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4,489 results for “transit”
Data from: Timing marine-freshwater transitions in the diatom order Thalassiosirales
With species found throughout both marine and fresh waters, the diatom order Thalassiosirales is one of the most phylogenetically and ecologically diverse lineages of planktonic diatoms. A clear understanding of the timescale of Thalassiosirales evolution would provide novel insights into the rates and patterns of species diversification associated with major habitat shifts, as well as provide valuable context for understanding the age and evolutionary history of the model species, Cyclotella nana (= Thalassiosira pseudonana). The freshwater fossil record for Thalassiosirales is extensive, well characterized, and generally supportive of a Miocene origin for the major freshwater lineages. The marine record is, by comparison, more sparse and in many cases, unverified. The discovery of freshwater thalassiosiroids in Eocene sediments pushed the freshwater fossil record considerably further back in time, highlighting an apparent gap of some 30 million years. An alternative interpretation is that the Miocene and Eocene reports represent competing hypotheses. In the absence of additional independent and decisive fossil data, I explored the relative plausibility of these two scenarios with Bayesian relaxed molecular clock methods under a range of fossil calibration schemes. Although I found no support for the Eocene fossil dates, the two major freshwater colonization events probably occurred much earlier than previously thought—as early as the Paleocene for Cyclotella, followed by an Eocene origin for the cyclostephanoid lineage. Much of the extant freshwater diversity in both lineages traces back to the Miocene, however, giving the impression of a single Miocene origin. Efforts to infer the timescale of Thalassiosirales evolution more accurately would benefit from a systematic reevaluation of the marine fossil record and formal integration of fossil species into existing phylogenetic hypotheses.
Supplementary data for: Mosquito phytophagy – sources exploited, ecological function, and evolutionary transition to haematophagy
<p>This dataset consists of two files:</p> <p><strong>Floral visitation records of mosquitoes</strong><br> Plant sugar, primarily in the form of floral nectar, is the ubiquitous basic food of adult mosquitoes. However, records of mosquito floral visitation are not usually the focus of research publications and, as such, are often reported as secondary parts of larger studies and are scattered throughout more than a century of scientific literature. Here we provide a summary of more than 500 recorded literature and field instances of floral and extra-floral nectary visitation by mosquitoes, including the plant and mosquito species involved as well as known pollination records.<br> <em>file name: Summary_of_Field_Mosquito_Floral_Visitation_Instances.xlsx</em></p> <p><strong>Summary of floral semiochemical blends that are attractive to mosquitoes</strong><br> Floral nectar is the primary food source of adult mosquitoes and mosquitoes, along with many other pollinators, use floral semiochemicals to locate this resource. Here we provide a summary of floral semiochemical blends attractive to mosquitoes that have been reported in the literature. The mosquito species involved have also been listed.<br> <em>file name: Summary_of_Floral_Semiochemical_Blends_Attractive_to_Mosquitoes.xlsx</em></p>
Data from: Apparent signal of competition limits diversification after ecological transitions from marine to freshwater habitats
Adaptive radiations are typically triggered when a lineage encounters a significant range of open niche space (ecological opportunity), stemming from i) colonization of new areas, ii) extinction of competitors, or iii) key innovations. The most well-known of these is the colonization of new areas, either through geographic dispersal or the invasion of a novel ecological habitats. One aspect of ecological opportunity that has rarely been studied, however, is whether the existence of potential competitors may act to limit evolutionary diversification in newly colonized adaptive zones. Here, we show that in multiple geographically independent reinvasions of freshwaters by marine Sea Catfishes (Ariidae), rates of diversification (estimated as a function of morphological disparity and cladogenesis) have been constrained by pre-existing high diversity freshwater lineages. Only one region (Australia-New Guinea), characterized by an otherwise-depauperate freshwater fauna, has an ariid invasion gained any substantial traction. This is true at both regional and community scales, suggesting that competitive constraints may be an important factor for adaptive radiation.
