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Given that climate variability and change present unprecedented challenges to the rail sector, efforts to produce relevant climate data/information for climate risk management and adaptive decision making in the rail sector are gaining traction. However, inadequate understanding of climate change impact and information needs raises several concerns for the sector. This paper addressed the question: What climate risk information services are needed to support the adaptation needs of the rail sector? Data from interviews, literature reviews, and workshops were used. The results show that changes in precipitation, temperature, sea-level rise, and thunderstorms are the top drivers of climate risk in the sector. Additionally, the need for tailor-made climate information to manage these changes is in high demand. Although insufficient, rail organizations use special protocols to manage climate risk. Understudied countries have operational and design standards formulated in metrics and codes related to specific critical weather conditions as part of their Natural Hazard Management process. However, desirable adjustments in the standards are currently based on past events rather than future climate conditions. Future climate change information is relevant for medium- to longer-term decisions, strategy, and policymaking. For operational and design standards, weather and climate information provided by national weather service agencies are used but they also refer to the European standards and databases. National level data/information is preferred for developing thresholds for standards yet pan-European level information is also relevant in filling in missing data gaps. Therefore, rail organizations operate on flexibility and a “use of best available data” policy. Understanding how climate information is used to support decision-making in the rail sector is by no means an easy task given the variety of decisions to be taken at different spatial and temporal scales. However, stakeholder engagement proved to be an important step to better inform tailor-made information that is user relevant.

Climate change, urbanisation and population growth are causing water availability and safety issues in cities around the world. Of all natural hazards, flood and drought affected the most people between 2000 and 2019. Around 1.65 billion people were impacted by floods and 1.43 billion by drought. Whether it be too much water too quickly, with extreme rainfall resulting in flash flooding in urban areas, or not enough water, because of long-term drought conditions, no city is immune to these climatic changes. Sea-level rise and storm surges could force hundreds of millions of people in coastal cities from their homes at a total cost of more than US$ 1 trillion a year by 2050. This increased migration and urbanisation is putting pressure on city water systems and infrastructure. Floods and droughts are, therefore, threatening the welfare of urban citizens and the critical services and operation of cities. Cities and their leaders need to understand this complex and imminent threat and its consequences. Knowing how much flooding and drought a city will experience and the potential impacts of these hazards will prompt city authorities and financiers to take action on adaptation and resilience. To this end, the analysis behind Water-safe Cities report quantifies the future hazards of flooding and drought in 97 C40 cities by 2050 and the expected annual impact this will have on populations, urban infrastructure and the gross domestic product (GDP) of a city. The modelling and analysis have been used to develop interactive maps hosted on the Water-safe Cities webpage and the key headlines and messages of the research.

'Cultural evolution' as a field applies the insight that cultural change may be like biological evolution. Concepts, methods and ideas from the well-established theory of biological evolution are applied to cultural processes, such as the spread and diversification of languages or technology. Some researchers even suggest that evolutionary theory may serve as a synthetic framework for unifying the humanities and the social sciences, just as biological evolution is viewed as a unifying principle underlying all life sciences. This theme issue examines the theoretical and methodological core of this rapidly expanding field. What premises form the foundation? What are the disparities? The issue unites perspectives and fosters dialogue between scholars across disciplines - breaking ground in the study of the dynamics and diversity of culture.

