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Five decades ago, a landmark paper in Science titled The Cave Environment heralded caves as ideal natural experimental laboratories in which to develop and address general questions in geology, ecology, biogeography, and evolutionary biology. Although the 'caves as laboratory' paradigm has since been advocated by subterranean biologists, there are few examples of studies that successfully translated their results into general principles. The contemporary era of big data, modelling tools, and revolutionary advances in genetics and (meta)genomics provides an opportunity to revisit unresolved questions and challenges, as well as examine promising new avenues of research in subterranean biology. Accordingly, we have developed a roadmap to guide future research endeavours in subterranean biology by adapting a well-established methodology of 'horizon scanning' to identify the highest priority research questions across six subject areas. Based on the expert opinion of 30 scientists from around the globe with complementary expertise and of different academic ages, we assembled an initial list of 258 fundamental questions concentrating on macroecology and microbial ecology, adaptation , evolution, and conservation. Subsequently, through online surveys, 130 subterranean biologists with various backgrounds assisted us in reducing our list to 50 top-priority questions. These research questions are broad in scope and ready to be addressed in the next decade. We believe this exercise will stimulate research towards a deeper understanding of subterranean biology and foster hypothesis-driven studies likely to resonate broadly from the traditional boundaries of this field.
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... Horizon scanning is a valuable and increasingly popular approach because it allows input and synthesis from a large and diverse scientific community (Sutherland et al. 2011). Several previous initiatives have successfully sought to identify and prioritise research questions within scientific fields, including ecology (Sutherland et al. 2013), global change biology (Sutherland et al. 2020), invasion biology (Ricciardi et al. 2017), island biology (Patiño et al. 2017), palaeoecology (Seddon et al. 2014) and subterranean biology (Mammola et al. 2020). ...
... This first phase (Phase 1 in Figure 1) produced 258 questions, which were then screened by the survey coordinators for duplication or ambiguity. The survey coordinators also took care to homogenise wording to ensure that the proposed questions were presented in a straightforward style with a consistent level of readability (Mammola et al. 2020). This first phase resulted in a curated list of 224 questions (hereafter termed List #1). ...
... The top 33 questions of List #4 were then refined to eliminate redundant questions or ambiguities through discussions among the survey coordinators, and then merged with the top 67 questions retained from List #2. A final round of rewording to improve readability and to eliminate ambiguities and overlap (sensu Mammola et al. 2020) reduced the number of questions from 100 to 90 (see Figure 1). ...
... Poulson and White (1969) considered caves as "natural laboratories," as they can be used to understand the principles governing the dynamics of more complex environments. Subterranean habitats have been regarded as ideal systems for investigating many of the unresolved questions in ecology, biogeography, and evolutionary and subterranean biology (Juan et al., 2010;Mammola et al., 2020). In this perspective, the checklist of European troglobitic springtails herein presented aims at setting an in-depth review of all reports in order to provide a sound basis for future studies. ...
... With respect to Collembola, there is a significant lack of knowledge concerning eco-evolutionary processes within caves. This is largely driven by insufficiency of functional ecology studies on Collembola species, the weakness of trait-based approaches (Fiera, Habel, Puchałka, et al., 2018;Zhang et al., 2018), the lack of sampling in many places in Europe (see Figure 2), and also the paucity of systematic sampling techniques for most taxonomic groups living in caves Although many research questions from macroecology and biogeography about subterranean Collembola and again for other cave groups are still unanswered (Mammola et al., 2020), this paper represents a strong potential for fast advancements in our understanding to clarify the indices of endemism, as well as to generate data for future biogeographic studies. ...
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en This paper provides an overview on troglobitic springtails found in European caves, including a checklist at species level. The paper also reviews what is currently known about Collembola, which occur in caves of the most important mountain ranges in Europe. Only troglobitic species were included since many troglophiles were of uncertain ecological status. A total of 338 troglobitic species of Collembola is recorded from European caves, distributed across 12 families. Spain and France appear to host the highest richness of species, including endemics. From a biogeographic perspective, troglobitic species are unevenly distributed in Europe, especially in the most important mountain ranges, like the Alps, the Carpathians, the Pyrenees, the Caucasus, and other European mountains. Troglobitic springtails are far more abundant in temperate zones than in the tropics. Despite this, several genera of Collembola appear to be well represented, while some are poorly represented (or lacking) in European caves. Many advances in knowledge of subterranean springtails have been made, particularly in the description of new species. However, there are still major gaps in the knowledge of the biology, environmental requirements, and impacts on subterranean fauna. This paper highlights the need for further research and provides baseline data for such efforts. Resumen es En este trabajo se proporciona una visión general de los colémbolos troglobios encontrados en las cuevas europeas, incluyendo un listado a nivel de especie. También se revisa lo que hasta ahora se conoce sobre los colémbolos que se encuentran en las cuevas de las cadenas montañosas más importantes de Europa. Se incluyen solamente las especies troglobias ya que el estado ecológico de muchos troglófilos es dudoso. Se registran 338 especies troglobias de Collembola en cuevas europeas, distribuidas en 12 familias. España y Francia parecen albergar la mayor riqueza de especies, incluidas las endémicas. Desde una perspectiva biogeográfica, las especies troglobias se distribuyen de forma desigual en Europa, especialmente en las cadenas montañosas más importantes, como los Alpes, los Cárpatos, los Pirineos, el Cáucaso y otras montañas europeas. Los colémbolos troglobios son mucho más abundantes en las zonas templadas que en los trópicos. A pesar de esto, varios géneros de Collembola parecen estar bien representados, mientras que otros están poco representados (o no existen) en las cuevas europeas. Últimamente se han realizado muchos avances en el conocimiento de los colémbolos subterráneos, particularmente en la descripción de nuevas especies. Sin embargo, aún existen importantes lagunas sobre su biología, los requisitos ambientales y los impactos sobre la fauna subterránea. Este trabajo destaca la necesidad de realizar más investigaciones y aporta datos de referencia en este sentido.
... Quantifying long-term changes in abundance of cave-dwelling organisms and identifying indicator species, reflecting the health status of subterranean ecosystems, are among the fundamental research goals of modern subterranean conservation biology (Mammola et al., 2020). For instance, the lack of knowledge about the factors underpinning abundance patterns in space and time are among the main impediments to the effective protection of cave fauna (Cardoso et al., 2011). ...
... Such environmental indicators (McGeoch, 1998) seek to provide cost and time effective guidelines to address pressing conservation issues, such as those faced by large-scale mining projects (Sonter, Ali & Watson, 2018). Assessing the response of subterranean fauna to anthropogenic disturbance nevertheless requires access to long-term cave monitoring datasets, which are remarkably rare for tropical caves (McGeoch, 1998;Carignan & Villard, 2002;Mammola et al., 2020). Here we identified 20 taxa where overall abundance responded to cave disturbance, and five where temporal abundance trends where associated with disturbance. ...
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Understanding the factors underpinning species abundance patterns in space and time is essential to implement effective cave conservation actions. Yet, the methods employed to monitor cave biodiversity still lack standardization, and no quantitative assessment has yet tried to optimize the amount and type of information required to efficiently identify disturbances in cave ecosystems. Using a comprehensive monitoring dataset for tropical iron caves, comprising abundance measurements for 33 target taxa surveyed across 95 caves along four years, here we provide the first evidence-based recommendations to optimize monitoring programs seeking to follow target species abundance through time. We found that seasonality did not influence the ability to detect temporal abundance trends. However, in most species, abundance estimates assessed during the dry season resulted in a more accurate detection of temporal abundance trends, and at least three surveys were required to identify global temporal abundance trends. Finally, we identified a subset of species that could potentially serve as short-term disturbance indicators. Results suggest that iron cave monitoring programs implemented in our study region could focus sampling efforts in the dry season, where detectability of target species is higher, while assuring data collection for at least three years. More generally, our study reveals the importance of long-term cave monitoring programs for detecting possible disturbances in subterranean ecosystems, and for using the generated information to optimize future monitoring efforts.
... Habitat loss and degradation are among the main concerns of cave researchers, since karstic systems all over the world have been suffering impacts from distinct human activities (Van Beynen and Townsend 2005;Mammola et al. 2019Mammola et al. , 2020Iannella et al. 2020). Activities in the epigean environments may affect directly or indirectly the dynamics of clastic and organic sediments, which are carried into the caves, thus influencing the trophic dynamics, hydrodynamics, and quality of groundwaters (Watson et al. 1997;Schneider et al. 2011;Borges et al. 2019;Piccini et al. 2019;Fattorini et al. 2020;Moldovan et al. 2020). ...
... Furthermore, caves also shelter obligate cave species and microorganisms with economic and environmental value, real or potential (Cheeptham et al. 2013;Culver and Pipan 2019). Finally, scientists are warning that understanding global species richness patterns (which, in turn, depend on local and regional assessments) is fundamental for a better understanding of subterranean biology and encourage studies based on much more robust hypotheses (Mammola et al. 2020;Iannella et al. 2020). ...
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The definition of priority for conservation becomes an emergency because habitat loss and degradation are among the main impacts on karst landscapes. In this sense, the present study aimed to evaluate the priorities for cave conservation through the combination of indexes that use species richness, species distribution, and proportion of the deforested area (PDA). The caves presented 287 non-troglobitic species and 37 species (11.7 %) with troglomorphic traits that are distributed in 50 % of the caves. The caves also present a high phylogenetic and functional diversity of terrestrial, aquatic, and amphibious cave-restricted species, including many predators, scavengers, and one phytophagous species, most of them presenting remarkable specialized traits and restrict distribution in a few caves and in specific biotopes. The PDA were positively related to the distance from the limestone out-crop, because of the restrictive landforms for agropastoral activities. At least two caves present extremely high priority for conservation (Baixão and Baixa da Fortuna caves), while four caves present high priority, and almost all others require at least a conservation action. Suggestively, in this specific case, a coherent strategy was shown to maintain the preserved vegetation around the caves, improving the restoration of small fragments and minimizing alterations. Despite the results of the indices, the singularity of the area regarding the taxo-nomic and functional diversity of troglobites also reinforces the urgent need for conservation actions.
