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Semantic change in adults is not primarily a generational phenomenon

A central question in the study of language change is whether or not such change is generational. If a language changes over time generation-by-generation, the process looks as follows: New generations of speakers introduce innovations, while older speakers conserve their usage patterns, and the language changes as new generations replace older ones. At the opposite extreme, language change could be a zeitgeist phenomenon, in which changes are universally adopted by speakers simultaneously, regardless of age or generational cohort. This paper asks this question in the context of word meaning change. We analyze meaning change in over 100 words across more than 7.9 million U.S. congressional speeches, to observe whether, when a word sense rises or falls in prominence, adult speakers from different generations uniformly adopt it, or those from older generations conserve their prior usage. Using language model-based word sense induction methods, we identify different senses of each word, and then model the prevalence of each of these word senses as a function of time and speaker age. We find that most words show a small but statistically significant effect of speaker age; across almost 140 y of Congress, older speakers typically take longer than younger speakers to follow changes in word usage, but nevertheless do so within a few years. Our findings indicate that despite minor age-based differences, word meaning change among mature speakers is likely not a generational process, but rather a zeitgeist process, in which older adult speakers can readily adopt new word usage patterns.

Indigenous territories and protected areas are crucial for ecosystem connectivity in the Amazon basin

Ecosystem connectivity—the uninterrupted flow of natural processes within and among ecosystems—is critical for maintaining healthy ecosystem functions. However, in the Amazon drainage basin, multiple anthropogenic activities are rapidly disrupting connectivity. To assess the severity of this problem, we analyzed the spatial distributions of six major anthropogenic activities: dam construction, deforestation, fire, mining, oil and gas exploitation, and roads. We examined their impacts across four key landscapes: Amazonian Andes, lowland nonflooded forests, wetlands, and rivers. Using a resistance-based connectivity model, we quantified connectivity across terrestrial, wetland, and river ecosystems and found a marked decline in connectivity across the basin. A central focus of our study was the role of Indigenous Territories and Protected Areas (ITPAs), which collectively cover over 50% of the basin. Our findings show that ITPAs sustain significantly high levels of ecosystem connectivity. Only 14 to 16% of ITPA land is impacted by anthropogenic activities, compared to 38% in unprotected areas. Terrestrial ecosystems in the southern and eastern Amazon are heavily impacted by deforestation, mining, and fires, with significantly higher connectivity inside ITPAs than in unprotected areas ( P < 0.01). Wetlands and riverine ecosystems also face severe fragmentation, particularly from dams and illegal mining—but maintain stronger connectivity within ITPAs (wetlands: P < 0.01; rivers: P < 0.001), with the few remaining free-flowing Andean rivers increasingly isolated from the lowland Amazon. Strengthening governance and sustainable initiatives in ITPAs, in partnership with local inhabitants, represents an expedient, efficient, and cost-effective strategy for conserving ecosystem connectivity in the Amazon basin.

Perchlorate in stratospheric aerosol particles

Perchlorate is a toxic, regulated contaminant in drinking water. According to previous isotopic studies, much of the perchlorate deposited to the Earth’s surface is formed in the atmosphere, with 36 Cl suggesting a large contribution from the stratosphere. Here, we present measurements of perchlorate in stratospheric aerosol particles and confirm that the stratosphere is an important source of perchlorate, whereas we did not observe production in the troposphere. Mass mixing ratios of aerosol perchlorate in the stratosphere were 1 to 10 parts per trillion by mass (pptm), with the highest concentrations observed in summer and in the Southern Hemisphere. Almost all of the perchlorate is in biomass burning and nitrogen-rich particles, despite those types contributing only a few percent of the aerosol particles. Such particles are less acidic than the majority of sulfuric acid particles. If the formation of perchlorate is sensitive to acidity, then the injection of some materials for solar radiation modification might significantly increase the global production of perchlorate.

