Population dynamics in voles: characterization and modelling of global spatio-temporal patterns

Population fluctuations of rodents have always aroused human interest due to their importance in ecosystems and human welfare. However, their scientific study became especially relevant in the late 19th and early 20th centuries when Robert Collet and Charles S. Elton described periodic eruptions of lemmings and voles. Since then, hundreds of theoretical, experimental, and field works have provided a basis for understanding the mechanisms underlying the different population fluctuations observed in nature. However, the generality of these mechanisms across different species and geographic areas remains one of the greatest unknowns in ecology; posing a problem for understanding natural ecosystems, as well as for managing species and their effects on human welfare. This dissertation takes advantage of the vast amount of data and knowledge on vole population dynamics to test the existence of general demographic mechanisms, as well as to identify predictors of events such as plagues to better understand and manage these species. This dissertation compiles nearly 70 years of capture-mark-recapture data from 17 trapping areas with weekly, biweekly and monthly sampling frequency from five populations of four vole species in North America and Europe (M. agrestis = 4 sampling areas or spatiotemporal replicates, M. ochrogaster = 4, M. pennsylvanicus = 5 and M. townsendii = 4); being to date the largest database of rodent demographic data with high temporal resolution (monthly resolution or higher). Subsequently, this dissertation analyses whether part of the inter-annual fluctuations is produced by common demographic mechanisms in different species and geographic areas (e.g. similar variations in survival, reproduction or migration). But to do so, it first overcomes one of the main obstacles in the study of population dynamics of rodents and many other species, the relatively low number of observations to make models sufficiently complex and informative to understand population dynamics. Specifically, this thesis proposes an extension of traditional capture-mark-recapture models, using regularization techniques widely used in different fields of statistics such as in the calculation of random effects, in order to estimate demographic parameters under conditions of relatively low data availability. With this new analysis tool, whose usefulness goes far beyond the study of rodent demography (e.g. elusive species or species with low densities such as some endangered species), this dissertation estimates the abundances and vital rates of the four vole species in the 17 sampling areas at a fine enough temporal scale to study biological models that allow an adequate understanding of their population dynamics. This dissertation uses these estimated demographic parameters to evaluate the existence of common general patterns. The results show not only the existence of such common demographic mechanisms, but also suggest their great relevance; reopening an interesting debate on the relative importance of common and specific factors in the origin of population fluctuations. Furthermore, by testing predictions of the most accepted hypotheses in the scientific community, it showed that feeding and social interactions are more likely underlying these common demographic patterns. Finally, the dissertation shows how theoretical knowledge about population dynamics can be used to solve or mitigate a human welfare problem, such as vole outbreaks. Specifically, this dissertation identifies an early warning signal capable of predicting outbreaks of the common vole (M. arvalis) one year in advance in Castilla y León (Spain). This predictor facilitates farmers and regional government to take preventive measures to mitigate the impact of vole outbreaks in crop fields. Complementarily, this dissertation proposes an approach to solve an important but little discussed problem in applied ecology, which is that erroneous predictions entail costs for users. This dissertation proposes an approach to measure the usefulness of predictors in decision making by considering their hit and error rate (statistical aspect) as well as the expenses, effectiveness, and indirect effects of the treatment to be applied based on the predictions (management aspect). This last contribution aims that scientific researches proposing predictive models explicitly indicate their usefulness for each potential user; which can enhance and improve its use in applied ecology. In general, this dissertation focuses on vole population dynamics from a basic, theoretical, and applied ecology point of view. On the one hand, it provides fundamental theoretical knowledge to understand the generalities of vole population dynamics, as well as vole outbreaks in Mediterranean environments. On the other hand, it provides diverse conceptual and analytical approaches with great multidisciplinary utility. All this together makes the present dissertation an important key piece in future research in various fields of science.Las fluctuaciones poblacionales de roedores han despertado siempre el interés humano debido a su importancia en los ecosistemas y en el bienestar humano. Sin embargo, su estudio científico empezó a ser especialmente relevante a finales del siglo XIX y principios del XX cuando Robert Collet y Charles S. Elton describieron las erupciones