Evidence For Extinction Research Articles

Morphological traits of reef corals predict extinction risk but not conservation status

AbstractAimThe current assessment of extinction risk in reef corals by the International Union for Conservation of Nature (IUCN) has been criticized, because coral life‐history traits associated with resilience are not reflected in the conservation status. We aimed to carry out a quantitative assessment of the link between reef coral traits and species extinction risk informed by extinctions of reef corals observed in the fossil record.LocationGlobal.Time periodPlio‐Pleistocene and present day.Major taxa studiedScleractinian reef corals.MethodsWe used morphological traits, phylogenetic information and evidence of extinction during the Plio‐Pleistocene to predict the extinction risk of contemporary reef corals. Our model was trained using 138 Caribbean fossil coral species and an automatic machine learning algorithm. We then used this model to predict the extinction risk of 674 modern coral species.ResultsModel validation confirmed 77% accuracy in predicting extinction risk of fossil corals. Extinction risk predicted by our model showed a near‐random (57%) match with the IUCN conservation status. Our model also suggested that corals in the Least Concern or Near Threatened categories might be at higher risk of extinction than currently believed.Main conclusionsMorphological traits of fossil corals linked to their extinction risk in the Plio‐Pleistocene Caribbean Sea are known to reflect the vulnerability of extant corals. However, the results from our fossil‐calibrated model do not match the IUCN assessment of reef corals, with increased overall extinction risk. This does not necessarily indicate near‐future extinction risk, because fossil extinctions are spread over thousands of years. However, we show the applicability of using fossil data to inform the extinction risk of modern corals and recommend that future assessments of extinction risk of reef corals should consider incorporating the relationship between morphological traits and resilience, calibrated by fossil data, to maximize the utility of the extinction risk assessment.

Concurrent evidence of extinction making acquisition context specific and ABA and ABC renewal effects in human predictive learning.

Two experiments evaluated whether the experience of extinction makes acquisition context specific (EMACS) while the extinction learning itself also becomes context dependent under ABA and ABC renewal designs in a human predictive learning situation. Two groups of participants received X-Outcome pairings in context A followed by P-Outcome pairings in context B. For participants in group E, cue X was then extinguished in context B while cue P was trained. Participants in group NE were trained with P, but they did not have the extinction experience. Testing target cues outside the context B (i.e. the context in which P was trained and X was extinguished) in group E led to an increase in responding to cue X (Renewal effect) and a decrease in responding to cue P (EMACS effect) regardless of whether the test was conducted in context A (Experiment 1) or in an alternative context C (Experiment 2). Combined results suggest that Renewal and EMACS effects may be based on the same underlying mechanism. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Supplemental Material for Concurrent Evidence of Extinction Making Acquisition Context Specific and ABA and ABC Renewal Effects in Human Predictive Learning

Supplemental Material for Concurrent Evidence of Extinction Making Acquisition Context Specific and ABA and ABC Renewal Effects in Human Predictive Learning

Using environmental DNA and occupancy modelling to estimate rangewide metapopulation dynamics

We demonstrate the power of combining two emergent tools for resolving rangewide metapopulation dynamics. First, we employed environmental DNA (eDNA) surveys to efficiently generate multiseason rangewide site occupancy histories. Second, we developed a novel dynamic, spatial multiscale occupancy model to estimate metapopulation dynamics. The model incorporates spatial relationships, explicitly accounts for non-detection bias and allows direct evaluation of the drivers of extinction and colonization. We applied these tools to examine metapopulation dynamics of endangered tidewater goby, a species endemic to California estuarine habitats. We analysed rangewide eDNA data from 190 geographically isolated sites (813 total water samples) surveyed from 2years (2016 and 2017). Rangewide estimates of the proportion of sites that were occupied varied little between 2016 (0.52) and 2017 (0.51). However, there was evidence of extinction and colonization dynamics. The probability of extinction of an occupied site (0.106) and probability of colonization of an unoccupied site (0.085) were nearly equal. Stability in site occupancy proportions combined with nearly equal rates of extinction and colonization suggests a dynamic equilibrium between the 2years surveyed. Assessment of covariate effects revealed that colonization probability increased as the number of occupied neighbouring sites increased and as distance between occupied sites decreased. We show that eDNA surveys can rapidly provide a snapshot of a species distribution over a broad geographic range and, when these surveys are paired with occupancy modelling, can uncover metapopulation dynamics and their drivers.

