Combining ranger records and biogeographical models to identify the current and potential distribution of an expanding mesocarnivore in southern Europe.

Human-wildlife conflicts (HWC) are increasing and are potentially harmful to both people and wildlife. Understanding the current and potential distribution of wildlife species involved in HWC, such as carnivores, is essential for implementing management and conservation measures for such species. In this study, we assessed both the current distribution and potential distribution (forecast) of the Egyptian mongoose (Herpestes ichneumon) in the central part of the Iberian Peninsula. We acquired data concerning mongoose occurrences through an online questionnaire sent to environmental rangers. We used the municipality level as the sampling unit because all municipalities within the study area were covered at least by one ranger. Using the information provided by rangers (i.e. occurrences in their municipalities), we constructed environmental favourability distribution models to assess current and potential mongoose distribution through current distribution models (CDM) and ecological models (EM), respectively. >300 rangers participated in the survey and mongooses were reported in a total of 181 of 921 municipalities studied. The CDM model showed a current distribution mainly concentrated on the western part of the study area, where intermediate-high favourability values predominated. The EM model revealed a wider potential distribution, including the south-east part of the study area, which was also characterised by intermediate-high favourability values. Our predictions were verified using independent data, including confirmation of mongoose reproduction by rangers, reports by other experts, and field sampling in some areas. Our innovative approach based on an online survey to rangers coupled with environmental favourability models is shown to be a useful methodology for assessing the current distribution of cryptic but expanding wildlife species, while also enabling estimations of future steps in their expansion. The approach proposed may help policy decision-makers seeking to ensure the conservation of expanding wildlife species, for example, by designing awareness campaigns in areas where the target species is expected to arrive.

Low Level of Concern Among European Society About Zoonotic Diseases.

Zoonotic emerging diseases (ZEDs) are increasing and may deeply impact human wellbeing, but our recent survey of public opinion in six European countries (n = 2415 participants) suggests a low concern among Europeans about the risk associated with ZEDs. This contrasts with Europeans' high awareness of climate change risks, which was confirmed by our survey. Given the increasing risk of ZEDs, it is therefore essential to increase Europeans' awareness of their impacts. In addition, our study suggests that Europeans may be more likely to support sustainable environmental policies that would reduce the risk associated with ZEDs, consequently improving the human wellbeing.

Identification of potential invasive alien species in Spain through horizon scanning.

Invasive alien species have widespread impacts on native biodiversity and ecosystem services. Since the number of introductions worldwide is continuously rising, it is essential to prevent the entry, establishment and spread of new alien species through a systematic examination of future potential threats. Applying a three-step horizon scanning consensus method, we evaluated non-established alien species that could potentially arrive, establish and cause major ecological impact in Spain within the next 10 years. Overall, we identified 47 species with a very high risk (e.g. Oreochromis niloticus, Popillia japonica, Hemidactylus frenatus, Crassula helmsii or Halophila stipulacea), 61 with high risk, 93 with moderate risk, and 732 species with low risk. Many of the species categorized as very high or high risk to Spanish biodiversity are either already present in Europe and neighbouring countries or have a long invasive history elsewhere. This study provides an updated list of potential invasive alien species useful for prioritizing efforts and resources against their introduction. Compared to previous horizon scanning exercises in Spain, the current study screens potential invaders from a wider range of terrestrial, freshwater, and marine organisms, and can serve as a basis for more comprehensive risk analyses to improve management and increase the efficiency of the early warning and rapid response framework for invasive alien species. We also stress the usefulness of measuring agreement and consistency as two different properties of the reliability of expert scores, in order to more easily elaborate consensus ranked lists of potential invasive alien species.

Beyond rural vs urban differences: A close match in european preferences in some basic wildlife management and conservation principles.

