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Continents are formed by the amalgamation of numerous micro-terranes and island arcs, so they have spatially varying lithosphere strengths. The crème brûlée (CB) model and the jelly sandwich (JS) model have been commonly used to describe continental lithosphere strength–depth variations. Depending on the strength of the continental lower crust, the CB and JS models can be further subdivided into two subclasses in which the I subclass (CB-I and JS-I) and II subclass (CB-II and JS-II), respectively, have a strong or weak lower crust. During the continental collision, lithosphere deformation is the byproduct of the comprehensive interaction of multiple terranes. Here we used 2-D thermomechanical numerical models that contain three continental terranes to systematically explore the effects of terranes with various strengths on continental deformation and studied the effects of different rheological assumptions on terrane deformation. We found four types of lithosphere deformation patterns: collision, subduction, thickening and delamination, and replacement. These simulation patterns are seen in observed deformation patterns and structures in East Asia, suggesting they are likely to be naturally occurring modes of intracontinental orogenesis.

Abstract To evaluate regional axonal-related parameters as a function of disease stage in primary open angle glaucoma (POAG) and visual field (VF) sensitivity. Spectral domain optical coherence tomography was used to acquire 20° scans of POAG (n = 117) or healthy control (n = 52) human optic nerve heads (ONHs). Region specific and mean nerve fibre layer (NFL) thicknesses, border NFL and peripapillary NFL, minimum rim width (MRW)/ area (MRA) and prelamina thickness; and volume were compared across POAG disease stages and with visual field sensitivity. Differences identified between early glaucoma (EG), preperimetric glaucoma (PG) and control (C) ONHs included thinner PG prelamina regions than in controls (p

Abstract The generalized abundance index (GAI) provides a useful tool for estimating relative population sizes and trends of seasonal invertebrates from species' count data and offers potential for inferring which external factors may influence phenology and demography through parametric descriptions of seasonal variation. We provide an R package that extends previous software with the ability to include covariates when fitting parametric GAI models, where seasonal variation is described by either a mixture of Normal distributions or a stopover model which provides estimates of life span. The package also generalizes the models to allow any number of broods/generations in the target population within a defined season. The option to perform bootstrapping, either parametrically or nonparametrically, is also provided. The new package allows models to be far more flexible when describing seasonal variation, which may be dependent on site‐specific environmental factors or consist of many broods/generations which may overlap, as demonstrated by two case studies. Our open‐source software, available at https://github.com/calliste‐fagard‐jenkin/rGAI, makes these extensions widely and freely available, allowing the complexity of GAI models used by ecologists and applied statisticians to increase accordingly.

Diaphorencyrtus aligarhensis (Hymenoptera: Encyrtidae) was first released in California for biological control of Diaphorina citri (Hemiptera: Liviidae) in December 2014. The establishment and parasitism rates of D. aligarhensis, along with those of another introduced species, Tamarixia radiata (Hymenoptera: Eulophidae), first released in 2011, were assessed at 15 D. aligarhensis release and 24 no-release control sites over the period 2016–2018. Study sites with citrus trees that were infested with D. citri eggs, nymphs, and adults, were located in residential areas in southern California that spanned three different climatic zones: coastal, intermediate, and desert interior sites. Parasitism rates of D. aligarhensis were low, averaging 0.62% compared to 21.2% for T. radiata which had spread naturally and established widely through the study area approximately one year earlier. Recoveries of D. aligarhensis at release sites were made eight times in 2016 and 2017. Conversely, T. radiata was recovered consistently at 34 of the 39 sites surveyed. Analyses indicated that parasitism of D. citri nymphs by T. radiata exhibited delayed density-dependence with a 12-month lag associated with reductions of D. citri densities by 50%. Irrespective of the climatic zone, the highest frequency of parasitized D. citri nymphs for T. radiata was recorded during peak periods of citrus flush growth from March through June and October through November each year. The findings reported here suggest that it is unlikely D. aligarhensis has established in California and that competition from T. radiata may, in part, have contributed to establishment failure. Consequently, biological control efforts targeting D. citri in California should focus on T. radiata.