... The herein described citizen science approach offers the potential of sampling an extended timescale and to capture potential seasonal patterns (Dickinson et al. 2010;Gouraguine et al. 2019). This is especially needed since data series or seasonal data about groundwater fauna are generally very scarce and temporal dynamics only poorly understood (Mammola et al. 2020). Consequently, little is known about the ecosystem services provided by these organisms (Griebler and Avramov 2015), such as drinking water provisioning, and if groundwater communities could be indicative of the ecological status of subterranean ecosystems (Griebler et al. 2014;Mammola et al. 2020). ...
... This is especially needed since data series or seasonal data about groundwater fauna are generally very scarce and temporal dynamics only poorly understood (Mammola et al. 2020). Consequently, little is known about the ecosystem services provided by these organisms (Griebler and Avramov 2015), such as drinking water provisioning, and if groundwater communities could be indicative of the ecological status of subterranean ecosystems (Griebler et al. 2014;Mammola et al. 2020). We thus expect that citizen science approaches may be generally valid and useful for gaining access to an unprecedented number of samples for hitherto largely understudied ecosystems such as groundwater. ...
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Knowledge on the diversity and distribution of subterranean organisms is still scattered, even in faunistically relatively well-researched countries such as Switzerland. This is mostly due to the restricted access to these subterranean habitats. Better knowledge on these organisms is needed, because they contribute substantially to overall biodiversity of a region, often contain unique elements of biodiversity, and can potentially be indicative of the ecological status of subterranean ecosystems that are providing important ecosystem services such as drinking water. Past research on subterranean organisms has often used highly specialised sampling techniques and expert knowledge. Here, we show that inclusion of non-professionals can be an alternative and highly promising sampling strategy. We retrieved citizen science-based samples from municipal groundwater wells across Switzerland, mainly from the Swiss Plateau. Opportunistic samples from 313 sites revealed a previously undocumented groundwater fauna including organisms from different major invertebrate groups, with a dominance of crustaceans. Here, we studied amphipods of the genus Niphargus . Among all 363 individuals sampled, we found in total eight nominal species. Two of them, namely N. fontanus and N. kieferi , are reported for Switzerland for the first time. We also found four further phylogenetic lineages that are potentially new species to science. One of them is here formally described as Niphargus arolaensis sp. nov. The description is based on molecular and morphometric data. Our study proves the suitability of citizen science to document subterranean diversity, supports groundwater conservation efforts with data, and raises awareness for the relevance and biodiversity of groundwater amphipods among stakeholders.
... Subterranean habitats, intended as all the natural and artificial voids suitable for the occurrence of life, are intriguing scientists since the beginning of scientific disciplines (Vandel 1964) and are gaining the attention of zoologists and ecologists in recent times because of their great potential to solve broad biological questions (Mammola et al. 2020). This potential is linked to the peculiar ecological features that characterize the subterranean realm; one of the more obvious is the absence of light, with solar radiation not able to penetrate beyond the more or less short ecotonal area that connects subterranean habitats to the surface, thus preventing plant growth. ...
... The ensemble of subterranean-dwelling organisms is thus likely to form a gradient from the entrance to the deepest sectors of the cave that, although complex, should lead to rather simple (or more understandable) ecological dynamics compared to surface communities; however, biological studies on underground communities are poor, despite the great potential to solve broad ecological questions (Mammola et al. 2020), especially because of the habitat impediments (Mammola et al. 2021). ...
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Biological studies on factors shaping underground communities are poor, especially those considering simultaneously organisms with different degrees of adaptation to cave life. In this study, we assessed the annual dynamics and use of both horizontal and vertical microhabitats of a whole community with the aim of understanding whether cave-dwelling organisms have a similar distribution among vertical and ground-level microhabitats and to find out which microhabitat features influence such distribution. We monthly assessed from 2017 to 2018, by direct observation combined with quadrat sampling method on the ground and transects on the walls, richness and abundance of 62 cave-dwelling species in a cave of Northern Italy. Environmental factors such as light intensity, temperature, relative humidity and min-eralogical composition of the substrates were measured during each monitoring session, influencing the dynamics of the whole community and revealing significant differences between ground and wall micro-habitats. A gradient of variation of the species assemblages occurred from the entrance toward inner areas, however, evidence that the dynamics of the walls are very different from those occurring at the ground independent from the distance from the surface are shown. Biodiversity indices highlighted sampling area diversity and a discrete total cave fauna biodiversity with the highest values found near the entrance and the lowest in the inner part of the cave.
... Recent 'horizon scanning' identified the highest priority research questions in subterranean ecology (Mammola et al., 2020). These research questions covered six subject areas, i.e. (1) adaptation, (2) origin and evolution, (3) community ecology, (4) macroecology and biogeography, (5) conservation ecology, (6) microbiology and applied topics. ...
... These research questions covered six subject areas, i.e. (1) adaptation, (2) origin and evolution, (3) community ecology, (4) macroecology and biogeography, (5) conservation ecology, (6) microbiology and applied topics. Rather than repeating knowledge gaps already identified in previous works (Larned, 2012;Mammola et al., 2020), we will complement their list of research questions with respect to microbial ecology. We provide below 10 topics where there is an urgent need for microbiological research in groundwater. ...
Chapter
Aim: The aim of this chapter is to critically highlight existing knowledge gaps, obstacles, and research frontiers in groundwater microbial ecology. Main concepts covered: We have identified and discuss below 10 topics where there is an urgent need for microbiological research in groundwater. Main methods covered: We consider the challenges in groundwater microbiology research, including the limited accessibility of aquifers, methods to robustly characterize communities, the importance of microbial interactions, and the current lack of underpinning ecological theory and the testing of basic concepts in groundwater. Conclusion/Outlook: There is enormous opportunity to progress fundamental ecological understanding through further research of microbiology in the terrestrial subsurface.
... Subterranean environments not only provide vital resources to humanity, such as key water reservoirs for industry, agriculture, and human consumption (Danielopol et al., 2003), but also host complex ecosystems, the diversity and function of which are just being revealed (Mammola et al., 2020;Saccò et al., 2019a). Compared to their surficial freshwater counterparts, subterranean habitats, due to their poor accessibility and the cryptic nature of their inhabitants (Hancock et al., 2005), provide challenging and fascinating natural laboratories to investigate ecological dynamics (Griebler et al., 2014) and evolutionary trends (Mammola, 2019). ...
... Therefore, there is an urgent need for research on subterranean communities and the elements within them. In their roadmap guide to future research in subterranean ecosystems, Mammola et al. (2020) identified fifty priority research questions across six subject areas in subterranean biology. Here we use eight relevant questions from their study to highlight the areas of research to which eDNA data can contribute. ...
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Monitoring of biota is pivotal for the assessment and conservation of ecosystems. Environments worldwide are being continuously and increasingly exposed to multiple adverse impacts, and the accuracy and reliability of the biomonitoring tools that can be employed shape not only the present, but more importantly, the future of entire habitats. The analysis of environmental DNA (eDNA) metabarcoding data provides a quick, affordable, and reliable molecular approach for biodiversity assessments. However, while extensively employed in aquatic and terrestrial surface environments, eDNA-based studies targeting subterranean ecosystems are still uncommon due to the lack of accessibility and the cryptic nature of these environments and their species. Recent advances in genetic and genomic analyses have established a promising framework for shedding new light on subterranean biodiversity and ecology. To address current knowledge and the future use of eDNA methods in groundwaters and caves, this review explores conceptual and technical aspects of the application and its potential in subterranean systems. We briefly introduce subterranean biota and describe the most used traditional sampling techniques. Next, eDNA characteristics, application, and limitations in the subsurface environment are outlined. Last, we provide suggestions on how to overcome caveats and delineate some of the research avenues that will likely shape this field in the near future. We advocate that eDNA analyses, when carefully conducted and ideally combined with conventional sampling techniques, will substantially increase understanding and enable crucial expansion of subterranean community characterisation. Given the importance of groundwater and cave ecosystems for nature and humans, eDNA can bring to the surface essential insights, such as study of ecosystem assemblages and rare species detection, which are critical for the preservation of life below, as well as above, the ground.
... The second approach views caves as powerful natural laboratories for evolutionary, ecological and behavioural studies on their inhabitants (Culver & Pipan, 2014;Culver & Pipan, 2019). The idea of caves as natural laboratories, first postulated by the speleologist Édouard-Alfred Martel (1894), has been espoused for more than one hundred years of subterranean studies (Poulson & White, 1969) and recently updated and broadened in the current context of biological research (Mammola, 2019;Mammola et al., 2020) . However, of the relatively large number of caves that were effectively used as laboratories during last century (Vandel, 1964), few remain active. ...
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Springs are interfaces between groundwater and surface habitats and may play an important role in the study of subterranean animals. In this systematic evidence review and meta-analysis, we explore whether observations of stygobionts in springs are relevant and more common than observations of epigean animals in groundwater. We searched the Web of Science database for papers on groundwater fauna and spring fauna. For each paper we found, we recorded whether the paper reported the occurrence of typical stygobionts in springs, of surface animals in groundwater, or of the same taxa in both habitats. If so, we recorded how many such species were reported. We also recorded the scientific discipline of each study and the year of publication. Our search yielded 342 papers. A considerable number of these papers reported stygobionts in springs: 20% of papers dealing with groundwater fauna and 16% of papers dealing with spring fauna reported the occurrence of stygobionts in spring habitats. Both the number of papers that mentioned stygobionts in springs, and the number of stygobiont species that were documented in springs, were higher than equivalent measures for the occurrence of surface fauna underground. We also detected a positive relationship between year of publication and the number of reports of stygofauna in springs. To broaden the insights from biological research on underground environments, we suggest that springs should be considered not only as simple sampling points of stygobionts but also as core stygobiont habitats.
