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Transitional vegetation zones in the neotropics harbor high biodiversity and are threatened by advancing deforestation and climate change. Besides, the diversity patterns at multiple spatial scales are little understood. We investigated the woody flora of eight savanna sites over 700 km along the transition zone between the Cerrado and Amazonia. We assessed plant diversity at three spatial scales: alpha (α = local richness), beta (βJac = Jaccard mean dissimilarity of species composition between sites), and gamma (γ = regional diversity). We also measured the sites' contribution to beta diversity (LCBD) to unveil the ecological singularity of the transition. We found high local richness (α = ∼80 species per hectare) and high between-site dissimilarity (βJac = 0.651; LCBD = 0.354), which together contributed to high regional diversity (γ = 167). There was no relationship between floristic composition and proximity between sites or proximity to Amazonia. The locally dominant species (representing 80% or more of the total abundance) also differed across sites, indicating the unique composition of each community. This high floristic diversity at different spatial scales is severely threatened by extensive deforestation in recent decades and a paucity of protected areas, stressing the need for protected areas and conservation actions. [ABSTRACT FROM AUTHOR]

Aim Location Time period Major taxa studied Methods Results Main conclusions Ecological and anthropogenic factors shift the abundances of dominant and rare tree species within local forest communities, thus affecting species composition and ecosystem functioning. To inform forest and conservation management it is important to understand the drivers of dominance and rarity in local tree communities. We answer the following research questions: (1) What are the patterns of dominance and rarity in tree communities? (2) Which ecological and anthropogenic factors predict these patterns? And (3) what is the extinction risk of locally dominant and rare tree species?Global.1990–2017.Trees.We used 1.2 million forest plots and quantified local tree dominance as the relative plot basal area of the single most dominant species and local rarity as the percentage of species that contribute together to the least 10% of plot basal area. We mapped global community dominance and rarity using machine learning models and evaluated the ecological and anthropogenic predictors with linear models. Extinction risk, for example threatened status, of geographically widespread dominant and rare species was evaluated.Community dominance and rarity show contrasting latitudinal trends, with boreal forests having high levels of dominance and tropical forests having high levels of rarity. Increasing annual precipitation reduces community dominance, probably because precipitation is related to an increase in tree density and richness. Additionally, stand age is positively related to community dominance, due to stem diameter increase of the most dominant species. Surprisingly, we find that locally dominant and rare species, which are geographically widespread in our data, have an equally high rate of elevated extinction due to declining populations through large‐scale land degradation.By linking patterns and predictors of community dominance and rarity to extinction risk, our results suggest that also widespread species should be considered in large‐scale management and conservation practices. [ABSTRACT FROM AUTHOR]

Species rarity is a common phenomenon across global ecosystems that is becoming increasingly more common under climate change. Although species rarity is often considered to be a stochastic response to environmental and ecological constraints, we examined the hypothesis that plant rarity is a consequence of natural selection acting on performance traits that affect a species range size, habitat specificity, and population aggregation; three primary descriptors of rarity. Using a common garden of 25 species of Tasmanian Eucalyptus, we find that the rarest species have 70% lower biomass than common species. Although rare species demonstrate lower biomass, rare species allocated proportionally more biomass aboveground than common species. There is also a negative phylogenetic autocorrelation underlying the biomass of rare and common species, indicating that traits associated with rarity have diverged within subgenera as a result of environmental factors to reach different associated optima. In support of our hypothesis, we found significant positive relationships between species biomass, range size and habitat specificity, but not population aggregation. These results demonstrate repeated convergent evolution of the trait‐based determinants of rarity across the phylogeny in Tasmanian eucalypts. Furthermore, the phylogenetically driven patterns in biomass and biomass allocation seen in rare species may be representative of a larger plant strategy, not yet considered, but offering a mechanism as to how rare species continue to persist despite inherent constraints of small, specialized ranges and populations. These results suggest that if rarity can evolve and is related to plant traits such as biomass, rather than a random outcome of environmental constraints, we may need to revise conservation efforts in these and other rare species to reconsider the abiotic and biotic factors that underlie the distributions of rare plant species. [ABSTRACT FROM AUTHOR]

