Uncertain Relationships Research Articles

Optimizing Warehouse Selection Through Topological Index Based Energy of q-Rung Orthopair Fuzzy Graphs

In recent years, the study of q-rung orthopair fuzzy graphs (or q-ROFGs) has gained significant attention due to their ability to model complex and uncertain relationships. One crucial aspect in analyzing such graphs is the computation of their energy, which provides insights into their structural properties and dynamics. q-rung orthopair fuzzy sets were introduced, as a method for adjusting the range of indication of decision information by modifying a parameter q. This article presents a comprehensive approach for computing the energy of q-ROFGs. The new concepts of Zagreb energy of q-ROFGs are proposed and some bounds are determined. To demonstrate the applicability of the developed approach and show its viability, a numerical model related to the selection of the most suitable warehouse location is provided. Lastly, a comparative analysis is done, and the proposed approach is found to be compatible with existing models.

Integrative phylogeny of Corydoradinae (Siluriformes: Callichthyidae) with an emphasis on northwestern La Plata species, including descriptions of a new genus and species

The knowledge about the diversity and phylogeny of South American callichthyid armored catfishes of the subfamily Corydoradinae is still growing, after important recent contributions, and many species have uncertain relationships. In this study, we present the first combined phylogenetic hypothesis for the genus based on five genes, 83 morphological characters, and 153 species, providing synapomorphies for some of the main genera of Corydoradinae, as recently defined. The inclusion of species not previously analyzed in a phylogenetic context challenged the monophyly of Hoplisoma and required the definition of a new genus for endemic species from the Andean portion of the northwestern La Plata basin (ANWLP): Hoplisoma gladysae, Hoplisoma micracanthum, and Hoplisoma petracinii. We found Hoplisoma non monophyletic with Hoplisoma sensu stricto not sister to a clade of species herein named the ‘Hoplisoma’ paleatum clade. In this clade we recovered a new species of Hoplisoma, which is endemic to the upper Bermejo basin, as sister to ‘Hoplisoma’ paleatum from the lower La Plata basin. The new species is distinguished from all congeners by a unique coloration similar to that of the syntopic H. micracanthum, suggesting a putative case of Müllerian co-mimicry.

Understanding normal and restricted normal products in soft directed graphs

This paper extends the framework of soft set theory to directed graphs by introducing and analyzing the concepts of the normal product and restricted normal product of soft directed graphs. Building on Molodtsov’s foundational work in developing soft set theory to address uncertainty in data, this study presents new methods for modeling and understanding complex systems where uncertainty plays a significant role. Soft directed graphs, which enhance traditional graph models by incorporating parameters and uncertain relationships, serve as the foundation for this investigation. The normal product, defined as a combination of two soft directed graphs based on their respective parameter sets, and the restricted normal product, which combines soft directed graphs only where their parameter sets intersect, provide a comprehensive framework for these new operations. This paper also establishes the structural properties of these products, ensuring they are well-defined and retain the key features of soft directed graphs. Furthermore, we derive combinatorial identities related to vertex and arc counts, as well as degree sums, offering deeper insights into the composition and behavior of these graph products.

Exploring the association between patient-drawn pain diagrams and psychological and physical health variables: A large-scale study of patients with low back pain.