periódicas de lemmings y topillos. Desde entonces, cientos de trabajos teóricos, experimentales y de campo han proporcionado una base para entender los mecanismos que subyacen a las diferentes fluctuaciones poblacionales observadas en la naturaleza. Sin embargo, la generalidad de estos mecanismos a lo largo de las diferentes especies y áreas geográficas sigue siendo una de las mayores incógnitas de la ecología; lo que supone un problema para comprender los ecosistemas naturales, así como para gestionar las especies y sus efectos en el bienestar humano. Esta tesis aprovecha la amplia cantidad de datos y conocimientos sobre las dinámicas poblacionales de topillos para testar la existencia de mecanismos demográficos generales, así como para identificar predictores de eventos como las plagas que permitan entender y gestionar mejor estas especies. En primer lugar, esta tesis recopila casi 70 años de datos de captura-marcado-recaptura en 17 áreas de muestro con frecuencia de muestreo semanal, quincenal y mensual de cinco poblaciones de cuatro especies de topillos en Norteamérica y Europa (M. agrestis = 4 áreas de muestreo o réplicas espacio-temporales, M. ochrogaster = 4, M. pennsylvanicus = 5 y M. townsendii = 4); siendo hasta la fecha la mayor base de datos demográficos de roedores con alta resolución temporal (i.e., resolución mensual o mayor). Posteriormente, esta tesis analiza si parte de las fluctuaciones interanuales se producen por mecanismos demográficos comunes en diferentes especies y áreas geográficas (e.g. variaciones similares en la supervivencia, reproducción o migración). Pero para ello, antes supera uno de los principales obstáculos en el estudio de la dinámica poblacional de los roedores y de muchas otras especies, la relativa baja cantidad de observaciones para realizar modelos lo suficientemente complejos e informativos para entender las dinámicas poblacionales. En concreto, esta tesis propone una extensión de los modelos de captura-marcado-recaptura tradicionales, mediante el uso de técnicas de regularización ampliamente utilizadas en diferentes campos de la estadística como en el cálculo de los efectos aleatorios, y así poder estimar parámetros demográficos en condiciones de relativa baja disponibilidad de datos. Con esta nueva herramienta de análisis, cuya utilidad va mucho más allá del estudio de la demografía de roedores (e.g. especies esquivas o con bajas densidades como algunas en peligro de extinción), esta tesis estima las abundancias y tasas vitales de las cuatro especies de topillo en las 17 áreas de muestro a una escala temporal lo suficientemente fina como para poder estudiar modelos biológicos que permitan una adecuada comprensión de sus dinámicas poblacionales. Esta tesis utiliza esos parámetros demográficos estimados para evaluar la existencia de patrones generales comunes. Los resultados muestran no sólo la existencia de tales mecanismos demográficos comunes, sino que también sugieren su gran relevancia; reabriendo un interesante debate sobre la importancia relativa de los factores comunes y específicos en el origen de las fluctuaciones poblacionales. Además, esta tesis pone a prueba las predicciones de las hipótesis más aceptadas en la comunidad científica sobre los factores causales que subyacen a las variaciones demográficas (e.g. la alimentación, la depredación o las interacciones sociales). Los resultados sugieren que el alimento y las interacciones sociales podrían ser los factores causales detrás de las variaciones en las tasas vitales que producen los patrones comunes. Por último, la tesis muestra cómo el conocimiento teórico sobre la dinámica poblacional puede utilizarse para resolver o mitigar un problema de bienestar humano, como las plagas de topillos. En concreto, esta tesis identifica una señal de alerta temprana capaz de predecir las plagas de topillo campesino (M. arvalis) con un año de antelación en Castilla y León (España). Este predictor facilita que agricultores y gobierno regional tomen medidas preventivas para mitigar el impacto de las plagas de topillo en los campos de cultivo. Complementariamente, esta tesis propone un enfoque para solventar un problema importante pero poco discutido en ecología aplicada como es que las predicciones erróneas conllevan gastos para los usuarios. En particular, esta tesis propone un enfoque para medir la utilidad de un predictor en la toma de decisiones considerando la tasa de acierto y error (aspecto estadístico) y los costes, efectividad, y efectos indirectos del tratamiento que se aplicará en base a las predicciones (aspecto de gestión). Esta última contribución tiene como objetivo que las investigaciones científicas que proponen modelos predictivos indiquen explícitamente su utilidad para cada posible usuario; lo que puede potenciar y mejorar el uso de predictores en ecología aplicada. En general, esta tesis se centra en las dinámicas poblacionales de topillos desde un punto de vista de la ecología básica, teórica, y aplicada. Por un lado, proporciona un conocimiento teórico fundamental para entender las generalidades en las dinámicas poblacionales de topillos, así como de las plagas de topillos en ambientes mediterráneos. Por otro lado, proporciona diversos enfoques conceptuales y analíticos con una gran utilidad multidisciplinar. Todo esto junto hace que la presente tesis pueda ser una pieza importante clave en investigaciones futuras de diversos campos de la ciencia