The EU biodiversity strategy for 2030 sets out a framework of commitments and actions to tackle the main drivers of biodiversity loss. Such framework needs to be built on a whole-of-society approach to biodiversity protection, mobilizing private and public funding. In this context, our goal was estimating societal support and preferences about some basic wildlife management principles, which may be useful to inform EU decision-makers about societal priorities and other additional funding sources for wildlife conservation. A discrete choice experiment was conducted by 2415 inhabitants in six European countries (Spain, France, Italy, UK, Germany, Sweden), including residents in both rural (47% of respondents) and urban areas. Our findings reveal a clear pattern across western Europe with similar trends along the studied countries, and even between rural and urban citizens, on some basic wildlife management principles. According to our survey, payments for environmental services contribute to achieving a higher well-being from European citizens in any of the prospective wildlife programs considered, which suggests it is an acceptable tool to share out funds for biodiversity conservation. In addition, managing scarce species is preferred over managing too abundant species; management in forest, agricultural and aquatic habitats is prioritized over that in urban landscapes; and management in protected areas is preferred over management in non-protected ones. These findings suggest that there is a common culture in Europe related to the management of wildlife even when considering citizens with contrasted ways of life: rural vs urban citizens from northern to southwestern Europe. Overall, this study may help in the design of wildlife management policies that maximize societal acceptability and gather higher support.

Lack of evidence for differences in the spread of classic (Lagovirus europaeus/GI.1) and novel (Lagovirus europaeus/GI.2) rabbit haemorrhagic disease viruses in Europe and North Africa.

BACKGROUND: Fast-spreading diseases affecting wildlife populations threaten biodiversity. Two caliciviruses, Lagovirus europaeus/GI.1 and Lagovirus europaeus/GI.2, caused rabbit haemorrhagic disease virus (RHDV) in wild rabbits. Despite having different characteristics, these variants spread quickly, posing a threat to wild rabbit populations. METHODS: In this study, we conducted a thorough review of the scientific literature and reports of international organisations of first detections of both variants of RHDV in the Euro-Mediterranean region. We concentrated on this area to avoid bias due to intentional human introductions. RESULTS: The estimated mean spread rate of GI.2 was higher than that of GI.1 (GI.2: 479 km/year, range: 47-7346; GI.1: 330 km/year, 37-6248). These differences were not statistically significant. This lack of difference may be due to the interactions between each variant's virulence characteristics. Humans may have a dominant effect on their spread. Potential limitations associated with the observational process could have hindered our ability to identify statistical differences. CONCLUSIONS: The lack of difference in the spread patterns of the two variants could be due to a biological cause, human facilitation or a lack of statistical power. Adapting protocols to detect diseases in wildlife using homogeneous criteria will be indispensable in the coming years.

Estate-level decision-making and socioeconomics determine annual harvest in the European Turtle-dove in central Spain.

Designing evidence-based policies that regulate harvest levels is essential to avoid unsustainable hunting. This requires a good understanding of the relationship between bag sizes and regulatory mechanisms of harvest, and particularly of how these mechanisms are implemented locally and how they vary between game estates. The European Turtle-dove (Streptopelia turtur) has decreased by 30-49% since the late 1990s. The three main identified threats for the species are habitat loss, illegal killing and unsustainable legal hunting. We assessed how turtle dove estate-level harvest varies in relation to hunter density, number of hunting days, the adopted hunting method, game management intensity and the economic investment of the estate. Additionally, we assessed whether estate-level harvest had declined concomitantly with the population decline, and whether trends had been similar in relation to hunting method. We analysed Hunting Management Plans and Annual Hunting Reports of several thousand estates in central Spain, one of the main breeding and hunting areas of the species. Annual estate harvest was positively associated with hunter density, and was higher on estates that offered fixed-position hunting compared to those that only provided walked-up shooting. Importantly, these decisions are made by managers at the estate level and are not directly regulated by policy. We also found that more turtle doves are harvested on estates that invest more money in management, suggesting that the socioeconomic characteristics of the estate also influence local decisions on harvest intensity. Average annual estate-level harvest declined by 27% between 2007 and 2018, accompanied by a switch from fixed-position to walked-up hunting practices. Our study indicates that reducing hunting density or the number of fixed-position hunting days may be the most efficient ways to reduce turtle dove harvest, and that factors influencing estate-level decision-making have to be understood if reduction of hunting pressure in declining species is sought.

Keeping an eye on the use of eye-lens weight as a universal indicator of age for European wild rabbits.

