Shared Cultural History as a Predictor of Political and Economic Changes among Nation States

Political and economic risks arise from social phenomena that spread within and across countries. Regime changes, protest movements, and stock market and default shocks can have ramifications across the globe. Quantitative models have made great strides at predicting these events in recent decades but incorporate few explicitly measured cultural variables. However, in recent years cultural evolutionary theory has emerged as a major paradigm to understand the inheritance and diffusion of human cultural variation. Here, we combine these two strands of research by proposing that measures of socio-linguistic affiliation derived from language phylogenies track variation in cultural norms that influence how political and economic changes diffuse across the globe. First, we show that changes over time in a country’s democratic or autocratic character correlate with simultaneous changes among their socio-linguistic affiliations more than with changes of spatially proximate countries. Second, we find that models of changes in sovereign default status favor including socio-linguistic affiliations in addition to spatial data. These findings suggest that better measurement of cultural networks could be profoundly useful to policy makers who wish to diversify commercial, social, and other forms of investment across political and economic risks on an international scale.     

Chick begging as a signal: are nestlings honest?

Begging by dependent avian offspring is known to correlate withhunger level, and parents use this as a signal of brood demandto adjust their chick feeding behavior. While there is informationon how each chick adjusts its begging to its own condition,little is known of how chicks adjust to the state of their nestmates. In two experiments we manipulated the competitive environmentof individual European starling (Sturnus vulgaris) chicks byaltering the state of nest mates while holding the state oftarget chicks constant In the first experiment we placed thetarget chick's nest mates in neighboring nests with brood sizesof two, five, or eight chicks. Following the manipulation wereturned them to their own nests and recorded begging behavioron videotape. In the second experiment we separated a targetchick from its siblings and manipulated feeding level in thelaboratory. The siblings were fed at one of three levels; meanwhile,all the target chicks were fed at the intermediate level. Afterthe manipulation we placed the target chicks with their siblingsand recorded their begging in response to an artificial stimulus.In neither experiment was the begging effort of the unmanipulatedtarget chicks affected by the changes in begging behavior oftheir siblings. This result supports the view that begging isa reliable signal of individual chick state and does not involveresponses to the effort of nest mates.     

Neutrophil extracellular trap cell death requires both autophagy and superoxide generation

Neutrophil extracellular traps (NETs) are extracellular chromatin structures that can trap and degrade microbes. They arise from neutrophils that have activated a cell death program called NET cell death, or NETosis. Activation of NETosis has been shown to involve NADPH oxidase activity, disintegration of the nuclear envelope and most granule membranes, decondensation of nuclear chromatin and formation of NETs. We report that in phorbol myristate acetate (PMA)-stimulated neutrophils, intracellular chromatin decondensation and NET formation follow autophagy and superoxide production, both of which are required to mediate PMA-induced NETosis and occur independently of each other. Neutrophils from patients with chronic granulomatous disease, which lack NADPH oxidase activity, still exhibit PMA-induced autophagy. Conversely, PMA-induced NADPH oxidase activity is not affected by pharmacological inhibition of autophagy. Interestingly, inhibition of either autophagy or NADPH oxidase prevents intracellular chromatin decondensation, which is essential for NETosis and NET formation, and results in cell death characterized by hallmarks of apoptosis. These results indicate that apoptosis might function as a backup program for NETosis when autophagy or NADPH oxidase activity is prevented.     

Low and annually variable migratory connectivity in a long‐distance migrant: Whinchats Saxicola rubetra may show a bet‐hedging strategy