Contexte: Les champignons mycorhiziens à arbuscules (AMF) établissent des relations symbiotiques avec la plupart des plantes grâce à leurs réseaux d’hyphes qui s’associent avec les racines de leurs hôtes. De précédentes études ont révélé des niveaux de variation génétique extrêmes pour des loci spécifiques permettant de supposer que les AMF peuvent contenir des milliers de noyaux génétiquement divergents dans un même cytoplasme. Si aucun processus de reproduction sexuée n’a jusqu’ici été observé chez ces mycorhizes, on constate cependant que des niveaux élevés de variation génétique peuvent être maintenus à la fois par l’échange de noyaux entre hyphes et par des processus fréquents de recombinaison entre noyaux. Les AMF se propagent par l’intermédiaire de spores qui contiennent chacune un échantillon d’une population initiale de noyaux hétérogènes, directement hérités du mycélium parent. À notre connaissance les AMF sont les seuls organismes qui ne passent jamais par un stade mononucléaire, ce qui permet aux noyaux de diverger génétiquement dans un même cytoplasme. Ces aspects singuliers de la biologie des AMF rendent l’estimation de leur diversité génétique problématique. Ceci constitue un défi majeur pour les écologistes sur le terrain mais également pour les biologistes moléculaires dans leur laboratoire. Au-delà même des problématiques de diversité spécifique, l’amplitude du polymorphisme entre noyaux mycorhiziens est mal connue. Le travail proposé dans ce manuscrit de thèse explore donc les différents aspects de l’architecture génomique singulière des AMF. Résultats L’ampleur du polymorphisme intra-isolat a été déjà observée pour la grande sous-unité d’ARN ribosomal de l’isolat Glomus irregulare DAOM-197198 (précédemment identifié comme G. intraradices) et pour le gène de la polymerase1-like (PLS) de Glomus etunicatum isolat NPI. Dans un premier temps, nous avons pu confirmer ces résultats et nous avons également pu constater que ces variations étaient transcrites. Nous avons ensuite pu mettre en évidence la présence d’un goulot d’étranglement génétique au moment de la sporulation pour le locus PLS chez l’espèce G. etunicatum illustrant les importants effets d’échantillonnage qui se produisaient entre chaque génération de spore. Enfin, nous avons estimé la différentiation génétique des AMF en utilisant à la fois les réseaux de gènes appliqués aux données de séquençage haut-débit ainsi que cinq nouveaux marqueurs génomiques en copie unique. Ces analyses révèlent que la différenciation génomique est présente de manière systématique dans deux espèces (G. irregulare et G. diaphanum). Conclusions Les résultats de cette thèse fournissent des preuves supplémentaires en faveur du scénario d’une différenciation génomique entre noyaux au sein du même isolat mycorhizien. Ainsi, au moins trois membres du genre Glomus, G. irregulare, G. diaphanum and G. etunicatum, apparaissent comme des organismes dont l’organisation des génomes ne peut pas être décrit d’après un modèle Mendélien strict, ce qui corrobore l’hypothèse que les noyaux mycorhiziens génétiquement différenciés forment un pangenome., Background: Arbuscular mycorrhizal fungi (AMF) are root-inhabiting fungi whose hyphal networks form symbioses with plants. Previous studies have revealed extremely high levels of genetic variation for some loci, which has lead to the proposition that AMF contain thousands of genetically divergent nuclei that share the same cytoplasm, i.e. they are heterokaryotic coenocytes. No reproductive stage has as yet been observed in AMF, yet evidence is accumulating that the observed high levels of diversity could be maintained by the exchange of nuclei between hyphal systems and (meiotic) recombination. AMF spores contain varying fractions of this heterogeneous population of nuclei, which migrate directly from the parent mycelium. To our knowledge, AMF are the only organisms that never pass through a single nucleus stage in their life cycle, which allows nuclei to diverge into genetically distinct nuclei within the same cytoplasm. Thus, estimating genetic diversity in arbuscular mycorrhizal fungi (AMF) is a major challenge, not only for ecologists in the field but also for molecular biologists in the lab. It is unclear what the extent of polymorphism is in AMF genomes. The present thesis investigates different aspects of this peculiar genome organization. Results The second chapter in this thesis confirms the extensive intra-isolate polymorphism that was previously observed for large subunit rDNA (in G. irregulare DAOM-197198) and the polymerase1-like gene, PLS (in G. etunicatum), and shows that this polymorphism is transcribed. In the third chapter I report the presence of a bottleneck of genetic variation at sporulation for the PLS locus, in G. etunicatum. Analyses in the fourth chapter, based on a conservative network-based clustering approach and five novel single copy genomic markers, reveal extensive genome-wide patterns of diversity in two different AMF species (G. irregulare and G. diaphanum). Conclusions The results from this thesis provide additional evidence in favor of genome differentiation between nuclei in the same isolate for AMF. Thus, at least three members of the Glomus genus, G. irregulare, G. diaphanum and G. etunicatum appear to be organisms whose genome organization cannot be described by a single genome sequence: genetically differentiated nuclei in AMF form a pangenome.