Despite the use of Patient-Drawn Pain Drawings (PDPDs) in clinical settings, their validity as indicators of psychological distress remains debated. We aimed to assess the association between PDPD areas and physical health and psychological variables. This study analysed digitally-drawn PDPDs from 15,345 chronic low back pain (LBP) patients at a Danish outpatient hospital unit. We employed a novel quantitative approach to calculate four log-transformed geometric pain areas for each PDPD. We assessed six psychological constructs and seven physical health variables. Associations were modelled using multivariable linear regression. Increasing leg pain intensity (estimates from 0.12 to 0.25), disability (estimates from 0.3 to 0.14), and pain duration (estimates from 0.10 to 0.33) had the strongest associations with increasing pain areas. Conversely, increasing fear of movement (estimates from -0.02 to -0.05) and catastrophizing (estimates from -0.02 to -0.03) were associated with slight reductions in pain areas. Anxiety and depression had the weakest and most uncertain relationships to pain area size. Increasing levels of leg pain intensity, pain duration, and pain-related disability were consistently associated with larger geometric pain areas in PDPDs. Conversely, the associations between the psychological constructs and the geometric pain areas exhibited varying directions and were notably weaker. Clinicians are encouraged to focus on the association of PDPDs with physical symptoms rather than psychological conditions during clinical assessments. This large-scale study demonstrates that extensive pain areas in pain drawings drawn by LBP patients do not signify psychological distress. Our findings reveal that these pain representations are more closely linked to increased pain intensity, pain duration, and disability rather than being independently associated with psychological factors. Clinicians are encouraged to focus on the association of extensive pain areas with physical symptoms rather than psychological distress during clinical assessments.

Phylogenomic analyses of all species of swordtail fishes (genus Xiphophorus) show that hybridization preceded speciation

Hybridization has been recognized to play important roles in evolution, however studies of the genetic consequence are still lagging behind in vertebrates due to the lack of appropriate experimental systems. Fish of the genus Xiphophorus are proposed to have evolved with multiple ancient and ongoing hybridization events. They have served as an informative research model in evolutionary biology and in biomedical research on human disease for more than a century. Here, we provide the complete genomic resource including annotations for all described 26 Xiphophorus species and three undescribed taxa and resolve all uncertain phylogenetic relationships. We investigate the molecular evolution of genes related to cancers such as melanoma and for the genetic control of puberty timing, focusing on genes that are predicted to be involved in pre-and postzygotic isolation and thus affect hybridization. We discovered dramatic size-variation of some gene families. These persisted despite reticulate evolution, rapid speciation and short divergence time. Finally, we clarify the hybridization history in the entire genus settling disputed hybridization history of two Southern swordtails. Our comparative genomic analyses revealed hybridization ancestries that are manifested in the mosaic fused genomes and show that hybridization often preceded speciation.

Optimization of teacher evaluation indicator system based on fuzzy-DEMATEL-BP

The establishment of a reasonable teacher evaluation indicator system has always been a research hotspot in teacher evaluation. Simplifying and essential indicators are the foundation for maintaining the speed and accuracy of teacher evaluation. Therefore, optimizing indicators in a convincing and interpretable manner becomes highly important. Due to the complex causal relationships and fuzzy uncertainties among teacher evaluation indicators, this paper proposes a method that combines the Triangular Fuzzy Decision-making Trial and Evaluation Laboratory Model (Fuzzy-DEMATEL) with Backpropagation Neural Network (BP) to optimize the complexity of assessment systems and identify key indicators, thereby establishing a precise and rational teacher evaluation index system. DEMATEL allows us to simplify and analyze the complex causal relationships among assessment indicators, mapping them into a causal relationship diagram. Fuzzy logic effectively handles the fuzzy and uncertain relationships among the indicators, converting fuzzy information into computable forms. The BP neural network is a data training model that, from an objective data perspective, compensates for subjective errors, thereby optimizing our indicator results. In addition, we conducted empirical and comparative research using relevant data from the TIMSS 2019 dataset, and found that this method can reduce the original indicator quantity by approximately 28 %–30 %, compared to methods such as Multi-Criteria Decision Making (MCDM), the results are superior and the indicators are more accurate.