CHANG-ES X: Spatially Resolved Separation of Thermal Contribution from Radio Continuum Emission in Edge-on Galaxies

Abstract We analyze the application of star formation rate calibrations using Hα and 22 μm infrared (IR) imaging data in predicting the thermal radio component for a test sample of three edge-on galaxies (NGC 891, NGC 3044, and NGC 4631) in the Continuum Halos in Nearby Galaxies—an EVLA Survey (CHANG-ES). We use a mixture of Hα and 24 μm calibration from Calzetti et al. and a linear 22 μm only calibration from Jarrett et al. on the test sample. We apply these relations on a pixel-to-pixel basis to create thermal prediction maps in the two CHANG-ES bands: L and C band (1.5 GHz and 6.0 GHz, respectively). We analyze the resulting nonthermal spectral index maps, and find a characteristic steepening of the nonthermal spectral index with vertical distance from the disk after application of all methods. We find possible evidence of extinction in the 22 μm data as compared to 70 μm Spitzer Multiband Imaging Photometer imaging in NGC 891. We analyze a larger sample of edge-on and face-on galaxy 25–100 μm flux ratios, and find that the ratios for edge-ons are systematically lower by a factor of 1.36, a result we attribute to excess extinction in the mid-IR in edge-ons. We introduce a new calibration for correcting the Hα luminosity for dust when galaxies are edge-on or very dusty.

Synergistic interactions between a variety of insecticides and an ergosterol biosynthesis inhibitor fungicide in dietary exposures of bumble bees (Bombus terrestris L.).

In recent years, concern has been raised over honey bee colony losses, and also among wild bees there is evidence for extinctions and range contractions in Europe and North America. Pesticides have been proposed as a potential cause of this decline. Bees are exposed simultaneously to a variety of agrochemicals, which may cause synergistically detrimental impacts, which are incompletely understood. We investigated the toxicity of the fungicide imazalil in mixture with four common insecticides: fipronil (phenylpyrazoid), cypermethrin (pyrethroid), thiamethoxam, and imidacloprid (neonicotinoids). Ergosterol biosynthesis inhibitor (EBI) fungicides like imazalil can inhibit P450 detoxification systems in insects and therefore fungicide - insecticide co-occurrence might produce synergistic toxicity in bees. We assessed the impact of dietary fungicide - insecticide mixtures on the mortality and feeding rates of laboratory bumble bees (Bombus terrestris L.). Regarding mortality, imazalil synergised the toxicity of fipronil, cypermethrin and thiamethoxam, but not imidacloprid. We found no synergistic effects on feeding rates. Our findings suggest that P450-based detoxification processes are differentially important in mitigating the toxicity of certain insecticides, even those of the same chemical class. Our evidence that cocktail effects can arise in bumble bees should extend concern about the potential impacts of agrochemical mixtures to include wild bee species in farmland. © 2017 Society of Chemical Industry.

Is HE 0436–4717 Anemic? A deep look at a bare Seyfert 1 galaxy

A multi-epoch, multi-instrument analysis of the Seyfert 1 galaxy HE 0436-4717 is conducted using optical to X-ray data from XMM-Newton and Swift (including the BAT). Fitting of the UV-to-X-ray spectral energy distribution shows little evidence of extinction and the X-ray spectral analysis does not confirm previous reports of deep absorption edges from OVIII. HE 0436-4717 is a "bare" Seyfert with negligible line-of-sight absorption making it ideal to study the central X-ray emitting region. Three scenarios were considered to describe the X-ray data: partial covering absorption, blurred reflection, and soft Comptonization. All three interpretations describe the 0.5-10.0 keV spectra well. Extrapolating the models to 100 keV results in poorer fits for the the partial covering model. When also considering the rapid variability during one of the XMM-Newton observations, the blurred reflection model appears to describe all the observations in the most self-consistent manner. If adopted, the blurred reflection model requires a very low iron abundance in HE 0436-4717. We consider the possibilities that this is an artifact of the fitting process, but it appears possible that it is intrinsic to the object.

