Institute of Advanced Study, Berlin
Recent publications
China's rising influence in parts of the developing world has raised concerns among the US and its allies. In the wake of the COVID-19 outbreak, the provision of vaccines and aid to countries in the Global South have further heightened anxieties over the potential for diffusion of China's ideals. China's investments are thought to promote the diffusion of its perspectives of rule of law and democracy, posing a challenge to the global dominance of Western liberal democratic values. Nonetheless, few studies have examined how the diffusion of China's ideals may occur through its investments and infrastructure projects in young democracies such as Malaysia whose governance and legal system significantly outperform China's according to various global indexes. This article investigates the increasing engagement with China and the reasons for this trend against the backdrop of Malaysia's legal and political institutions inherited from the West. It considers how young democracies like Malaysia are vulnerable to China's influence, intentional or unintentional, through investment. The analysis sheds light on the mechanisms that give rise to such vulnerability, exploring how the electoral system and rule of law may facilitate and amplify the impact of Chinese investment, with broader implications. Shared tacit understandings, such as the instrumentality of law and the nexus between state and business, which facilitate cross-country cooperation are also examined.
People differ greatly in their attitudes towards well-evidenced science. What characterises this variation? Here, we consider this issue in the context of genetics and allied sciences. While most prior research has focused on the relationship between attitude to science and what people know about it, recent evidence suggests that individuals with strongly negative attitudes towards specific genetic technologies (genetic modification (GM) technology and vaccines) commonly do not objectively understand the science, but, importantly, believe that they do. Here, using data from a probability survey of United Kingdom adults, we extend this prior work in 2 regards. First, we ask whether people with more extreme attitudes, be they positive or negative, are more likely to believe that they understand the science. Second, as negativity to genetics is commonly framed around issues particular to specific technologies, we ask whether attitudinal trends are contingent on specification of technology. We find (1) that individuals with strongly positive or negative attitudes towards genetics more strongly believe that they well understand the science; but (2) only for those most positive to the science is this self-confidence warranted; and (3) these effects are not contingent on specification of any particular technologies. These results suggest a potentially general model to explain why people differ in their degree of acceptance or rejection of science, this being that the more someone believes they understand the science, the more confident they will be in their acceptance or rejection of it. While there are more technology nonspecific opponents who also oppose GM technology than expected by chance, most GM opponents fit a different demographic. For the most part, opposition to GM appears not to reflect a smokescreen concealing a broader underlying negativity.
Spatial and social behaviour are fundamental aspects of an animal's biology, and their social and spatial environments are indelibly linked through mutual causes and shared consequences. We define the ‘spatial–social interface’ as intersection of social and spatial aspects of individuals' phenotypes and environments. Behavioural variation at the spatial–social interface has implications for ecological and evolutionary processes including pathogen transmission, population dynamics, and the evolution of social systems. We link spatial and social processes through a foundation of shared theory, vocabulary, and methods. We provide examples and future directions for the integration of spatial and social behaviour and environments. We introduce key concepts and approaches that either implicitly or explicitly integrate social and spatial processes, for example, graph theory, density‐dependent habitat selection, and niche specialization. Finally, we discuss how movement ecology helps link the spatial–social interface. Our review integrates social and spatial behavioural ecology and identifies testable hypotheses at the spatial–social interface.
A critical function of animal coloration is avoiding attack, either by warning predators or reducing detectability. Evolution of these divergent strategies may depend on prey palatability and apparency to predators: conspicuous coloration may be favoured if species are distasteful, or habitats make hiding difficult; by contrast, camouflage may be effective if prey lack defences or environments are visually complex. For insect herbivores, host plants provide both chemical defence and the background against which they are detected or obscured; thus, plant traits may be key to coloration in these foundational terrestrial organisms. We use 1808 species of larval Lepidoptera to explore macroevolution of protective coloration strategy. We find that colour and pattern evolve jointly in caterpillars, similar to an array of species across the animal kingdom, while individual elements of coloration evolve closely with diet ecology. Consistent with key tenets of plant defence and plant-herbivore coevolutionary theory, conspicuous colours are associated with herbaceous host plants-thought to be defended by toxins-while camouflage colours and patterns are associated with woody plants and grasses. Contrary to theory, dietary specialization is not associated with conspicuous coloration. Our results add valuable insights into the evolutionary forces shaping colour and pattern in nature.