Tectonic Evolution of the Condrey Mountain Schist: An Intact Record of Late Jurassic to Early Cretaceous Franciscan Subduction and Underplating

AbstractThe Klamath Mountains in northern California and southern Oregon are thought to record 200+ m.y. of subduction and terrane accretion, whereas the outboard Franciscan Complex records ocean‐continent subduction along the North American margin. Unraveling the Klamath Mountains' Late Jurassic history could help constrain this transition in subduction style. Key is the Mesozoic Condrey Mountain Schist (CMS), comprising, in part, a subduction complex that occupies a structural window through older, overlying central Klamath thrust sheets but with otherwise uncertain relationships to more outboard Klamath or Franciscan terranes. The CMS consists of two units (upper and lower), which could be correlated with (a) other Klamath terranes, (b) the Franciscan, or (c) neither based on regional structures and limited extant age data. Upper CMS protolith and metamorphic dates overlap with other Klamath terranes, but the lower CMS remains enigmatic. We used multiple geochronometers to constrain the timing of lower CMS deposition and metamorphism. Maximum depositional ages (MDAs) derived from detrital zircon geochronology of metasedimentary rocks are 153–135 Ma. Metamorphic ages from white mica K‐Ar and Rb‐Sr multi‐mineral isochrons from intercalated and coherently deformed metamafic lenses are 133–116 Ma. Lower CMS MDAs (<153 Ma) predominantly postdate other Klamath terrane ages, but subduction metamorphism appears to start before the earliest coherent Franciscan underplating (ca. 123 Ma). The lower CMS thus occupies a spatial and temporal position between the Klamath Mountains and Franciscan and preserves a non‐retrogressed record of the Franciscan Complex's early history (>123 Ma), otherwise only partially preserved in retrogressed Franciscan high grade blocks.

Embracing uncertainty: The way forward in plant fossil phylogenetics.

Although molecular phylogenetics remains the most widely used method of inferring the evolutionary history of living groups, the last decade has seen a renewed interest in morphological phylogenetics, mostly driven by the promises that integrating the fossil record in phylogenetic trees offers to our understanding of macroevolutionary processes and dynamics and the possibility that the inclusion of fossil taxa could lead to more accurate phylogenetic hypotheses. The plant fossil record presents some challenges to its integration in a phylogenetic framework. Phylogenies including plant fossils often retrieve uncertain relationships with low support, or lack of resolution. This low support is due to the pervasiveness of morphological convergence among plant organs and the fragmentary nature of many plant fossils, and it is often perceived as a fundamental weakness reducing the utility of plant fossils in phylogenetics. Here I discuss the importance of uncertainty in morphological phylogenetics and how we can identify important information from different patterns and types of uncertainty. I also review a set of methodologies that can allow us to understand the causes underpinning uncertainty and how these practices can help us to further our knowledge of plant fossils. I also propose that a new visual language, including the use of networks instead of trees, represents an improvement on the old visualization based on consensus trees and more adequately serves phylogeneticists working with plant fossils. This set of methods and visualization tools represents an important way forward in a fundamental field for our understanding of the evolutionary history of plants.

Implementation of Bayesian networks and Bayesian inference using a Cu0.1Te0.9/HfO2/Pt threshold switching memristor.

Bayesian networks and Bayesian inference, which forecast uncertain causal relationships within a stochastic framework, are used in various artificial intelligence applications. However, implementing hardware circuits for the Bayesian inference has shortcomings regarding device performance and circuit complexity. This work proposed a Bayesian network and inference circuit using a Cu0.1Te0.9/HfO2/Pt volatile memristor, a probabilistic bit neuron that can control the probability of being 'true' or 'false.' Nodal probabilities within the network are feasibly sampled with low errors, even with the device's cycle-to-cycle variations. Furthermore, Bayesian inference of all conditional probabilities within the network is implemented with low power (<186 nW) and energy consumption (441.4 fJ), and a normalized mean squared error of ∼7.5 × 10-4 through division feedback logic with a variational learning rate to suppress the inherent variation of the memristor. The suggested memristor-based Bayesian network shows the potential to replace the conventional complementary metal oxide semiconductor-based Bayesian estimation method with power efficiency using a stochastic computing method.