Methane-munching symbionts fuel sea spiders in the deep sea

Genomics of Neotropical biodiversity indicators: Two butterfly radiations with rampant chromosomal rearrangements and hybridization

A central question in evolutionary biology is what drives the diversification of lineages. Rapid, recent radiations are ideal systems for this question because they still show key morphological and ecological adaptations associated with speciation. While most research on recent radiations focuses on those occurring in insular environments, less attention has been given to continental radiations with complex species interactions. Here, we study the drivers of continental radiations of Melinaea and Mechanitis butterflies (Nymphalidae: Ithomiini), which have rapidly radiated in the continental Neotropics. They are classical models for Amazonian biogeography and color pattern mimicry and have been proposed as biodiversity indicators. We generated reference genomes for five species of each genus and whole-genome resequencing data of most species and subspecies covering a wide geographic range to assess phylogeographic relationships, hybridization patterns, and chromosomal rearrangements. Our data help resolve the classification of these taxonomically challenging butterflies and reveal very high diversification rates. We find rampant evidence of historical hybridization and putative hybrid species in both radiations, which may have facilitated their rapid diversification by enriching the genetic diversity. Moreover, we identified dozens of chromosomal fusions and fissions between congeneric species that have likely expedited reproductive isolation. We conclude that interactions between geography, hybridization and chromosomal rearrangements have contributed to these rapid radiations in the highly diverse Neotropical region. We hypothesize that rapid radiations may be spurred if repeated periods of geographic isolation are combined with lineage-specific rapid accumulation of incompatibilities, followed by secondary contact with some gene exchange.

Synergies between speciation and conservation science yield novel insights for mitigating the biodiversity crisis of the Anthropocene

Phylogenetic networks empower biodiversity research

Reticulate evolution has long been recognized as a key mechanism that contributes to genetic and trait diversity. With the widespread availability of genomic data, investigating historical reticulate evolution across taxa has gained significant attention, driven by the rapid development of statistical methods for detecting nontreelike patterns. Phylogenetic networks provide a biologically intuitive approach to depicting evolutionary processes such as hybrid speciation and introgressive hybridization, which result in signatures of historical gene flow. Interpreting phylogenetic networks is especially critical for groups of conservation concern that lack reference genome resources and explicit hypotheses from prior investigation, such as those based on molecular data, morphology, or species distributions. Here, we highlight recent advances in computational methods for inferring networks from genome-scale data and offer guidelines for deriving biological insights from phylogenetic networks. Particular emphasis is placed on modeling hybridization and whole-genome duplication in the context of allopolyploidization. Practical recommendations for empirical studies and the limitations of commonly used methods are discussed throughout. We anticipate that phylogenetic networks will influence conservation biology and biodiversity research, emphasizing the need for careful consideration of reticulate evolution inferred from these networks in the near future. Networks will accelerate other pressing avenues of biodiversity research, especially investigations of orphan crops and climate change resilience in natural systems. The promise of phylogenetic networks connects with broader themes in the special feature Monitoring and restoring gene flow in the increasingly fragmented ecosystems of the Anthropocene by providing an emerging probabilistic framework for inferring historical connectivity between species and populations.

From science to impact: Conserving ecological connectivity in large conservation landscapes

Implementing ecological connectivity conservation in large landscapes requires cutting-edge science combined with consideration of ecological, socioeconomic, and cultural factors that collectively shape the outcomes of conservation efforts. We outline a theory of change (ToC) for connectivity conservation to improve the ecological condition of landscapes and biodiversity and the ecosystem services upon which humans depend. We review connectivity conservation efforts on four continents in large landscapes that span gradients of latitude, fragmentation, biodiversity value, socioeconomic characteristics, and the richness of data used to assess connectivity and target action. We share the substantial but variable progress made in each landscape and outline specific challenges to achieving conservation goals. Opportunities and challenges in public and private sectors can further leverage the potential of large-scale connectivity conservation to reduce isolation and improve gene flow in functional landscapes worldwide.