... In deciphering these mechanisms, organisms under strong selection pressure from extreme envi-ronments, including subterranean habitats, have proven particularly useful. 12 In the evolutionary transition from a surfacedwelling to a subterranean lifestyle, populations are faced with perpetual darkness, nutrient scarcity, constant temperature, high humidity, and impoverished species communities. Established cave species often evolve a set of characteristic phenotypic traits known as troglomorphisms. ...
Article
Deciphering the genetic code of organisms with unusual phenotypes can help answer fundamental biological questions and provide insight into mechanisms relevant to human biomedical research. The cave salamander Proteus anguinus (Urodela: Proteidae), also known as the olm, is an example of a species with unique morphological and physiological adaptations to its subterranean environment, including regenerative abilities, resistance to prolonged starvation, and a life span of more than 100 years. However, the structure and sequence of the olm genome is still largely unknown owing to its enormous size, estimated at nearly 50 gigabases. An international Proteus Genome Research Consortium has been formed to decipher the olm genome. This perspective provides the scientific and biomedical rationale for exploring the olm genome and outlines potential outcomes, challenges, and methodological approaches required to analyze and annotate the genome of this unique amphibian. An international Proteus Genome Research Consortium has been formed to decipher the genome of Proteus anguinus (the olm). This perspective provides the scientific and biomedical rationale for exploring the olm genome and outlines potential outcomes, challenges, and methodological approaches required to analyze and annotate the genome of this unique amphibian.
... In contrast to most surface systems, two main factors constrain these processes in porous groundwater: the lack of light [10] and the porosity [11]. The lack of light excludes all phototrophic production, and groundwater systems rely on heterotrophy and chemolithoautotrophy. ...
Article
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The largest freshwater ecosystem on earth is in the subsurface: the groundwater. It is populated by animals of almost all phyla and by bacteria, archaea, and fungi. Processes on the macro-, meso-, and micro-scale shape this ecosystem. Bioremediation, i.e., the degradation of contaminants, is steered on the scale of micrometers. However, processes that take place on the micrometer scale are still poorly understood and have not been studied extensively. They are usually lacking from models. In this communication, the plea for studying and making models for the processes that take place on the micrometer scale is based on the conceptual model of bottom-up effects of the pore scale environment. Such conceptual models may influence how quantitative models are built by structuring them.
... One of the most studied among these impacts is the effect of touristic activities in caves opened to visitors (Cigna, 2016). Human-induced impacts associated to tourist caves can affect different ecosystem components (Mammola, 2019), but our understanding of the nuances of these effects remains scarce (Mammola et al., 2020). A massive presence of tourist directly alters the underground microclimate resulting in seasonal variations in temperature and relative humidity (Cigna, 2004). ...
Article
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Human activities in subterranean environments can affect different ecosystem components, including the resident fauna. Subterranean terrestrial invertebrates are particularly sensitive to environmental change, especially microclimatic variations. For instance, microclimate modifications caused by the visitors may directly affect local fauna in caves opened to the public. However, since numerous factors act synergistically in modulating the distribution and abundance of subterranean species, it remains challenging to differentiate the impact of human intervention from that of other factors. Therefore, evidence of the impact of tourism on cave invertebrate fauna remains scarce. Over a year and with approximately two visits a month, we investigated the effects of the presence of visitors on the subterranean endemic woodlouse Armadillidium lagrecai in the strict natural reserve of Monello Cave (Sicily, Italy). We found that natural microclimatic fluctuations, and not direct human disturbance, were the main factors driving the distribution of A. lagrecai. Specifically, A. lagrecai select for more climatically stable areas of the cave, where the temperature was constantly warm and the relative humidity close to saturation. We also observed a significant temporal effect, with a greater abundance of A. lagrecai in summer and a gradual decrease during the winter months. The number of visitors in the Monello cave had no effect on the abundance and distribution of A. lagrecai. However, considering the high sensitivity of the species to microclimatic variations, it seems likely that a significant increase in the number of visitors to the cave could indirectly affect this species by altering local microclimate. Constant monitoring of the environmental parameters within the cave is therefore recommended.
... Assessing the effects of pollution is recently considered among the most relevant aims for subterranean biology [35]. However, the impact of pollution on stygofauna varies according to pollutants typology and abundance [32], and assessing its effects may not be trivial. ...
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Assessing the effects of pollution in groundwaters is recently considered among the most relevant aims for subterranean biology; with this perspective, we aim to provide examples of the most relevant effects that pollution may cause on stygofauna community and underline patterns deserving further investigations. We retrieved different cases in which pollution caused alteration of groundwater trophic webs, favored invasions by epigean mesopredators, damaged stygobiont keystone species, and promoted interspecific competition between stygobionts and epigean animals. The results and the remarks derived from our perspective review underline that pollution may play multifaceted effects on groundwaters communities, and the paucity of information that exists on community-level changes and threats underlines the necessity for further studies.
... The strict environmental conditions subterranean environments play over its biota have been demonstrated to drive morphological, physiological, and behavioural adaptations. Examples are loss of pigmentation, reduction of eyes, and elongation of appendages (Mammola et al. 2020). Here, the observed difference of embryonic development in Charinus, that is, longer development time in cave species, might also result from adaptation to those constraints, such as food availability (i.e. ...
Article
Parthenogenesis is documented in a few species of Amblypygi, but it is unknown how widespread in the order this reproductive behaviour is, and little has been researched regarding aspects of embryonic and post-embryonic development in the group. Here, we studied the parthenogenetic capacity of an Amazonian whip spider (Charinus guto) evaluating the time of egg and embryonic development and inter-moult period. We also provide a review on embryonic and post-embryonic development in Amblypygi, compiling and analysing data from 43 species in three families. Fifty-two females and 42 juveniles of C. guto were collected in fragments of a secondary forest in Belém (Brazil); specimens were kept in captivity and observed weekly from 2018 to 2020. Nineteen specimens were collected with and 32 without egg sacs. Fourteen of the nonovigerous females developed eggs in captivity, six of them moulted (i.e. lost stored sperm from previous contacts with males) before developing an egg sac, proving to be parthenogenetic. The mean time between the first day in captivity and moult was 96 days. In both adults and juveniles, a mean of 147 days passed between first day in captivity and first moult, and 125 days for a second moult. After moulting, a mean of 113 days passed for the females to develop an egg sac; the embryonic development took a mean of 59 days. Juveniles left the mother’s abdomen after 10 days of hatching from the egg and the mean number of live free-living protonymphs was five. Other amblypygids, especially charinids, have similar embryonic development and post-embryonic growth and a detailed discussion with all known information for whip spiders is presented. We also demonstrate a positive correlation between clutch size and female size across Amblypygi, in which larger females carry more eggs and have larger offspring regardless of climate and habitat.
... Global change is negatively impacting groundwater and subterranean biodiversity; yet, we are hampered by lack of knowledge of even fundamental aspects such as taxonomic diversity, distribution, and threats [13,14]. Exploration into and research on subterranean biodiversity in the WG have advanced in the past 2 years with the discovery of several peculiar and highly unusual vertebrate and invertebrate species. ...
Article
Groundwater depletion is a significant global issue, but its impact on the often-enigmatic subterranean biodiversity and its conservation remains poorly understood. In the Western Ghats biodiversity hotspot of India, poor governance of groundwater resources is threatening its evolutionarily distinct subterranean freshwater fauna, some taxa of which represent Gondwanan relics.
... PPCS retains its appeal for biological research, with organisms that have the potential to answer key questions in speleobiology [130]. One research direction could address cave colonization in the context of adaptation and speciation processes from surface ancestor to subterranean descendant [131]. ...
Article
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The Postojna-Planina Cave System (PPCS) in central Slovenia is a globally exceptional site of subterranean biodiversity, comprised of many interconnected caves with cumulative passage length exceeding 34 km. Two rivers sink into the caves of the PPCS, called the Pivka and Rak, and join underground into Unica River, which emerges to the surface. The studies of fauna of PPCS began in the 19th century with the first scientific descriptions of specialized cave animals in the world, making it “the cradle of speleobiology”. Currently, the species list of PPCS contains 117 troglobiotic animal species belonging to eight phyla, confirming its status as the richest in the world. Of these, 47 species have been scientifically described from the PPCS, and more than 10 await formal taxonomic descriptions. We expect that further sampling, detailed analyses of less studied taxa, and the use of molecular methods may reveal more species. To keep the cave animals’ checklist in PPCS up-to-date, we have supplemented the printed checklist with an online interface. As the revised checklist is a necessary first step for further activities, we discuss the importance of PPCS in terms of future research and conservation.
... In subterranean biology, the concept of model organism has also been applied to supra-specific lineages widely used to investigate evolutionary processes associated with cave colonization or to answer biogeographic and macroecological questions. Similar studies typically rely on comparative methods within explicit phylogenetic frameworks, allowing us to distinguish the role played by ecological adaptations and evolutionary history on the observed ecological and distribution patterns (Juan et al., 2010;Mammola et al., 2020). Some of these models account for lineages including both surface and subterranean species exhibiting different degrees of adaptations and ecological preferences, such as Asellus (Verovnik et al., 2004), Niphargus (Amphipoda: ...
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• Caves and other subterranean habitats fulfill the requirements of experimental model systems to address general questions in ecology and evolution. Yet, the harsh working conditions of these environments and the uniqueness of the subterranean organisms have challenged most attempts to pursuit standardized research. • Two main obstacles have synergistically hampered previous attempts. First, there is a habitat impediment related to the objective difficulties of exploring subterranean habitats and our inability to access the network of fissures that represents the elective habitat for the so-called “cave species.” Second, there is a biological impediment illustrated by the rarity of most subterranean species and their low physiological tolerance, often limiting sample size and complicating laboratory experiments. • We explore the advantages and disadvantages of four general experimental setups (in situ, quasi in situ, ex situ, and in silico) in the light of habitat and biological impediments. We also discuss the potential of indirect approaches to research. Furthermore, using bibliometric data, we provide a quantitative overview of the model organisms that scientists have exploited in the study of subterranean life. • Our over-arching goal is to promote caves as model systems where one can perform standardized scientific research. This is important not only to achieve an in-depth understanding of the functioning of subterranean ecosystems but also to fully exploit their long-discussed potential in addressing general scientific questions with implications beyond the boundaries of this discipline.