Is 3rd G Cephalosporin & Carbapenam Antibiotic Weaponry at the Verge of Extinction Evidence Based Medicine

Our antibiotic weaponry in the form of resistance inhibitors and combination therapies are proving a failure with the extensive drug resistance scenario leaving the multidrug resistance part far behind. Culture and sensitivity interpretation redefined. Scientific innovations get modified from time to time& so get interpretations. What is logic today may not be applicable tomorrow. We have to change as per the changing times & keep abreast with latest developments& incorporate need based surveillance and research tools in our systems otherwise wrongs would continue to happen.

A new sphenodontian (Lepidosauria: Rhynchocephalia) from the Late Triassic of Argentina and the early origin of the herbivore opisthodontians.

Sphenodontians were a successful group of rhynchocephalian reptiles that dominated the fossil record of Lepidosauria during the Triassic and Jurassic. Although evidence of extinction is seen at the end of the Laurasian Early Cretaceous, they appeared to remain numerically abundant in South America until the end of the period. Most of the known Late Cretaceous record in South America is composed of opisthodontians, the herbivorous branch of Sphenodontia, whose oldest members were until recently reported to be from the Kimmeridgian-Tithonian (Late Jurassic). Here, we report a new sphenodontian, Sphenotitan leyesi gen. et sp. nov., collected from the Upper Triassic Quebrada del Barro Formation of northwestern Argentina. Phylogenetic analysis identifies Sphenotitan as a basal member of Opisthodontia, extending the known record of opisthodontians and the origin of herbivory in this group by 50 Myr.

Shallow lake sediments provide evidence for metapopulation dynamics: a pilot study

The aim of this pilot study is to test the hypotheses that sediment cores can provide evidence for metapopulation dynamics and that these can be linked with site characteristics. We focus on temporal patterns of incidence and abundance of overwintering stages (statoblasts) produced by the freshwater bryozoan Cristatella mucedo, an organism characterised by a metapopulation ecology, in sediment cores retrieved from 18 UK lakes. Runs and goodness-of-fit tests provided evidence for population instability, periods of low abundance and absence, and of asynchrony—all signatures of metapopulation dynamics. Further hypothesis testing indicated that extinction risk is greater in more isolated sites and in sites of smaller size. Absence of statoblasts from the top sections of spatially separated, replicate cores provided independent evidence for extinction in one site. Our study demonstrates how the abundances of sedimentary-bound propagules may be analysed initially for metapopulation dynamics and subsequently how this may lead to working hypotheses regarding the drivers of such dynamics. The sediment archive represents a unique historical record whose potential for characterising metapopulation dynamics has previously been untapped but is broadly relevant for understanding the population biology of freshwater organisms.

Gene flow across secondary contact zones of the Emys orbicularis complex in the Western Mediterranean and evidence for extinction and re-introduction of pond turtles on Corsica and Sardinia (Testudines: Emydidae)

European pond turtles represent a phylogeographically deeply structured complex of distinct taxa. Here, we use mitochondrial DNA sequences (cytochrome b gene) and eight polymorphic microsatellite loci to investigate genetic differentiation and gene flow of Sicilian, Corsican and Sardinian pond turtles and of subspecies involved in two secondary contact zones in the Pyrenean region and Southern Italy. Mitochondrial and microsatellite differentiation is largely concordant in populations from the core regions of the distribution ranges of the studied taxa. Both marker systems provide no evidence for gene flow between Sicilian pond turtles (Emys trinacris) and Southern Italian subspecies of E. orbicularis .B y contrast, in the contact zones limited gene flow occurs between distinct subspecies of E. orbicularis. Although the Southern Italian contact zone is significantly older than the Pyrenean contact zone of Holocene age, patterns of asymmetric introgression are similar. Introgressive hybridization leads to the exchange of mitochondria, but microsatellite data indicate only a few individuals with mixed ancestry. This suggests that incipient isolating mechanisms maintain largely discrete nuclear genomic gene pools. Furthermore, this implies that Southern Italy acted as a hotspot rather than as a melting pot of genetic diversity during the last glacial. Pond turtles from Corsica and Sardinia are not differentiated from continental populations of the subspecies E. o. galloitalica, neither in the mitochondrial nor in the quickly evolving microsatellite markers. As the fossil record argues for a continuous presence of pond turtles on both islands since the Middle Pleistocene, this suggests that the native island populations became extinct and the extant turtles were later introduced by prehistoric settlers. The lack of genetic differentiation of pond turtles from Corsica and Sardinia supports the view that the subspecies described from these islands are not valid.