Accurate methods for age determination are critical to the knowledge of wildlife populations' age structure and, therefore, to their successful management. The reliability of age estimation may have profound economic and ecological consequences on the management of the European wild rabbits, Oryctolagus cuniculus, in its native and introduced range, where it is a keystone species and a major pest, respectively. As in other mammal species, European rabbits' age is often estimated using the Gompertz relationship between age and lens' weight. The growth rate formula has been developed based on data collected from European rabbits introduced in Australia, where a single subspecies (O. cuniculus cuniculus, Occ) is present. However, this curve has never been validated in the species native range, the Iberian Peninsula, where two subspecies (Occ, and O. c. algirus, Oca) coexist naturally. In this study, we tested the relationship between age and lens' weight using 173 Occ and 112 Oca wild rabbits that were surveyed in two experimental facilities in Spain. Our findings show that, in the native range, the published growth curve formula fits well Occ but not Oca data. Therefore, we recommend using the formula reported in this study to estimate the age of Oca (Lens dry weight = 240 × 10(-64.9/(Age+32))). This study supports Oca rabbits' distinctiveness revealed by previous studies, which suggests that management interventions should be applied to protect this subspecies whose distribution range is very narrow and whose populations seem to be declining. More broadly, our findings point to the importance of testing the suitability of growth curves defined for other species with different genetic forms as occurs in the European wild rabbit case.

Individual fate and gut microbiome composition in the European wild rabbit (Oryctolagus cuniculus).

Studies connecting microbiome composition and functional performance in wildlife have received little attention and understanding their connections with wildlife physical condition are sorely needed. We studied the variation in gut microbiota (hard fecal pellets) between allopatric subspecies of the European wild rabbit in wild populations and in captured individuals studied under captivity. We evaluated the influence of environmental and host-specific factors. The microbiome of wild rabbit populations reduced its heterogeneity under controlled conditions. None of the host-specific factors tested correlated with the microbiota composition. We only observed significant intra-group dispersion for the age factor. The most diverse microbiomes were rich in Ruminococcaceae potentially holding an enriched functional profile with dominance of cellulases and xylanases, and suggesting higher efficiency in the digestion of fiber-rich food. Conversely, low diversity gut microbiomes showed dominance of Enterobacteriaceae potentially rich in amylases. We preliminary noticed geographical variations in field populations with higher dominance of Ruminococcaceae in south-western than in north-eastern Spain. Spatial differences appeared not to be subspecies driven, since they were lost in captivity, but environmentally driven, although differences in social structure and behavior may also play a role that deserve further investigations. A marginally significant relationship between the Ruminococcaceae/Enterobacteriaceae ratio and potential life expectancy was observed in captive rabbits. We hypothesize that the gut microbiome may determine the efficiency of feeding resource exploitation, and can also be a potential proxy for life expectancy, with potential applications for the management of declining wild herbivorous populations. Such hypotheses remain to be explored in the future.

Dear deer? Maybe for now. People's perception on red deer (Cervus elaphus) populations in Portugal.

The human dimension of wildlife is a subject of increasing interest, especially considering the potential impact of people's perceptions on decision-making concerning wildlife management and thus on species' distribution and abundance. This is particularly important for species that inhabit human-dominated landscapes, where conflicts are likely to arise. These conflicts typically emerge between different human collectives when their interests collide and thus an assessment of their perceptions is valuable. Throughout Europe, ungulates have expanded, and Portugal is no exception. The expansion of red deer (Cervus elaphus) comes with benefits (e.g. hunting opportunities), but also with costs (e.g. vehicle collision or damage to crops), that can shape people's perceptions of these populations. To assess perceptions of red deer populations in continental Portugal, we developed a questionnaire survey with three interest groups: general public, farmers and hunters (total n = 1532). Our results show that perceptions about red deer were generally positive with a high acknowledgement of deer benefits, which we link to a broad level of sympathy towards this species. In addition, farmers showed a higher concern with crop damage caused by deer than non-farmers. Nonetheless, a general lack of knowledge regarding wildlife was present, particularly among younger people, who are potentially more apart and disconnected from nature. Now is the time to implement preventive and mitigation measures - e.g. fencing, reduction of population density - which can be a small contribution to address this problem. The focus should be put on people's acceptance of the required strategies to manage deer populations (which can also include unpopular practices, such as hunting). For that, an evaluation of people's attitudes towards deer populations and awareness of associated problems is essential. People's opinions, as well as the success of monitoring and management strategies, should be evaluated through multi-disciplinary teams, that include natural and social scientists, to ensure their success.

Addressing social attitudes toward lethal control of wildlife in national parks.