While humans are highly cooperative, they can also behave spitefully. Yet spite remains understudied. Spite can be normatively driven and while previous experiments have found some evidence that cooperation and punishment may spread via social learning, no experiments have considered the social transmission of spiteful behaviour. Here we present an online experiment where, following an opportunity to earn wealth, we asked participants to choose an action towards an anonymous partner across a full spectrum of social behaviour, from spite to altruism. In accordance with cultural evolutionary theory, participants were presented with social information that varied in source and content. Across six conditions, we informed participants that either the majority or the highest earner had chosen to behave spitefully, neutrally or altruistically. We found an overall tendency towards altruism, but at lower levels among those exposed to spite compared with altruism. We found no difference between social information that came from the majority or the highest earner. Exploratory analysis revealed that participants’ earnings negatively correlated with altruistic behaviour. Our results contrast with previous literature that report high rates of spite in experimental samples and a greater propensity for individuals to copy successful individuals over the majority.

Recent studies have shown that maternal vitamin D deficiency (VDD) causes long-term metabolic changes in offspring. However, little is known about the impact of maternal VDD on offspring endocrine pancreas development and insulin secretion in the adult life of male and female animals. Female rats (Wistar Hannover) were fed either control (1000 IU Vitamin D3/kg), VDD (0 IU Vitamin D3/kg), or a Ca2+-enriched VDD diet (0 IU Vitamin D3/kg + Ca2+ and P/kg) for 6 weeks and during gestation and lactation. At weaning, VDD status was confirmed based on low serum calcidiol levels in dams and pups. Next, male and female offspring were randomly separated and fed a standard diet for up to 90 days. At this age, serum calcidiol levels were restored to normal levels in all groups, but serum insulin levels were decreased in VDD males without affecting glucagon levels, glycemia, or glucose tolerance. Islets isolated from VDD males showed lower insulin secretion in response to different glucose concentrations, but this effect was not observed in VDD females. Furthermore, VDD males, but not females, showed a smaller total pancreatic islet area and lower β cell mass, an effect that was accompanied by reduced gene expression of Ins1, Ins2, Pdx1, and SLC2A2. The decrease in Pdx1 expression was not related to the methylation profile of the promoter region of this gene. Most of these effects were observed in the male VDD+Ca2+ group, indicating that the effects were not due to alterations in Ca2+ metabolism. These data show that maternal VDD selectively impairs the morphology and function of β cells in adult male offspring rats and that female offspring are fully protected from these deleterious effects.

Here we present a newly developed ice core gas-phase proxy that directly samples a component of the large-scale atmospheric circulation: synoptic-scale pressure variability. Surface pressure changes weakly disrupt gravitational isotopic settling in the firn layer, which is recorded in krypton-86 excess (86Krxs). The 86Krxs may therefore reflect the time-averaged synoptic pressure variability over several years (site “storminess”), but it likely cannot record individual synoptic events as ice core gas samples typically average over several years. We validate 86Krxs using late Holocene ice samples from 11 Antarctic ice cores and 1 Greenland ice core that collectively represent a wide range of surface pressure variability in the modern climate. We find a strong spatial correlation (r=-0.94, p) between site average 86Krxs and time-averaged synoptic variability from reanalysis data. The main uncertainties in the analysis are the corrections for gas loss and thermal fractionation and the relatively large scatter in the data. Limited scientific understanding of the firn physics and potential biases of 86Krxs require caution in interpreting this proxy at present. We show that Antarctic 86Krxs appears to be linked to the position of the Southern Hemisphere eddy-driven subpolar jet (SPJ), with a southern position enhancing pressure variability. We present a 86Krxs record covering the last 24 kyr from the West Antarctic Ice Sheet (WAIS) Divide ice core. Based on the empirical spatial correlation of synoptic activity and 86Krxs at various Antarctic sites, we interpret this record to show that West Antarctic synoptic activity is slightly below modern levels during the Last Glacial Maximum (LGM), increases during the Heinrich Stadial 1 and Younger Dryas North Atlantic cold periods, weakens abruptly at the Holocene onset, remains low during the early and mid-Holocene, and gradually increases to its modern value. The WAIS Divide 86Krxs record resembles records of monsoon intensity thought to reflect changes in the meridional position of the Intertropical Convergence Zone (ITCZ) on orbital and millennial timescales such that West Antarctic storminess is weaker when the ITCZ is displaced northward and stronger when it is displaced southward. We interpret variations in synoptic activity as reflecting movement of the South Pacific SPJ in parallel to the ITCZ migrations, which is the expected zonal mean response of the eddy-driven jet in models and proxy data. Past changes to Pacific climate and the El Niño–Southern Oscillation (ENSO) may amplify the signal of the SPJ migration. Our interpretation is broadly consistent with opal flux records from the Pacific Antarctic zone thought to reflect wind-driven upwelling. We emphasize that 86Krxs is a new proxy, and more work is called for to confirm, replicate, and better understand these results; until such time, our conclusions regarding past atmospheric dynamics remain speculative. Current scientific understanding of firn air transport and trapping is insufficient to explain all the observed variations in 86Krxs. A list of suggested future studies is provided.