Sexually antagonistic selection, which favours different optimums in males and females, is predicted to play an important role in the evolution of sex chromosomes. Body size is a sexually antagonistic trait in the shell-brooding cichlid fish Lamprologous callipterus as ‘bourgeois’ males must be large enough to carry empty snail shells to build nests whereas females must be small enough to fit into shells for breeding. In this species, there is also a second male morph: smaller ‘dwarf’ males employ an alternative reproductive strategy by wriggling past spawning females into shells to fertilise eggs. L. callipterus male morphology is passed strictly from father to son, suggesting Y-linkage. However, sex chromosomes had not been previously identified in this species, and the genomic basis of size dimorphism was unknown. Here we used whole-genome sequencing to identify a 2.4 Mb sex-linked region on scaffold_23 with reduced coverage and SNP density in both male morphs compared to females. Within this sex region, distinct Y-haplotypes delineate the two male morphs, and candidate genes for body size (GHRHR, a known dwarfism gene) and sex determination (ADCYAP1R1) are in high linkage disequilibrium (LD). Because differences in body size between females and males are under strong selection in L. callipterus, we hypothesise that sexual antagonism over body size initiated early events in sex chromosome evolution, followed by Y divergence to give rise to bourgeois and dwarf male reproductive strategies. Our results are consistent with the hypothesis that sexually antagonistic traits should be linked to young sex chromosomes.
Mechanisms selecting for the evolution of cooperative breeding are hotly debated. While kin selection theory has been the central paradigm to explain the seemingly altruistic behaviour of non-reproducing helpers, it is increasingly recognized that direct fitness benefits may be highly relevant. The group augmentation hypothesis proposes that alloparental care may evolve to enhance group size when larger groups yield increased survival and/or reproductive success. However, there is a lack of empirical tests. Here we use the cooperatively breeding cichlid fish Neolamprologus pulcher, in which group size predicts survival and group stability, to test this hypothesis experimentally by prompting two cooperative tasks: defence against an egg predator and digging out sand from the breeding shelter. We controlled for alternative mechanisms such as kin selection, load lightening and coercion. As predicted by the group augmentation hypothesis, helpers increased defence against an egg predator in small compared with large groups. This difference was only evident in large helpers owing to size-specific task specialization. Furthermore, helpers showed more digging effort in the breeding chamber compared with alternative personal shelters, indicating that digging is an altruistic service to the dominant breeders.
Plant invasions have been linked to displacement of native vegetation and altering of fire regimes and might influence vector mosquito populations by altering habitats or nutrient inputs. Whereas wildfire effects on terrestrial ecosystems are relatively well-studied, ash depositions into aquatic ecosystems and effects on semi-aquatic taxa such as mosquitoes have remained overlooked. Here, we investigated mosquito colonization in water treated with ash from native plants [quinine tree (Rauvolfia caf-fra), Transvaal milk plum (Englerophytum magalismontanum), apple leaf (Philenoptera violacea)] and invasive alien plants [i.e., lantana (Lantana camara), guava (Psidium gua-java), red river gum (Eucalyptus camaldulensis)] in containers at two ash concentrations (i.e., 1, 2 g/L). Overall, there was no statistically clear difference in colonization be-tween ash from native and alien species. We recorded colonization by two mosquito genera (Culex spp. and Anopheles spp.), with Culex generally much more abundant than Anopheles. Few differences were identified among the plants, with statistically clear effects of ash type and concentration on larval and pupal stages. High Culex egg and larval abundances were shown in lantana and apple leaf treatments compared to controls, and milkplum versus controls for pupae of both genera. Further research is required to elucidate the influence of nutrient inputs from different ash species on vector mosquito population dynamics.