The spatial scale of non‐breeding areas used by long‐distance migrant animals can vary from specific, relatively small non‐breeding areas for each independent breeding population (high connectivity) to a distribution over a large non‐breeding area with mixing of breeding populations (low connectivity). Measuring variation in the degree of connectivity and how it arises is crucial to predict how migratory animals can respond to global habitat and climate change because low connectivity is likely to be an adaptation to environmental uncertainty. Here, we assess whether use of non‐breeding areas in a long‐distance migrant may be stochastic by measuring the degree of connectivity, and whether it is annually variable. Twenty‐nine wintering Whinchats tagged with geolocators over 2 years within 40 km² in central Nigeria were found to be breeding over 2.55 million km² (26% of the land area of Europe), without an asymptote being approached in the relationship between area and sample size. Ranges differed in size between years by 1.51 million km² and only 15% of the total breeding range across both years overlapped (8% overlap between years when only first‐year birds were considered), well above the range size difference and below the proportion of overlap that would be predicted from two equivalent groups breeding at random locations within the observed range. Mean distance between breeding locations (i.e. migratory spread) differed significantly between years (604 ± 18 km in 2013 and 869 ± 33 km in 2014). The results showed very low and variable connectivity that was reasonably robust to the errors and assumptions inherent in the use of geolocators, but with the caveat of having only ranges of 2 years to compare, and the sensitivity of range to the breeding locations of a small number of individuals. However, if representative, the results suggest the scope for between‐year variation (cohort effects) to determine migrant distribution on a large scale. Furthermore, for species with similarly low connectivity, we would predict breeding population trends to reflect average conditions across large non‐breeding areas: thus, as large areas of Africa become subject to habitat loss, migrant populations throughout Europe will decline.     

Three new Ecuadorian species of Axinaea (Melastomataceae)

Three new Ecuadorian species of Axinaea (Melastomataceae) are described: Axinaea flava, A. glauca, and A.lawessonii. All three species are endemic to southern Ecuador. Axinaea flava and A.glauca grow in the transition zone between montane forest and pbramo. They share characters such as shrubby habit, dense to moderate pubescence and coriaceous, rigid, erect leaves, which may be related to their high altitude habitat. Axinaea flava is the only species of the genus with a yellow corolla. Axinaea glauca, a shrub less than 1 m high, is the smallest Axinaea species known. Field observations show that these two species have a restricted habitat and their known populations are small, probably less than 100 individuals. The third species, A.lawessonii, grows in wet montane forests. It can grow as a shrub or a slender tree and its leaves are glabrous and less rigid than those of A.flava and A.glauca, characters which are probably a consequence of the more humid and benign habitat. Axinaea lawessonii is the only species of the genus in which the leaf margins have uncinate teeth. The species is rather frequent in southern Ecuador and has been collected in a dozen localities, most of which are within the Podocarpus National Park.     

Negative Feedback Enables Fast and Flexible Collective Decision-Making in Ants

Positive feedback plays a major role in the emergence of many collective animal behaviours. In many ants pheromone trails recruit and direct nestmate foragers to food sources. The strong positive feedback caused by trail pheromones allows fast collective responses but can compromise flexibility. Previous laboratory experiments have shown that when the environment changes, colonies are often unable to reallocate their foragers to a more rewarding food source. Here we show both experimentally, using colonies of Lasius niger, and with an agent-based simulation model, that negative feedback caused by crowding at feeding sites allows ant colonies to maintain foraging flexibility even with strong recruitment to food sources. In a constant environment, negative feedback prevents the frequently found bias towards one feeder (symmetry breaking) and leads to equal distribution of foragers. In a changing environment, negative feedback allows a colony to quickly reallocate the majority of its foragers to a superior food patch that becomes available when foraging at an inferior patch is already well underway. The model confirms these experimental findings and shows that the ability of colonies to switch to a superior food source does not require the decay of trail pheromones. Our results help to resolve inconsistencies between collective foraging patterns seen in laboratory studies and observations in the wild, and show that the simultaneous action of negative and positive feedback is important for efficient foraging in mass-recruiting insect colonies.     

The bactericidal effect of TiO2 photocatalysis involves adsorption onto catalyst and the loss of membrane integrity

The bactericidal effect of photocatalysis with TiO2 is well recognized, although its mode of action is still poorly characterized. It may involve oxidation, as illuminated TiO2 generates reactive oxygen species. Here we analyze the bactericidal effect of illuminated TiO2 in NaCl-KCl or sodium phosphate solutions. We found that adsorption of bacteria on the catalyst occurred immediately in NaCl-KCl solution, whereas it was delayed in the sodium phosphate solution. We also show that the rate of adsorption of cells onto TiO2 is positively correlated with its bactericidal effect. Importantly, adsorption was consistently associated with a reduction or loss of bacterial membrane integrity, as revealed by flow cytometry. Our work suggests that adsorption of cells onto aggregated TiO2, followed by loss of membrane integrity, is key to the bactericidal effect of photocatalysis.