Predicting Methane Formation Rates of Freshwater Sediments in Different Biogeographic Regions

AbstractFreshwater lakes and reservoirs cover a small fraction of the Earth, however their emission of the greenhouse gas methane (CH4) from the sediment to the atmosphere is disproportionately high. Currently, there is still a limited understanding of the links between sediment characteristics and CH4 formation. Earlier studies have indicated that sediment age and nitrogen content are related to sediment CH4 formation rates, but it is uncertain such relationships are valid across gradients of sediment characteristics. We therefore measured potential CH4 formation rates in multiple layers of sediment sampled from nine lakes situated in the temperate, boreal and alpine biogeographic regions of Sweden, thus differing in productivity, catchment and climate properties. Potential CH4 formation varied over 3 orders of magnitude, and was broadly related to the quantity and reactivity of organic matter, and generally decreased with sediment depth. Sediment age and total nitrogen content were found to be the key controlling factors of potential CH4 formation rates, together explaining 62% of its variability. Moreover, the model developed from the Swedish lake sediment data was able to successfully predict the potential CH4 formation rates in reservoirs situated in different biogeographic regions of Brazil (R2 = 0.62). Therefore, potential CH4 formation rates in sediments of highly contrasting lakes and reservoirs, from Amazonia to alpine tundra, could be accurately predicted using one common model (RMSE = 1.6 in ln‐units). Our model provides a valuable tool to improve estimates of CH4 emission from lakes and reservoirs, and illustrates the fundamental regulation of microbial CH4 formation by organic matter characteristics.

Fuzzy self-consistent clustering ensemble

The subject of clustering ensemble (CE) has emerged as a pivotal area of exploration within unsupervised learning, primarily due to its remarkable capacity to integrate multiple base clusterings. However, the conventional CE framework exhibits limitations in effectively handling fuzzy relations and ensuring robustness. This study introduces an innovative and robust fuzzy self-consistent clustering ensemble (FSCE) model. Departing from customary approaches to processing base clustering outcomes, the FSCE model considers the scalable dummy variable representation of base clustering results as a novel feature attributes intrinsic to the original dataset. Subsequently, a γ-fuzzy operator ε+ is formulated, enabling the adjustment of coupling strength contingent upon the uncertainties inherent in practical problems. Leveraging this operator, the model reappraises the fuzzy relationships among objects, thereby engendering a corresponding relation matrix. This matrix profoundly enhances the model's capacity to contend with uncertain relationships. The resultant relation matrix assumes a pivotal role as the primary input in the consensus function, culminating in the derivation of the ensemble outcome. Moreover, the FSCE model deviates from the conventional CE paradigm by introducing a reallocation strategy for fuzzy objects within ensemble outcome. Through comprehensive experimentation, we substantiate that the introduction of γ-fuzzy operator ε+ offers a viable novel approach to enhancing both the overall performance and the fuzzy interpretability of the CE model. The FSCE model distinctly excels in consensus formation and robustness when juxtaposed against eight archetypal and state-of-the-art clustering models.

A Morrison stem gekkotan reveals gecko evolution and Jurassic biogeography.

Geckos are a speciose and globally distributed clade of Squamata (lizards, including snakes and amphisbaenians) that are characterized by a host of modifications for nocturnal, scansorial and insectivorous ecologies. They are among the oldest divergences in the lizard crown, so understanding the origin of geckoes (Gekkota) is essential to understanding the origin of Squamata, the most species-rich extant tetrapod clade. However, the poor fossil record of gekkotans has obscured the sequence and timing of the assembly of their distinctive morphology. Here, we describe the first North American stem gekkotan based on a three-dimensionally preserved skull from the Morrison Formation of western North America. Despite its Late Jurassic age, the new species already possesses several key characteristics of the gekkotan skull along with retained ancestral features. We show that this new stem gekkotan, and several previously named species of uncertain phylogenetic relationships, comprise a widespread clade of early crown lizards, substantiating faunal homogeneity in Laurasia during the Late Jurassic that extended across disparate ecological, body-size and physiological classes.

How can we apply decision-making theories to wild animal behavior? Predictions arising from dual process theory and Bayesian decision theory.