... The temporal and spatial dynamics of invertebrate communities of the terrestrial subsurface habitats remain largely unstudied, and whether these habitats constitute "a gateway to colonize deep zones" is currently one of the fundamental questions in subterranean biology (Mammola et al., 2020). This study presents the first data on invertebrate (Diplopoda, Diplura, Orthoptera and Coleoptera) seasonal abundance variation for the MSS in continental Portugal, and reveals a large seasonal variation for these groups, but little influence of sediment properties on abundance. ...
Article
The mesovoid shallow substratum (MSS) can act as a climatic refuge for invertebrates, as a biogeographic corridor to deeper substrates or as a permanent habitat for some species. This study characterizes the seasonal invertebrate diversity and abundance of MSS ecosystems in central Portugal focusing on Diplopoda, Diplura, Orthoptera and Coleoptera during one year. Sampling was performed with standard MSS pitfalls in scree slopes (colluvial MSS) of karst areas and environmental parameters (temperature, pH, conductivity, water content, organic carbon, nitrate, phosphate and ammonium) were quantified. Our results show that winter was the season with the highest arthropod abundance and that the MSS acts as a permanent habitat for chordeumatidan millipedes and as a climatic refuge for orthopterans and most beetles. All Diplura collected belong to a single species known previously from surface habitats in the Iberian Peninsula, which does not seem to use the Portuguese MSS as a refuge. MSS habitats in central Portugal, classified as western Mediterranean and thermophile deposits protected by the Natura 2000 network based on plant communities and geology, revealed an abundant and diverse invertebrate community that urges characterization and protection.
... The conservation priorities we highlight here are among those identified as top priority in the context of conservation of subterranean ecosystems by subterranean biologists (Mammola et al. 2020). Bolstering the protections afforded to North American stygosnails and other invertebrate taxa would assist in maintaining the health of groundwater and This article is protected by copyright. ...
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Many taxonomic groups have successfully exploited groundwater environments and adapted to a subterranean (stygobiotic) existence. Among these groups are freshwater gastropods (stygosnails), which represent a widespread and taxonomically diverse component of groundwater ecosystems in the United States and Mexico; no stygosnails are known from Canada. North American stygosnails have convergently evolved a miniaturized body plan compared to their surface relatives and have independently colonized a variety of groundwater habitats ranging from cave passages to deep, human‐inaccessible aquifers. Owing to sampling difficulty and lack of targeted study, stygosnails remain among the most understudied of all subterranean groups. Compared to their surface relatives, of which over 75% are already considered threatened in North America, stygosnails may face additional stressors. As currently understood, most stygosnails exhibit extreme narrow‐range endemism, resulting in a high risk of extinction from a single catastrophic event, particularly when combined with increasingly modified underground habitats. Anthropogenically‐driven changes to surface environments have led to changes in local hydrology and degradation of groundwater systems through increased sedimentation, introduction of invasive species, groundwater extraction, and/or physical collapse of water‐bearing passages. Consequently, 32 of the 39 described North American stygosnail species have been assessed as imperiled under NatureServe criteria, and 10 species have been assessed as threatened under International Union for Conservation of Nature (IUCN) criteria. Although imperilment rates of stygosnails and above‐ground freshwater snails in North America are similar, stygosnail conservation is uniquely hindered by difficulties associated with accessing subterranean habitats for monitoring and active management. Furthermore, only three species are afforded federal protection in either U.S. or Mexico, and current law regulating water pollution may be inadequate for protecting stygosnail habitats. Here, we review the biology of stygosnails in North America and discuss conservation needs and policy considerations that will aid in their protection. This article is protected by copyright. All rights reserved
... The lack of terminological agreement among cave scientists has preserved most of these words, which are still commonly found in the literature and are the central subject of heated etymological debates (figure 1). We took advantage of the long tradition of multidisciplinarity [23,24] and high terminological specialization [25] offered by cave literature to investigate the effect of jargon use on article success-measured as the number of citations. ...
Article
Words are the building blocks of communicating science. As our understanding of the world progresses, scientific disciplines naturally enrich their specialized vocabulary (jargon). However, in the era of interdisciplinar-ity, the use of jargon may hinder effective communication among scientists that do not share a common scientific background. The question of how jargon limits the transmission of scientific knowledge has long been debated but rarely addressed quantitatively. We explored the relationship between the use of jargon and citations, using 21 486 articles focusing on cave research, a multidisciplinary field particularly prone to terminological specialization, and where linguistic disagreement among peers is frequent. We demonstrate a significant negative relationship between the proportion of jargon words in the title and abstract and the number of citations a paper receives. Given that these elements are the hook to readers, we urge scientists to restrict jargon to sections of the paper where its use is unavoidable.
... Our results support common findings of high biodiversity and short-range endemism in groundwater faunas internationally (e.g., Boulton, 2020;Gladstone et al., 2021) and likewise for the use of genetic data in identifying morphologically cryptic species, which are common in groundwaters (Boulton, 2020;Delic et al., 2017;Eme et al., 2018;Gladstone et al., 2021). By contributing to knowledge of the biodiversity and spatial distributions of groundwater taxa, we hope to help address some of the knowledge gaps inhibiting conservation of groundwater biodiversity (e.g., Boulton, 2020;Mammola et al., 2019Mammola et al., , 2020. ...
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We used DNA barcoding to assess the diversity and distribution of New Zealand's groundwater amphipods and isopods (Crustacea) and to determine whether biodiversity and endemism within tectonically active New Zealand are similar to those of more tectonically stable continents. Sixty-five wells were sampled in seven aquifers across four regions within the North and South islands of New Zealand, and resident invertebrates were morphologically identified and then assessed using sequencing of the mitochondrial DNA cytochrome c oxidase subunit one (COI) gene. Invertebrates were found in 54 wells. Of the 228 individual amphipods and isopods found in 36 of the wells, 154 individuals were successfully sequenced for COI (68% success rate) from 25 wells, with at least one well in each aquifer containing sequenced individuals. Of the 45 putative species identified using Barcode Index Numbers (BINs), 30 BINs (78% of all taxa and 83% of amphipods) were previously unrecorded. Substantial morphologically cryptic, species-level diversity was revealed, particularly within the amphipod Family Paraleptamphopidae. Similarly, one isopod taxon morphologically identified as Cruregens fontanus was assigned to five well-separated BINs based on COI sequences. Endemism appeared high, with all taxa regionally endemic; 87% of species were restricted to one aquifer and more than 50% restricted to one well. Non-saturated species accumulation curves indicated that, while additional sampling may increase the range of some currently identified taxa, additional range-restricted taxa are also likely to be discovered. Patterns of diversity and short-range endemism were similar to those found elsewhere, including locations which are more tectonically stable. The predominance of local endemism within New Zealand's groundwater fauna suggests that land-use activities and groundwater extraction require careful evaluation to minimize threats to groundwater biodiversity.
... Likewise, the regions that remained permanently forested at the surface may have been important for the diversification of palpigrades in soils, as similarly observed in other arthropod groups(Hoffmeister & Ferrari, 2016;Peres et al., 2015). However, these explanations remain speculative: detailed studies on divergence time of the Brazilian lineages are needed if we want to understand the extent to which climatic fluctuations and consequent changes in rainfall regime and vegetation cover affected their speciation rates(Mammola, Amorim, et al., 2020). ...
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Aim Historically, research on global distribution patterns has mostly concentrated on conspicuous organisms and thus a large proportion of biodiversity on Earth remains unmapped. We examined the global distribution of palpigrades, a poorly studied group of low dispersive arachnids specialized to subterranean life. We asked what is their typical range size, the ecological factors driving their distributions, and to what extent sampling bias may influence the observed patterns. Location Global. Taxon Palpigrades (Arachnida: Palpigradi) in the genus Eukoenenia. Methods We assembled a database of over 1000 localities and referring to 57 soil‐ and 69 cave‐adapted palpigrades. We tested for differences in range sizes of soil‐ and cave‐adapted species. We used variance partitioning analysis to explore the contribution of climate, nutrient availability and geology in driving observed distributions. Finally, we verified the potential correlation between the number of occurrence records and the number of palpigrades' researchers. Results Europe and Brazil emerged as centres of diversification of cave‐adapted palpigrades. Conversely, the diversity of soil‐adapted species was distributed over a broader geographical expanse, mainly in the Southern Hemisphere. Both cave and soil species had narrow distribution ranges, with a median value of 0.01 km²; only a few parthenogenetic species were distributed over multiple continents. The distribution of cave‐ and soil‐adapted palpigrades was primarily explained by climatic conditions, and secondarily by nutrient and habitat availability. In the Alps, the distribution of cave‐adapted species also bears the signature of historical events related to glaciation cycles. We observed, however, a pronounced people‐species correlation, suggesting that the observed patterns are not generalizable to poorly explored areas. Main conclusions Our study highlights enormous gaps in current knowledge about the biogeography of palpigrades. Even if the information is largely incomplete and biased, we show how data can be harnesses to draw a preliminary picture of the global distribution patterns of palpigrades. Thus, we offer a jumping‐off point for future studies on the macroecology and conservation of poorly known organisms.
... If subterranean organisms have lost the ability to adapt to a changing environment has been a fundamental question in subterranean biology (Mammola et al., 2020), because the degree of specialization to deep subterranean environments is a key driver for the vulnerability to climate change . Therefore, shedding light in the relationship among thermal tolerance, subterranean specialization, and current habitat temperature is pivotal for the conservation of subterranean fauna from a climate change perspective. ...
