Large-scale phylogenomics of the genus Macrostomum (Platyhelminthes) reveals cryptic diversity and novel sexual traits

Abstract Large-scale global efforts on DNA barcoding have repeatedly revealed unexpected patterns of variability in mtDNA, including deep intraspecific divergences and haplotype sharing between species. Understanding the evolutionary causes behind these patterns calls for insights from the nuclear genome. While building a near-complete DNA barcode library of Finnish caddisflies, a case of barcode-sharing and some cases of deep intraspecific divergences were observed. In this study, the Apatania zonella (Zetterstedt, 1840) group and three Limnephilus Leach, 1815 species were studied using double digest RAD sequencing (ddRAD-seq), morphology, and DNA barcoding. The results support the present species boundaries in the A. zonella group species. A morphologically distinct but mitogenetically nondistinct taxon related to parthenogenetic Apatania hispida (Forsslund, 1930) got only weak support for its validity as a distinct species. The morphology and genomic-scale data do not indicate cryptic diversity in any of the three Limnephilus species despite the observed deep intraspecific divergences in DNA barcodes. This demonstrates that polymorphism in mtDNA may not reflect cryptic diversity, but mitonuclear discordance due to other evolutionary causes.

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‌‌Cryptic‌ ‌diversity‌ ‌within‌ ‌the‌ ‌‌Poecilochirus‌ ‌carabi‌ ‌mite‌ ‌species‌ ‌complex‌ ‌phoretic‌ ‌on‌ ‌‌Nicrophorus‌ ‌burying‌ ‌beetles:‌ ‌phylogeny,‌ ‌biogeography, and host specificity

10.1101/2021.05.20.443311 ◽

2021 ◽

Author(s):

Julia Canitz ◽

Derek S Sikes ◽

Wayne Knee ◽

Julia Baumann ◽

Petra Haftaro ◽

...

Keyword(s):

Large Scale ◽

Evolutionary Ecology ◽

Molecular Data ◽

Sensu Stricto ◽

Biological Species ◽

Morphological Divergence ◽

Cryptic Diversity ◽

Abiotic Conditions ◽

Genetic Clusters ◽

Geographic Separation

Coevolution is often considered a major driver of speciation, but evidence for this claim is not always found because diversity might be cryptic. When morphological divergence is low, molecular data are needed to uncover diversity. A taxon for which this holds true are the mites, which are known for their extensive and often cryptic diversity. We studied mites of the genus Poecilochirus that are phoretic on burying beetles (Silphidae: Nicrophorus). Poecilochirus taxonomy is poorly understood. Most studies on this genus focus on the evolutionary ecology of Poecilochirus carabi sensu lato, a complex of at least two biological species. Based on molecular data of 232 specimens from 44 locations worldwide, we identified 24 genetic clusters that may represent species. We estimate that these mites began to diversify during the Paleogene, when the clade containing P. subterraneus branched off and the remaining mites diverged into two further clades. One clade resembles P. monospinosus and P. austroasiaticus. The other clade contains 17 genetic clusters resembling P. carabi s.l.. Among these are P. carabi sensu stricto, P. necrophori, and potentially many additional cryptic species. Our analyses suggest that these clades were formed in the miocene by large-scale geographic separation. Diversification also seems to have happened on a smaller scale, potentially due to adaptation to specific hosts or local abiotic conditions, causing some clusters to specialize on certain beetle species. Our results suggest that biodiversity in this genus was generated by multiple interacting forces shaping the tangled webs of life.

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Large-scale phylogenomics of the genus Macrostomum (Platyhelminthes) reveals cryptic diversity and novel sexual traits

10.1101/2021.03.28.437366 ◽

2021 ◽

Cited By ~ 1

Author(s):

Jeremias N. Brand ◽

Gudrun Viktorin ◽

R. Axel W. Wiberg ◽

Christian Beisel ◽

Lukas Schärer

Keyword(s):