Variations in the Dolivo-Dobrovol'sky symmetry index for minerals through time reveal several factors that influence the emergence of crystalline symmetry in natural processes. Of special interest in this regard are the numerous paragenetic modes—different processes of mineral genesis that reflect changes in physical, chemical, and ultimately biological environments that foster the emergence of new mineral species. Here, we consider the roles of hydrogen content, rarity, formation temperature and pressure, and age on the average symmetry of minerals from 57 different modes of formation (i.e., paragenetic modes). We find four significant trends in the average mineral symmetry index for all minerals in each paragenetic mode: specifically, this average index is (1) lower for minerals with greater hydrogen content; (2) greater for minerals formed at higher pressure; (3) lower for minerals of greater rarity; and (4) greater for older paragenetic modes. These findings elucidate some of the intricate relationships among paragenetic modes, average mineral attributes, and the Dolivo-Dobrovol'sky symmetry index, providing insights into the geological processes governing mineral formation. [ABSTRACT FROM AUTHOR]

Three species of the tropical hydrocoral genus Millepora were common and abundant in the Maldives before 1998, characterizing extensive shallow reef areas known as 'Millepora zones'. The 1998 heat wave resulted in mass mortality of all the Millepora species, the characteristic Millepora zones disappeared, and only a few observations of isolated colonies were reported in the years ahead. A recent expedition (January 2024) to the northernmost region of the Maldives (Ihavandhippolhu Atoll) revealed new Millepora zones at 7–13 m depth, suggesting a potential repopulation of a vulnerable genus considered regionally extinct. [ABSTRACT FROM AUTHOR]

Abstract Fungi are among the least known organisms on earth, with an estimated number of species between 1.5 and 10 million. This number is expected to be refined, especially with increasing knowledge about microfungi in undersampled habitats and increasing amounts of data derived from environmental DNA sequencing. A significant proportion of newly generated sequences fail to match with already named species, and thus represent what has been referred to as fungal “dark taxa”. Due to the challenges associated with observing, identifying, and preserving sporophores, many macro- and microfungal species are only known from a single collection, specimen, isolate, and/or sequence—a singleton. Mycologists are consequently used to working with “rare” sequences and specimens. However, rarity and singleton phenomena lack consideration and valorization in fungal studies. In particular, the practice of publishing new fungal species names based on a single specimen remains a cause of debate. Here, we provide some elements of reflection on this issue in the light of the specificities of the fungal kingdom and global change context. If multiple independent sources of data support the existence of a new taxon, we encourage mycologists to proceed with formal description, irrespective of the number of specimens at hand. Although the description of singleton-based species may not be considered best practice, it does represent responsible science in the light of closing the Linnean biodiversity shortfall.

We report the rediscovery of two species of rare snake in Espírito Santo state, Brazil: Aposto­lepis longicaudata Gomes, 1921 (also rare elsewhere in Brazil) and Drymoluber brazili (Gomes, 1918). Apostolepis longicaudata has gone undetected in Espírito Santo for 66 years and Drymoluber brazili for 46 years. Espírito Santo state has only 10% of its forests remaining, and so the rediscovery of these forest‑dwelling species emphasizes the importance of small forest remnants for the conservation. These species have been assessed as Critically Endangered and Endangered in Espírito Santo state.

Local abundance and regional distribution are two aspects of a species’ rarity. They are suggested to differentially alter genetic processes in plants: Locally rare species are hypothesized to suffer less from inbreeding and outbreeding than locally common species, thanks to genetic purging through long inbreeding histories and weaker local adaptations, respectively. Regionally rare species are hypothesized to be more susceptible to outbreeding, but less to inbreeding, compared to regionally common ones, due to small and declining range size. While this has major implications for plant conservation practices, we lack evidences and general understanding on how breeding effects on a plant’s early life fitness are related to its local and regional rarity. To investigate effects of inbreeding and outbreeding on plants’ early fitness, we performed self-, within- and between-population pollinations in eight pairs of closely related species differing in regional and local rarity. To avoid biases due to context dependency, we took species competitive ability, habitat resource-richness and resource-allocation strategy into account in the analyses. We then tested how inbreeding and outbreeding affected five fruit-, seed- and seedling-related traits. Inbreeding did not generally have more negative effects on early fitness of regionally rare and non-competitive species than on regionally common and competitive ones. Outbreeding was generally beneficial to early fitness of plant species across the gradients of regional rarity, competitive ability and habitat resource-richness. Our results show that outbreeding may be beneficial to the early fitness of plant species, including rare and non-competitive ones and may be considered for conservation strategies.