UNVEILING THE ORIGIN OF GRB 090709A: LACK OF PERIODICITY IN A REDDENED COSMOLOGICAL LONG-DURATION GAMMA-RAY BURST

We present broadband (gamma-ray, X-ray, near-infrared, optical, and radio) observations of the gamma-ray burst (GRB) 090709A and its afterglow in an effort to ascertain the origin of this high-energy transient. Previous analyses suggested that GRB 090709A exhibited quasi-periodic oscillations with a period of 8.06 s, a trait unknown in long-duration GRBs but typical of flares from soft gamma-ray repeaters. When properly accounting for the underlying shape of the power-density spectrum of GRB 090709A, we find no conclusive (> 3 sigma) evidence for the reported periodicity. In conjunction with the location of the transient (far from the Galactic plane and absent any nearby host galaxy in the local universe) and the evidence for extinction in excess of the Galactic value, we consider a magnetar origin relatively unlikely. A long-duration GRB, however, can account for the majority of the observed properties of this source. GRB 090709A is distinguished from other long-duration GRBs primarily by the large amount of obscuration from its host galaxy (A_K,obs >~ 2 mag).

No evidence for dust extinction in GRB 050904 atz~ 6.3

Context: GRB afterglows are excellent probes of gas and dust in star-forming galaxies at all epochs. It has been posited that dust in the early Universe must be different from dust at lower z. To date two reports directly support this contention, one of which is based on the spectral shape of GRB 050904 at z = 6.295. Aims: We reinvestigate the afterglow to understand dust at high z. We address the claimed evidence for unusual (SN-origin) dust in its host galaxy by simultaneously examining the X-ray and optical/NIR spectrophotometric data. Methods: We derive the intrinsic SED of the afterglow at 0.47, 1.25 and 3.4 days, by re-reducing the Swift X-ray data, the 1.25 days FORS2 z-Gunn photometric data, the spectroscopic and z'-band photometric data at ~3 days from the Subaru telescope, as well as the critical UKIRT Z-band photometry at 0.47 days, upon which the claim of dust detection largely relies. Results: We find no evidence of dust extinction in the SED. We compute flux densities at lambda_rest = 1250 AA directly from the observed counts at all epochs. In the earliest epoch, 0.47 days, the Z-band suppression is found to be smaller (0.3 +- 0.2 mag) than previously reported and statistically insignificant (<1.5 sigma). Furthermore we find that the photometry of this band is unstable and difficult to calibrate. Conclusions: From the afterglow SED we demonstrate that there is no evidence for dust extinction -- the SED at all times can be reproduced without dust, and at 1.25 days in particular, significant extinction can be excluded, with A(3000 AA) < 0.27 mag at 95% confidence using the SN-type extinction curve. We conclude that there is no evidence of any extinction in the afterglow of GRB 050904 and that the presence of SN-origin dust in the host of GRB 050904 must be viewed skeptically. [abridged]

Evidence of extinction in strongly textured high-purity copper

In order to test the influence of extinction on texture measurements, pole figures of four copper samples were measured using neutron diffraction with three different wavelengths. The copper samples had previously been cold rolled to different extents and partially annealed. Therefore, three of the samples presented a relatively strong texture and the fourth sample a relatively weak texture. In this study, the results from equivalent pole figures were compared between the different samples. These investigations showed that, in general, except for the sample with weak texture, the 222 reflection showed higher pole density maxima than the 111 reflection. Since all measuring conditions were the same for both reflections, this difference was attributed to extinction. The pole density maxima of strong reflections also revealed a slight tendency to lower values with decreasing wavelengths. This phenomenon is attributed to the fact that more reflections exist at shorter wavelengths and therefore an increase in secondary extinction is measurable at these wavelengths.

