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Sexual selection and speciation : a meta-analysis of comparative studies
Get PDFFunding: T.J. is funded by the CNRS, M.G.R. by NERC (UK), T.C.M. by US NSF 2026334, and J.T. by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 101078021)Understanding the drivers of biodiversity is a central goal in evolutionary biology. In particular, sexual selection has long been proposed as a potential catalyst of speciation, but empirical evidence remains inconclusive. Here, we present a comprehensive meta-analysis synthesizing 145 effect sizes from 50 comparative studies testing the relationship between proxies of sexual selection and species diversity across the animal kingdom. Our results reveal a modest but consistent positive association (global effect size: r = 0.201; 95% confidence interval: 0.035–0.366), supporting the hypothesis that sexual selection contributes to speciation. However, the global effect size corresponds to an R2 of only 0.04, suggesting that sexual selection is not a dominant driver of speciation. We also uncover substantial heterogeneity among effect sizes, largely attributable to between-study variation and taxonomic affinities of effect sizes. Studies that fail to account for phylogenetic non-independence tend to report stronger effects. In contrast, other tested methodological and biological moderators, such as the proxies used to estimate the strength of sexual selection or proxies of speciation, do not explain the observed heterogeneity in effect sizes. Sensitivity analyses confirm the robustness of our results, and we find no signatures of publication bias. We highlight the need for broader taxonomic coverage and a greater focus on understudied mechanisms, such as post-copulatory sexual selection, to refine our understanding of the role of sexual selection in shaping species diversity.Peer reviewe
Tropical cloud feedbacks estimated from observed multidecadal trends
Get PDFFunding: E. V. acknowledges funding from the U.K. Natural Environment Research Council, Doctoral Training Partnership in Environmental Research (Grant NE/S007474/1). M. P. B. was supported by the U.K. Natural Environment Research Council (Grant NE/T006269/1).Tropical cloud feedbacks are an important source of uncertainty in estimates of climate sensitivity. The extent to which changes in atmospheric circulation contribute to these feedbacks remains an open question. Here, all-sky radiative flux observations and an atmospheric reanalysis are used to estimate tropical cloud feedbacks from multidecadal trends (1985–2020) in cloud radiative effect and surface temperature. We decompose the observed feedbacks into dynamic and nondynamic components to quantify the impact of circulation trends. Narrowing and strengthening of tropical ascent lead to substantial dynamic feedbacks on regional scales that are similar in magnitude to the nondynamic feedbacks. However, as previously shown for high- and low-resolution climate models, large dynamic feedbacks in different circulation regimes are connected by the atmospheric mass budget and approximately cancel when averaged across the tropics due to the quasi-linear relationship between cloud radiative effect and vertical velocity. This results in small dynamic contributions to the tropical-mean net, longwave, and shortwave feedbacks. We suggest that this result will hold in future and thus that isolating the nondynamic components associated with individual cloud types can provide important insights into the processes controlling the tropical-mean cloud feedback and its uncertainty. Additionally, we show that feedbacks estimated from multidecadal trends differ from those estimated from interannual variability. We demonstrate that, for dynamic feedbacks, this is because changes are controlled by different mechanisms and this leads to a differing spatial distribution of temperature sensitivity. Finally, we provide new estimates of the uncertain combined tropical anvil area and albedo feedback using both multidecadal trends and interannual variability.Peer reviewe
Higher-order shortest paths in hypergraphs