Large Scale ◽

Model Organism ◽

Phylogenetic Information ◽

Free Living ◽

Additional Species ◽

Phylogenetic Methods ◽

Sampling Campaign ◽

Molecular Phylogenetic ◽

Sexual Traits ◽

Future Work

AbstractFree-living flatworms of the genus Macrostomum are small and transparent animals, representing attractive study organisms for a broad range of topics in evolutionary, developmental, and molecular biology. The genus includes the model organism M. lignano for which extensive molecular resources are available, and recently there is a growing interest in extending work to additional species in the genus. These endeavours are currently hindered because, even though >200 Macrostomum species have been taxonomically described, molecular phylogenetic information and geographic sampling remain limited. We report on a global sampling campaign aimed at increasing taxon sampling and geographic representation of the genus. Specifically, we use extensive transcriptome and single-locus data to generate phylogenomic hypotheses including 145 species. Across different phylogenetic methods and alignments used, we identify several consistent clades, while their exact grouping is less clear, possibly due to a radiation early in Macrostomum evolution. Moreover, we uncover a large undescribed diversity, with 94 of the studied species likely being new to science, and we identify multiple novel morphological traits. Furthermore, we identify cryptic speciation in a taxonomically challenging assemblage of species, suggesting that the use of molecular markers is a prerequisite for future work, and we describe the distribution of possible synapomorphies and suggest taxonomic revisions based on our finding. Our large-scale phylogenomic dataset now provides a robust foundation for comparative analyses of morphological, behavioural and molecular evolution in this genus.

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Eunuchs or Females? Causes and Consequences of Gynodioecy on Morphology, Ploidy, and Ecology of Stellaria graminea L. (Caryophyllaceae)

Frontiers in Plant Science ◽

10.3389/fpls.2021.589093 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jaromír Kučera ◽

Marek Svitok ◽

Eliška Gbúrová Štubňová ◽

Lenka Mártonfiová ◽

Clément Lafon Placette ◽

...

Keyword(s):

Sexual Selection ◽

Life History ◽

Reproductive Strategy ◽

Large Scale ◽

Flower Morphology ◽

Divergent Evolution ◽

Ecological Niches ◽

Wide Range ◽

Speciation Continuum ◽

Sexual Traits

Plant speciation results from intricate processes such as polyploidization, reproductive strategy shifts and adaptation. These evolutionary processes often co-occur, blurring their respective contributions and interactions in the speciation continuum. Here, relying on a large-scale study, we tested whether gynodioecy triggers the divergent evolution of flower morphology and genome between sexes, and contributes to the establishment of polyploids and colonization of ecological niches in Stellaria graminea. We found that gynodioecy in S. graminea leads to flower morphology divergence between females and hermaphrodites, likely due to sexual selection. Contrary to our expectations, gynodioecy occurs evenly in diploids and tetraploids, suggesting that this reproductive strategy was not involved in the establishment of polyploids. Both diploid and tetraploid females have a larger genome size than hermaphrodites, suggesting the presence of sex chromosomes. Finally, ecology differs between cytotypes and to a lesser extent between sexes, suggesting that the link between environment and presence of females is indirect and likely explained by other aspects of the species’ life history. Our study shows that gynodioecy leads to the consistent evolution of sexual traits across a wide range of populations, cytotypes and environments within a given species, and this likely contributes to the phenotypic and genetic distinctiveness of the species from its sister clades.

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Polyphyly and cryptic diversity in the hydrozoan families Lafoeidae and Hebellidae (Cnidaria:Hydrozoa)

Invertebrate Systematics ◽

10.1071/is11045 ◽

2011 ◽

Vol 25 (5) ◽

pp. 454 ◽

Cited By ~ 15

Author(s):

Carlos J. Moura ◽

Marina R. Cunha ◽

Filipe M. Porteiro ◽

Alex D. Rogers

Keyword(s):

Cryptic Species ◽

Large Scale ◽

Morphological Characters ◽

Distribution Data ◽

Nominal Species ◽

Cryptic Diversity ◽

Phylogenetic Relations ◽

North East ◽

The North ◽

Deep Waters

The taxonomy of the putative superfamily Lafoeoidea (Hydrozoa), which includes the families Hebellidae and Lafoeidae, has been widely disputed at all systematic levels, mainly because these are morphologically simple and plastic animals. We used the molecular marker 16S mRNA to address phylogenetic relations of ‘Lafoeoidea’ hydroids mainly from shallow and deep waters of the north-east Atlantic and west Mediterranean. This study proves that the morphological simplicity of the ‘Lafoeoidea’ has led to several erroneous taxonomic assignments. We demonstrate that the superfamily ‘Lafoeoidea’ is not monophyletic and thus not valid; the families Hebellidae and Lafoeidae are polyphyletic. The ‘Lafoeidae’ subfamilies ‘Lafoeinae’ and ‘Zygophylacinae’ were recovered as monophyletic but quite distantly related and should be erected to the level of distinct families. The 16S haplotype data analysed in conjunction with morphological characters and distribution data were useful in differentiating morphologically undistinguishable, nominal and cryptic or pseudo-cryptic species, including undescribed taxa. Particularly within the ‘Lafoeinae’ group, unexpectedly high genetic biodiversity (including cryptic species) was encountered in the possibly not monophyletic genera Lafoea, Acryptolaria and Filellum. Cryptic diversity is also likely associated with the ‘Zygophylacinae’ nominal species Cryptolaria pectinata. The indications of genetic segregation by geographical distance of the ‘Lafoeoidea’ hydroids, particularly verified in deep waters, is probably a consequence of their reduced potential for large-scale dispersal, which likely interacts with the influence of the seabed topography, oceanographic circulation and adaptability to tolerate different abiotic conditions.