Putative extinction of two sawfish species in Mexico and the United States

All species of sawfish are listed by the International Union for the Conservation of Nature (IUCN) as endangered or critically endangered. In fact, the smalltooth sawfish Pristis pectinata, and the largetooth sawfish Pristis pristis, have been declared to be regionally and locally extinct from the US Atlantic coast and the Gulf of California, Mexico, respectively, likely due to overfishing. However, here we dispute these claims by illustrating how lack of existence of a given species within a region can be misconstrued as evidence for extinction.

Support for a metapopulation structure among mammals

ABSTRACTThe metapopulation metaphor is increasingly used to explain the spatial dynamics of animal populations. However, metapopulation structure is difficult to identify in long‐lived species that are widely distributed in stochastic environments, where they can resist extinctions. The literature on mammals may not provide supporting evidence for classic metapopulation dynamics, which call for the availability of discrete habitat patches, asynchrony in local population dynamics, evidence for extinction and colonization processes, and dispersal between local populations.Empirical evidence for metapopulation structure among mammals may exist when applying more lenient criteria. To meet these criteria, mammals should live in landscapes as discrete local breeding populations, and their demography should be asynchronous.We examined the literature for empirical evidence in support of the classical criteria set byHanski (1999), and for the more lenient subset of criteria proposed byElmhagen &amp; Angerbjörn (2001). We suggest circumstances where metapopulation theory could be important in understanding population processes in mammals of different body sizes.The patchy distribution of large (&gt;100 kg) mammals and dispersal often motivate inferences in support of a metapopulation structure. Published studies seldom address the full suite of classical criteria. However, studies on small mammals are more likely to record classic metapopulation criteria than those on large mammals. The slow turnover rate that is typical for medium‐sized and large mammals apparently makes it difficult to identify a metapopulation structure during studies of short duration.To identify a metapopulation structure, studies should combine the criteria set byHanski (1999) andElmhagen &amp; Angerbjörn (2001). Mammals frequently live in fragmented landscapes, and processes involved in the maintenance of a metapopulation structure should be considered in conservation planning and management.

Towards a complete census of AGN in nearby Galaxies: a large population of optically unidentified AGN

Using Spitzer-IRS spectroscopy, we investigate the ubiquity of Active Galactic Nuclei (AGN) in a complete (~94%), volume-limited sample of the most bolometrically-luminous galaxies (L_IR > (0.3-20) x 10^10 L_sun) to D < 15 Mpc. Our analyses are based on the detection of the high-excitation emission line [NeV](\lambda 14.32 um; 97.1 eV) to unambiguously identify AGN activity. We find that 17 of the 64 IR-bright galaxies in our sample host AGN activity (~27^{+8}_{-6}%), >50% of which are not identified as AGNs using optical spectroscopy. The large AGN fraction indicates a tighter connection between AGN activity and IR luminosity for galaxies in the local Universe than previously found, potentially indicating a close association between AGN activity and star formation. The optically unidentified AGNs span a wide range of galaxy type (S0-Ir) and are typically starburst-dominated systems hosting modest-luminosity AGN activity (L_[NeV] ~ 10^37 - 10^39 erg s^-1). The non-identification of optical AGN signatures in the majority of these galaxies appears to be due to extinction towards the AGN, rather than intrinsically low-luminosity AGN activity. Examination of optical images shows that the optically unidentified AGNs with evidence for extinction are hosted in either highly inclined galaxies or galaxies with dust lanes, indicating that obscuration of the AGN is not necessarily due to an obscuring torus. We therefore conclude that optical spectroscopic surveys miss approximately half of the AGN population simply due to extinction through the host galaxy.