Data from: Homeostasis of metabolites in Escherichia coli on transition from anaerobic to aerobic conditions and the transient secretion of pyruvate
We have developed a method for rapid quenching of samples taken from chemostat cultures of Escherichia coli that gives reproducible and reliable measurements of extracellular and intracellular metabolites by 1H NMR and have applied it to study the major central metabolites during the transition from anaerobic to aerobic growth. Almost all metabolites showed a gradual change after perturbation with air, consistent with immediate inhibition of pyruvate formate-lyase, dilution of overflow metabolites and induction of aerobic enzymes. Surprisingly, although pyruvate showed almost no change in intracellular concentration, the extracellular concentration transiently increased. The absence of intracellular accumulation of pyruvate suggested that one or more glycolytic enzymes might relocate to the cell membrane. To test this hypothesis, chromosomal pyruvate kinase (pykF) was modified to express either PykF-green fluorescent protein or PykF-FLAG fusion proteins. Measurements showed that PykF-FLAG relocates to the cell membrane within 5 min of aeration and then slowly returns to the cytoplasm, suggesting that on aeration, PykF associates with the membrane to facilitate secretion of pyruvate to maintain constant intracellular levels.
Data from: A global change in RNA polymerase II pausing during the Drosophila midblastula transition
Massive zygotic transcription begins in many organisms during the midblastula transition when the cell cycle of the dividing egg slows down. A few genes are transcribed before this stage but how this differential activation is accomplished is still an open question. We have performed ChIP-seq experiments on tightly staged Drosophila embryos and show that massive recruitment of RNA polymerase II (Pol II) with widespread pausing occurs de novo during the midblastula transition. However, ∼100 genes are strongly occupied by Pol II before this timepoint and most of them do not show Pol II pausing, consistent with a requirement for rapid transcription during the fast nuclear cycles. This global change in Pol II pausing correlates with distinct core promoter elements and associates a TATA-enriched promoter with the rapid early transcription. This suggests that promoters are differentially used during the zygotic genome activation, presumably because they have distinct dynamic properties.
Data from: A phylogenomic analysis of the role and timing of molecular adaptation in the aquatic transition of cetartiodactyl mammals
Recent studies have reported multiple cases of molecular adaptation in cetaceans related to their aquatic abilities. However, none of these has included the hippopotamus, precluding an understanding of whether molecular adaptations in cetaceans occurred before or after they split from their semi-aquatic sister taxa. Here, we obtained new transcriptomes from the hippopotamus and humpback whale, and analysed these together with available data from eight other cetaceans. We identified more than 11 000 orthologous genes and compiled a genome-wide dataset of 6845 coding DNA sequences among 23 mammals, to our knowledge the largest phylogenomic dataset to date for cetaceans. We found positive selection in nine genes on the branch leading to the common ancestor of hippopotamus and whales, and 461 genes in cetaceans compared to 64 in hippopotamus. Functional annotation revealed adaptations in diverse processes, including lipid metabolism, hypoxia, muscle and brain function. By combining these findings with data on protein–protein interactions, we found evidence suggesting clustering among gene products relating to nervous and muscular systems in cetaceans. We found little support for shared ancestral adaptations in the two taxa; most molecular adaptations in extant cetaceans occurred after their split with hippopotamids.
Data from: A new phylogenetic hypothesis of turtles with implications for the timing and number of evolutionary transitions to marine lifestyles in the group
Evolutionary transitions to marine habitats occurred frequently among Mesozoic reptiles. Only one such clade survives to the present: sea turtles (Chelonioidea). Other marine turtles originated during the Mesozoic, but uncertain affinities of key fossils have obscured the number of transitions to marine life, and the timing of the origin of marine adaptation in chelonioids. Phylogenetic studies support either a highly‐inclusive chelonioid total‐group including fossil marine clades from the Jurassic and Cretaceous (e.g. protostegids, thalassochelydians, sandownids) or a less inclusive chelonioid total‐group excluding those clades. Under this paradigm, these clades belong outside Cryptodira, and represent at least one additional evolutionary transition to marine life in turtles. We present a new phylogenetic hypothesis informed by high resolution computed tomographic data of living and fossil taxa. Besides a well‐supported Chelonioidea, which includes protostegids, we recover a previously unknown clade of stem‐group turtles, Angolachelonia, which includes the Late Jurassic thalassochelydians, and the Cretaceous–Palaeogene sandownids. Accounting for the Triassic Odontochelys, our results indicate three independent evolutionary transitions to marine life in non‐pleurodiran turtles (plus an additional two‐three in pleurodires). Among all independent origins of marine habits, a pelagic ecology only evolved once, among chelonioids. All turtle groups that independently invaded marine habitats in the Jurassic–Cretaceous (chelonioids, angolachelonians, bothremydid pleurodires) survived the Cretaceous–Palaeogene mass extinction event. This highlights extensive survival of marine turtles compared to other marine reptiles. Furthermore, deeply‐nested clades such as chelonioids are found by the middle Early Cretaceous, suggesting a rapid diversification of crown‐group turtles during the Early Cretaceous.