Our understanding of decision-making processes and cognitive biases is ever increasing, thanks to an accumulation of testable models and a large body of research over the last several decades. The vast majority of this work has been done in humans and laboratory animals because these study subjects and situations allow for tightly controlled experiments. However, it raises questions about how this knowledge can be applied to wild animals in their complex environments. Here, we review two prominent decision-making theories, dual process theory and Bayesian decision theory, to assess the similarities in these approaches and consider how they may apply to wild animals living in heterogenous environments within complicated social groupings. In particular, we wanted to assess when wild animals are likely to respond to a situation with a quick heuristic decision and when they are likely to spend more time and energy on the decision-making process. Based on the literature and evidence from our multi-destination routing experiments on primates, we find that individuals are likely to make quick, heuristic decisions when they encounter routine situations, or signals/cues that accurately predict a certain outcome, or easy problems that experience or evolutionary history has prepared them for. Conversely, effortful decision-making is likely in novel or surprising situations, when signals and cues have unpredictable or uncertain relationships to an outcome, and when problems are computationally complex. Though if problems are overly complex, satisficing via heuristics is likely, to avoid costly mental effort. We present hypotheses for how animals with different socio-ecologies may have to distribute their cognitive effort. Finally, we examine the conservation implications and potential cognitive overload for animals experiencing increasingly novel situations caused by current human-induced rapid environmental change.

Anchored phylogenomics and revised classification of the Miltogramminae (Diptera: Sarcophagidae)

AbstractThe Miltogramminae (Diptera: Sarcophagidae) includes ~600 species across &gt;40 genera, which constitute ~20% of global Sarcophagidae. While molecular phylogenetic hypotheses have been produced for this group, critical problems persist, including the presence of paraphyletic genera, uncertain relationships between genera, a bias of sampling towards Palaearctic taxa, and low support for many branches. The present study remedies these issues through the application of Anchored Hybrid Enrichment (AHE) to a sample including ~60% of the currently recognised genera (16% of known species) representing all biogeographic regions except the Neotropical. An alignment of 1,281 concatenated loci was analysed with maximum likelihood (RAxML, IQ‐TREE), Bayesian inference (ExaBayes) and coalescent‐based approaches (ASTRAL, SVDquartets), which resulted in highly supported and concordant topologies, providing unprecedented insight into the relationships of this subfamily of flesh flies, allowing a major update to miltogrammine classification. The AHE phylogenetic hypothesis supports the monophyly of a large proportion of genera. The monophyly of Metopia Meigen is restored by synonymy with Aenigmetopia Malloch, syn.n. To achieve monophyly of Miltogramma Meigen, eight species are transferred from Pterella Robineau‐Desvoidy. The genus Pterella is shown to be paraphyletic in its current circumscription, and to restore generic monophyly Pterella is restricted to contain only Pt. grisea (Meigen). Erioprocta Enderlein, stat.rev., is resurrected. The genus Senotainia Macquart is reconstructed as paraphyletic. The monotypic genus Metopodia Brauer &amp; Bergenstamm is synonymised with Taxigramma Macquart, syn.n. In light of our phylogenetic hypotheses, a new Miltogramminae tribal classification is proposed, composed of six tribes.

1H, 15N and 13C backbone and side chain solution NMR assignments of the TPM domain-containing protein of the thermophilic bacterium Rhodothermus marinus.

The InterPro family IPR007621 TPM_phosphatase is a widely conserved family of protein domains found in prokaryotes, plants and invertebrates. Despite similar predicted protein folding, members of this family are involved in different cellular processes. In recent years, the structural and biochemical characterization of evolutionarily divergent TPM domains has shown their ability to hydrolyze phosphate groups of different substrates. However, there are still inaccurate functional annotations and uncertain relationships between the structure and function of this domain family. We here report the 1H, 13C, and 15N backbone and sidechain resonances of the TPM domain of a predicted TPM domain-containing protein of the thermophilic bacterium Rhodothermus marinus. These data will lay the groundwork for future NMR-based investigations, contributing to a thorough comprehension of the intricate aspects governing the interplay between structure and function of TPM domains. Additionally, they will unlock opportunities to explore dynamic structural changes, providing valuable insights into the molecular mechanisms underlying the evolutionary adaptations to extreme environmental conditions within this protein family.