Begging signals are widespread in animals and have been extensively studied in the context of brood care. In contrast, the functionality of begging signals expressed among adults has not yet been scrutinised experimentally. Norway rats (Rattus norvegicus) have been shown to express 50‐kHz calls towards a social partner when in need of help to obtain food. Here, we tested with help of playbacks whether focal subjects exposed to a high rate of ultrasonic calls would increase their helping rate towards their social partner. The propensity to help a partner was significantly enhanced when the focal rats were exposed to playback with a doubled number of calls relative to baseline conditions. To the best of our knowledge, this provides the first evidence of increased help in response to an experimentally altered begging signal in adult animals. Norway rats help social partners to obtain food in response to enhanced levels of begging calls played back to them in a sequential iterated prisoner's dilemma paradigm testing for reciprocal cooperation. These results suggest that begging signals uttered by adult conspecifics significantly raise the cooperation propensity of wild‐type Norway rats.
The decision rule of direct reciprocity states that an individual helps someone who previously helped them. An alternative explanation to observations of reciprocal exchanges of help is copying by imitation. Norway rats, Rattus norvegicus, are known to exchange food and allogrooming reciprocally among social partners. We asked whether this behaviour is based on copying by imitation or the application of the direct reciprocity decision rule. Norway rats used a sequential food-pulling paradigm. To assess whether focal rats help according to the direct reciprocity decision rule, we predicted that focal rats should be less helpful to partners from an experimental defection or self-pulling treatment than to partners that previously helped them in a cooperation treatment. To assess whether focal rats help partners by copying via imitation, we predicted that focal rats should be more helpful to partners that previously pulled more often than to partners that had pulled less often. The experimental design involved experience phases consisting of three treatments and three sessions per treatment for each experimental subject, in which a partner operated a stick-pulling apparatus providing food to the focal rat or only for themselves. This was followed by a test phase in which the focal rat could help the partners. Focal rats gave less help to partners from the defection or self-pulling treatments than to previously cooperative partners, and latency to the first help by focal rats was longer for partners from the self-pulling treatments than for cooperative partners, which are results consistent with the direct reciprocity decision rule. Focal rats did not give more help to partners that pulled more often, which is not consistent with copying by imitation. Hence our results are consistent with the direct reciprocity decision rule but not with copying by imitation.
The absence of microbial exposure early in life leaves individuals vulnerable to immune overreaction later in life, manifesting as immunopathology, autoimmunity, or allergies. A key factor is thought to be a “critical window” during which the host's immune system can “learn” tolerance, and beyond which learning is no longer possible. Animal models indicate that many mechanisms have evolved to enable critical windows, and that their time limits are distinct and consistent. Such a variety of mechanisms, and precision in their manifestation suggest the outcome of strong evolutionary selection. To strengthen our understanding of critical windows, we explore their underlying evolutionary ecology using models encompassing demographic and epidemiological transitions, identifying the length of the critical window that would maximize fitness in different environments. We characterize how direct effects of microbes on host mortality, but also indirect effects via microbial ecology, will drive the optimal length of the critical window. We find that indirect effects such as magnitude of transmission, duration of infection, rates of reinfection, vertical transmission, host demography, and seasonality in transmission all have the effect of redistributing the timing and/or likelihood of encounters with microbial taxa across age, and thus increasing or decreasing the optimal length of the critical window. Declining microbial population abundance and diversity are predicted to result in increases in immune dysfunction later in life. We also make predictions for the length of the critical window across different taxa and environments. Overall, our modeling efforts demonstrate how critical windows will be impacted over evolution as a function of both host‐microbiome/pathogen interactions and dispersal, raising central questions about potential mismatches between these evolved systems and the current loss of microbial diversity and/or increases in infectious disease.