Cities are sometimes characterized as homogenous with species assemblages composed of abundant, generalist species having similar ecological functions. Under this assumption, rare species, or species observed infrequently, would have especially high conservation value in cities for their potential to increase functional diversity. Management to increase the number of rare species in cities could be an important conservation strategy in a rapidly urbanizing world. However, most studies of species rarity define rarity in relatively pristine environments where human management and disturbance is minimized. We know little about what species are rare, how many species are rare, and what management practices promote rare species in urban environments. Here, we identified which plants and species of birds and bees that control pests and pollinate crops are rare in urban gardens and assessed how social, biophysical factors, and cross-taxonomic comparisons influence rare species richness. We found overwhelming numbers of rare species, with more than 50% of plants observed classified as rare. Our results highlight the importance of women, older individuals, and gardeners who live closer to garden sites in increasing the number of rare plants within urban areas. Fewer rare plants were found in older gardens and gardens with more bare soil. There were more rare bird species in larger gardens and more rare bee species for which canopy cover was higher. We also found that in some cases, rarity begets rarity, with positive correlations found between the number of rare plants and bee species and between bee and bird species. Overall, our results suggest that urban gardens include a high number of species existing at low frequency and that social and biophysical factors promoting rare, planned biodiversity can cascade down to promote rare, associated biodiversity.

Fungi are among the least known organisms on earth, with an estimated number of species between 1.5 and 10 million. This number is expected to be refined, especially with increasing knowledge about microfungi in undersampled habitats and increasing amounts of data derived from environmental DNA sequencing. A significant proportion of newly generated sequences fail to match with already named species, and thus represent what has been referred to as fungal "dark taxa". Due to the challenges associated with observing, identifying, and preserving sporophores, many macro- and microfungal species are only known from a single collection, specimen, isolate, and/or sequence—a singleton. Mycologists are consequently used to working with "rare" sequences and specimens. However, rarity and singleton phenomena lack consideration and valorization in fungal studies. In particular, the practice of publishing new fungal species names based on a single specimen remains a cause of debate. Here, we provide some elements of reflection on this issue in the light of the specificities of the fungal kingdom and global change context. If multiple independent sources of data support the existence of a new taxon, we encourage mycologists to proceed with formal description, irrespective of the number of specimens at hand. Although the description of singleton-based species may not be considered best practice, it does represent responsible science in the light of closing the Linnean biodiversity shortfall. [ABSTRACT FROM AUTHOR]

Black ruff (Centrolophus niger) is a rare and poorly studied species found in both the Atlantic and Pacific Oceans and also in the Mediterranean Sea. It is sporadically caught south of Iceland during the annual International Ecosystem Summer Survey of the Nordic Seas. In total, 43 specimens were caught from 2009 to 2021, of which 41 specimens were caught during 2017–2021. All specimens, except one, were caught using a pelagic trawl (cod‐end mesh‐size: 50 mm) close to the surface (trawl depth: 0–35 m) with in situ temperature ranging from 9 to 13°C. The area south of Iceland is characterized by having warmer temperatures than other areas around the island, which might be indicative of a northern limit for the distribution of black ruff. The fish were primarily in the range of 29–46 cm with a few larger individuals up to 71 cm. Fourteen fish, caught in 2017 and 2021, were dissected to gather biological information on this species. These fish were all juveniles with no obvious sign of gonad development. Correlations between total length, fork length, and standard length are presented. Otoliths were thin and delicate with a length of ~13–16 mm, and otolith size (length, width, and area) was correlated with fish size. Much of the stomach content was at an advanced stage of digestion, but some contents could be identified and consisted of invertebrates, primarily of the orders Amphipoda and Calanoida with some unidentified fish also present. [ABSTRACT FROM AUTHOR]