Plant community assembly in invaded recipient californian grasslands and putative donor grasslands in Spain

The introduction of exotic species to new regions offers opportunities to test fundamental questions in ecology, such as the context-dependency of community structure and assembly. Annual grasslands provide a model system of a major unidirectional introduction of plant species from Europe to North America. We compared the community structure of grasslands in two Mediterranean regions by surveying plots in Spain and in California with similar environmental and management conditions. All species found in Spanish grasslands were native to Spain, and over half of them (74 of 139 species) are known to have colonized California. In contrast, in California, over half of the species (52 of 95 species) were exotic species, all of them native to Spain. Nineteen species were found in multiple plots in both regions (i.e., shared species). The abundance of shared species in California was either similar to (13 species) or greater than (6 species) in Spain. In California, plants considered pests were more likely than non-pest species to have higher abundance. Co-occurring shared species tended to maintain their relative abundance in native and introduced communities, which indicates that pools of exotic species might assemble similarly at home and away. These findings provide interesting insights into community assembly in novel ecosystems. They also highlight an example of startling global and local floristic homogenization.Ministerio de Ciencia, Innovación y Universidades PCI2018-09293

The EICAT+ framework enables classification of positive impacts of alien taxa on native biodiversity

Species introduced through human-related activities beyond their native range, termed alien species, have various impacts worldwide. The IUCN Environmental Impact Classification for Alien Taxa (EICAT) is a global standard to assess negative impacts of alien species on native biodiversity. Alien species can also positively affect biodiversity (for instance, through food and habitat provisioning or dispersal facilitation) but there is currently no standardized and evidence-based system to classify positive impacts. We fill this gap by proposing EICAT+, which uses 5 semiquantitative scenarios to categorize the magnitude of positive impacts, and describes underlying mechanisms. EICAT+ can be applied to all alien taxa at different spatial and organizational scales. The application of EICAT+ expands our understanding of the consequences of biological invasions and can inform conservation decisions.Agencia Estatal de Investigación PCI2018-092939, PCI2018-092986Swiss National Science Foundation 31003A_179491, 31BD30_184114Austrian Fonds zur Förderung der Wissenschaftlichen Forschung 4011-B32German Bundesministerium für Bildung und Forschung 16LC1803A, 01LC1807CFrench National Research Agency ANR-18-EBI4-0001-06US National Science Foundation ICER-1852060National Research Foundation of South Africa 89967Australian Research Council DP200101680UK Natural Environment Research Council NE/V007548/1Hellenic Foundation for Research and Innovation (H.F.R.I.) HFRIFM17-159

Emerging laws must not protect stray cats and their impacts

Our moral circles—that is, the entities believed as worthy of moral concern and thus deserving moral considerations—have historically expanded beyond humans to include also nonhuman beings (Crimston et al., 2018). As a result, various emerging legal instruments around the world have been granting rights to animals. However, the inclusion of animals within moral circles is subjected to important biases, with a preference for charismatic, familiar, and beautiful vertebrates (Klebl et al., 2021). We argue that legal instruments embracing such biases may jeopardize biodiversity conservation.The authors would like to thank all researchers who have kindly contributed to the discussion of this conservation problem in Spain.Peer reviewe

Supporting information: The EICAT+ framework enables classification of positive impacts of alien taxa on native biodiversity [dataset]