Get PDFFunding: F.B. acknowledges support from the Austrian Science Fund (FWF) through project 10.55776/PAT1052824 and project 10.55776/PAT1652425. B.L.N. gratefully acknowledges the hospitality of the Central European University during the period in which this manuscript was completed. The computational results have been achieved in part using the Austrian Scientific Computing (ASC) infrastructure.One of the defining features of complex networks is the connectivity properties that we observe emerging from local interactions. Recently, hypergraphs have emerged as a versatile tool to model networks with nondyadic, higher-order interactions. Nevertheless, the connectivity properties of real-world hypergraphs remain largely understudied. In this work we introduce path size as a measure to characterize higher-order connectivity and quantify the relevance of nondyadic ties for efficient shortest paths in a diverse set of empirical networks with and without temporal information. By comparing our results with simple randomized null models, our analysis presents a nuanced picture, suggesting that nondyadic ties are often central and are vital for system connectivity, while dyadic edges remain essential to connect more peripheral nodes, an effect which is particularly pronounced for time-varying systems. Our work contributes to a better understanding of the structural organization of systems with higher-order interactions.Peer reviewe
Effect of caesarean birth on perinatal mortality for singleton breech presentation in spontaneous preterm labour – a target trial emulation using Scottish health record data
Get PDFFunding: HWU was supported by a Glasgow Children’s Hospital Charity Research Fund Project Support Grant (GCHC/PSG/2018/10) and a Menzies School of Health Research Maple-Brown Foundation Future Leaders Fellowship. SB was supported by a National Health Service (NHS) Fife Research and Development Bursary. SJS was funded by a Wellcome Clinical Career Development Fellowship 209560/Z/17/Z. SAU was funded by a National Health Service (NHS) Scotland Research (NRS) Fellowship.Background The effects of mode of birth for women in preterm breech labour could not be successfully determined in randomised trials. We aimed to explore the effect of caesarean birth on perinatal mortality for women in spontaneous-onset preterm labour with a singleton baby presenting breech through target trial emulation. Methods A target trial emulation of a parallel group randomised controlled trial using routinely collected Scottish electronic health record data was performed. Participants were pregnant women at 24–36 gestational weeks with a singleton breech baby, no prior caesarean birth, in spontaneous labour with a live baby at labour onset (1 January 1997 to 31 December 2019). We compared caesarean birth (intervention) to vaginal breech birth (control) in a per-protocol analysis (actual mode of birth). The primary outcome was extended perinatal mortality (intrapartum stillbirths and neonatal deaths). A multiple logistic regression model with inverse probability weight was used to adjust for measured confounders. There were 2,092 caesarean births and 967 vaginal breech births. In the emulated trial, caesarean birth reduced extended perinatal mortality compared to vaginal breech birth (odds ratio [OR] 0.35, 95% confidence interval [CI] 0.27 to 0.43). At 24 weeks’ gestation, caesarean birth decreased the odds of perinatal death by 47.7% (OR: 0.53, 95% CI: 0.35 to 0.78). At 36 gestational weeks it was associated with an 82.1% reduction in the odds of perinatal death (OR: 0.18, 95% CI: 0.10 to 0.32). As the risk of perinatal mortality is inversely correlated with gestational age at birth, seven and 88 caesarean births were needed to prevent one perinatal death at 24 weeks and 36 weeks’ gestation, respectively. Conclusions Caesarean birth was associated with a reduced risk of extended perinatal mortality in spontaneous preterm singleton breech labour in a per-protocol trial emulation. Observational data that accurately captures planned mode of birth and unmeasured confounders such as breech subtype is required to emulate an intention-to-treat analysis.Peer reviewe
Simplicial complexes defined on groups
Get PDFThis study makes some preliminary observations towards an extension of current work on graphs defined on groups to simplicial complexes. I define a variety of simplicial complexes on a group, which are preserved by automorphisms of the group, and in many cases have a relation to familiar graphs on the group. The ones which seem to reach deepest into the graph structure are two forms of independence complex, and some results on the class of groups for which these two complexes coincide are given. Other examples are treated more briefly.Peer reviewe
Sustainable management of non-timber forest products in Peruvian Amazonia : lessons learnt from participatory use of smartphone technology