The effect of habitat loss and fragmentation on isolation by distance and divergence

Natural habitats have undergone drastic changes in quality, continuity, and extent during the Pleistocene, influencing the distribution of many species. More recently, human activities have converted continuous habitats into fragmented and isolated patches. Recent meta-analyses suggest that habitat loss and fragmentation (HL&F) have negatively impacted the genetic diversity of species but very few studies have analyzed the consequences of HL&F on the spatial distribution of genetic diversity and on isolation by distance (IBD) patterns (i.e., correlations between genetic and geographical distances) observed in many species. In this work, we use spatial simulations to investigate the speed at which IBD patterns generated in continuous habitats are lost in a context of HL&F. We characterized the behavior of IBD in the case of i) instantaneous HL&F, ii) gradual (two-steps) HL&F, and iii) range expansion followed by instantaneous HL&F. In addition, we show that a spatially explicit theoretical framework based on previous IBD theoretical results can be modified and applied to a toroidal stepping-stone model undergoing HL&F. Our results suggest that IBD patterns can be maintained for long periods of time after HL&F, thus pointing to the long-term persistence of signatures associated to past habitat connectivity in the genetic diversity of many species, even if they went through major and sometimes ancient fragmentation events. This suggests that some present-day fragmented species, who still exhibit significant IBD patterns, may have been partly disconnected for very long periods, on the order of tens of thousands of years for species with long generation time.

Face (e)motion and the third visual pathway

Biodiversity conservation requires integration of species-centric and process-based strategies

Conservation science and policy are geared primarily toward the preservation of species and habitats, with priority often given to the rarest, most vulnerable or most charismatic forms. This pattern-based approach has broad appeal and offers a pragmatic short-cut for targeting conservation action. However, the long-term efficacy of species and landscape conservation programs remains highly uncertain, amid growing evidence that sustainable conservation action requires an increased emphasis on preserving ecological and evolutionary processes. This reframing of conservation goals was first proposed 50 y ago, but the concept has struggled to gain traction, particularly in terms of translation into policy. Nonetheless, recent events have shifted the narrative, with multiple interlinked global challenges—including biological invasions, food security, disease, and climate change—putting ecological processes firmly back on the agenda. Concurrently, conservation finance is changing rapidly, driven in part by the 2022 Kunming-Montreal Global Biodiversity Framework, which prioritized actions to enhance and restore ecosystem stability, connectivity, and resilience. These ecosystem properties are fundamentally process-driven and appear to create an operational gulf between current conservation practice and the targets of international agreements. We describe how new approaches can be used to close this gap by redirecting conservation attention toward processes at the heart of ecosystem function, including adaptation, gene flow, dispersal, and trophic interactions. Wider adoption of these approaches is urgently needed to forge a deeper connection between conservation practice and policy targets, thereby ensuring that ongoing investment in biodiversity conservation goes beyond damage limitation and instead leaves a lasting legacy of resilient ecosystems.

Fossil samples archive functional diversity in marine ecosystems: An empirical test from a present-day coastal environment

The fossil record of functional diversity is increasingly used to study ecosystem evolution, extinction recovery, and factors affecting long-term trends in biodiversity. In addition, the youngest fossil record (late Quaternary) can provide insights into the natural range of functional variability of present-day ecosystems, providing a historical framework for conservation and restoration. However, the reliability of common functional diversity measures derived from fossils is uncertain. If fossils yield reasonable estimates of functional diversity, paleontological data could provide information on ecological attributes and trophic structure in past ecosystems allowing for temporally scalable assessments of ecological and evolutionary processes. To assess how well fossils preserve functional diversity across multiple types of marine invertebrates with varying preservation potential, we compared the live benthos (135 species from 6 phyla) with sympatric skeletal accumulations (150 species) and the predicted fossil record (112 species) for 51 coastal sites in North Carolina (USA). High functional fidelity between the live, dead, and fossil assemblages was supported by congruence in quantitative functional diversity indices (e.g., functional richness, redundancy, overredundancy, and vulnerability), overlap in multidimensional functional space, and species distributions among functional groups ( ρ > 0.85, P ≪ 0.001). Calculating vulnerability using a threshold of ≤2 species also reasonably approximated the vulnerability in the live assemblages. The results suggest that, despite differential preservation and time-averaging, functional estimates based on fossils may allow for historical assessments of ecological and evolutionary processes, including short-term community responses to human impacts as well as long-term macroevolutionary dynamics of marine ecosystems.