The extraordinary population growth of certain ungulate species is increasingly a concern in agroforestry areas because overabundance may negatively affect natural environments and human livelihoods. However, society may have negative perceptions of killing wildlife to reduce their numbers and mitigate damage. We used an online survey that included a choice experiment to determine Spanish citizens' (n = 190) preferences toward wildlife population control measures related to negative effects of ungulate overabundance (negative impacts on vegetation and other wildlife species and disease transmission to livestock) in 2 agroforestry national parks in Spain. We used latent-class and willingness-to-pay in space models to analyze survey results. Two percent of respondents thought a national park should have no human intervention even if lack of management may cause environmental degradation, whereas 95% of respondents favored efforts to reduce damage caused by overabundant ungulate species. We estimated human well-being losses of survey respondents when sustainable effects of deer overabundance on the environment became unsustainable effects and well-being gains when sustainable effects transitioned to no visible effects. We found that the type of wildlife-control program was a very relevant issue for the respondents; indirect control in which killing was avoided was the preferred action. Sixty-six percent of respondents agreed with the option of hunters paying for culling animals to reduce ungulate impacts rather than management cost coming out of taxes, whereas 19% of respondents were against this option and willing to pay for other solutions in national parks. Our results suggest that killing wildlife in national parks could be a socially acceptable tool to manage overabundance problems in certain contexts, but it could also generate social conflicts.

Soluciones para las Actitudes Sociales hacia el Control Letal de la Fauna en Parques Nacionales Resumen El extraordinario crecimiento de ciertas poblaciones de ungulados es cada vez más preocupante en las áreas agroforestales ya que la sobreabundancia puede afectar negativamente al ambiente natural y el sustento humano. Sin embargo, la sociedad puede percibir negativamente el exterminio de fauna para reducir sus números y mitigar el daño. Usamos una encuesta en línea que incluía un experimento de elección para determinar las preferencias de los ciudadanos españoles (n = 190) por las medidas de control poblacional relacionadas con los efectos negativos de la sobreabundancia de ungulados (impactos negativos sobre la vegetación y otras especies silvestres y el contagio de enfermedades al ganado) en dos parques nacionales agroforestales de España. Usamos la clase latente y la disposición para pagar dentro modelos espaciales para analizar los resultados de la encuesta. El 2% de los respondientes creyó que un parque nacional no debería tener intervención humana, incluso si la falta de manejo pudiera causar una degradación ambiental. Mientras tanto, el 95% de los respondientes estuvieron a favor de los esfuerzos para reducir el daño causado por la sobreabundancia de ungulados. Cuando los efectos sustentables sobre el ambiente de la sobreabundancia de venados se convertían en efectos insostenibles, los estimamos como pérdidas de bienestar humano para los respondientes de la encuesta; cuando los efectos sustentables transitaron hacia la nula visibilidad de efectos, los estimamos como ganancias de bienestar. Descubrimos que el tipo de programa de control de fauna era un tema muy relevante para los respondientes; el control indirecto, en el que se evita el exterminio, fue la acción preferida por los respondientes. El 66% de los respondientes estuvo de acuerdo con la opción de que los cazadores paguen por sacrificar animales para reducir el impacto de los ungulados en lugar de que el costo del manejo provenga de los impuestos, mientras que el 19% de los respondientes estuvo en contra de esta opción y dispuesto a pagar por otras soluciones en los parques nacionales. Nuestros resultados sugieren que el exterminio de vida silvestre en los parques nacionales podría ser una herramienta socialmente aceptable para manejar problemas de sobreabundancia en ciertos contextos, pero también podría generar algunos conflictos sociales.

Wolf Media Coverage in the Region of Castilla y León (Spain): Variations over Time and in Two Contrasting Socio-Ecological Settings.

People's attitudes towards large carnivores, and thus public support for their conservation, can be influenced by how these species are framed in the media. Therefore, assessing media coverage of large carnivores is of particular interest for their coexistence with humans. I used content analysis to assess how the grey wolf was portrayed in a newspaper in northern Spain, how wolf media coverage varied over time (2006-2017), and in two different socio-ecological settings. Most documents addressed the conflictive relationship between the wolf and livestock (60%; n = 902). Moreover, coverage of this relationship increased over the study period in the south of the study area, where the wolf is strictly protected, has recolonised new localities, and damage to livestock has increased. Overall, other topics, such as wolf conservation or hunting, appeared much less frequently in the media, but predominated in the north of the study area, where the wolf is more abundant and huntable. Conflictive issues like wolf-livestock interactions are generally attractive for audiences, but drawing attention to this issue may compromise the management of conflicts associated with wolves. Ideally, the media should promote potential wolf conservation values if coexistence between wolves and humans is sought.

