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Cenozoic evolution of spring persistent rainfall in East Asia and North America driven by paleogeography
Spring persistent rainfall is a unique climate phenomenon that prevails in East Asia today, providing precious water resources to this densely populated region. However, its Cenozoic history and underlying mechanisms remain poorly understood. Here we show that the spring persistent rainfall in East Asia has emerged since the Miocene, whereas it previously flourished in North America during the Eocene, as revealed by climate models integrated with climate proxies. The contrasting evolution of spring persistent rainfall in East Asia and North America is determined by paleogeography and further influenced by CO2-induced warming. The uplift of the Tibetan Plateau and the westward drift of the Rocky Mountains have triggered a mid-latitude Rossby wave train since the Miocene, altering the position and intensity of the subtropical highs and thus rainfall patterns. Our results illuminate the Cenozoic evolution of spring persistent rainfall, with implications for the spring climate under the extreme future warming.
The 2023 Türkiye-Syria earthquake disaster was exacerbated by an atmospheric river
Strong earthquakes in mountain landscapes can trigger widespread slope failures, initiating chains of multiple hydro-geomorphic hazards. These impacts disrupting ongoing response operations may be amplified by extreme post-seismic precipitation delivered by atmospheric rivers (ARs). However, to our knowledge, cases of ARs following major earthquakes have not been previously documented. Here, we document the combined effects of seismic and precipitation extremes that perturbed the area struck by the February 6, 2023, Türkiye-Syrian earthquakes. Strong ground shaking triggered thousands of landslides, and 36 days later, an exceptionally strong AR delivered up to 183 mm of precipitation in just 20 hours. This extreme precipitation induced additional landslides, debris flows, and flooding, disrupting recovery efforts, affecting temporary settlement areas, and claiming more lives. This cascade of hazards highlights the need to integrate seismic and weather extremes into rapid hazard assessment protocols to enhance disaster preparedness and response.
Identification and cultivation of anaerobic bacterial scavengers of dead cells
The cycle of life and death and Earth’s carbon cycle(s) are intimately linked, yet how bacterial cells, one of the largest pools of biomass on Earth, are recycled back into the carbon cycle remains enigmatic. In particular, no bacteria capable of scavenging dead cells in oxygen-depleted environments have been reported thus far. In this study, we discover the first anaerobes that scavenge dead cells and the two isolated strains use distinct strategies. Based on live-cell imaging, transmission electron microscopy, and hydrolytic enzyme assays, one strain (designated CYCD) relied on cell-to-cell contact and cell invagination for degrading dead food bacteria where as the other strain (MGCD) degraded dead food bacteria via excretion of lytic extracellular enzymes. Both strains could degrade dead cells of differing taxonomy (bacteria and archaea) and differing extents of cell damage, including those without artificially inflicted physical damage. In addition, both depended on symbiotic metabolic interactions for maximizing cell degradation, representing the first cultured syntrophic Bacteroidota. We collectively revealed multiple symbiotic bacterial decomposition routes of dead prokaryotic cells, providing novel insight into the last step of the carbon cycle.
A decision-making framework to maximise the evolutionary potential of populations – Genetic and genomic insights from the common midwife toad (Alytes obstetricans) at its range limits
Anthropogenic habitat modification and climate change are fundamental drivers of biodiversity declines, reducing the evolutionary potential of species, particularly at their distributional limits. Supportive breeding or reintroductions of individuals are often made to replenish declining populations, sometimes informed by genetic analysis. However, most approaches utilised (i.e. single locus markers) do not have the resolution to account for local adaptation to environmental conditions, a crucial aspect to consider when selecting donor and recipient populations. Here, we incorporate genetic (microsatellite) and genome-wide SNP (ddRAD-seq) markers, accounting for both neutral and putative adaptive genetic diversity, to inform the conservation management of the threatened common midwife toad, Alytes obstetricans at the northern and eastern edges of its range in Europe. We find geographically structured populations (n = 4), weak genetic differentiation and fairly consistent levels of genetic diversity across localities (observed heterozygosity and allelic richness). Categorising individuals based on putatively adaptive regions of the genome showed that the majority of localities are not strongly locally adapted. However, several localities present high numbers of private alleles in tandem with local adaptation to warmer conditions and rough topography. Combining genetic diversity and local adaptations with estimates of migration rates, we develop a decision-making framework for selecting donor and recipient populations which maximises the geographic dispersal of neutral and putatively adaptive genetic diversity. Our framework is generally applicable to any species, but especially to amphibians, so armed with this information, conservationists may avoid the reintroduction of unsuitable/maladapted individuals to new sites and increase the evolutionary potential of populations within species.
Origin and de novo domestication of sweet orange
Sweet orange is cultivated worldwide but suffers from various devastating diseases because of its monogenetic background. The elucidation of the origin of a crop facilitates the domestication of new crops that may better cope with new challenges. Here we collected and sequenced 226 citrus accessions and assembled telomere-to-telomere phased diploid genomes of sweet orange and sour orange. On the basis of a high-resolution haplotype-resolved genome analysis, we inferred that sweet orange originated from a sour orange × mandarin cross and confirmed this model using artificial hybridization experiments. We identified defense-related metabolites that potently inhibited the growth of multiple industrially important pathogenic bacteria. We introduced diversity to sweet orange, which showed wide segregation in fruit flavor and disease resistance and produced canker-resistant sweet orange by selecting defense-related metabolites. Our findings elucidate the origin of sweet orange and de novo domesticated disease-resistant sweet oranges, illuminating a strategy for the rapid domestication of perennial crops.
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