Viruses of bacteriophages (phages) have broad effects on bacterial ecology and evolution in nature that mediate microbial interactions, shape bacterial diversity, and influence nutrient cycling and ecosystem function. The unrelenting impact of phages within the microbial realm is the result, in large part, of their ability to rapidly evolve in response to bacterial host dynamics. The knowledge gained from laboratory systems, typically using pairwise interactions between single-host and single-phage systems, has made clear that phages coevolve with their bacterial hosts rapidly, somewhat predictably, and primarily by counteradapting to host resistance. Recent advancement in metagenomics approaches, as well as a shifting focus toward natural microbial communities and host-associated microbiomes, is beginning to uncover the full picture of phage evolution and ecology within more complex settings. As these data reach their full potential, it will be critical to ask when and how insights gained from studies of phage evolution in vitro can be meaningfully applied to understanding bacteria-phage interactions in nature. In this review, we explore the myriad ways that phages shape and are themselves shaped by bacterial host populations and communities, with a particular focus on observed and predicted differences between the laboratory and complex microbial communities. Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see for revised estimates.
Large wood deposited in rivers provides ecological benefits for multiple trophic groups, but public perceptions of these deposits can be varied. In particular, flooding experiences linked to large wood debris could influence how the public and stake-holders view large wood deposited into the river ecosystem. Here, we assessed the perceptions towards large wood using groups of undergraduates, postgraduates and staff from a local university in Limpopo Province of South Africa. A survey was conducted using questionnaires, which were distributed online to a sample of 104 participants across these groups, using both visual (i.e. paired photographs of different river scenarios) and categorical questions. Large shares of respondents regularly used river systems recreationally (62.9%), with woodless systems perceived as being significantly more aesthetic, less dangerous and least in need of improvement. These perceptions, however, differed among university groups, with staff having stronger perceptions of aesthetics (median = 5.5, mean 5.4 ± 2.8), less dangerousness (median = 3.0, mean 4.2 ± 3.0) and naturalness (median = 6.0, mean 5.8 ± 2.6) towards systems with large wood. Correlation analyses indicated significant interre-latedness among perceptions of aesthetics, naturalness, danger and improvement needs. However, negative perceptions towards large wood in the river were generally not determined by any recent experience of flooding in the area, with large wood-related dangers rather associated with leisure activities in rivers by students. These results highlight a need for passing on the knowledge of natural river systems with wood to people in Vhembe Biosphere Reserve and communities' scientists and assessing wider perceptions outside of the university context.
Helminths are common parasites of wild ungulates that can have substantial costs for growth, mortality and reproduction. Whilst these costs are relatively well documented for mature animals, knowledge of helminths' impacts on juveniles is more limited. Identifying these effects is important because young individuals are often heavily infected, and juvenile mortality is a key process regulating wild populations. Here, we investigated associations between helminth infection and overwinter survival in juvenile wild red deer (Cervus elaphus) on the Isle of Rum, Scotland. We collected fecal samples non-invasively from known individuals and used them to count propagules of 3 helminth taxa (strongyle nematodes, Fasciola hepatica and Elaphostrongylus cervi). Using generalized linear models, we investigated associations between parasite counts and overwinter survival for calves and yearlings. Strongyles were associated with reduced survival in both age classes, and F. hepatica was associated with reduced survival in yearlings, whilst E. cervi infection showed no association with survival in either age class. This study provides observational evidence for fitness costs of helminth infection in juveniles of a wild mammal, and suggests that these parasites could play a role in regulating population dynamics.