Implications for Conservation of Collection of Mediterranean Spur-Thighed Tortoise as Pets in Morocco: Residents' Perceptions, Habits, and Knowledge.

The trading and collection of wild animals as pets may be cause for concern regarding animal welfare and species conservation. These concerns can be exemplified by Mediterranean spur-thighed tortoise (Testudo graeca), a long-living species whose use as pets is long established. The human dimension plays a major role in the wildlife for the pet collection, and is particularly important in countries like Morocco, where this might pose a threat to the conservation of the species involved. This study, which is based on a questionnaire survey (n = 480 participants), documents the fact that many people in Morocco keep tortoises as pets: 55% of the participants in the survey and over two tortoises/person. Importantly, most captive tortoises, particularly juveniles, had been collected directly from wild populations by their owners (42%, n = 264). In general, the tortoise owners had limited knowledge of their tortoises' habits and requirements, although rural people were more likely to acknowledge that the tortoise is a wild and threatened species. Our study reveals that non-commercial collection is a common activity in Morocco that may threaten wild tortoise populations and hence species conservation, and it could have consequences regarding the welfare of the animals. We were also able to identify the profile of people towards whom education campaigns should be directed in order to reduce the number of tortoises collected from wild populations. Additional field research should also be conducted to quantify the impact of pet collection on wild tortoise populations.

Understanding conservation conflicts associated with rodent outbreaks in farmland areas.

Rodent outbreaks affect many farmland areas worldwide and the negative environmental impacts of control campaigns cause intense social tensions. In such conservation conflicts, understanding stakeholders' viewpoints is critical to promote ecologically sustainable management. We used Q-methodology, a framework standing between qualitative and quantitative social research, to investigate human subjectivity and understand conflicts caused by rodent outbreaks in Spain. We interviewed farmers, conservationists, hunters, and governmental agencies, and identified five main discourses about the origins and consequences of the conflictive situation. Finding sustainable management is impaired by opposing views about causes and consequences of vole outbreaks and their management, which are at the root of the conflict. Social tensions will likely remain until the underlying conflicts between people holding different views are also managed. Decision-making should therefore focus on mitigating underlying conflicts. Using trained independent mediators would help the effective resolution of conservation conflicts caused by rodent outbreaks and their management.

Worldwide rapid spread of the novel rabbit haemorrhagic disease virus (GI.2/RHDV2/b).

We describe the extremely rapid worldwide spread of the Lagovirus europaeus/GI.2/RHDV2/b (henceforth GI.2), the causative infectious agent of the so-called 'novel' rabbit haemorrhagic disease of the European rabbit (Oryctolagus cuniculus). We tracked down all novel confirmed detections of GI.2 between May 2010 and November 2018 by carrying out a two-step in-depth review. We suggest that such spread would not have been possible without anthropogenic involvement. Our results also point out the importance of reviewing and adapting the protocols of virus detection and management in order to control, mitigate and contain properly, not only GI.2, but also new viruses that may emerge in the future.

A large-scale assessment of European rabbit damage to agriculture in Spain.

BACKGROUND: Numerous small and medium-sized mammal pests cause widespread and economically significant damage to crops all over the globe. However, most research on pest species has focused on accounts of the level of damage. There are fewer studies concentrating on the description of crop damage caused by pests at large geographical scales, or on analysis of the ecological and anthropogenic factors correlated with these observed patterns. We investigated the relationship between agricultural damage by the European rabbit (Oryctolagus cuniculus) and environmental and anthropogenic variables throughout Spain. RESULTS: Rabbit damage was mainly concentrated within the central-southern regions of Spain. We found that rabbit damage increased significantly between the early 2000s and 2013. Greater losses were typical of those areas where farming dominated and natural vegetation was scarce, where main railways and highways were present, and where environmental conditions were generally favourable for rabbit populations to proliferate. CONCLUSION: From our analysis, we suggest that roads and railway lines act as potential corridors along which rabbits can spread. The recent increase in Spain of such infrastructure may explain the rise in rabbit damage reported in this study. Our approach is valuable as a method for assessing drivers of wildlife pest damage at large spatial scales, and can be used to propose methods to reduce human - wildlife conflict. © 2017 Society of Chemical Industry.

