Using broadband seismic waveforms recorded on the seafloor by more than 200 broadband ocean bottom seismometers, as well as those on land, we measured the phase speed dispersions of Love and Rayleigh ...waves up to the 4th higher mode to determine the three-dimensional radially anisotropic shear-wave speed structure in the upper mantle beneath the Pacific Ocean. The fastest anomalies at depths shallower than 100 km were located beneath southeast of the Shatsky Rise and strong radial anisotropy was located in the central Pacific at depths of 100–200 km. The isotropic shear-wave speed structures showed age dependence. From the age-bin-averaged shear-wave speed profiles and a half-space cooling model, we estimated the thermo-speed relationship for the Pacific Plate to construct a reference age-dependent shear-wave speed model, which was further used as an initial model for tomography iteration. Deviation maps in the Pacific Ocean from the reference model indicated that large negative residuals, which may be due to partial melting, anelasticity, and/or added heat from mantle plumes, were located along the ridges and beneath hotspots, and that large positive residuals were found beneath the northwestern Pacific Ocean. The use of an age-dependent reference model, as well as the incorporation of OBS data, greatly improves the accuracy of local phase speed estimates in tomography, as evident from a direct comparison with in situ array measurements.
•Using seafloor and land data, we obtained the upper mantle structure in the Pacific.•Isotropic shear wave structure shows clear age dependence.•Reference age-dependent shear wave model is used for tomography inversion.•Large residuals from the age-dependent model are located beneath the hotspots.•Seafloor data and age-dependent model improves the accuracy of tomography.
Caenis rivulorum
Eaton, 1884 is widely distributed and has been reported from a wide range in the Palearctic Region.
We report this species from Japan for the first time, from five localities of ...Hokkaido, based on morphology and molecular data.
The evolution of a female penis is an extremely rare event and is only known to have occurred in a tribe of small cave insects, Sensitibillini (Psocodea: Trogiomorpha: Prionoglarididae). The female ...penis, which is protrudable and inserted into the male vagina‐like cavity during copulation to receive semen, is thought to have evolved independently twice in this tribe, in the Brazilian Neotrogla and the African Afrotrogla. These findings strongly suggest that there are some factors unique to Sensitibillini that have facilitated female penis evolution. Here, several hypothetical factors are presented that may have enabled the evolution of the female penis in Sensitibillini. The female–female competition for nutritious semen, the oligotrophic environment, and the twin insemination slots with switching valve are considered to be the driving factors for female penis evolution. Additionally, the following factors are considered responsible for relaxing the constraint against female penis evolution: preexistence of the female‐above mating position, the elongated duct connecting the female pre‐penis with the sperm storage organ, and the small male genital cavity accepting the female genital tubercle bearing the opening of this duct. Understanding the factors enabling female penis evolution may also shed light on the evolution of the male penis.
The evolution of a female penis is an extremely rare event and is only known to have occurred in a tribe of small cave insects, Sensitibillini (Psocodea: Prionoglarididae). Here, the hypotheses about the factors favoring/constraining the evolution of a female penis are presented.
Palaeosiamoglaris hkamtiensis sp. nov. of the family Prionoglarididae is described from Hkamti amber (ca. 110 Ma), together with Psyllipsocus myanmarensis sp. nov., the third fossil psyllipsocid ...species described from Noije Bum Hill (ca. 98 Ma). Based on the current observations of Palaeosiamoglaris hkamtiensis sp. nov., we discuss the synapomorphic characters proposed to define the tribe Siamoglaridini. Palaeosiamoglaris hkamtiensis sp. nov. is, inter alia, characterized by the maxillary palpomere 3 ca. 0.66 times as long as maxillary palpomere 4, the second anal vein concavity turned toward posterior wing margin in forewing, Sc reaching R1 nearly at middle of radial cell. The new species Psyllipsocus myanmarensis sp. nov. is, inter alia, characterized by antennae with 11 segments, the radial cell closed and six-angled, and the quadrangular pterostigma.