Article
The climatic variability hypothesis predicts the evolution of species with wide thermal tolerance ranges in environments with variable temperatures, and the evolution of thermal specialists in thermally stable environments. In caves, the extent of spatial and temporal thermal variability experienced by taxa decreases with their degree of specialization to deep subterranean habitats. We use Phylogenetic Generalized Least Squares to model the relationship between thermal tolerance (upper lethal limits), subterranean specialization (estimated using ecomorphological traits) and habitat temperature in sixteen beetle species of the tribe Leptodirini (Leiodidae). We found a significant, negative relationship between thermal tolerance and the degree of subterranean specialization. Conversely, habitat temperature had only a marginal effect on lethal limits. In agreement with the climatic variability hypothesis and under a climate change context, we show that the specialization process to live in deep subterranean habitats involves a reduction of upper lethal limits, but not an adjustment to habitat temperature. Thermal variability seems to exert a higher evolutionary pressure than mean habitat temperature to configure the thermal niche of subterranean species. Our results provide novel insights on thermal physiology of species with poor dispersal capabilities and on the evolutionary process of adaptation to subterranean environments. We further emphasize that the pathways determining vulnerability of subterranean species to climate change greatly depend on the degree of specialization to deep subterranean environments.
... G roundwaters contain diverse assemblages of metazoans that represent an important yet underestimated component of the Earth's freshwater biodiversity . The characteristic traits of obligate groundwater metazoans are sources of unexpected scientific discoveries that have wide theoretical and applied implications (Griebler et al., 2014;Mammola et al., 2020). Metazoans play a potentially important, albeit insufficiently documented role, in maintaining goods and services delivered by groundwater ecosystems to humankind (Boulton et al., 2008;Griebler and Avramov, 2015). ...
Chapter
Aim: Groundwater hosts a high diversity of metazoans that dwell in open spaces within the rock. That diversity makes an important, yet underestimated, contribution to freshwater biodiversity. Here, we briefly describe groundwater habitats, the composition and spatial distribution of groundwater metazoan assemblages, the characteristic traits of specialist groundwater organisms, and their role in groundwater ecosystems. Main concepts covered/Main methods covered: Groundwater habitats all have in common that they are dark and hence they lack photosynthetic production. They are nevertheless highly diverse in terms of void space available to metazoans, interconnectedness of the voids and hydrological linkages to surface ecosystems. Groundwater metazoan assemblages are made of species living exclusively in groundwater, which we refer to as specialist groundwater species, and species that complete their life cycle both in groundwater and in surface water, which we refer to as generalists. Assemblages of specialist groundwater metazoans show a high spatial turnover in species composition over short distances and low local species diversity relative to regional diversity. A major evolutionary hypothesis is that selective pressures specific to groundwater shape converging phenotypes among specialist groundwater species, which differ strikingly from those observed in surface species. Phenotypes of specialist groundwater metazoans are nevertheless extremely diverse, even though the combination of selective pressures causing that diversity is yet to be elucidated. Groundwater metazoans have direct and indirect effect on hydraulic attributes of aquifers and ecosystem processes, which contribute to delivering important ecosystem services such as water provision and purification. Conclusion/outlook: Groundwater metazoans belong to the invisible component of Earth's biodiversity. Documenting and understanding their compositional and functional diversity has revealed the fascinating content of a Pandora's Box of which much still remains unknown. Much of the progress achieved in understanding mechanisms shaping phenotypes, biodiversity distribution patterns and organisms' function is yet to translate into policies that frame the management of groundwater ecosystems and the important services they deliver to humans.
... A fundamental question in subterranean biology is whether the current patterns of subterranean biodiversity are best explained by a "history of colonization of surface ancestors or by in situ speciation and dispersal in subterranean habitats" (Mammola et al. 2020). The CRH and ASH are the generally accepted scenarios for the evolution of cave species in major animal groups-insects, arachnids, and vertebrates (Holsinger 1988(Holsinger , 2000Peck and Finston 1993;Leys et al. 2003;Juan et al. 2010). ...
Article
Most subterranean animals are assumed to have evolved from surface ancestors following colonization of a cave system; however , very few studies have raised the possibility of "subterranean speciation" in underground habitats (i.e., obligate cave-dwelling organisms [troglobionts] descended from troglobiotic ancestors). Numerous endemic subterranean diving beetle species from spatially discrete calcrete aquifers in Western Australia (stygobionts) have evolved independently from surface ancestors; however, several cases of sympatric sister species raise the possibility of subterranean speciation. We tested this hypothesis using vision (phototransduction) genes that are evolving under neutral processes in subterranean species and purifying selection in surface species. Using sequence data from 32 subterranean and five surface species in the genus Paroster (Dytiscidae), we identified dele-terious mutations in long wavelength opsin (lwop), arrestin 1 (arr1), and arrestin 2 (arr2) shared by a sympatric sister-species triplet, arr1 shared by a sympatric sister-species pair, and lwop and arr2 shared among closely related species in adjacent calcrete aquifers. In all cases, a common ancestor possessed the function-altering mutations, implying they were already adapted to aphotic environments. Our study represents one of the first confirmed cases of subterranean speciation in cave insects. The assessment of genes undergoing pseudogenization provides a novel way of testing modes of speciation and the history of diversification in blind cave animals. K E Y W O R D S : Adaptive-shift hypothesis, climatic-relict hypothesis, long wavelength opsin, stygobionts, subterranean animals, subterranean speciation.
... Adopting standardized monitoring protocols for a quantitative assessment of biodiversity can be even more challenging, given the logistical constraints associated to these environments (Culver et al., 2012;Mammola et al., 2021). Therefore, we urgently need new approaches to better understand the functioning of subterranean ecosystems and to fully exploit their potential in addressing evolutionary and ecological questions (Mammola, 2019;Mammola et al., 2020;Mammola et al., 2021;Canedoli et al., 2022). ...
Article
Subterranean environments host a substantial amount of biodiversity, however assessing the distribution of species living underground is still extremely challenging. Environmental DNA (eDNA) metabarcoding is a powerful tool to estimate biodiversity in poorly known environments and has excellent performance for soil organisms. Here, we tested 1) whether eDNA metabarcoding from cave soils allows to successfully detect springtails (Hexapoda: Collembola) and insects (Hexapoda: Insecta); 2) whether eDNA mostly represents autochthonous (cave-dwelling) organisms or it also incorporates information from species living in surface environments; 3) whether eDNA detection probability changes across taxa with different ecology. Environmental DNA metabarcoding analyses detected a large number of Molecular Operational taxonomic Units (MOTUs) for both insects and springtails. For springtails, detection probability was high, with a substantial proportion of hypogean species, suggesting that eDNA provides good information on the distribution of these organisms in caves. Conversely, for insects most of MOTUs represented taxa living outside caves, and the majority of them represented taxa/organisms living in freshwater environments (Ephemeroptera, Plecoptera and Trichoptera). The eDNA of freshwater insects was particularly abundant in deep sectors of caves, far from the entrance. Furthermore, average detection probability of insects was significantly lower than the one of springtails. This suggests that cave soils act as “conveyer belts of biodiversity information”, possibly because percolating water lead to the accumulation of eDNA of organisms living in nearby areas. Cave soils hold a complex mix of autochthonous and allochthonous eDNA. eDNA provided unprecedented information on the understudied subterranean cave organisms; analyses of detection probability and occupancy can help teasing apart local eDNA from the eDNA representing spatially-integrated biodiversity for whole landscape.
... The existing knowledge on Mediterranean marine cave decapods is far from being complete: only a small number of existing caves have been explored and, mostly, in a superficial and incomplete manner, while many caves (especially the deepest ones) are still unknown. Future research should focus on filling regional gaps (e.g., south-eastern Mediterranean, Alboran Sea) and is expected to lead to an increment in the number of species known and to help answer many fundamental questions in cave biology and ecology [104]. An aspect of cave decapod biology that deserves further investigation is their role in cave ecosystem functioning. ...
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Decapod crustaceans are important components of the fauna of marine caves worldwide, yet information on their ecology is still scarce. Mediterranean marine caves are perhaps the best known of the world and may offer paradigms to the students of marine cave decapods from other geographic regions. This review summarizes and updates the existing knowledge about the decapod fauna of Mediterranean marine caves on the basis of a dataset of 76 species from 133 caves in 13 Mediterranean countries. Most species were found occasionally, while 15 species were comparatively frequent (found in at least seven caves). They comprise cryptobiotic and bathyphilic species that only secondarily colonize caves (secondary stygobiosis). Little is known about the population biology of cave decapods, and quantitative data are virtually lacking. The knowledge on Mediterranean marine cave decapods is far from being complete. Future research should focus on filling regional gaps and on the decapod ecological role: getting out at night to feed and resting in caves during daytime, decapods may import organic matter to the cave ecosystem. Some decapod species occurring in caves are protected by law. Ecological interest and the need for conservation initiatives combine to claim for intensifying research on the decapod fauna of the Mediterranean Sea caves.
... The existing knowledge on Mediterranean marine cave decapods is far from being complete: only a small number of existing caves have been explored and, mostly, in a superficial and incomplete manner, while many caves (especially the deepest ones) are still unknown. Future research should focus on filling regional gaps (e.g., south-eastern Mediterranean, Alboran Sea) and is expected to lead to an increment in the number of species known and to help answer many fundamental questions in cave biology and ecology [104]. An aspect of cave decapod biology that deserves further investigation is their role in cave ecosystem functioning. ...
Article
Distribution and Ecology of Decapod Crustaceans in Mediterranean Marine Caves: A Review
... Têm também fertilidade reduzida e a desenvolvem estratégias reprodutivas tipo k, que implicam a redução do número dos instares larvares e redução do número de ovos, que por sua vez são mais ricos em nutrientes (Christiansen, 2012). Tudo isto contribui para que estas espécies tenham ciclos de vida mais longos, atingindo a maturidade sexual mais tarde que os seus parentes próximos à superfície (Mammola et al. 2020). ...
