Intermediate Morphology Research Articles

The hybrid skull of the eastern coyote (Canis latrans var.): Nonmetric traits and craniomandibular shape

The increasing awareness that hybridization, and resultant gene flow, plays a major role in animal diversification has led to a growing number of studies that have focused on assessing the morphological consequences of this process. Analyses of mammalian hybrids have identified skeletal effects of hybridization, including a suite of anomalous dental and sutural traits on the skull that are present at high frequencies in hybrid populations. These studies have also detected consistent patterns of morphological shape and size differences between hybrids and parental taxa across a wide variety of organisms. However, more research is required to understand the universality of these traits and shape/size differences. Building on these previous studies, a sample of genetically determined canid hybrids was examined, specifically the eastern coyote (Canis latrans var.), a hybrid between coyotes, wolves, and dogs, to test whether this group exhibits a comparable pattern of anomalous nonmetric characters, and to assess differences in craniomandibular shape and size. First, specimens of C. latrans var., C. latrans, and C. lupus were scored for anomalous traits, including supernumerary and rotated teeth, dental crowding, and sutural anomalies. Geometric morphometric analyses were then conducted on a subset of these individuals to explore craniomandibular size and shape variation, as well as allometry. The results are largely consistent with other studies, indicating that the incidence of dental anomalies, dental crowding, and sutural anomalies is significantly higher in hybrids. However, differences are not significant for supernumerary teeth. The exploration of morphometric variation identifies intermediate morphology in the hybrids, and some indication of greater morphological variability in the mandible. When these results are combined with previous studies, they suggest that skeletal signatures of hybridization are common to different mammalian taxa across multiple generations; however, some traits such as supernumerary teeth may be lost after a few generations.

Are All Post-starbursts Mergers? HST Reveals Hidden Disturbances in the Majority of PSBs

Abstract How do galaxies transform from blue, star-forming spirals to red, quiescent early-type galaxies? To answer this question, we analyzed a set of 26 gas-rich, shocked post-starburst galaxies with Hubble Space Telescope (HST) imaging in B, I, and H bands and Sloan Digital Sky Survey (SDSS) i-band imaging of similar depth but lower resolution. We found that post-starbursts in our sample have intermediate morphologies between disk- and bulge-dominated (Sérsic n = 1.7 − 0.0 + 0.3 ) and have red bulges, likely due to dust obscuration in the cores. A majority of galaxies in our sample are more morphologically disturbed than regular galaxies (88%, corresponding to >3σ significance) when observed with HST, with asymmetry and Sérsic residual flux fraction being the most successful measures of disturbance. Most disturbances are undetected at the lower resolution of SDSS imaging. Although ∼27% galaxies are clear merger remnants, we found that disturbances in another ∼30% of the sample are internal, caused by small-scale perturbations or dust substructures rather than tidal features, and require high-resolution imaging to detect. We found 2.8σ evidence that asymmetry features fade on timescales ∼200 Myr, and may vanish entirely after ∼750 Myr, so we do not rule out a possible merger origin of all post-starbursts given that asymmetric features may have already faded. This work highlights the importance of small-scale disturbances, detected only in high-resolution imaging, in understanding structural evolution of transitioning galaxies.

Polymorphism of Kdo-Based Glycolipids: The Elaborately Determined Stable and Dynamic Bicelles

Polymorphism of Kdo-Based Glycolipids: The Elaborately Determined Stable and Dynamic Bicelles

Gene Flow and Diversification in Himalopsyche martynovi Species Complex (Trichoptera: Rhyacophilidae) in the Hengduan Mountains