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Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

International Astronomical Union Colloquium ◽

10.1017/s0252921100031493 ◽

1999 ◽

Vol 173 ◽

pp. 243-248

Author(s):

D. Kubáček ◽

A. Galád ◽

A. Pravda

Keyword(s):

Image Processing ◽

Large Scale ◽

Harvard College ◽

Oak Ridge ◽

Large Scale Structures ◽

Short Period Comet ◽

Short Period ◽

Scale Structures ◽

Harvard College Observatory ◽

Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

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Evolution of Large-Scale Coronal Structures

International Astronomical Union Colloquium ◽

10.1017/s0252921100024945 ◽

1994 ◽

Vol 144 ◽

pp. 29-33

Author(s):

P. Ambrož

Keyword(s):

Magnetic Field ◽

Field Line ◽

Large Scale ◽

Coronal Magnetic Field ◽

Source Surface ◽

Solar Cycles ◽

Characteristic Relationship ◽

The Magnetic Field ◽

Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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Large-scale Motion of Solar Filaments

International Astronomical Union Colloquium ◽

10.1017/s0252921100064502 ◽

2000 ◽

Vol 179 ◽

pp. 205-208

Author(s):

Pavel Ambrož ◽

Alfred Schroll

Keyword(s):

Magnetic Flux ◽

Proper Motion ◽

Time Scale ◽

Large Scale ◽

Accuracy Of Measurements ◽

Solar Filaments ◽

General Movement ◽

Scale Motion ◽

Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

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Some applications of electron beam microanalysis techniques in VLSI process evaluation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007463x ◽

1983 ◽

Vol 41 ◽

pp. 160-161

Author(s):

Simon Thomas

Keyword(s):

Integrated Circuits ◽

Process Evaluation ◽

Large Scale ◽

Technology Development ◽

Analytical Techniques ◽

Successful Implementation ◽

Analysis Of Failures ◽

Characterization Of Materials ◽

Circuits Vlsi

Trends in the technology development of very large scale integrated circuits (VLSI) have been in the direction of higher density of components with smaller dimensions. The scaling down of device dimensions has been not only laterally but also in depth. Such efforts in miniaturization bring with them new developments in materials and processing. Successful implementation of these efforts is, to a large extent, dependent on the proper understanding of the material properties, process technologies and reliability issues, through adequate analytical studies. The analytical instrumentation technology has, fortunately, kept pace with the basic requirements of devices with lateral dimensions in the micron/ submicron range and depths of the order of nonometers. Often, newer analytical techniques have emerged or the more conventional techniques have been adapted to meet the more stringent requirements. As such, a variety of analytical techniques are available today to aid an analyst in the efforts of VLSI process evaluation. Generally such analytical efforts are divided into the characterization of materials, evaluation of processing steps and the analysis of failures.

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Electron microscopy study of reactively sputter-deposited Ti/N films on silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131449 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1362-1363

Author(s):

V. C. Kannan ◽

A. K. Singh ◽

R. B. Irwin ◽

S. Chittipeddi ◽

F. D. Nkansah ◽

...

Keyword(s):

Integrated Circuits ◽

Large Scale ◽

Hexagonal Phase ◽

Microscopy Study ◽

Electron Microscopy Study ◽

Process Conditions ◽

Tin Films ◽

Wide Range ◽

Fcc Phase ◽

Circuits Vlsi

Titanium nitride (TiN) films have historically been used as diffusion barrier between silicon and aluminum, as an adhesion layer for tungsten deposition and as an interconnect material etc. Recently, the role of TiN films as contact barriers in very large scale silicon integrated circuits (VLSI) has been extensively studied. TiN films have resistivities on the order of 20μ Ω-cm which is much lower than that of titanium (nearly 66μ Ω-cm). Deposited TiN films show resistivities which vary from 20 to 100μ Ω-cm depending upon the type of deposition and process conditions. TiNx is known to have a NaCl type crystal structure for a wide range of compositions. Change in color from metallic luster to gold reflects the stabilization of the TiNx (FCC) phase over the close packed Ti(N) hexagonal phase. It was found that TiN (1:1) ideal composition with the FCC (NaCl-type) structure gives the best electrical property.

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