Wetlands physical and biological processes are fundamental to the distribution and structuring of organic matter in sediments. This study investigated spatial and temporal changes in organic matter sources in sediments within the Nylsvley Wetland, South Africa across two seasons, five sites and three wetland zones and identified pertinent contributors to sediment organic matter. Results showed distributions were uneven throughout the wetlands, with the seasonal zone having slightly high sediment organic matter in the cool-dry season and the permanent zone had high sediment organic matter in the hot-wet season, whereas the temporary zone had low SOM concentrations. Significant differences in nutrient concentrations were observed across wetland zones and seasons for Phosphorous, Potassium, Calcium and Magnesium, with the seasonal zone tending to be the most nutrient-rich in the cool-dry season, and with permanent zone nutrient levels rising substantially in the hot-wet season. Sediment δ13C differed significantly among wetland zones, whereas δ15N was statistically similar. Autochthonous plants were the main sources of organic matter in sediments overall across sites and zones. This study’s findings help to better understand the distribution of organic matter in wetland ecosystems and the role wetland zones play in the seasonal provisioning of allochthonous inputs.
Wetlands are amongst the world’s most important ecosystems, providing direct and indirect benefits to local communities. However, wetlands worldwide continue to be degraded due to unsustainable use and improper resource management. In this paper, we assess the perceptions, importance, management and utilisation of wetlands among local community members using a household questionnaire and field observations within the seven Thulamela municipality wetlands, Vhembe Biosphere Reserve in South Africa. Seven wetlands were chosen for the study, with 140 household respondents randomly selected for a questionnaire survey. The study indicated that wetlands were beneficial in supporting local communities through resource provisioning. The unemployment rate and household respondents’ income were the main contributors to increased wetland dependency and utilisation. We found that urban and rural developments, unregulated use and extensive agricultural practices (i.e., cultivation, livestock grazing) have resulted in wetland degradation. We observed that the local communities around the wetlands were interested in the benefits they receive from wetlands when compared to their conservation. Furthermore, the study observed poor wetland co-management or collaboration among the local stakeholders. This has resulted in a lack of openly known, active platforms to discuss wetlands management issues. These results highlight that centralized, top–down approaches to wetland use are insufficient for maintaining and managing wetland ecosystems, posing a challenge to sustainable wetland management. Therefore, there is a need to develop a shared understanding through bottom-up approaches to wetland management nested within national regulatory frameworks, ideally combined with awareness building and knowledge sharing on ecological benefits and management of wetlands.
Social relationships are important to many aspects of animals’ lives, and an individual’s connections may change over the course of their lifespan. Currently, it is unclear whether social connectedness declines within individuals as they age, and what the underlying mechanisms might be, so the role of age in structuring animal social systems remains unresolved, particularly in non-primates. Here we describe senescent declines in social connectedness using 46 years of data in a wild, individually monitored population of a long-lived mammal (European red deer, Cervus elaphus). Applying a series of spatial and social network analyses, we demonstrate that these declines occur because of within-individual changes in social behaviour, with correlated changes in spatial behaviour (smaller home ranges and movements to lower-density, lower-quality areas). These findings demonstrate that within-individual socio-spatial behavioural changes can lead older animals in fission–fusion societies to become less socially connected, shedding light on the ecological and evolutionary processes structuring wild animal populations.
We review demographic and sociological literature on family dynamics in Latin America and the Caribbean (LAC) and systematize major trends in union formation and fertility in recent decades. We also highlight the singularities that distinguish family patterns and trends in LAC from those in other world regions and discuss the contextual factors underlying these singularities. Latin American families have undergone substantial changes in their configurations and dynamics. We highlight the persistence of an early pattern of family formation despite considerable educational expansion and emerging subreplacement fertility levels, the bottom-up diffusion of cohabitation from low- to high-education groups, the frequent coresidence of single mothers with extended family members, and the substantial divergence in family forms and trajectories across social classes. These family trends do not conform entirely to any of the major theoretical frameworks devised to explain family change in Western societies. Pervasive socioeconomic inequality, high levels of informality in the labor market, weak social protection systems, and slow progress toward gender equality are among the contextual factors that shape the diversity and singularities of Latin American families.
