mitochondrial markers. The species studied were: Herichthys carpintis (Jordan et Snyder, 1899) and Herichthys pantostictus (Taylor et Miller, 1983). We estimate their genetic diversity, gene flow, and demographic history and perform biogeographic reconstructions using a Bayesian computation approach and environmental niche modeling. The biogeographic reconstruction suggests a different history for each species. Environmental niche modeling indicates that both species experienced a demographic expansion during the Pleistocene but responded differently to Pleistocene climatic changes. In summary, their current sympatric distribution could be the outcome of contemporary and not historical processes reflecting a pseudo-incongruent pattern.