We investigate the market value of rarity theoretically and empirically. Prior studies find that the market value of rarity follows a power law, but this finding lacks a theoretical foundation. We provide a micro-foundation for this finding, demonstrating that the observed power law emerges in a competitive market where agents have rank-dependent utility preferences. The model leads to two new theoretical insights: (i) the rank of an item within a set of close substitutes and the quantity of that item known to exist are both natural measures of rarity, but rank is predicted to perform better; (ii) there is a systematic relationship between the estimated slope and intercept from a regression of log price on log rank. When we test the model on data from over 4000 auction records of rare baseball cards, we find that a regression with only log rank and grading company explains 60% of the variation in log price. [ABSTRACT FROM AUTHOR]

Background: The northern Western Ghats (NWG) – a part of the Western Ghats and Sri Lanka biodiversity hotspot supports tropical forests of conservation priority, due to anthropogenic intensification. Woody species diversity and ecology in NWG is poorly studied, necessitating the knowledge of spatial variability in species and underlying environmental factors, for effective conservation. Aims: We described woody plant community composition and related it to climate data across a latitude of 1.4 degrees to obtain information about spatial and environmental variation to support protected area planning. Methods: To estimate abundance, importance value index, diversity indices and rank – abundance, we recorded woody species in 144 plots across 12 sites. Elevation, temperature, rainfall, humidity data were related to diversity descriptors in a canonical correspondence analysis. Results: We recorded 10,291 trees representing 187 species of 52 families. Divergent geo-climatic factors were related to distinct plant community structures, elevation and humidity being the most influential drivers of plant diversity and density. Numerous rare species were found restricted to environmentally distinct forests. Conclusion: The wide-ranging environment and corresponding variations in forest community composition across the narrow latitudinal range of the study area revealed the importance of including such gradients in planning future protected areas in the NWG. [ABSTRACT FROM AUTHOR]

The Younger Dryas-Holocene transition represents a period of significant thermal change, comparable in magnitude to modern warming, yet in a colder context and without the effect of anthropogenic disturbance. This is useful as a reference to tackle how biodiversity is affected by temperature in natural conditions. Here, we addressed the thermal change during this period in a southern Baltic coastal lake (Konarzewo Lake, Poland), as inferred by chironomid remains. We evaluated changes in chironomid communities and used Hill numbers to explore how commonness and rarity underlie biodiversity changes attributable to warming. We found evidence of warming at Konarzewo Lake during the Younger Dryas-Holocene transition, with inferred temperatures in the Younger Dryas period supporting the NW–SE gradient in Younger Dryas summer temperatures across Europe. Chironomid communities drastically changed during the thermal transition. However, Hill numbers showed no response to temperature when rare morphotypes were emphasized (order q = 0) or a weak response when they were balanced with common morphotypes (order q = 1). Hill number of order q = 2, emphasizing the most common morphotypes, consistently increased with temperature across different sample sizes or coverages. This illustrates how common morphotypes, rather than the rare ones, may boost biodiversity facing warming. [ABSTRACT FROM AUTHOR]

The three‐dimensional rarity typology proposed by Rabinowitz in 1981, based on geographic range, habitat specificity, and local abundance, is among the most widely used frameworks for describing rarity in ecological and conservation research. While this framework is descriptive and is not meant to explain the causes of rarity, recent advances in ecology may be leveraged to add explanatory power. Here we present a macroecological exploration of rarity and its underlying causes. We propose a modification of Rabinowitz's typology to better distinguish between the dimensions of rarity and the ecological processes that drive them, and explore the conservation implications of our modified framework. We propose to add occupancy (the proportion of occupied sites within a species' range) as a rarity axis, and recast habitat specificity as a cause of rarity, thus yielding a modified classification based on range size, occupancy, and local abundance. Under our framework, habitat specialists are no longer considered rare if they are widespread and abundant; we argue that this modification more accurately identifies truly rare species, as habitat specialists may be common if their habitat is abundant. Finally, we draw on the macroecological and theoretical literature to identify the key processes and associated traits that drive each rarity axis. In this respect, we identify four processes (environmental filtering, movement, demography and interactions), and hypothesise that range size and occupancy are primarily driven by environmental filtering and movement, whereas local abundance is more strongly influenced by demography and interactions. We further use ecological theory to hypothesise the conservation concerns associated with each rarity axis, and propose conservation measures that may be suitable for conserving different types of rare species. Our work may provide a basis for developing hypotheses about the causes of rarity of particular focal taxa or groups, and inform the development of targeted conservation strategies. [ABSTRACT FROM AUTHOR]