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O Planalto das Cesaredas é formado por calcários marinhos do Jurássico Inferior a Superior (Toarciano ao Titoniano, ~180 a 144 milhões de anos) e alberga várias cavidades naturais com condições propícias à vida subterrânea. Localizado a baixa altitude na transição entre o maciço de Montejunto e vale Tifónico das Caldas da Rainha, este afloramento cársico inclui-se no distrito bioespeleológico Lusitânico, unidade biogeográfica que inclui os maciços da Arrábida, Estremenho, Sicó-Condeixa-Alvaiázere, Outil-Cantanhede e os afloramentos calcários da Península de Lisboa. O interesse científico sobre a biologia das grutas das Cesaredas teve o seu despertar há sete décadas e investigações recentes revelaram que a sua fauna estritamente subterrânea é composta sobretudo por invertebrados: moluscos, aracnídeos, miriápodes, crustáceos e insectos. A descoberta de espécies endémicas, i.e., cuja única área de distribuição mundial se encontra confinada ao Planalto das Cesaredas, lança grandes desafios em termos de conservação e urge estabelecer medidas de proteção para salvaguardar a sua biodiversidade subterrânea. Este artigo oferece uma perspectiva sobre a geologia, composição faunística e a ecologia das grutas das Cesaredas.
... We determined the main threats to subterranean ecosystems based on recent syntheses (Mammola et al., 2019a(Mammola et al., , 2020a complemented by our expert opinion. We grouped threats into the following eight categories: (i) Alien species & Pathogens (impacts due to alien species or pathogens); (ii) Climate change (impacts related to the alteration of climatic conditions); (iii) Overexploitation & Poaching (indiscriminate collection of species or overexploitation of biological resources); (iv) Pollution (organic and inorganic pollution events); (v) Surface habitat change (habitat alteration at the surface that affect subterranean systems; e.g. ...
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Subterranean ecosystems are among the most widespread environments on Earth, yet we still have poor knowledge of their biodiversity. To raise awareness of subterranean ecosystems, the essential services they provide, and their unique conservation challenges, 2021 and 2022 were designated International Years of Caves and Karst. As these ecosystems have traditionally been overlooked in global conservation agendas and multilateral agreements, a quantitative assessment of solution-based approaches to safeguard subterranean biota and associated habitats is timely. This assessment allows researchers and practitioners to understand the progress made and research needs in subterranean ecology and management. We conducted a systematic review of peer-reviewed and grey literature focused on subterranean ecosystems globally (terrestrial, freshwater, and saltwater systems), to quantify the available evidence-base for the effectiveness of conservation interventions. We selected 708 publications from the years 1964 to 2021 that discussed, recommended, or implemented 1,954 conservation interventions in subterranean ecosystems. We noted a steep increase in the number of studies from the 2000s while, surprisingly, the proportion of studies quantifying the impact of conservation interventions has steadily and significantly decreased in recent years. The effectiveness of 31% of conservation interventions has been tested statistically. We further highlight that 64% of the reported research occurred in the Palearctic and Nearctic biogeographic regions. Assessments of the effectiveness of conservation interventions were heavily biased towards indirect measures (monitoring and risk assessment), a limited sample of organisms (mostly arthropods and bats), and more accessible systems (terrestrial caves). Our results indicate that most conservation science in the field of subterranean biology does not apply a rigorous quantitative approach, resulting in sparse evidence for the effectiveness of interventions. This raises the important question of how to make conservation efforts more feasible to implement, cost-effective, and long-lasting. Although there is no single remedy, we propose a suite of potential solutions to focus our efforts better towards increasing statistical testing and stress the importance of standardising study reporting to facilitate meta-analytical exercises. We also provide a database summarising the available literature, which will help to build quantitative knowledge about interventions likely to yield the greatest impacts depending upon the subterranean species and habitats of interest. We view this as a starting point to shift away from the widespread tendency of recommending conservation interventions based on anecdotal and expert-based information rather than scientific evidence, without quantitatively testing their effectiveness.
... As reason prevailed upon mythology, caves became the arena for debating scientific ideas and ultimately good model systems for understanding the outside world (Poulson and White 1969). Yet, while we typically insist that our research is exciting, adventurous, and important to answer cutting-edge questions (Juan et al. 2010;Sánchez-Fernández et al. 2018;Mammola 2019;Mammola et al. 2019Mammola et al. , 2020, this potential is often lost when the results are translated into scientific publications. Too often, the generality of our results remains unexpressed insofar as cave research is written by cave scientists for cave scientists. ...
Article
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Whereas scientists interested in subterranean life typically insist that their research is exciting, adventurous, and important to answer general questions, this enthusiasm and potential often fade when the results are translated into scientific publications. This is because cave research is often written by cave scientists for cave scientists; thus, it rarely “leaves the cave”. However, the status quo is changing rapidly. We analysed 21,486 articles focused on subterranean ecosystems published over the last three decades and observed a recent, near-exponential increase in their annual citations and impact factor. Cave research is now more often published in non-specialized journals, thanks to a number of authors who are exploiting subterranean habitats as model systems for addressing important scientific questions. Encouraged by this positive trend, we here propose a few personal ideas for improving the generality of subterranean literature, including tips for framing broadly scoped research and making it accessible to a general audience, even when published in cave-specialized journals. Hopefully, this small contribution will succeed in condensing and broadcasting even further the collective effort taken by the subterranean biology community to bring their research “outside the cave”.
... Trait-based ecology is a critical framework to this end 73 . By focusing on how traits interact mechanistically with environments across spatial scales and levels of organization, we can use geographically ubiquitous and ecologically diverse cave spiders to test hypotheses in subterranean biology and beyond 22 . Here, we provide some examples of avenues of research, hoping to both stimulate re-use of the dataset and the quest for developing similar databases for both spiders outside Europe and for other subterranean taxa. ...
Article
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Species traits are an essential currency in ecology, evolution, biogeography, and conservation biology. However, trait databases are unavailable for most organisms, especially those living in difficult-to- access habitats such as caves and other subterranean ecosystems. We compiled an expert-curated trait database for subterranean spiders in Europe using both literature data (including grey literature published in many different languages) and direct morphological measurements whenever specimens were available to us. We started by updating the checklist of European subterranean spiders, now including 512 species across 20 families, of which at least 192 have been found uniquely in subterranean habitats. For each of these species, we compiled 64 traits. The trait database encompasses morphological measures, including several traits related to subterranean adaptation, and ecological traits referring to habitat preference, dispersal, and feeding strategies. By making these data freely available, we open up opportunities for exploring different research questions, from the quantification of functional dimensions of subterranean adaptation to the study of spatial patterns in functional diversity across European caves.
Article
Groundwater is an indispensable resource for humankind and sustainable biomes functioning. Anthropogenic disturbance threatens groundwater ecosystems globally, but to which extent groundwater organisms respond to stressors remains poorly understood. Groundwater animals are rare, with small populations, difficult to find and to breed in the lab, which poses a main challenge to the assessment of their responses to pollutants. Despite the difficulties, assessing the toxicity of a large spectrum of stressors to groundwater organisms is a priority to inform towards appropriate environmental protection of these ecosystems. We tested the sensitivity to CuSO4, diclofenac, and NaCl of a groundwater population of the copepod Diacyclops crassicaudis crassicaudis and compared its sensitivity with the model organism Daphnia magna. We ranked its sensitivity using a species sensitivity distribution (SSD) approach using the feasible data available for groundwater and surface crustaceans. Our results show that the most toxic compound was CuSO4 for which higher amount of data was recorded and wider variability in response was observed. It was followed by diclofenac, largely lacking data for groundwater-adapted organisms, and the least toxic compound was NaCl. The differential sensitivity between D. crassicaudis and D. magna was contaminant-dependent. As a general trend D. crassicaudis was always distributed in the upper part of the SSD curves together with other groundwater-adapted organisms. Our results highlight that the widespread groundwater populations of the D. crassicaudis species complex, which can be successfully breed in the lab, may provide a reasonable approach to assess the ecological effects of anthropogenic stressors in groundwater ecosystems.
Article
Gli organismi di grotta sono ritenuti modelli ideali per studi evolutivi. La particolarità del clima sotterraneo rende le grotte dei laboratori naturali per lo studio del riscaldamento globale.
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(1) Caves and other subterranean habitats fulfill the requirements of experimental model systems to address general questions in ecology and evolution. Yet, the harsh working conditions of these environments and the uniqueness of the subterranean organisms have challenged most attempts to pursuit standardized research (2) Two main obstacles have synergistically hampered previous attempts. First, there is a habitat impediment related to the objective difficulties of exploring subterranean habitats and our inability to access the network of fissures that represent the elective habitat for the so-called “cave species.” Second, there is a biological impediment illustrated by the rarity of most subterranean species and their low physiological tolerance, often limiting sample size and complicating lab experiments. (3) We explore the advantages and disadvantages of four general experimental setups (in-situ, quasi in-situ, ex-situ, and in-silico) in the light of habitat and biological impediments. We also discuss the potential of indirect approaches to research. Furthermore, using bibliometric data, we provide a quantitative overview of the model organisms that scientists have exploited in the study of subterranean life. (4) Our over-arching goal is to promote caves as model systems where one can perform standardised scientific research. This is important not only to achieve an in-depth understanding of the functioning of subterranean ecosystems but also to fully exploit their long-discussed potential in addressing general scientific questions with implications beyond the boundaries of this discipline.