Simple SummaryHimalopsyche is a group of aquatic insects endemic to the Hengduan Mountains, of which species are usually easily identifiable based on male genitalia, except for a few morphologically variable groups including the Himalopsyche martynovi complex. In order to clarify species boundaries within this complex, we investigated its evolutionary history (phylogenetics and gene flow analyses) using a large genomic dataset (~500,000 sites). We found three clades in the Himalopsyche martynovi complex, one of which being very variable morphologically while being involved in gene flow with other related lineages. When interpreted in the light of past geological, climatic and palaeohydrological changes, our study suggests that biological novelty—here, trait variation and recombination—may have been acquired via hybridization and represent a source of mountain biodiversity.The Hengduan Mountains are one of the most species-rich mountainous areas in the world. The origin and evolution of such a remarkable biodiversity are likely to be associated with geological or climatic dynamics, as well as taxon-specific biotic processes (e.g., hybridization, polyploidization, etc.). Here, we investigate the mechanisms fostering the diversification of the endemic Himalopsyche martynovi complex, a poorly known group of aquatic insects. We used multiple allelic datasets generated from 691 AHE loci to reconstruct species and RaxML phylogenetic trees. We selected the most reliable phylogenetic tree to perform network and gene flow analyses. The phylogenetic reconstructions and network analysis identified three clades, including H. epikur, H. martynovi sensu stricto and H. cf. martynovi. Himalopsyche martynovi sensu stricto and H. cf. martynovi present an intermediate morphology between H. epikur and H. viteceki, the closest known relative to the H. martynovi-complex. The gene flow analysis revealed extensive gene flow among these lineages. Our results suggest that H. viteceki and H. epikur are likely to have contributed to the evolution of H. martynovi sensu stricto and H. cf. martynovi via gene flow, and thus, our study provides insights in the diversification process of a lesser-known ecological group, and hints at the potential role of gene flow in the emergence of biological novelty in the Hengduan Mountains.

Species Delimitation and Conservation in Taxonomically Challenging Lineages: The Case of Two Clades of Capurodendron (Sapotaceae) in Madagascar.

Capurodendron is the largest endemic genus of plants from Madagascar, with around 76% of its species threatened by deforestation and illegal logging. However, some species are not well circumscribed and many of them remain undescribed, impeding a confident evaluation of their conservation status. Here we focus on taxa delimitation and conservation of two species complexes within Capurodendron: the Arid and Western complexes, each containing undescribed morphologies as well as intermediate specimens alongside well-delimited taxa. To solve these taxonomic issues, we studied 381 specimens morphologically and selected 85 of them to obtain intergenic, intronic, and exonic protein-coding sequences of 794 nuclear genes and 227 microsatellite loci. These data were used to test species limits and putative hybrid patterns using different approaches such as phylogenies, PCA, structure analyses, heterozygosity level, FST, and ABBA-BABA tests. The potential distributions were furthermore estimated for each inferred species. The results show that the Capurodendron Western Complex contains three well-delimited species, C. oblongifolium, C. perrieri, and C. pervillei, the first two hybridizing sporadically with the last and producing morphologies similar to, but genetically distinct from C. pervillei. The Arid Complex shows a more intricate situation, as it contains three species morphologically well-delimited but genetically intermixed. Capurodendron mikeorum nom. prov. is shown to be an undescribed species with a restricted distribution, while C. androyense and C. mandrarense have wider and mostly sympatric distributions. Each of the latter two species contains two major genetic pools, one showing interspecific admixture in areas where both taxa coexist, and the other being less admixed and comprising allopatric populations having fewer contacts with the other species. Only two specimens out of 172 showed clear genetic and morphological signals of recent hybridization, while all the others were morphologically well-delimited, independent of their degree of genetic admixture. Hybridization between Capurodendron androyense and C. microphyllum, the sister species of the Arid Complex, was additionally detected in areas where both species coexist, producing intermediate morphologies. Among the two complexes, species are well-defined morphologically with the exception of seven specimens (1.8%) displaying intermediate patterns and genetic signals compatible with a F1 hybridization. A provisional conservation assessment for each species is provided.

A fossil record of land plant origins from charophyte algae.

Molecular time trees indicating that embryophytes originated around 500 million years ago (Ma) during the Cambrian are at odds with the record of fossil plants, which first appear in the mid-Silurian almost 80 million years later. This time gap has been attributed to a missing fossil plant record, but that attribution belies the case for fossil spores. Here, we describe a Tremadocian (Early Ordovician, about 480 Ma) assemblage with elements of both Cambrian and younger embryophyte spores that provides a new level of evolutionary continuity between embryophytes and their algal ancestors. This finding suggests that the molecular phylogenetic signal retains a latent evolutionary history of the acquisition of the embryophytic developmental genome, a history that perhaps began during Ediacaran-Cambrian time but was not completed until the mid-Silurian (about 430 Ma).