Supporting information A in S1 File. Glossary of additional key terms. Supporting information B in S1 File. Table reporting contrasting arguments and approaches used to define how alien taxa are considered and should be managed in accordance with different conservation values/motivations. As multiple values/motivations exist and determine which entities we are interested in (see also Supporting information A), distinct conservation targets can be identified. Note that here, we only consider conservation values/motivations that are expressed regardless of any nature’s instrumental (utilitarian) value, i.e., regardless of nature’s contributions to human well-being (see “nature for itself” framing [9]). Also, note that such contrasting arguments and approaches are not necessarily mutually exclusive and have been occasionally combined to find a middle ground to achieve broader conservation goals [10–13]. Supporting information C in S1 File. Circumstances under which the prevention/mitigation of a decreasing change is considered as a positive change under EICAT+. In EICAT+, we also consider as positive impacts (i.e., increasing changes) cases in which an alien species prevents/mitigates decreasing changes, e.g., when the performance of a native individual, the size of a native population, or the occupancy of a native species would have decreased, or decreased to a greater extent, if the alien species had not been introduced. Although some of these positive impacts can be inferred, the prevention of a decreasing change should be assessed under EICAT+ only when there is convincing evidence that a certain biodiversity attribute (e.g., population size) would have decreased, or decreased to a greater extent, in the absence of the alien species. In the case of extinction prevention, for instance, it must be clear that (i) the population was locally heading toward extinction before the introduction of the alien; and (ii) the alien taxon prevented, through a specific impact mechanism, an extinction that would have occurred in its absence [41,42] (Fig 2b). Other cases where an alien species may prevent or mitigate decreasing changes are, for instance, those in which the abundance (i.e., a proxy for population size) of a native species declined in the uninvaded (i.e., control) plots but not, or to a lesser extent, in the plots invaded by the alien. Note that positive impacts associated with the prevention/mitigation of a decreasing change will generally be more difficult to study and identify than those associated with actual increasing changes, as the former require extensive data regarding the temporal trend of individual performance, population size, or area of occupancy. Supporting information D in S1 File. EICAT+ mechanisms and submechanisms by which an alien taxon can cause positive impacts on native biodiversity attributes and examples of positive impacts sourced from the literature and assessed under EICAT+ (ML+ = Minimal positive impact, MN+ = Minor positive impact, MO+ = Moderate positive impact, MR+ = Major positive impact, MV+ = Massive positive impact). Rationales behind the formulation of the mechanisms and submechanisms can be found in the main text and in Supporting information G, H, and J. Supporting information E in S1 File. Table reporting examples sourced from the literature and classified as information that cannot be classified under EICAT+, but that contain information about mechanisms and might set the stage for future studies. Although these studies described the existence of mechanisms by which alien taxa may cause positive impacts on native taxa, such literature is considered as nonrelevant, as it did not measure, or provide information on, biodiversity attributes used in EICAT+ (e.g., performance of individuals or population size). Rationales behind the formulation of the mechanisms and submechanisms can be found in the main text and in Supporting information G, H, and J. Supporting information F in S1 File. How to attribute a confidence score in EICAT+. Supporting information G in S1 File. Additional information around the rationale behind the formulation of the EICAT+ mechanisms and submechanisms. Supporting information H in S1 File. Additional information about how alien species can cause positive impacts on native biodiversity through overcompensation. Supporting information J in S1 File. Additional information about how alien species can cause positive impacts on native biodiversity through hybridization. Supporting information K in S1 File. References used in the Supporting information.Peer reviewe

A scenario‐guided strategy for the future management of biological invasions

Future dynamics of biological invasions are highly uncertain because they depend on multiple social–ecological drivers. We used a scenario-based approach to explore potential management options for invasive species in Europe. During two workshops involving a multidisciplinary team of experts, we developed a management strategy arranged into 19 goals relating to policy, research, public awareness, and biosecurity. We conceived solutions for achieving these goals under different plausible future scenarios, and identified four interrelated recommendations around which any long-term strategy for managing invasive species can be structured: (1) a European biosecurity regime, (2) a dedicated communication strategy, (3) data standardization and management tools, and (4) a monitoring and assessment system. Finally, we assessed the feasibility of the management strategy and found substantial differences among scenarios. Collectively, our results indicate that it is time for a new strategy for managing biological invasions in Europe, one that is based on a more integrative approach across socioeconomic sectors and countries

