編譯 | 李言
Science , 1 MAR 2024, VOL 383, ISSUE 6686
【科學】 2024年3月1日，第383卷，6686期
天文學 Astronomy
A far-ultraviolet–driven photoevaporation flow observed in a protoplanetary disk
在原行星盤中觀察到遠紫外線驅動的光致蒸發流
▲ 作者：OLIVIER BERNÉ, EMILIE HABART et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.adp861
▲ 摘要：
大多數低質素恒星都是在包含大質素恒星的星團中形成的，這些恒星是遠紫外線（FUV）輻射的來源。理論模型預測，這種FUV輻射會在低質素恒星周圍的原行星盤表面產生光解離區（PDRs），從而影響盤內行星的形成。
我們報告韋布太空望遠鏡和阿塔卡馬大型毫米波陣列在獵戶座星雲中觀測到一個FUV輻射原行星盤。從PDR中檢測到了發射線；對它們的動力學和激發進行建模使我們能夠限制氣體中的物理情況。
我們量化了FUV輻射引起的質素損失率，發現它足以在不到一百萬年的時間內從星盤中剝離氣體。這個速度足以影響盤內巨行星的形成。
▲ Abstract：
Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.
生物學 Biology
Defective pollen tube tip growth induces neo-polyploid infertility
花粉管尖端生長缺陷導致新多倍體不育
▲ 作者：JENS WESTERMANN, THANVI SRIKANT et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.adh0755
▲ 摘要：
在此，我們報告了阿拉伯芥新多倍體花粉管尖端生長的嚴重育性缺陷。新形成的多倍體阿拉伯芥 A. arenosa 花粉管生長緩慢，具有解剖和生理異常的情況，且經常過早破裂，導致基因表現改變。
這些表型會在前進演化的多倍體中恢復。我們還發現，在自然四倍體 A. arenosa 中，有兩個尖端生長基因的配子體（花粉管）基因型與四倍體的花粉管效能密切相關。我們的工作確定了花粉管尖端生長是新多倍體植物的重要生育挑戰，並為自然前進演化的多基因解決方案提供了見解。
▲ Abstract：
Here we report that a severe fertility-compromising defect in pollen tube tip growth arises in new polyploids of Arabidopsis arenosa. Pollen tubes of newly polyploid A. arenosa grow slowly, have aberrant anatomy and disrupted physiology, often burst prematurely, and have altered gene expression. These phenotypes recover in evolved polyploids. We also show that gametophytic (pollen tube) genotypes of two tip-growth genes under selection in natural tetraploid A. arenosa are strongly associated with pollen tube performance in the tetraploid. Our work establishes pollen tube tip growth as an important fertility challenge for neo-polyploid plants and provides insights into a naturally evolved multigenic solution.
Divergent responses of pelagic and benthic fish body-size structure to remoteness and protection from humans
遠洋和底棲魚類體型結構在遠離人類和人類保護情況下的不同反應
▲ 作者：TOM B. LETESSIER, DAVID MOUILLOT et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.adi7562
▲ 摘要：
在這項研究中，我們從17411個立體誘餌影片部署中得出魚類體積指示，以測試遠洋和底棲生物對遠離人類壓力的反應差異以及海洋保護區（MPAs）的有效性。
透過研究823849條魚的記錄，我們報告了不同系統之間的不同反應，遠洋魚類的梯級結構相比底棲魚類的體積結構在人類活動區域附近受到更嚴重的侵蝕，這表明上層海洋系統更容易受到人類壓力的影響。
透過設立海洋保護區，可以有效地保護底棲魚類的體積結構，從而有助於底棲魚類棲息地和相關魚類的恢復。相比之下，要恢復世界上最大和最瀕危的遠洋魚類，就需要在偏遠地區——包括保護工作滯後的公海——建立高度保護區。
▲ Abstract：
In this work, we derive fish size indicators from 17,411 stereo baited-video deployments to test for differences between pelagic and benthic responses to remoteness from human pressures and effectiveness of marine protected areas (MPAs). From records of 823,849 individual fish, we report divergent responses between systems, with pelagic size structure more profoundly eroded near human markets than benthic size structure, signifying greater vulnerability of pelagic systems to human pressure. Effective protection of benthic size structure can be achieved through MPAs placed near markets, thereby contributing to benthic habitat restoration and the recovery of associated fishes. By contrast, recovery of the world’s largest and most endangered fishes in pelagic systems requires the creation of highly protected areas in remote locations, including on the High Seas, where protection efforts lag.