The timing of land plant origins

Paleobotany Until now, the first fossil evidence of land plants was from the Devonian era 420 million years ago. However, molecular phylogenetic evidence has suggested an earlier origin in the Cambrian. Strother and Foster describe an assemblage of fossil spores from Ordivician deposits in Australia dating to approximately 480 million years ago (see the Perspective by Gensel). These spores are of intermediate morphology between confirmed land plant spores and earlier forms of uncertain relationship. This finding may help to resolve discrepancies between molecular and fossil data for the timing of land plant origins. Science , abj2927, this issue p. [792][1]; see also abl5297, p. [736][2] [1]: /lookup/doi/10.1126/science.abj2927 [2]: /lookup/doi/10.1126/science.abl5297

Morphology mirrors trophic niche in a freshwater amphipod community

Abstract Amphipod crustaceans are ubiquitous in temperate freshwaters, where they radiated multiple times in a broad range of habitats. This has led to significant morphological and ecological disparity. However, a limited knowledge of functional morphology and its relation to ecology has often led to the view that freshwater amphipods are omnivorous shredders. Herein, we hypothesise that trophic differentiation is related to functional morphology in a sympatric assemblage of three species belonging to three widespread families: Crangonyctidae, Gammaridae, and Niphargidae. We quantified seasonal diet composition by examining gut contents, and measured 42 functional morphological traits. Our results reveal a clear trophic and morphological differentiation among these sympatric species. The carnivorous Niphargus valachicus exhibited predatory traits exemplified by a smaller molar surface and stomach length, and larger/longer grasping, locomotory, and sensory appendages in comparison to the herbivorous Gammarus dacicus. The third species, Synurella ambulans, was omnivorous given its intermediate diet and morphology. We did not find consistent evidence for seasonal diet variation, except for the summer and winter diet of G. dacicus. The observed niches stretched along a broad trophic spectrum, indicating that even small riverine amphipod communities can exhibit significant functional disparity. The apparent connection between morphology and diet is similar to that observed in other crustaceans, strengthening our mechanistic understanding of the niche–morphology link. However, the generality of these conclusions needs to be tested on larger species datasets.

Asymmetric hybridization origin of Rhododendron agastum (Ericaceae) in Guizhou, China

Rhododendron is one of the famous flowers in the world. Four wild Rhododendron species, namely, R. delavayi Franch., R. agastum Balf. f. et W. W. Smith., R. decorum Franch., and R. irroratum Franch., belong to subgenus Hymenanthes, which are sympatrically distributed in the Baili Rhododendron Nature Reserve of Guizhou Province, China. The intermediate morphology of R. agastum in the reserve, which is between R. delavayi and R irroratum or between R. delavayi and R. decorum, has been speculated that R. agastum is a hybrid of one of the two combinations. However, the exact parentage of R. agastum in the reserve remains controversial. In this study, the four Rhododendron species were investigated to identify the parental origin of R. agastum based on 13 morphological characteristics, 20 co-dominant inherited microsatellite markers, and two maternal inherited plastid DNA makers. Results of genetic structure and origin scenario clearly support that R. agastum is a natural hybrid between R. delavayi and R. irroratum rather than R. delavayi and R. decorum, which is consistent with their morphological characteristics. In addition, hybridization analysis indicates that R. agastum is dominated by F2 generation in the reserve. Furthermore, haplotype analysis suggests that natural hybridization between R. delavayi and R. irroratum is bidirectional but asymmetric with R. delavayi, the main maternal parent of R. agastum. Our results provide theoretical basis for future utilization and conservation of genetic resources of these Rhododendron species.