General anesthesia in early infancy accelerates visual cortical development

How human brain function is established through protracted trajectories of development is not yet fully understood. Maturation of γ-aminobutyric acid (GABA) circuits drives critical periods of cortical development in animal models. Whether early functional inhibition similarly impacts the pace of human brain development remains unknown. Here, in a longitudinal study of 93 infants across a range of repeated exposures to general anesthesia shortly after birth, we observed a dramatically accelerated development of visual evoked potential (VEP) waveforms (but not their latency) consistent with a conserved biological mechanism across species. Such sequelae of prolonged GABA-active anesthesia in the first half year after birth may particularly impact those at-risk of altered excitatory–inhibitory circuit balance.

SARS-CoV-2 uptake and inflammatory response in senescent endothelial cells are regulated by the BSG/VEGFR2 pathway

Aging is a risk factor for severe COVID-19, characterized by vascular endothelial dysfunction. Although possible susceptibility of vascular endothelial cells (ECs) to SARS-CoV-2 infection has been suggested, the details of entry into cells have not been clarified. Previously, we reported that in an aged mouse model of severe COVID-19, ECs show a massive viral uptake and inflammatory response. Here, we focused on the endocytic capacity of senescent ECs. We found that the senescent ECs showed high endocytic capacity and SARS-CoV-2 virus uptake. This triggers an nuclear factor-kappa B (NF-κB) pathway–mediated inflammatory response. Further, Basigin enhanced endocytosis in the senescent ECs by activating the intracellular vascular endothelial growth factor signaling. Thus, EC senescence is associated with enhanced SARS-CoV-2 endocytosis and subsequent vascular endothelial dysfunction. This could prove a potential target for treating severe COVID-19 in older adults.

From biologging to conservation: Tracking individual performance in changing environments

Under an accelerating biodiversity crisis, increased urbanization, habitat fragmentation, and climate change require new approaches to assess conservation impact. We argue that animal biologging is a cost-effective method for monitoring biodiversity at its source, including tracked animals and the habitats they occupy. Biologging, or animal-mounted sensors to record data, can act as a reporting, measurement, and verification system, and deliver direct insights into environments of selection. Using a case study of migrating white storks ( Ciconia ciconia ), we show that biologging yields real-time measurements of individual performance, mechanistic insights into environments of selection, and the potential for gene flow across anthropogenically influenced habitats. These insights can inform the success of biodiversity targets and conservation initiatives and improve real-time species management. At the global scale, we further illustrate that biologging studies display substantial bias in the types of environments and human conditions sampled. Studies appear biased toward sparsely populated areas and remain particularly rare in highly urbanized areas, areas experiencing high rates of recent forest fragmentation, and key areas for global biodiversity conservation efforts. We highlight the need for equitable access to technology to leverage the biodiversity potential of biologging in the Global South. Advances in software-defined tracking technology will soon give real-time information on energy budgets, survival, reproduction, and ultimately demographic processes and population-level parameters. When deployed into areas most needed, biologging can operationalize access to key measures of biodiversity maintenance such as gene flow, especially in difficult-to-access areas that are key to the future persistence of a species.