Dynamic Probabilistic Risk Assessment of Overpressure Burst of Pipeline with Pressure-Protection Systems in Case of Blockage

Although overpressure burst of pipeline with pressure-protection systems occurs infrequently in case of blockage, it endangers personnel safety and causes serious economic loss when it happens. Therefore, assessing the dynamic probabilistic risk of overpressure burst of pipeline with pressure-protection systems in case of blockage is necessary to prevent accidents. This study proposes a method based on a dynamic Bayesian network (DBN) for assessing the dynamic probabilistic risk of overpressure burst of pipeline with pressure-protection systems in case of blockage. First, a fault tree (FT) model of pipeline overpressure burst is constructed. The constructed FT model is then mapped into the DBN model to solve the uncertainty of the model. Second, the leaky Noisy-OR gate is used to define the uncertain logical relationships of relevant nodes in the DBN model. The effect of common cause failures on a pipeline’s redundant pressure-protection system is analyzed using the multiple error shock model. Finally, a natural gas export pipeline is presented as an example to demonstrate the proposed method. Results show that the method can effectively assess the dynamic probabilistic risk of overpressure burst of pipeline with pressure-protection systems in case of blockage.

New record of aquatic snakes (Squamata, Palaeophiidae) from the Paleocene of South America

ABSTRACT The Paleocene deposits from the Cerrejón Formation (Colombia, South America) have provided abundant snake remains. All this material has been assigned to the giant snake Titanoboa cerrejonensis. Here, we describe six vertebrae from among the referred materials that do not correspond to Titanoboa. All six vertebrae are morphologically identical, of a similar size, and display a distinct morphology that differs from Titanoboa. This new and unnamed taxon is a large snake estimated to be around eight meters in total length. Anatomical comparisons show that these vertebrae possess certain features typical of the Palaeophiidae, a group of extinct snakes of uncertain relationships known almost exclusively from vertebrae. Among the Palaeophiidae, the new taxon resembles the more generalized forms assigned to the genus Palaeophis, but lacks the extreme aquatic adaptations that define forms assigned to the genus Pterosphenus. We regard the new taxon as an undetermined palaeophiine but do not assign it to Palaeophis as a number of features differ from that described genus. This new record expands the known diversity of aquatic snakes from the Paleogene of South America and provides a substantial new record for the paleogeographic distribution of the Palaeophiidae. The oldest records are from the Cretaceous of Africa, while Paleocene records are poorly known and restricted to Africa, North America, and Europe. The majority of vertebral forms assigned to Palaeophiidae are from the Eocene, principally from the Tethys region, with only one previous South American record coming from the Eocene of Ecuador.

Identification of Acrossocheilus fasciatus (Teleostei: Cyprinidae) from Three Different Phylogeographic Sources using Morphology and COI DNA Barcoding

Background: Accurate species delimitation is essential for phylogenetic, phylogeographic, ecological, conservation and biogeographic investigations. Acrossocheilus species classification has long been contentious, owing to their uncertain evolutionary relationships, high levels of morphological homoplasy and a lack of knowledge of the taxonomic validity of conventionally utilized morphological characters. Methods: A final data set consisting of 102 mitochondrial cytochrome oxidase I (COI) gene sequences was analysed for K2P intraspecific and interspecific divergence in the current study, using reconstruction methods (maximum likelihood) and various models (ABGD, PTP, GMYC) to divide the sequences according to the pattern of genetic variation. We used landmark-based geometric morphometrics to identify specimens. Result: Two taxa were identified according to the phylogenetic tree (maximum likelihood method) and three different models (ABGD, PTP, GMYC). The molecular taxonomy of Acrossocheilus agreed with the morphological identification of specimens from the same collection locality. Therefore, the COI gene and geometric morphometrics were effective in species identification of A. fasciatus.