European scenarios for future biological invasions

1. Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, nature's contributions to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in the future across spatial scales. 2. Based on previous work on global invasion scenarios, we developed a workflow to downscale global scenarios to a regional and policy-relevant context. We applied this workflow at the European scale to create four European scenarios of biological invasions until 2050 that consider different environmental, socio-economic and socio-cultural trajectories, namely the European Alien Species Narratives (Eur-ASNs). 3. We compared the Eur-ASNs with their previously published global counterparts (Global-ASNs), assessing changes in 26 scenario variables. This assessment showed a high consistency between global and European scenarios in the logic and assumptions of the scenario variables. However, several discrepancies in scenario variable trends were detected that could be attributed to scale differences. This suggests that the workflow is able to capture scale-dependent differences across scenarios. 4. We also compared the Global- and Eur-ASNs with the widely used Global and European Shared Socioeconomic Pathways (SSPs), a set of scenarios developed in the context of climate change to capture different future socio-economic trends. Our comparison showed considerable divergences in the scenario space occupied by the different scenarios, with overall larger differences between the ASNs and SSPs than across scales (global vs. European) within the scenario initiatives. 5. Given the differences between the ASNs and SSPs, it seems that the SSPs do not adequately capture the scenario space relevant to understanding the complex future of biological invasions. This underlines the importance of developing independent but complementary scenarios focussed on biological invasions. The downscaling workflow we implemented and presented here provides a tool to develop such scenarios across different regions and contexts. This is a major step towards an improved understanding of all major drivers of global change, including biological invasions

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Stopping Winter Flooding of Rice Fields to Control Invasive Snails Has no Effect on Waterbird Abundance at the Landscape Scale

The invasive apple snail (Pomacea maculata) appeared in 2010 in the Ebro Delta Natural Park, an important area for rice production and waterbird conservation in the eastern Mediterranean. To control crop damage, farmers stopped flooding their rice fields in winter, an agri-environmental scheme (AES) applied for more than 20 years in some European and American regions to favor flora and fauna from wetlands, including wintering waterbirds. Thus, apple snail control is controversial because of its potential side effects on international waterbird conservation efforts. Despite the fact that 10 years have passed since the first flooding limitations, and the alarms raised by the managers of the Natural Park, the side effects of apple snail management on waterbird conservation have not been evaluated. Here we fill this gap by analyzing a 35-year time series to assess whether abundance trends of 27 waterbird species, from five functional groups, decreased in the Ebro Delta after stopping winter flooding. We considered the effects of confounding local factors by also assessing trend changes in l’Albufera, a similar nearby not invaded wetland where flooding has not been interrupted. In addition, as a control of the positive effect of winter flooding, we also assessed whether abundance trends increased in both wetlands after applying this AES winter flooding. Our results showed complex and decoupled trend changes across species and geographical areas, without statistical evidences, in general or for any particular functional group, on the positive effect of winter flooding in both wetlands neither on the negative effect of its cessation in Ebro Delta. These results suggest the safety of this apple snail control in terms of waterbird abundance at a landscape scale. In addition, these results question, at least in two important wintering areas in Europe, the attractor role associated with the flooding agri-environmental scheme applied for decades.This research was funded by the Spanish Ministry of Science and Innovation (PCI2018-092939, PCI2018-092986, MCI/AEI/FEDER, UE) participating in the project InvasiBES through the 2017–2018 Belmont Forum and BIODIVERSA joint call for research proposals, under the BiodivScen ERANet COFUND program. BG was supported by a research fellowship funded by the Spanish Program of R + D + I (RyC2018-025160-I).Peer reviewe

Exploring the solution landscape enables more reliable network community detection

To understand how a complex system is organized and functions, researchers often identify communities in the system's network of interactions. Because it is practically impossible to explore all solutions to guarantee the best one, many community-detection algorithms rely on multiple stochastic searches. But for a given combination of network and stochastic algorithms, how many searches are sufficient to find a solution that is good enough? The standard approach is to pick a reasonably large number of searches and select the network partition with the highest quality or derive a consensus solution based on all network partitions. However, if different partitions have similar qualities such that the solution landscape is degenerate, the single best partition may miss relevant information, and a consensus solution may blur complementary communities. Here we address this degeneracy problem with coarse-grained descriptions of the solution landscape. We cluster network partitions based on their similarity and suggest an approach to determine the minimum number of searches required to describe the solution landscape adequately. To make good use of all partitions, we also propose different ways to explore the solution landscape, including a significance clustering procedure. We test these approaches on synthetic networks and a real-world network using two contrasting community-detection algorithms: The algorithm that can identify more general structures requires more searches, and networks with clearer community structures require fewer searches. We also find that exploring the coarse-grained solution landscape can reveal complementary solutions and enable more reliable community detection