Abstract State‐space models are an increasingly common and important tool in the quantitative ecologists’ armoury, particularly for the analysis of time‐series data. This is due to both their flexibility and intuitive structure, describing the different individual processes of a complex system, thus simplifying the model specification step. State‐space models are composed of two processes (a) the system (or state) process that describes the dynamics of the true underlying state of the system over time; and (b) the observation process that links the observed data with the current true state of the system at that time. Specification of the general model structure consists of considering each distinct ecological process within the system and observation processes, which are then automatically combined within the state‐space structure. There is typically a trade‐off between the complexity of the model and the associated model‐fitting process. Simpler model specifications permit the application of simpler model‐fitting tools; whereas more complex model specifications, with nonlinear dynamics and/or non‐Gaussian stochasticity often require more sophisticated model‐fitting algorithms to be applied. We provide a brief overview of general state‐space models before focusing on the different model‐fitting tools available. In particular for different general state‐space model structures we discuss established model‐fitting tools that are available. We also offer practical guidance for choosing a specific fitting procedure.

Gas isotope thermometry using the isotopes of molecular nitrogen and argon has been used extensively to reconstruct past surface temperature change from Greenland ice cores. The gas isotope ratios δ15N and δ40Ar in the ice core are each set by the amount of gravitational and thermal fractionation in the firn. The gravitational component of fractionation is proportional to the firn thickness, and the thermal component is proportional to the temperature difference between the top and bottom of the firn column, which can be related to surface temperature change. Compared to Greenland, Antarctic climate change is typically more gradual and smaller in magnitude, which results in smaller thermal fractionation signals that are harder to detect. This has hampered application of gas isotope thermometry to Antarctic ice cores. Here, we present an analytical method for measuring δ15N and δ40Ar with a precision of 0.002 ‰ per atomic mass unit, a two-fold improvement on previous work. This allows us to reconstruct changes in firn thickness and temperature difference at the South Pole between 30 and 5 kyr BP. We find that variability in firn thickness is controlled in part by changes in snow accumulation rate, which is, in turn, influenced strongly by the along-flowline topography upstream of the ice core site. Variability in our firn temperature difference record cannot be explained by annual-mean processes. We therefore propose that the ice core gas isotopes contain a seasonal bias due to rectification of seasonal signals in the upper firn. The strength of the rectification also appears to be linked to fluctuations in the upstream topography. As further evidence for the existence of rectification, we present new data from the Dome Fuji ice core that are also consistent with a seasonal bias throughout the Holocene. Our findings have important implications for the interpretation of ice core gas records. For example, we show that the effects of upstream topography on ice core records can be significant at flank sites like the South Pole – they are responsible for some of the largest signals in our record. Presumably upstream signals impact other flank-flow ice cores such as EDML, Vostok, and EGRIP similarly. Additionally, future work is required to confirm the existence of seasonal rectification in polar firn, to determine how spatially and temporally widespread rectifier effects are, and to incorporate the relevant physics into firn air models.