Get PDFFunding: This project was funded by a Leverhulme Trust Research Project Grant (RPG-2018-306), the Scottish Funding Council - Global Challenges Research Fund (SFC/AN/10/2018), a British Council Newton Fund grant (414608248) and the Natural Environment Research Council (NERC) standard grant (NE/R000751/1)Over a billion people rely on tropical forest resources for their livelihoods, so sustainable resource use is essential for long-term human and ecosystem health. Smartphone technologies are increasingly proposed as a cost-effective and accessible way of widening community participation in environmental monitoring, but existing studies typically focus on the technological capabilities of smartphones for data collection, rather than how they represent local community interests or affect conservation outcomes. To address this gap, we report on the participatory and technical potential and limitations of smartphone-assisted collaboration for sustainable management of aguaje palms (Mauritia flexuosa), a commercially valuable species in the Peruvian Amazon. We assessed the potential of smartphone-based data collection, using OpenDataKit (ODK), for monitoring forest resources, working with a community management group and the Peruvian National Service of Natural Protected Areas to quantify and map the distribution, abundance and productivity of aguaje palms. Our study highlights tensions between technical and participatory elements of the process. We demonstrate the accessibility of ODK to users with varied levels of digital literacy, its ability to represent multiple interests and the potential to innovatively combine small ODK datasets with vegetation data and Google Earth Engine mapping. However, our work highlights the risk that dependence on digital technologies can exclude stakeholders with poor connectivity, since the process mainly engaged digitally connected partners. Based on this experience, we provide four lessons to support good practice and avoid misalignment of technological and participatory interests in the design and implementation of participatory environmental management using smartphone and open-source technology.Peer reviewe
Pronounced postmating response in the Drosophila female reproductive tract fluid proteome
Get PDFFunding: This work was supported by a National Science Foundation Graduate Research Fellowship (to C. E. M.-G.), by grants from the National Science Foundation (DEB-1655840 to S. D. and S. P.) and the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R21-HD088910 to S. D. and S. P.).Fertility depends on the progression of complex and coordinated postmating processes within the extracellular environment of the female reproductive tract (FRT). Molecular interactions between ejaculate and FRT proteins regulate many of these processes, including sperm motility, migration, storage, and modification, along with concurrent changes in the female. Although extensive progress has been made in the proteomic characterization of the male-derived components of sperm and seminal fluid, investigations into the FRT have remained more limited. To achieve a comparable level of knowledge regarding female-derived proteins that comprise the reproductive environment, we utilized semiquantitative MS-based proteomics to study the composition of the FRT tissue and, separately, the luminal fluid, before and after mating in Drosophila melanogaster. Our approach leveraged whole-fly isotopic labeling to delineate female proteins from transferred male ejaculate proteins. Our results revealed several characteristics that distinguish the FRT fluid proteome from the FRT tissue proteome: (1) the fluid proteome is encoded by genes with higher overall levels of FRT gene expression and tissue specificity, including many genes with enriched expression in the fat body, (2) fluid-biased proteins are enriched for metabolic functions, and (3) the fluid exhibits pronounced postmating compositional changes. The dynamic mating-induced proteomic changes in the FRT fluid inform our understanding of secretory mechanisms of the FRT, serve as a foundation for establishing female contributions to the ejaculate–female interactions that regulate fertility, and highlight the importance of applying proteomic approaches to characterize the composition and dynamics of the FRT environment.Peer reviewe
Invisible loot : maritime warfare and circulating objects in Hugo Grotius’ De Jure Praedae