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Caves are among the most visited geological features in the world, attracting over 70 million people every year in more than 1,200 caves worldwide, and amounting up to 800 million Euros in entrance fees alone. The global business of show caves employs roughly 25,000 people directly (management, guides), and at least 100 times more people if we consider the connected tourist activities (souvenir shops, local transport, travel agencies, restaurants, and bars). It is estimated that the whole show cave business has a global commercial value of roughly 2 billion Euros, a number that is increasing constantly. Show caves are generally fragile ecosystems, and care should be taken in their management to safeguard their value for future generations. The international scientific (speleological) community has issued international guidelines for the sustainable development and management of show caves eight years ago, but their application is still far from being applied globally, especially in developing and least developed countries. Cave tourism is expected to increase, especially in countries where caves are abundant but not yet considered as tourist attractions, and where economic and political instability slow down the development of tourism. There are still a lot of possibilities for the opening of new show caves, especially in countries with low Gross Domestic Income (GDI), but their management needs to be sustainable, so that caves become a means of sustaining local economies, educating people on these fragile geo- and ecosystems, and protecting contemporarily their scientific and cultural heritage for future generations.
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The cave biodiversity of continental Portugal faces tremendous conservation challenges, mostly linked to their direct destruction and contamination infiltrating from the surface. Beetles are the most diverse insects and one of the most diverse arthropod groups in caves of Portugal. We present the IUCN Red List profiles for the cave-adapted beetles from continental Portugal, all endemic to their respective geological units and massifs. Ground beetles (Carabidae) are the most diverse family of cave-adapted beetles in continental Portugal, followed by rove beetles (Staphylinidae). Beetles in caves of Portugal are mostly terrestrial and only one species is known to have evolved to live in groundwater. Trechus is the most diverse genus with four species, followed by Domene with three species and by Speonemadus and Iberoporus , both with one cave-adapted species. The aim of this contribution is to assess all endemic cave-adapted species of beetles from continental Portugal and to support their specific protection, to promote adequate management of surface habitats and the establishment of priority areas for conservation. The main biodiversity erosion drivers that are impacting the conservation of the studied species are pollution infiltrating from the surface, urbaniation, modifications of the natural habitat for touristic purposes and mining, quarrying and energy production infrastructures. This document can be used in spatial planning and territory management in karst, based on the current scientific knowledge.
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The subterranean environment comprises voids of any size in which life can develop in aphotic, aseasonal and largely oligotrophic conditions. A small proportion of living organisms have been able to evolve and adapt to such conditions. Some of them have become strictly dependent on this harsh environment, at the price of a set of profound biological adaptations. Key new discoveries shed light on ancient biogeographical patterns but challenge our views regarding the origin and history of the extant fauna, as illustrated by the recently discovered monospecific genus Iberotrechodes in a cave in Cantabria, Spain. Vicariance by plate tectonics remains the main explanatory factor for the amphi‐Atlantic distribution displayed by many groups of subterranean Crustacea. An accurate knowledge of subterranean diversity at the species level, combined with a comprehensive overview of the geological and paleoclimatic histories of the areas of interest, is a prerequisite to the understanding of biogeographic patterns.
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Subterranean habitats are environmentally stable with respect to temperature, humidity, and the absence of light. The transition to a subterranean lifestyle might therefore be expected to cause considerable shifts in an organism's physiology; here, we investigate how subterranean colonisation affects thermal tolerance. Subterranean organisms might be at an increased risk of decline in the face of global temperature rises, but robust data on the fauna is lacking, particularly at the molecular level. In this study we compare the heat shock response of two species of diving beetle in the genus Paroster : one surface-dwelling ( P. nigroadumbratus ), the other restricted to a single aquifer ( P. macrosturtensis ). P. macrosturtensis has been previously established as having a lower thermal tolerance compared to surface-dwelling relatives, but the genomic basis of this difference is unknown. By sequencing transcriptomes of experimentally heat-shocked individuals and performing differential expression analysis, we demonstrate both species can mount a heat shock response at high temperatures (35C), in agreement with past survival experiments. However, the genes involved in these responses differ between species, and far greater genes are differentially expressed in the surface species, which may explain its more robust response to heat stress. In contrast, the subterranean species significantly upregulated the heat shock protein gene Hsp68 in the experimental setup under conditions it would likely encounter in nature (25C), suggesting it may be more sensitive to ambient stressors, e.g. handling. The results presented here contribute to an emerging narrative concerning weakened thermal tolerances in obligate subterranean organisms at the molecular level.
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This article reports the current knowledge of trophic dynamics in both aquatic and terrestrial subterranean communities. Scarcity of nutrients characterizes subterranean food web interactions and drives opportunistic adaptive strategies. However, recent research contrasts the archetype of poorly structured food chains against emerging convoluted mechanisms sustaining a great range of biotic diversity and functional complexity. Novel analytical designs described in this work provide important new perspectives into the investigation of these key ecological dynamics, which, together with future advances, will enable the understanding of the immense conservational value of these often overlooked ecosystems.
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For humans, caves are dark, moist, and often dangerous places. However, caves are also home to many animals that live strange lives: blind beetles that eat bat poop and appreciate it; tiny spiders that spin webs to catch insects, also known as flying food; and white salamanders that swim in cave ponds without getting lost, at least not all the time. Most of these animals do not have eyes—why would you need eyes when you live in the dark? Instead, they have developed other special senses to “see” in the dark. These animals look nothing like the ones you know, and many of them are endangered because they can only live in caves. Mining, pollution, and climate change are threatening cave animals and all their weirdness. Anyone can study and help them, even you!
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Adaptive radiation plays a fundamental role in our understanding of the evolutionary process. However, the concept has provoked strong and differing opinions concerning its definition and nature among researchers studying a wide diversity of systems. Here, we take a broad view of what constitutes an adaptive radiation, and seek to find commonalities among disparate examples, ranging from plants to invertebrate and vertebrate animals, and remote islands to lakes and continents, to better understand processes shared across adaptive radiations. We surveyed many groups to evaluate factors considered important in a large variety of species radiations. In each of these studies, ecological opportunity of some form is identified as a prerequisite for adaptive radiation. However, evolvability, which can be enhanced by hybridization between distantly related species, may play a role in seeding entire radiations. Within radiations, the processes that lead to speciation depend largely on (1) whether the primary drivers of ecological shifts are (a) external to the membership of the radiation itself (mostly divergent or disruptive ecological selection) or (b) due to competition within the radiation membership (interactions among members) subsequent to reproductive isolation in similar environments, and (2) the extent and timing of admixture. These differences translate into different patterns of species accumulation and subsequent patterns of diversity across an adaptive radiation. Adaptive radiations occur in an extraordinary diversity of different ways, and continue to provide rich data for a better understanding of the diversification of life.
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We introduce a suite of software tools aimed at investigating multiple bio-ecological facets of aquatic Groundwater Dependent Ecosystems (GDEs). The suite focuses on: (1) threats posed by pollutants to GDE invertebrates (Ecological Risk, ER); (2) threats posed by hydrological and hydromorphological alterations on the subsurface zone of lotic systems and groundwater-fed springs (Hydrological-Hydromorphological Risk, HHR); and (3) the conservation priority of GDE communities (Groundwater Biodiversity Concern index, GBC). The ER is assessed by comparing tolerance limits of invertebrate species to specific pollutants with the maximum observed concentration of the same pollutants at the target site(s). Comparison is based on an original, comprehensive dataset including the most updated information on tolerance to 116 pollutants for 474 freshwater invertebrate species. The HHR is assessed by accounting for the main direct and indirect effects on both the hyporheic zone of lotic systems and groundwater-fed springs, and by scoring each impact according to the potential effect on subsurface invertebrates. Finally, the GBC index is computed on the basis of the taxonomical composition of a target community, and allows the evaluation of its conservation priority in comparison to others. The software suite is freely available at: http://app.aqualifeproject.eu by registered users.
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Macroecologists seek to identify drivers of community turnover (β-diversity) through broad spatial scales. However, the influence of local habitat features in driving broad-scale β-diversity patterns remains largely untested, owing to the objective challenges of associating local-scale variables to continental-framed datasets. We examined the relative contribution of local- versus broad-scale drivers of conti- nental β-diversity patterns, using a uniquely suited dataset of cave-dwelling spider communities across Europe (35–70° latitude). Generalized dissimilarity model- ling showed that geographical distance, mean annual temperature and size of the karst area in which caves occurred drove most of β-diversity, with differential contributions of each factor according to the level of subter- ranean specialization. Highly specialized communities were mostly influenced by geographical distance, while less specialized communities were mostly driven by mean annual temperature. Conversely, local-scale habitat features turned out to be meaningless predictors of community change, which emphasizes the idea of caves as the human accessible fraction of the extended network of fissures that more properly represents the elective habitat of the subterra- nean fauna. To the extent that the effect of local features turned to be inconspicuous, caves emerge as experimental model systems in which to study broad biological patterns without the confounding effect of local habitat features.
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Terrestrial life typically does not occur at depths greater than a few meters. Notable exceptions are massifs of fissured rock with caves and hollow spaces reaching depths of two kilometres and more. Recent biological discoveries from extremely deep caves have been reported as sensations analogous to wondrous deep sea creatures. However, the existence of unique deep terrestrial communities is questionable when caves are understood as integral parts of a bedrock fissure network (BFN) interconnecting all parts of a massif horizontally and vertically. We tested these two opposing hypotheses – unique deep cave fauna vs. BFN – by sampling subterranean communities within the 3D matrix of a typical karst massif. There was no distinction between deep core and shallow upper zone communities. Beta diversity patterns analysed against null models of random distribution were generally congruent with the BFN hypothesis, but suggested gravity-assisted concentration of fauna in deep caves and temperature-dependent horizontal distribution. We propose that the idea of a unique deep terrestrial fauna akin to deep oceanic life is unsupported by data and unwarranted by ecological considerations. Instead, the BFN hypothesis and local ecological and structural factors sufficiently explain the distribution of subterranean terrestrial life even in the deepest karst massifs.