The variations of δO2/N2 and δAr/N2 in the Dome Fuji ice core were measured from 112 m (bubbly ice) to 2001 m (clathrate hydrate ice). Our method, combined with the low storage temperature of the samples (−50 ∘C), successfully excludes post-coring gas-loss fractionation signals from our data. From the bubbly ice to the middle of the bubble–clathrate transition zone (BCTZ) (112–800 m) and below the BCTZ (>1200 m), the δO2/N2 and δAr/N2 data exhibit orbital-scale variations similar to local summer insolation. The data in the lower BCTZ (800–1200 m) have large scatter, which may be caused by millimeter-scale inhomogeneity of air composition combined with finite sample lengths. The insolation signal originally recorded at the bubble close-off remains through the BCTZ, and the insolation signal may be reconstructed by analyzing long ice samples (more than 50 cm for the Dome Fuji core). In the clathrate hydrate zone, the scatter around the orbital-scale variability decreases with depth, indicating diffusive smoothing of δO2/N2 and δAr/N2. A simple gas diffusion model was used to reproduce the smoothing and thus constrain their permeation coefficients. The relationship between δAr/N2 and δO2/N2 is markedly different for the datasets representing bubble close-off (slope ∼ 0.5), bubble–clathrate hydrate transformation (∼1), and post-coring gas loss (∼0.2), suggesting that the contributions of the mass-independent and mass-dependent fractionation processes are different for those cases. The method and data presented here may be useful for improving the orbital dating of deep ice cores over the multiple glacial cycles and further studying non-insolation-driven signals (e.g., atmospheric composition) of these gases.

Abstract Arc volcanoes are underlain by complex systems of molten‐rock reservoirs ranging from melt‐poor mush zones to melt‐rich magma chambers. Petrological and satellite data indicate that eruptible magma chambers form in the topmost few kilometres of the crust. However, very few chambers have ever been definitively located, suggesting that most are too short‐lived or too small to be imaged, which has direct implications for hazard assessment and modeling of magma differentiation. Here we use a high‐resolution technology based on inverting full seismic waveforms to image a small, high‐melt‐fraction magma chamber that was not detected with standard seismic tomography. The melt reservoir extends from ∼2 to at least 4 km below sea level (b.s.l.) at Kolumbo—a submarine volcano near Santorini, Greece. The chamber coincides with the termination point of the recent earthquake swarms and may be a missing link between a deeper melt reservoir and the high‐temperature hydrothermal system venting at the crater floor. The chamber poses a serious hazard as it could produce a highly explosive, tsunamigenic eruption in the near future. Our results suggest that similar reservoirs (relatively small but high‐melt‐fraction) may have gone undetected at other active volcanoes, challenging the existing eruption forecasts and reactive‐flow models of magma differentiation.

Human cooperation, occurring without reciprocation and between unrelated individuals in large populations, represents an evolutionary puzzle. One potential explanation is that cooperative behaviour may be transmitted between individuals via social learning. Using an online social dilemma experiment, we find evidence that participants’ contributions were more consistent with payoff-biased transmission than prestige-biased transmission or conformity. We also found some evidence for lower cooperation (i) when exposed to social information about peer cooperation levels than without such information, and (ii) in the prisoners’ dilemma game compared to the snowdrift game. A simulation model established that the observed cooperation was more likely to be caused by participants’ general propensity to cooperate than by the effect of social learning strategies employed within the experiment, but that this cooperative propensity could be reduced through selection. Overall, our results support previous experimental evidence indicating the role of payoff-biased transmission in explaining cooperative behaviour, but we find that this effect was small and was overwhelmed by participants’ general propensity for cooperation.