Get PDFThis article offers a new reading of Hugo Grotius’s early treatise De Jure Praedae Commentarius (on the law of prize and booty; 1604-1606), approaching this text from the perspective of material culture. Commissioned by the Verenigde Oostindische Compagnie (VOC) after Dutch seafarers confiscated the Portuguese carrack Santa Catarina and its cargo, Grotius’s text, this article proposes, deliberately obscures the ways the Dutch valued objects as trophies, loot, and spoils. Analysis of De Jure Praedae reveals that Grotius argues against the display of material wealth that the Dutch had acquired as loot, negatively associating it with the Portuguese and Spanish empires and instead propagating the invisible dispersal of the booty. In this way, De Jure Praedae, an early work by a major apologist of the VOC, rationalises the continuous circulation of objects at the service of Dutch empire-building. The article’s broader project is to speak to scholars of the global circulation of material culture and of empire alike to contribute to a history of how looted objects were conceived as key instruments in Dutch imperial expansion.Peer reviewe
Organic geochemical evidence for life in Archean rocks identified by pyrolysis–GC–MS and supervised machine learning
Get PDFFunding: Studies of molecular biosignatures have been supported by the John Templeton Foundation Grant 61783. Additional support has been provided by the NASA Astrobiology Institute ENIGMA Team Grant 80NSSC18M0093, a private foundation, and the Carnegie Institution for Science. A.C. and A.D.C. are supported by NSF-Earth Sciences grant 2029521. M.L.W.’s research is funded by NASA through the NASA Hubble Fellowship Program Grant HST-HF2-51521.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555.Throughout Earth’s history, organic molecules from both abiogenic and biogenic sources have been buried in sedimentary rocks. Most of these organic molecules have been significantly altered by geologic processes through deep time. Nonetheless, the nature and distribution of those ancient fragmentary organic remains have the potential to reveal diagnostic biomolecular information after billions of years of burial. Here, we analyzed 406 fossil, modern biological, meteoritic, and synthetic samples using pyrolysis gas chromatography and mass spectrometry. We explored these analytical data via supervised machine-learning methods to discriminate samples of biogenic vs. abiogenic origin, plant vs. animal phylogenetic affinity, and photosynthetic vs. nonphotosynthetic physiology. Dividing 272 samples with known phylogenetic affinity and physiology into 9 categories, each further divided into 75% training and 25% testing sets, our random forest models accurately predict pairwise assignments of modern vs. fossil or meteoritic organics (100% correct assignments), fossil plant tissues vs. meteoritic organics (97%), modern vs. fossil plant tissues (98%), and modern plants vs. animal tissues (95%). Pairwise comparisons between fossil biogenic samples vs. abiogenic samples resulted in 93% correct classifications, while analysis of modern and ancient photosynthetic vs. nonphotosynthetic samples also resulted in 93% correct assignments. Our analyses demonstrate that molecular biosignatures can survive in ancient fossils and allow for the identification of organismal origins and traits. Consistent with previous morphological and isotopic inferences, we present evidence for biogenic molecular assemblages in Paleoarchean rocks (3.33 Ga) and for photoautotrophy in Neoarchean rocks (2.52 Ga).Peer reviewe
NH3 synthesis with Ca2NH supported Ru catalyst under mild conditions
Get PDFFunding: This work was performed at the University St Andrews under the grant of TUBITAK 2219-International Postdoctoral Research Fellowship Program, Turkiye.Calcium nitride-hydride supported Ru has demonstrated superior catalytic performance among Ru-based catalysts according to literature. This work explores the impact of Ca2NH synthesis precursors on the catalytic performance of Ru–Ca2NH in ammonia synthesis, with the goal of gaining deeper insight into their role. For this reason, β-Ca2NH was synthesized using CaH2 and N2, which is different from reported in the literature. The structure of the synthesized material was carefully analysed and confirmed via XRD. Subsequently, Ru–Ca2NH catalysts were prepared at varying percentages, ranging from 1 % to 10 %, to determine the optimum amount of Ru. The performance of these catalysts was investigated in ammonia synthesis reactions conducted under the continuous gas flow at 340 °C and 0.1 MPa. UV–Vis spectrometry was carried out to determine total ammonia production rate, and was calculated as 1.6 mmol/g cat. h. This production rate was higher than the performance of most of the reported Ru-based catalysts.Peer reviewe
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