Data from: Egg shape changes at the theropod-bird transition, and a morphometric study of amniote eggs
The eggs of amniotes exhibit a remarkable variety of shapes, from spherical to elongate and from symmetrical to asymmetrical. We examine eggshell geometry in a diverse sample of fossil and living amniotes using geometric morphometrics and linear measurements. Our goal is to quantify patterns of morphospace occupation and shape variation in the eggs of recent through to Mesozoic birds (neornithe plus non-neornithe avialans), as well as in eggs attributed to non-avialan theropods. In most amniotes, eggs show significant deviation from sphericity, but departure from symmetry around the equatorial axis is mostly confined to theropods and birds. Mesozoic bird eggs differ significantly from extant bird eggs, but extinct Cenozoic bird eggs do not. This suggests that the range of egg shapes in extant birds had already been attained in the Cenozoic. We conclude with a discussion of possible biological factors imparting variation to egg shapes during their formation in the oviduct.
Data from: Thermal evolution of the crystal structure and phase transitions of KNbO3
The thermal evolution of the crystal structure and phase transitions of KNbO3 were investigated by high-temperature powder X-ray diffraction and Rietveld refinement of the diffraction data. Two phase transitions from orthorhombic (Amm2) to tetragonal (P4mm) and from tetragonal to cubic (Pm3 ̅m) were confirmed, both on heating and cooling. Both phase transtions are first order based on the observed hysteresis. The mixed displacive and order-disorder nature of the tetragonal to cubic transition is argued based on symmetry and apparent divergence of the atomic positions from pseudo-cubic values. The transition between the orthorhombic and tetragonal phase show no temperature-dependence for atomic positions and only thermal expansion of the unit cell parameters and is thus discussed in relation to a lattice dynamical instability.
Data from: Experiments and modelling of rate-dependent transition delay in a stochastic subcritical bifurcation
Complex systems exhibiting critical transitions when one of their governing parameters varies are ubiquitous in nature and in engineering applications. Despite a vast literature focusing on this topic, there are few studies dealing with the effect of the rate of change of the bifurcation parameter on the tipping points. In this work, we consider a subcritical stochastic Hopf bifurcation under two scenarios: the bifurcation parameter is first changed in a quasi-steady manner and then, with a finite ramping rate. In the latter case, a rate-dependent bifurcation delay is observed and exemplified experimentally using a thermoacoustic instability in a combustion chamber. This delay increases with the rate of change. This leads to a state transition of larger amplitude compared to the one that would be experienced by the system with a quasi-steady change of the parameter. We also bring experimental evidence of a dynamic hysteresis caused by the bifurcation delay when the parameter is ramped back. A surrogate model is derived in order to predict the statistic of these delays and to scrutinise the underlying stochastic dynamics. Our study highlights the dramatic influence of a finite rate of change of bifurcation parameters upon tipping points and it pinpoints the crucial need of considering this effect when investigating critical transitions.
Figure 3 from: Tello F, Verdú JR, Rossini M, Zunino M (2021) Onthophagus pilauco sp. nov. (Coleoptera, Scarabaeidae): evidence of beetle extinction in the Pleistocene–Holocene transition in Chilean Northern Patagonia. ZooKeys 1043: 133-145. https://doi.org/10.3897/zookeys.1043.61706
Figure 3 Artistic reconstruction of Onthophagus pilauco sp. nov. and its palaeoenvironment (by Mauricio Alvarez).