Estimating China's CO2 emissions under the influence of COVID-19 epidemic using a novel fractional multivariate nonlinear grey model.

The COVID-19 pandemic has posed a severe challenge to the global economic recovery and China's economic growth. Although China has achieved stage victory against the epidemic, the impact and influence of the epidemic on China's economy will linger. On the positive side, the epidemic has led to a dramatic reduction in air pollution levels and a sharp slowdown in greenhouse gas emissions such as CO2. Forecasting China's CO2 emissions under the impact of the COVID-19 epidemic is crucial for formulating policies that contribute to smooth economic development and rational energy consumption. To this end, this paper improves on the traditional grey model, GM(1, N), by developing a novel fractional multivariate nonlinear grey model, FMNGM(q, N). These improvements include two key points. First, different power exponents are assigned to each relevant factor variable to explain their nonlinear, uncertain, and complicated relationships with the system characteristic variables. Second, the integer accumulation is changed to fractional accumulation to preprocess the data, and the Caputo-type fractional derivative is used to characterize the endogenous relationships among the system characteristic data. In addition, the quantum particle swarm optimization (QPSO) algorithm is used to optimize the above parameters with the goal of minimizing MAPE. The collected data on China's CO2 emission from 2001 to 2018 were divided into two parts according to different stages of economic development: 2001-2009 and 2010-2018. Both sets of data were modelled and analysed separately and compared with other models. Results showed that the proposed model had better prediction accuracy than other models. Finally, the model built using the 2010-2018 data was used to forecast China's CO2 emissions. Results show that China's CO2 emissions in 2020 under the impact of COVID-19 will decrease by approximately 3.15% from 2019 to 9893 million tons. The results bear important policy implications for planners in investment in clean energy and infrastructure to achieving the goal of a low-carbon transition.

Population genomics indicate three different modes of divergence and speciation with gene flow in the green-winged teal duck complex

The processes leading to divergence and speciation can differ broadly among taxa with different life histories. We examine these processes in a small clade of ducks with historically uncertain relationships and species limits. The green-winged teal (Anas crecca) complex is a Holarctic species of dabbling duck currently categorized as three subspecies (Anas crecca crecca, A. c. nimia, and A. c. carolinensis) with a close relative, the yellow-billed teal (Anas flavirostris) from South America. A. c. crecca and A. c. carolinensis are seasonal migrants, while the other taxa are sedentary. We examined divergence and speciation patterns in this group, determining their phylogenetic relationships and the presence and levels of gene flow among lineages using both mitochondrial and genome-wide nuclear DNA obtained from 1,393 ultraconserved element (UCE) loci. Phylogenetic relationships using nuclear DNA among these taxa showed A. c. crecca, A. c. nimia, and A. c. carolinensis clustering together to form one polytomous clade, with A. flavirostris sister to this clade. This relationship can be summarized as (crecca, nimia, carolinensis)(flavirostris). However, whole mitogenomes revealed a different phylogeny: (crecca, nimia)(carolinensis, flavirostris). The best demographic model for key pairwise comparisons supported divergence with gene flow as the probable speciation mechanism in all three contrasts (crecca−nimia, crecca−carolinensis, and carolinensis−flavirostris). Given prior work, gene flow was expected among the Holarctic taxa, but gene flow between North American carolinensis and South American flavirostris (M ∼0.1–0.4 individuals/generation), albeit low, was not expected. Three geographically oriented modes of divergence are likely involved in the diversification of this complex: heteropatric (crecca−nimia), parapatric (crecca−carolinensis), and (mostly) allopatric (carolinensis−flavirostris). Our study shows that ultraconserved elements are a powerful tool for simultaneously studying systematics and population genomics in systems with historically uncertain relationships and species limits.