Genetic Structure of the Goniopora lobata and G. djiboutiensis Species Complex Is Better Explained by Oceanography Than by Morphological Characteristics

Species delimitation of closely related corals is often challenging due to high intraspecies morphological variation and phenotypic plasticity with a lack of characteristic features and scarcity of relevant molecular markers. Goniopora spp. are one such coralline group, and the species status of Goniopora lobata and Goniopora djiboutiensis, an Indian and Pacific Ocean hermatypic coral species complex, has been questioned on the basis of previous molecular and morphological analyses. To further examine the species boundaries between G. lobata and G. djiboutiensis in Japan, specimens collected from areas spanning from Ryukyu Island to temperate Japanese regions were morphologically identified based on traditional morphological descriptions. Then, the genetic structure of the G. lobata and G. djiboutiensis species complex was examined using six newly developed microsatellite markers. The majority of the collected specimens had intermediate morphologies, and a STRUCTURE analysis using the LOCPRIOR model based on typical G. lobata and G. djiboutiensis morphology indicated that there were no genetic differences between these morphologies. On the other hand, STRUCTURE analysis based on oceanographic regions revealed that there was a genetic break between the temperate and subtropical regions. This weak genetic break corresponded with the Kuroshio-associated barrier, which prevents larval transport between subtropical and temperate regions. This study confirms that the current morphological identification criteria for G. lobata and G. djiboutiensis do not match the existing genetic boundaries and thus the two should be regarded as a species complex. This study also highlighted the robustness of using a multi-locus population genetic approach, including a geographic context, to confirm the species boundaries of closely related species.

Sequential Lymphoma between Classical Hodgkin Lymphoma and Diffuse Large B Cell Lymphoma: Clinicopathological Characteristics and Outcome of 18 Patients from Lysa Center

Sequential Lymphoma between Classical Hodgkin Lymphoma and Diffuse Large B Cell Lymphoma: Clinicopathological Characteristics and Outcome of 18 Patients from Lysa Center

Thermosetting supramolecular polymerization of compartmentalized DNA fibers with stereo sequence and length control

Thermosetting supramolecular polymerization of compartmentalized DNA fibers with stereo sequence and length control

Genomic analyses overturn two long-standing homoploid hybrid speciation hypotheses.

The importance of hybridization in generating biological diversity has been historically controversial. Previously, inference about hybridization was limited by dependence on morphological data; with the advent of the next-generation sequencing tools for nonmodel organisms, the evolutionary significance of hybridization is more evident. Here, we test classic hypotheses of hybrid origins of two species in the Phlox pilosa complex. Morphological intermediacy motivated the hypotheses that Phlox amoena lighthipei and Phlox pilosa deamii were independent homoploid hybrid lineages derived from P. amoena amoena and P. pilosa pilosa. We use double-digest restriction site-associated DNA sequencing of individuals from throughout the range of these taxa to conduct the most thorough analysis of evolutionary history in this system to date. Surprisingly, we find no support for the hybrid origin of P. pilosa deamii or P. amoena lighthipei. Our data do identify a history of admixture in individuals collected at a contemporary hybrid zone between the putative parent lineages. We show that three very different evolutionary histories, only one of which involves hybrid origin, have produced intermediate or recombinant morphological traits between P. amoena amoena and P. pilosa pilosa. Although morphological data are still an efficient means of generating hypotheses about past gene flow, genomic data are now the standard of evidence for elucidating evolutionary history.

The rare Calappa tuerkayana Pastore, 1995 is a juvenile stage of the common Calappa granulata (Linnaeus, 1758) (Brachyura: Calappidae)

In the Mediterranean Sea, four species of the genus Calappa (Family Calappidae) are known, namely Calappa granulata (type species of the genus by subsequent designation), Calappa pelii, Calappa rosea, and Calappa tuerkayana. We hereby first tested the status of C. tuerkayana as a valid species through an integrative approach, thus analyzing morphologically and genetically specimens of both C. tuerkayana and C. granulata and comparing them with congeners. Molecular analyses based on mitochondrial and nuclear markers suggested that they account for a single species. Absence of ovigerous females in C. tuerkayana and presence of middle-sized specimens showing intermediate morphology in carapace and sexual organs between the two taxa point to the evidence that C. tuerkayana was described on a juvenile stage of C. granulata. The present paper makes C. tuerkayana a junior synonym of C. granulata, fills a gap in the knowledge of the ontogenetic changes of the common Mediterranean shame-faced crab during its various life stages, and first offers a redescription of C. granulata that includes its juveniles.