Genetic rescue of Florida panthers reduced homozygosity but did not swamp ancestral genotypes

Pumas ( Puma concolor ) occupy a vast geographical range spanning from Canada to Argentina. Due to urbanization and unregulated hunting, pumas in Florida, known as panthers, are the only breeding population east of the Mississippi River. In the 1990s, Florida panthers numbered <30 individuals suffering from inbreeding depression. In 1995, eight pumas from Texas were translocated into southern Florida to mitigate the effects of isolation. This translocation reduced inbreeding depression and increased population size. While genetic rescue is often suggested as a means of ameliorating the effects of small population size, the underlying genetic mechanism and its long-term efficacy remain understudied. We sequenced the genomes of posttranslocation Florida panthers (PTFPs) to elucidate the genomic consequences of genetic rescue. We inferred local ancestry across the genomes of PTFPs and found that no regions have been entirely replaced by Texas ancestry, discarding the possibility of genetic swamping. Furthermore, the beneficial effects of the translocation were likely caused by a reduction in homozygosity, alleviating recessive deleterious load, rather than by a reduction in the number of deleterious variants. We did not find evidence that selection has favored replacement of original Florida DNA with Texas DNA in any systematic fashion. Using simulations, we found that heterozygosity increased in the long-term compared to a no translocation scenario; however, the effects on fitness are more transient. Our findings hold significant implications not only for the management of Florida's panther population, but also for informing strategies for genetic rescue in other wild, inbred populations encompassing broader conservation efforts.

Translocations contribute to population rescue in an imperiled woodpecker

Anthropogenic destruction and fragmentation of habitat restrict many species to small, isolated populations, which often experience high extirpation risk. Restoring connectivity through translocations is one approach for mitigating the demographic and genetic perils faced by small populations. However, translocation interventions often lack substantial postrelease monitoring, and thus important information including the performance of translocated individuals, the long-term impacts on the recipient population, and the extent to which management objectives are fulfilled over time are often poorly known. Here, we examined the establishment dynamics and long-term outcomes of translocations from multiple donor populations into an intensively monitored population of the federally threatened red-cockaded woodpecker. We found evidence that translocations contributed to population growth and led to genetic admixture within the population. The translocated birds provided direct demographic benefits through high rates of establishment, breeding, and survival. We found that the survival and lifetime reproductive success of individuals were positively related to their amount of translocation ancestry, indicating that demographic benefits extended beyond the direct performances of the translocated birds. The translocations diversified the population’s genetic composition with the ancestry of most individuals in the latter years of the study deriving from multiple translocation donor populations. We found marked heterogeneity in the genetic contributions of translocated individuals and cohorts, leading to disproportionate representation of certain lineages. Encouragingly, despite some accumulation of inbreeding during the study, the translocations thus far have not substantially contributed to inbreeding. Our findings illustrate in precise detail how translocations can be an effective approach for managing imperiled taxa.

Combining MicroED and native mass spectrometry for structural discovery of enzyme–small molecule complexes

With the goal of accelerating the discovery of small molecule–protein complexes, we leverage fast, low-dose, event-based electron counting microcrystal electron diffraction (MicroED) data collection and native mass spectrometry. This approach, which we term electron diffraction with native mass spectrometry (ED-MS), allows assignment of protein target structures bound to ligands with data obtained from crystal slurries soaked with mixtures of known inhibitors and crude biosynthetic reactions. This extends to libraries of printed ligands dispensed directly onto TEM grids for later soaking with microcrystal slurries, and complexes with noncovalent ligands. ED-MS resolves structures of the natural product, epoxide-based cysteine protease inhibitor E-64, and its biosynthetic analogs bound to the model cysteine protease, papain. It further identifies papain binding to its preferred natural products, by showing that two analogs of E-64 outcompete others in binding to papain crystals, and by detecting papain bound to E-64 and an analog from crude biosynthetic reactions, without purification. ED-MS also resolves binding of the CTX-M-14 β-lactamase, a target of active drug development, to the non-β-lactam inhibitor, avibactam, alone or in a cocktail of unrelated compounds. These results illustrate the utility of ED-MS for natural product ligand discovery and for structure-based screening of small molecule binders to macromolecular targets, promising utility for drug discovery.

Molecular mechanisms of cryoablation-mediated lung cancer suppression unveiled by non-coding RNA regulatory network profiling

Decide, act, reflect, and maybe a self in all this?