Proposal for a unified classification system and nomenclature of lagoviruses.

Lagoviruses belong to the Caliciviridae family. They were first recognized as highly pathogenic viruses of the European rabbit (Oryctolagus cuniculus) and European brown hare (Lepus europaeus) that emerged in the 1970-1980s, namely, rabbit haemorrhagic disease virus (RHDV) and European brown hare syndrome virus (EBHSV), according to the host species from which they had been first detected. However, the diversity of lagoviruses has recently expanded to include new related viruses with varying pathogenicity, geographic distribution and host ranges. Together with the frequent recombination observed amongst circulating viruses, there is a clear need to establish precise guidelines for classifying and naming lagovirus strains. Therefore, here we propose a new nomenclature based on phylogenetic relationships. In this new nomenclature, a single species of lagovirus would be recognized and called Lagovirus europaeus. The species would be divided into two genogroups that correspond to RHDV- and EBHSV-related viruses, respectively. Genogroups could be subdivided into genotypes, which could themselves be subdivided into phylogenetically well-supported variants. Based on available sequences, pairwise distance cutoffs have been defined, but with the accumulation of new sequences these cutoffs may need to be revised. We propose that an international working group could coordinate the nomenclature of lagoviruses and any proposals for revision.

Large-scale assessment of myxomatosis prevalence in European wild rabbits (Oryctolagus cuniculus) 60years after first outbreak in Spain.

Myxomatosis is a viral disease that affects European rabbits (Oryctolagus cuniculus) worldwide. In Spain, populations of wild rabbits drastically decreased in the 1950s after the first outbreak of myxomatosis. Since that first appearance, it seems to be an annual epizootic in Spain with periodic outbreaks, predominantly in summer and autumn. Taking into account rabbit population structure, abundance, and genetic lineage, this paper attempts to make a large-scale characterization of myxomatosis seroprevalence based on the immune status of 29 rabbit populations distributed throughout Spain, where O. cuniculus cuniculus and O. c. algirus, the two known rabbit subspecies, naturally inhabit. A total of 654 samples were collected between 2003 and 2009, and seroprevalence of antibodies against Myxoma virus (MYXV) was determined. Overall, our results revealed that 53% of the rabbit samples were positive to antibodies against MYXV. Newborn and juvenile rabbits were the most susceptible animals to the virus, with 19% and 16% seropositivity for newborn and juveniles, respectively, while adult rabbits were the most protected, with 65% of seropositive samples. This suggests that prevalence is negatively related to the proportion of newborn and juvenile rabbits in a population. Our results also showed that seroprevalence against MYXV tended to be higher in high-abundance populations. In contrast, no differences were detected in seroprevalence between rabbit subspecies. This study confirms that >60years since first outbreak, myxomatosis is an endemic disease in Spain. Based on the results, the establishment of a myxomatosis surveillance protocol is proposed.

Rumours about wildlife pest introductions: European rabbits in Spain.

Rumours associated with wildlife are frequent, although they have received little attention in the scientific literature. Studying rumours is important because of their relevance not only in a broad theoretical sense but also in environmental management. The goal of this study is to explore the complexity of the relationships between humans and wildlife through a thematic analysis of rumours associated with allegedly introduced European rabbits (Oryctolagus cuniculus) that cause crop damage in Spain. For this purpose, potential rumours were identified using the Google search engine. Data analysis consisted of reading and re-reading Web-based texts to identify main themes, ideas and topics with the assistance of NVivo 10 software. The analysis identified three main themes: (1) the reviewed websites referred to allegedly introduced rabbits which differed from native rabbits; (2) differences were based on alleged observations of unnatural behaviour, physiology or physical appearance of introduced rabbits; (3) rumours were frequently used in the context of the rabbit management conflict; e.g. farmers accused hunters of releasing harmful rabbits. This study suggests that the analysis of wildlife-release rumours sheds light on the position of parties involved in conflicts associated with the (alleged) introduction of wildlife species. It stresses the importance of rumours in conservation and environmental management, and opens the door to future research.