Structure–Property Relationships in Single-Ion Conducting Multiblock Copolymers: A Phase Diagram and Ionic Conductivities

We investigated the nanoscale morphologies and ionic conductivities of polyethylene-based multiblock copolymers as single-ion conducting polymer electrolytes. These polymers contain short polar blocks with a single sodium sulfonate group separated by polyethylene blocks of fixed length (PESxNa, x = 10, 12, and 18). At room temperature, these multiblock copolymers exhibit layered ionic aggregates with semicrystalline polyethylene backbones. For PES12Na and PES18Na, the layered ionic aggregate morphologies transition into Ia3d gyroid morphologies upon melting the polyethylene blocks and further transition into hexagonal morphologies at higher temperatures. With a shorter polyethylene block, PES10Na exhibits a layered to hexagonal transition at the melting temperature, without an intermediate gyroid morphology. The phase diagram of these PESxNa polymers is reminiscent of conventional diblock copolymers and identifies the presence of gyroid morphologies at a polar block volume fraction of ∼0.27 to 0.41, which is broad compared to typical diblock copolymers. Temperature-dependent ionic conductivities reveal faster ion transport through bicontinuous gyroids than hexagonal ionic aggregate morphologies and a relationship between conductivity and the characteristic distance between ionic aggregates. This study presents material design strategies for single-ion conducting polymers with a bicontinuous ionic aggregate and toward efficient ion transport.

The fast and the tendinous? Locomotor modifications of the caudal peduncle in Gila spp. from the American Southwest

In the American Southwest, the fishes within the genus Gila evolved in an environment with seasonal rainstorms that caused stochastic flooding. Some species within this genus, such as bonytail (Gila elegans), possess locomotor morphologies that are similar to those seen in high-performance swimmers such as tuna and lamnid sharks. These shared features include a shallow caudal peduncle, lunate tail, and mechanisms to transmit force from the anterior musculature to the tail fin. We compared the skeletal anatomy of the caudal region of bonytail to roundtail chub (Gila robusta) and humpback chub (Gila cypha) to determine which vertebral elements have been modified to create a shallow peduncle. We also tested the tensile strength of the red (slow oxidative) axial muscle by performing a standard stress test. If the muscle can withstand a large load, this suggests it may play a tendon-like role in transmitting force from the anterior muscle to the hypural plate of the tail. Lastly, we measured the collagen content of the red axial muscle (visualized using serial sections and Masson’s trichrome stain) to determine if increased tensile strength is associated with increased collagen content. We found bonytail caudal peduncles are characterized by acute vertebral spines and have red axial muscle that can resist tearing under tension. Roundtail chub peduncles are characterized by relatively more obtuse angles and the red muscle tears easily under tension. Humpback chub possess an intermediate morphology, with relatively obtuse vertebral spine angles and the red muscle can resist tearing under tension. Bonytail have increased collagen content in posterior red axial muscle compared to the anterior musculature also suggesting a tendon-like role of the posterior red muscle. In combination with previous studies of swimming performance, our findings suggest that the axial musculature of bonytail may play a role in transmitting force directly to the shallow peduncle in a manner similar to that of the great lateral tendon of scombrids.

Construction of Highly Ordered Glyco‐Inside Nano‐Assemblies through RAFT Dispersion Polymerization of Galactose‐Decorated Monomer

AbstractGlyco‐assemblies derived from amphiphilic sugar‐decorated block copolymers (ASBCs) have emerged prominently due to their wide application, for example, in biomedicine and as drug carriers. However, to efficiently construct these glyco‐assemblies is still a challenge. Herein, we report an efficient technology for the synthesis of glyco‐inside nano‐assemblies by utilizing RAFT polymerization of a galactose‐decorated methacrylate for polymerization‐induced self‐assembly (PISA). Using this approach, a series of highly ordered glyco‐inside nano‐assemblies containing intermediate morphologies were fabricated by adjusting the length of the hydrophobic glycoblock and the polymerization solids content. A specific morphology of complex vesicles was captured during the PISA process and the formation mechanism is explained by the morphology of its precursor and intermediate. Thus, this method establishes a powerful route to fabricate glyco‐assemblies with tunable morphologies and variable sizes, which is significant to enable the large‐scale fabrication and wide application of glyco‐assemblies.