Mid‐Infrared Fine‐Structure Line Ratios in Active Galactic Nuclei Observed with theSpitzerIRS: Evidence for Extinction by the Torus

We present the first systematic investigation of the [Ne V] (14 μm/24 μm) and [S III] (18 μm/33 μm) infrared line flux ratios, traditionally used to estimate the density of the ionized gas, in a sample of 41 type 1 and type 2 active galactic nuclei (AGNs) observed with the Infrared Spectrograph on board Spitzer. The majority of galaxies with both [Ne V] lines detected have observed [Ne V] line flux ratios consistent with or below the theoretical low-density limit, based on calculations using currently available collision strengths and ignoring absorption and stimulated emission. We find that type 2 AGNs have lower line flux ratios than type 1 AGNs and that all of the galaxies with line flux ratios below the low-density limit are type 2 AGNs. We argue that differential infrared extinction to the [Ne V] emitting region due to dust in the obscuring torus is responsible for the ratios below the low-density limit and we suggest that the ratio may be a tracer of the inclination angle of the torus to our line of sight. Because the temperature of the gas, the amount of extinction, and the effect of absorption and stimulated emission on the line ratios are all unknown, we are not able to determine the electron densities associated with the [Ne V] line flux ratios for the objects in our sample. We also find that the [S III] emission from the galaxies in our sample is extended and originates primarily in star-forming regions. Since the emission from low-ionization species is extended, any analysis using line flux ratios from such species obtained from slits of different sizes is invalid for most nearby galaxies.

The lundgreni event in the Silurian of the East European Platform, Poland

The lundgreni event (late Wenlock, Silurian) is here interpreted in terms of palaeontologic (graptolites, microphytoplankton, benthos), biostratigraphic and geochemical evidence derived from Homerian deposits drilled in the Bartoszyce well (East European Platform in Poland). The lundgreni event in the graptolite record of Bartoszyce comprises extinction, survival and recovery phases. The graptolite extinction proceeded in three steps: lundgreni, testis and flemingii-dubius. The testis extinction eliminated the largest number of species. Only the long-lasting Pristiograptus dubius survived the combined extinctions and was joined during the survival phase by the opportunistic Gothograptus nassa and Pristiograptus parvus. The graptolite recovery is expressed by the diachronous arrival of new species in association with P. dubius. All documented phytoplankton taxa survived the lundgreni event. Phytoplankton frequency and diversity patterns, together with total organic carbon (TOC) fluctuations, indicate that oligotrophy/productivity regime was unsteady during the testis and flemingii-dubius extinctions and stable during the early graptolite survival. There is no evidence for extinction within benthic fauna assemblages. Diversified benthos appeared in a great abundance during the early survival phase. This records a redox-related event of substrate colonization that took place simultaneously with local decline in primary productivity. The last two phases of graptolite extinction and the onset of the survival correlate with strong, positive anomalies of δ 18O, δ 13C org and δ 13C carb. The anomalies coincide with the fall in local primary productivity and the enhanced storage of organic carbon in peri-Gondwanan upwelling zones (Sudeten, Thuringia). The stepped graptolite extinction in Bartoszyce occurred in an environment that was situated within the low-latitude Baltica shelf and was markedly stable in terms of bathymetry, distance from land and oxic regime. This local extinction was most likely caused by catastrophic fluctuations in nutrient supply, breaking primary productivity. The trophic perturbations on the Baltica shelf were coeval with and related to eutrophication of the high-latitude upwelling zones of the Rheic Ocean. The postulated spatial fluctuations in the trophic resource continuum may reflect palaeooceanographic changes that accompanied the global, late sea-level highstand of that time.

Evidence for Extinction and Accretion Variability in T Tauri South

We present angularly resolved spectra of T Tau North and South in the 3 μm water-ice feature and K band. Most of the water-ice absorption lies along the line of sight toward T Tau South, confirming that it is viewed through stronger extinction. A decrease in ice-band absorption toward T Tau S between 1998 December and 2000 January, significant at the 2 σ level, was associated with an increase in its near-IR flux. Brγ emission is detected in T Tau North and South and H2 (2.12 μm) emission toward only T Tau South, consistent with previous studies of infrared companions to T Tauri stars. Our results suggest that the near-IR variability of T Tau S is probably caused by both variations in accretion rate and variable extinction along the line of sight.