Recent molecular phylogenetic analyses of 18S rDNA have indicated that parasitic lice (order Phthiraptera) are possibly polyphyletic. These analyses recovered one of the parasitic louse suborders, ...Amblycera, as the sister group to the free-living booklouse family Liposcelididae. We further tested this hypothesis using DNA sequences from five genes: nuclear 18S rDNA, Histone 3, and wingless and mitochondrial 16S rDNA and COI. Combined analyses of these five genes provided reasonably strong support for the Amblycera
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Liposcelididae clade, supporting the polyphyly of lice hypothesis. To explore the robustness of this result, we examined the phylogenetic signal contained in each gene independently (except for wingless, which could not be readily amplified in many target taxa). Analyses of each gene separately and in various combinations with other genes revealed that clear signal supporting Amblycera
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Liposcelididae only existed in the 18S data, although no analysis supported monophyly of parasitic lice. Nevertheless, combined analyses of all genes provided stronger support for this relationship than that obtained from 18S data alone. The increase in support for this clade was mostly explained by the stabilization of other parts of the tree and potentially inappropriate substitution modeling. These findings demonstrate that the increased support values provided by combined data set does not always indicate corroboration of the hypothesis.
Morphological and behavioral characters are frequently examined for comparative studies. Unlike morphology, a single behavioral trait is difficult to subdivide as multiple characters, even when ...achieved by many evolutionary changes. Therefore, when similar behavioral traits evolved independently among closely related taxa, their distinction is difficult. Almost all members of the suborder Auchenorrhyncha (Insecta: Hemiptera) possess a jumping ability that uses metathoracic muscles, and this behavioral trait has been regarded as a synapomorphy. In this study, the anatomical observations of metathoracic muscles revealed that highly elaborated jumping ability was gained independently within the suborder, although the evolution of jumping ability might have been initiated at their common ancestor. Our results provide an example of identifying a true evolutionary pathway by dissecting a behavioral character into mechanical elements.
We report a functional switching valve within the female genitalia of the Brazilian cave insect
. The valve complex is composed of two plate-like sclerites, a closure element, and in-and-outflow ...canals. Females have a penis-like intromittent organ to coercively anchor males and obtain voluminous semen. The semen is packed in a capsule, whose formation is initiated by seminal injection. It is not only used for fertilization but also consumed by the female as nutrition. The valve complex has two slots for insemination so that
can continue mating while the first slot is occupied. In conjunction with the female penis, this switching valve is a morphological novelty enabling females to compete for seminal gifts in their nutrient-poor cave habitats through long copulation times and multiple seminal injections. The evolution of this switching valve may have been a prerequisite for the reversal of the intromittent organ in
.
The order Zoraptera is one of the most enigmatic insect groups. Its phylogenetic position is far from settled, and more than ten different placements have been discussed since the insects were first ...discovered. This problem is also difficult to resolve with molecular studies because of the unusual characteristics of zorapteran 18S rDNA sequences, which are the most widely used genetic markers for the estimation of the deep phylogeny of insects. In this study, the wing base structures of Zoraptera and various potential sister taxa were examined. Numbers of unique modifications were detected in the wing base structure of Zoraptera, and six were also observed in the wing base of Embiodea (Embioptera, Embiidina; webspinners). No possible synapomorphies supporting the other relationships were detected. This is the second unambiguous morphological synapomorphy providing strong evidence for the phylogenetic position of Zoraptera.
The gene composition, gene order and structure of the mitochondrial genome are remarkably stable across bilaterian animals. Lice (Insecta: Phthiraptera) are a major exception to this genomic ...stability in that the canonical single chromosome with 37 genes found in almost all other bilaterians has been lost in multiple lineages in favour of multiple, minicircular chromosomes with less than 37 genes on each chromosome.
Minicircular mt genomes are found in six of the ten louse species examined to date and three types of minicircles were identified: heteroplasmic minicircles which coexist with full sized mt genomes (type 1); multigene chromosomes with short, simple control regions, we infer that the genome consists of several such chromosomes (type 2); and multiple, single to three gene chromosomes with large, complex control regions (type 3). Mapping minicircle types onto a phylogenetic tree of lice fails to show a pattern of their occurrence consistent with an evolutionary series of minicircle types. Analysis of the nuclear-encoded, mitochondrially-targetted genes inferred from the body louse, Pediculus, suggests that the loss of mitochondrial single-stranded binding protein (mtSSB) may be responsible for the presence of minicircles in at least species with the most derived type 3 minicircles (Pediculus, Damalinia).
Minicircular mt genomes are common in lice and appear to have arisen multiple times within the group. Life history adaptive explanations which attribute minicircular mt genomes in lice to the adoption of blood-feeding in the Anoplura are not supported by this expanded data set as minicircles are found in multiple non-blood feeding louse groups but are not found in the blood-feeding genus Heterodoxus. In contrast, a mechanist explanation based on the loss of mtSSB suggests that minicircles may be selectively favoured due to the incapacity of the mt replisome to synthesize long replicative products without mtSSB and thus the loss of this gene lead to the formation of minicircles in lice.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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