A morphological basis for path-dependent evolution of visual systems
視覺系統路徑依賴前進演化的形態學基礎
▲ 作者：REBECCA M. VARNEY, DANIEL I. SPEISER et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.adg2689
▲ 摘要：
在此，我們展示了最近在石鱉中前進演化了兩次的兩種類別的分布式視覺系統，證明了一種復雜特征的、快速且路徑依賴的前進演化。石鱉可以前進演化出的視覺系統類別受到其殼板上感覺神經開口數量的限制。
開口較多的譜系前進演化出具有數千個眼點的視覺系統，而開口較少的譜系只能前進演化出數百個殼眼的視覺系統。這些由路徑依賴形成的宏觀前進演化結果既是確定性的，也是隨機的，因為雖然其可能性是有限的，但並不是完全可預測的。
▲ Abstract：
Here, we show that two types of distributed visual systems recently evolved twice within chitons, demonstrating rapid and path-dependent evolution of a complex trait. The type of visual system that a chiton lineage can evolve is constrained by the number of openings for sensory nerves in its shell plates. Lineages with more openings evolve visual systems with thousands of eyespots, whereas those with fewer openings evolve visual systems with hundreds of shell eyes. These macroevolutionary outcomes shaped by path dependence are both deterministic and stochastic because possibilities are restricted yet not entirely predictable.
地球科學 Earth Science
Large-scale self-organization in dry turbulent atmospheres
幹燥亂流大氣中的大範圍自組織情況
▲ 作者：ALEXANDROS ALEXAKIS, RAFFAELE MARINO et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.adg8269
▲ 摘要：
亂流對流波動如何在行星大氣中組織形成更大規模的結構，仍然是一個無法透過定量方法回答的問題。半個世紀前，在二維流體中提出了這個過程是逆級聯結果的假設，但它是否適用於大氣和海洋流動仍然存在激烈的爭論，這阻礙了我們對行星系統能量平衡的理解。
我們使用空間分辨率為122882× 384點的直接數值模擬表明，旋轉和分層流可以在三維空間中支持雙向的能量級聯，其羅斯貝與弗勞德數的比值與地球大氣的比值相當。我們的結果表明，自發秩序可以在幹燥的大氣中透過逆級聯到最大的空間尺度而產生。
▲ Abstract：
How turbulent convective fluctuations organize to form larger-scale structures in planetary atmospheres remains a question that eludes quantitative answers. The assumption that this process is the result of an inverse cascade was suggested half a century ago in two-dimensional fluids, but its applicability to atmospheric and oceanic flows remains heavily debated, hampering our understanding of the energy balance in planetary systems. We show using direct numerical simulations with spatial resolutions of 122882 × 384 points that rotating and stratified flows can support a bidirectional cascade of energy, in three dimensions, with a ratio of Rossby to Froude numbers comparable to that of Earth’s atmosphere. Our results establish that, in dry atmospheres, spontaneous order can arise through an inverse cascade to the largest spatial scales.
Anthropogenic climate change has influenced global river flow seasonality
人為氣候變遷影響了全球河流流量的季節性
▲ 作者：HONG WANG, JUNGUO LIU et al.
▲ 連結：
https://www.science.org/doi/10.1126/science.adi9501
▲ 摘要：
本研究引入了分配熵的使用，作為評估季節間流量—體積不均勻性的穩定措施，從而實作了全球範圍分析。我們發現，約21%的長期河流監測站在季節流量分布上表現出了顯著變化，但其中2/3與年平均流量趨勢無關。
透過將數據驅動的徑流重建與最先進的水文模擬相結合，我們確定了北部高緯度地區（北緯50°以上）河流流量季節性的明顯減弱，這一現象與人為氣候影響直接相關。
▲ Abstract：
This study introduces the use of apportionment entropy as a robust measure to assess flow-volume nonuniformity across seasons, enabling a global analysis. We found that ~21% of long-term river gauging stations exhibit significant alterations in seasonal flow distributions, but two-thirds of these are unrelated to trends in annual mean discharge. By combining a data-driven runoff reconstruction with state-of-the-art hydrological simulations, we identified a discernible weakening of river flow seasonality in northern high latitudes (above 50°N), a phenomenon directly linked to anthropogenic climate forcing.