Genomic Variation and Recent Population Histories of Spotted (Strix occidentalis) and Barred (Strix varia) Owls.

Spotted owls (SOs, Strix occidentalis) are a flagship species inhabiting old-growth forests in western North America. In recent decades, their populations have declined due to ongoing reductions in suitable habitat caused by logging, wildfires, and competition with the congeneric barred owl (BO, Strix varia). The northern spotted owl (S. o. caurina) has been listed as “threatened” under the Endangered Species Act since 1990. Here, we use an updated SO genome assembly along with 51 high-coverage whole-genome sequences to examine population structure, hybridization, and recent changes in population size in SO and BO. We found that potential hybrids identified from intermediate plumage morphology were a mixture of pure BO, F1 hybrids, and F1 × BO backcrosses. Also, although SO underwent a population bottleneck around the time of the Pleistocene–Holocene transition, their population sizes rebounded and show no evidence of any historical (i.e., 100–10,000 years ago) population decline. This suggests that the current decrease in SO abundance is due to events in the past century. Finally, we estimate that western and eastern BOs have been genetically separated for thousands of years, instead of the previously assumed recent (i.e., <150 years) divergence. Although this result is surprising, it is unclear where the ancestors of western BO lived after the separation. In particular, although BO may have colonized western North America much earlier than the first recorded observations, it is also possible that the estimated divergence time reflects unsampled BO population structure within central or eastern North America.

Construction of Highly Ordered Glyco-Inside Nano-Assemblies through RAFT Dispersion Polymerization of Galactose-Decorated Monomer.

Glyco‐assemblies derived from amphiphilic sugar‐decorated block copolymers (ASBCs) have emerged prominently due to their wide application, for example, in biomedicine and as drug carriers. However, to efficiently construct these glyco‐assemblies is still a challenge. Herein, we report an efficient technology for the synthesis of glyco‐inside nano‐assemblies by utilizing RAFT polymerization of a galactose‐decorated methacrylate for polymerization‐induced self‐assembly (PISA). Using this approach, a series of highly ordered glyco‐inside nano‐assemblies containing intermediate morphologies were fabricated by adjusting the length of the hydrophobic glycoblock and the polymerization solids content. A specific morphology of complex vesicles was captured during the PISA process and the formation mechanism is explained by the morphology of its precursor and intermediate. Thus, this method establishes a powerful route to fabricate glyco‐assemblies with tunable morphologies and variable sizes, which is significant to enable the large‐scale fabrication and wide application of glyco‐assemblies.

Hollow flower-like nickel particles as the promoter of ammonium perchlorate-based solid propellant

Hollow flower-like nickel particles were prepared by a facile polyol method, and applied to solid propellant as combustion promoter. Ni[C2H4(NH2)2]3(COOH)2 complex was used to fabricate hollow flower-like intermediate in ethylene glycol (EG), and then the intermediate was calcined and auto-reduced in nitrogen to obtain the hollow flower-like nickel particles. The hollow particles' shell thickness is about 120 nm, and the petals' thickness of the flower structure is about 10 nm. Importantly, the hollow spheres' diameter can be accurately controlled from 200 nm to 2 μm by adjusting the concentration of complex Ni[C2H4(NH2)2]3(COOH)2 in the reaction solution. The growth of the hollow flower-like particles was illustrated as an extraordinary growth-shrink-collapse process by analyzing the intermediate's morphologies as reaction going on. By adding a certain amount (typically 5 wt%) of the prepared nickel powders, the exothermic decomposition of ammonium perchlorate, which is the main component of solid propellant, was well promoted. The decomposition temperature was decreased by about 140 °C, and the exothermic peak at higher temperature shifted to the lower temperature range, heat released of AP's decomposition also increased by about 150%.