Anthropogenic activities have increasingly subjected freshwater ecosystems globally to various pressures. Increasing land use activities have been highly linked to deteriorating freshwater ecosystems and dwindling biodiversity. For sound management and conservation policies to be implemented, relations between land use, environmental, and biotic components need to be widely documented. To evaluate the impacts of land use on biotic components, this study analyzed the diatom and macroinvertebrate community composition of the Eastern Highlands (Zimbabwe) streams to assess the main spatial diatom and macroinvertebrate community variances and how environmental variables and spatial factors influence community composition. Diatom and macroinvertebrate sampling was done in 16 streams in protected areas (national parks) and impacted sites (timber plantation and communal areas). Water (pH, phosphorus, and ammonium) and sediment (nitrogen, phosphorus, calcium, magnesium, manganese, and zinc) and habitat (substrate embeddedness, and habitat) variables differed significantly with land use. Principal Component Analysis (PCA) showed that the protected area had the best water quality, particularly marked by high pH levels and low phosphorus concentrations among environment types. Heavy metals were high in the communal areas although mercury was higher in the national park. Significant differences were observed in diatom metrics, specifically dominance and evenness, with no significant differences being observed in macroinvertebrate metrics across land uses. Diatoms differed in terms of composition in response to land use. Results provide an important scientific reference for land use optimization and guidance for the formulation of policies to protect freshwater resources in African Highland streams. Management and conservation initiatives in the Eastern Highlands are further recommended as this study detected high levels of mercury in the protected area, implying high levels of illegal mining.
Many human embryos die in utero owing to an excess or deficit of chromosomes, a phenomenon known as aneuploidy; this is largely a consequence of nondisjunction during maternal meiosis I. Asymmetries of this division render it vulnerable to selfish centromeres that promote their own transmission, these being thought to somehow underpin aneuploidy. In this essay, I suggest that these vulnerabilities provide only half the solution to the enigma. In mammals, as in utero and postnatal provisioning is continuous, the costs of early death are mitigated. With such reproductive compensation, selection can favour a centromere because it induces lethal aneuploidy: if, when taken towards the polar body, it instead kills the embryo via aneuploidy, it gains. The model is consistent with the observation that reduced dosage of a murine drive suppressor induces aneuploidy and with the fact that high aneuploidy rates in vertebrates are seen exclusively in mammals. I propose further tests of this idea. The wastefulness of human reproduction may be a price we pay for nurturing our offspring.
Planktonic invasive species cause adverse effects on aquatic biodiversity and ecosystem services. However, these impacts are often underestimated because of unresolved taxonomic issues and limited biogeographic knowledge. Thus, it is pivotal to start a rigorous quantification of impacts undertaken by planktonic invasive species on global economies. We used the InvaCost database, the most up-to-date database of economic cost estimates of biological invasions worldwide, to produce the first critical assessment of the economic dimension of biological invasions caused by planktonic taxa. We found that in period spanning from 1960 to 2021, the cumulative global cost of plankton invasions was US$ 5.8 billion for permanent plankton (holoplankton) of which viruses encompassed nearly 93%. Apart from viruses, we found more costs related to zooplankton (US$ 297 million) than to the other groups summed, including myco- (US$ 73 million), phyto- (43 million), and bacterioplankton (US$ 0.7 million). Strikingly, harmful and potentially toxic cyanobacteria and dinoflagellates are completely absent from the database. Furthermore, the data base showed a decrease in costs over time, which is probably an artifact as a sharp rise of novel planktonic alien species has gained international attention. Also, assessments of the costs of larval meroplanktonic stages of littoral and benthic invasive invertebrates are lacking whereas cumulative global cost of their adult stages is high up to US$ 98 billion billion and increasing. Considering the challenges and perspectives of increasing but unnoticed or neglected impacts by plankton invasions, the assessment of their ecological and economic impacts should be of high priority.
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