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Acoustic communication allows the exchange of information within specific contexts and during specific behaviors. The blind, cave-adapted and the sighted, river-dwelling morphs of the species Astyanax mexicanus have evolved in markedly different environments. During their evolution in darkness, cavefish underwent a series of morphological, physiological and behavioral changes, allowing the study of adaptation to drastic environmental change. Here we discover that Astyanax is a sonic species, in the laboratory and in the wild, with sound production depending on the social contexts and the type of morph. We characterize one sound, the "Sharp Click", as a visually-triggered sound produced by dominant surface fish during agonistic behaviors and as a chemosensory-, food odor-triggered sound produced by cavefish during foraging. Sharp Clicks also elicit different reactions in the two morphs in play-back experiments. Our results demonstrate that acoustic communication does exist and has evolved in cavefish, accompanying the evolution of its behaviors.
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The relationships of crustaceans and hexapods (Pancrustacea) have been much discussed and partially elucidated following the emergence of phylogenomic data sets. However, major uncertainties still remain regarding the position of iconic taxa such as Branchiopoda, Copepoda, Remipedia, and Cephalocarida, and the sister group relationship of hexapods. We assembled the most taxon-rich phylogenomic pancrustacean data set to date and analyzed it using a variety of methodological approaches. We prioritised low levels of missing data and found that some clades were consistently recovered independently of the analytical approach used. These include, for example, Oligostraca and Altocrustacea. Substantial support was also found for Allotriocarida, with Remipedia as the sister of Hexapoda (i.e., Labiocarida), and Branchiopoda as the sister of Labiocarida, a clade that we name Athalassocarida (="non-marine shrimps"). Within Allotriocarida, Cephalocarida was found as the sister of Athalassocarida. Finally, moderate support was found for Hexanauplia (Copepoda as sister to Thecostraca) in alliance with Malacostraca. Mapping key crustacean tagmosis patterns and developmental characters across the revised phylogeny suggests that the ancestral pancrustacean was relatively short-bodied, with extreme body elongation and anamorphic development emerging later in pancrustacean evolution.
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In the Anthropocene, in which we now live, climate change is impacting most life on Earth. Microorganisms support the existence of all higher trophic life forms. To understand how humans and other life forms on Earth (including those we are yet to discover) can withstand anthropogenic climate change, it is vital to incorporate knowledge of the microbial ‘unseen majority’. We must learn not just how microorganisms affect climate change (including production and consumption of greenhouse gases) but also how they will be affected by climate change and other human activities. This Consensus Statement documents the central role and global importance of microorganisms in climate change biology. It also puts humanity on notice that the impact of climate change will depend heavily on responses of microorganisms, which are essential for achieving an environmentally sustainable future.
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Background The academic publishing world is changing significantly, with ever-growing numbers of publications each year and shifting publishing patterns. However, the metrics used to measure academic success, such as the number of publications, citation number, and impact factor, have not changed for decades. Moreover, recent studies indicate that these metrics have become targets and follow Goodhart’s Law, according to which, “when a measure becomes a target, it ceases to be a good measure.” Results In this study, we analyzed >120 million papers to examine how the academic publishing world has evolved over the last century, with a deeper look into the specific field of biology. Our study shows that the validity of citation-based measures is being compromised and their usefulness is lessening. In particular, the number of publications has ceased to be a good metric as a result of longer author lists, shorter papers, and surging publication numbers. Citation-based metrics, such citation number and h-index, are likewise affected by the flood of papers, self-citations, and lengthy reference lists. Measures such as a journal’s impact factor have also ceased to be good metrics due to the soaring numbers of papers that are published in top journals, particularly from the same pool of authors. Moreover, by analyzing properties of >2,600 research fields, we observed that citation-based metrics are not beneficial for comparing researchers in different fields, or even in the same department. Conclusions Academic publishing has changed considerably; now we need to reconsider how we measure success.
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Ever-increasing human pressures on cave biodiversity have amplified the need for systematic, repeatable, and intensive surveys of cave-dwelling arthropods to formulate evidence-based management decisions. We examined 110 papers (from 1967 to 2018) to: (i) understand how cave-dwelling invertebrates have been sampled; (ii) provide a summary of techniques most commonly applied and appropriateness of these techniques, and; (iii) make recommendations for sampling design improvement. Of the studies reviewed, over half (56) were biological inventories, 43 ecologically focused, seven were techniques papers, and four were conservation studies. Nearly one-half (48) of the papers applied systematic techniques. Few papers (24) provided enough information to repeat the study; of these, only 11 studies included cave maps. Most studies (56) used two or more techniques for sampling cave-dwelling invertebrates. Ten studies conducted ≥10 site visits per cave. The use of quantitative techniques was applied in 43 of the studies assessed. More than one-third (42) included some level of discussion on management. Future studies should employ a systematic study design, describe their methods in sufficient detail as to be repeatable, and apply multiple techniques and site visits. This level of effort and detail is required to obtain the most complete inventories, facilitate monitoring of sensitive cave arthropod populations, and make informed decisions regarding the management of cave habitats. We also identified naming inconsistencies of sampling techniques and provide recommendations towards standardization.
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Anchialine caves are characterized by high levels of endemism and extreme conditions. However, few ecological studies have been conducted in these ecosystems. This study integrates biotic and abiotic parameters of two sets of cave systems with contrasting high and low species richness. Seven ecological patterns are used to explain the expected species richness and density in an anchialine cave. In addition, the population size for conspicuous macrofauna was estimated. The high impact that single-events have on anchialine fauna are also reported. These findings reinforce the conclusions of previous studies of the high extinction risk of anchialine cave fauna, and substantiate the necessity of ad hoc conservation strategies for anchialine caves.
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• Species of conservation concern are usually considered important elements in site prioritization for biodiversity conservation. To overcome the lack of information on species conservation status, multidimensional measures of species rarity can be used as proxies of species vulnerability. • Under this assumption, a two‐step protocol for site prioritization of aquatic groundwater‐dependent ecosystems is proposed using invertebrate vulnerability estimated from species' traits. In the first step, each species occurring in the sites of interest are scored according to their vulnerability. In the second step, sites are prioritized using species' scores. • Species vulnerability scores are based on five dimensions, for which various traits are scored: (i) geography, (ii) ecology, (iii) biology, (iv) population, and (v) evolutionary history. For each species, the scores of the various traits belonging to the same dimension are multiplied to obtain a synthetic score. These scores are then ranked into four classes and, for each dimension, each species receives a new score that reflects its rank. The sum of these scores represents the species' overall score. • Site conservation priorities are assessed by combining species scores into three indices: Sum of Species Scores, Biodiversity Conservation Concern (which relates the sum of species scores with the local species richness) and Groundwater Biodiversity Concern (which is the average of the former two). The protocol is illustrated using case studies in Italy and it is fully implemented in the software AQUALIFE which is freely available at: http://app.aqualifeproject.eu by registered users. • Sensitivity analyses showed that the protocol is robust against the lack of information on species biology or sampling limitations. However, trait scoring rests with the user, who must be familiar with the study group. • This approach can be applied at any spatial scale and to different types of aquatic groundwater‐dependent ecosystems.
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In an environment where the impact of research is central, scientists face the dilemma of choosing between orthodox writing for objectivity and sensational writing to provoke interest. The use of superlatives in high-ranking ecology journals has increased significantly in recent years, a writing behavior that works against scientific objectivity.
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1. Ecological specialisation is an important mechanism enhancing species coexistence within a given community. Yet, unravelling the effect of multiple selective evolutionary and ecological factors leading the process of specialisation remains a key challenge in ecology. Subterranean habitats provide highly replicated experimental arenas in which to disentangle the relative contribution of evolutionary history (convergent evolution vs. character displacement) and ecological setting (environmental filtering vs. competitive exclusion) in driving community assembly. 2. We tested alternative hypotheses about the emergence of ecological specialisation using the radiation of a lineage of sheet‐weaver cave‐dwelling spiders as model system. We observed that at the local scale, a differential specialisation to cave microhabitats generally parallels moderate levels of morphological similarity and close phylogenetic relatedness among species. Conversely, geographic distance contributed little in explaining microhabitat occupation, possibly mirroring a limited role of competitive exclusion. Yet, compared to non‐coexisting species, co‐occurring species adapted to different microhabitats showed lower morphological niche overlap (i.e. higher dissimilarity) and deeper genetic distance. 3. The framework here developed suggests that in the subterranean domain, habitat specialisation is primarily driven by environmental filtering, secondarily by convergent evolution, and only marginally by character displacement or competitive exclusion. This pattern results in the establishment of replicated communities across geographical space, composed by ecologically equivalent species. Such process of community assembly well explains the numerous adaptive radiations observed in subterranean habitats, an eco‐evolutionary pattern well documented in oceanic islands or mountain summit communities.
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Superstition has it that tossing coins into wells or fountains brings good luck, thereby causing a potential accumulation of microbially contaminated metal particles in the water. Here, we characterized the microbiota and the resistance profile in biofilm on such coins and their surrounding sediments. The study site was a tidal marine lake within a touristic center located in a natural reserve area. Notwithstanding the fact that coin-related biofilms were dominated by typical marine taxa, coin biofilms had specific microbial communities that were different from the communities of the surrounding sediment. Moreover, the communities were different depending on whether the coin were made mainly of steel or of copper. Sequences affiliated with putative pathogens were found on every third coin but were not found in the surrounding sediment. Antibiotic resistance genes (ARGs) were detected on most of the coins, and interestingly, sediments close to the area where coins accumulate had a higher frequency of ARGs. We suggest that the surface of the coins might offer a niche for ARGs and faecal bacteria to survive, and, thus, tossed coins are a potential source and vector for ARGs into the surrounding environment.
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In this horizon scan, we highlight 15 emerging issues of potential relevance to global conservation in 2020. Seven relate to potentially extensive changes in vegetation or ecological systems. These changes are either relatively new, for example, conversion of kelp forests to simpler macroalgal systems, or may occur in the future, for example, as a result of the derivation of nanocelluose from wood or the rapid expansion of small hydropower schemes. Other topics highlight potential changes in national legislation that may have global effect on international agreements. Our panel of 23 scientists and practitioners selected these issues using a modified version of the Delphi technique from a long-list of 89 potential topics.