Figure 1 from: Tello F, Verdú JR, Rossini M, Zunino M (2021) Onthophagus pilauco sp. nov. (Coleoptera, Scarabaeidae): evidence of beetle extinction in the Pleistocene–Holocene transition in Chilean Northern Patagonia. ZooKeys 1043: 133-145. https://doi.org/10.3897/zookeys.1043.61706
Figure 1 Type locality of Onthophagus pilauco sp. nov. A shaded elevation map shows Pilauco and Monte Verde sites. Representation of profile of a grid of the Pilauco site B symbol (star) indicates the layer in which Onthophagus pilauco sp. nov. was collected.
Figure 2 from: Tello F, Verdú JR, Rossini M, Zunino M (2021) Onthophagus pilauco sp. nov. (Coleoptera, Scarabaeidae): evidence of beetle extinction in the Pleistocene–Holocene transition in Chilean Northern Patagonia. ZooKeys 1043: 133-145. https://doi.org/10.3897/zookeys.1043.61706
Figure 2 Holotype of Onthophagus pilauco sp. nov. A dorsal B ventral and C frontal views D detail of the microsculpture.
FIGURE 5. O in A new species of Onthophagus (Scarabaeoidea: Scarabaeinae) from the Mexican Transition Zone, with remarks on its relationships and distribution
FIGURE 5. O. bolivari female genitalia.
FIGURE 3 in A new species of Onthophagus (Scarabaeoidea: Scarabaeinae) from the Mexican Transition Zone, with remarks on its relationships and distribution
FIGURE 3. Onthophagus bolivari Habitus of the female.
FIGURE 2 in A new species of Onthophagus (Scarabaeoidea: Scarabaeinae) from the Mexican Transition Zone, with remarks on its relationships and distribution
FIGURE 2. Onthophagus bolivari Habitus of the minor male.
Revealing the frictional transition in shear thickening suspensions - Data
<p>Data corresponding to the article: Revealing the frictional transition in shear thickening suspensions</p>
FIGURE 14 in A new species of Miroculis Edmunds, 1963 (Ephemeroptera: Leptophlebiidae) from Cerrado-Amazonian forest transition zone, Brazil
FIGURE 14. Map with occurrence of Miroculis yuliae sp. nov.
Supplementary material: New Zealand Energy Transition and Green Hydrogen Export
Open the record for dataset details and reuse information.
Supplementary material 1 from: Zamora-Marín JM, Ruiz-Navarro A, Oficialdegui FJ, Anastácio PM, Miranda R, García-Murillo P, Cobo F, Ribeiro F, Gallardo B, García-Berthou E, Boix D, Medina L, Morcillo F, Oscoz J, Guillén A, Herrero-Reyes AA, Aguiar FC, Almeida D, Arias A, Ayres C, Banha F, Barca S, Biurrun I, Cabezas MP, Calero S, Campos JA, Capdevila-Argüelles L, Capinha C, Carapeto A, Casals F, Chainho P, Cirujano S, Clavero M, Cuesta JA, Deltoro V, Encarnação J, Fernández-Delgado C, Franco J, García-Meseguer AJ, Guareschi S, Guerrero-Gómez A, Hermoso V, López-Cañizares C, López-Soriano J, Machordom A, Martelo J, Mellado-Díaz A, Moreno JC, Olivo del Amo R, Otero JC, Perdices A, Pou-Rovira Q, Quiñonero-Salgado S, Rodríguez-Merino A, Ros M, Sánchez-Gullón E, Sánchez MI, Sánchez-Fernández D, Sánchez-González JR, Soriano O, Teodósio MA, Torralva M, Vieira-Lanero R, Zamora-López A, Oliva-Paterna FJ (2023) A multi-taxa assessment of aquatic non-indigenous species introduced into Iberian freshwater and transitional waters. NeoBiota 89: 17-44. https://doi.org/10.3897/neobiota.89.105994
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