Phytoplankton guilds are commonly characterised by dominance effects, while the main contribution to biological diversity is given by rare species. Here, we analysed the influence of rare species on taxonomic and functional diversity, which is described by taxa richness and composition, cell size, and size–abundance relationships in phytoplankton guilds. We explore these relationships at global and regional scales by analysing phytoplankton guilds from five biogeographical regions: the Northern Atlantic Ocean (Scotland), the South-Western Atlantic Ocean (Brazil), the South-Western Pacific Ocean (Australia), the Indo-Pacific Ocean (Maldives), and the Mediterranean Sea (Greece and Turkey). We have comparatively analysed the phytoplankton taxonomic diversity of the whole dataset and with the datasets obtained by progressively subtracting taxa occurring in the last 1%, 5%, 10%, and 25% of both numerical abundance and overall biomass. Globally, 306 taxa were identified across five ecoregions with only 27 taxa accounting for 75% of overall numerical abundance and biomass; almost 50% of taxa were lost on every step. The removal of 1% of most rare taxa significantly affected the phytoplankton size–abundance relationships and body-size structure, strongly impacting on small taxa. The progressive removal of additional rare taxa did not further affect phytoplankton size–abundance relationships and size structure. [ABSTRACT FROM AUTHOR]

Using data from a wide range of natural communities including the human microbiome, plants, fish, mushrooms, rodents, beetles, and trees, we show that universally just a few percent of the species account for most of the biomass. This is in line with the classical observation that the vast bulk of biodiversity is very rare. Attempts to find traits allowing the tiny fraction of abundant species to escape rarity have remained unsuccessful. Here, we argue that this might be explained by the fact that hyper-dominance can emerge through stochastic processes. We demonstrate that in neutrally competing groups of species, rarity tends to become a trap if environmental fluctuations result in gains and losses proportional to abundances. This counter-intuitive phenomenon arises because absolute change tends to zero for very small abundances, causing rarity to become a “sticky state”, a pseudoattractor that can be revealed numerically in classical ball-in-cup landscapes. As a result, the vast majority of species spend most of their time in rarity leaving space for just a few others to dominate the neutral community. However, fates remain stochastic. Provided that there is some response diversity, roles occasionally shift as stochastic events or natural enemies bring an abundant species down allowing a rare species to rise to dominance. Microbial time series spanning thousands of generations support this prediction. Our results suggest that near-neutrality within niches may allow numerous rare species to persist in the wings of the dominant ones. Stand-ins may serve as insurance when former key species collapse. [ABSTRACT FROM AUTHOR]

Species richness and abundance of hosts and parasites are often not perfectly correlated. This may be caused by higher parasite than host extinction rates or population declines, but lower parasite discovery effort has also been suggested.The Mexican free‐tailed bat Tadarida brasiliensis is one of the most common and widespread vertebrates in the Americas and host to the ectoparasite Primicimex cavernis, for which only 14 literature records from six sites worldwide exist.Here, we confirm a much smaller parasite than host range. Two dedicated field trips revealed two new P. cavernis sites. In Texas, we found 87% out of eight sites negative for P. cavernis. However, this more likely reflects rarity than low discovery effort, because in one large population (>1000 individuals) in Sonora, putatively negative records occurred at only 31% of 16 sampling dates. Currently, live individuals of P. cavernis are known from only one cave in the United States and one in Mexico.Protecting these existing sites is necessary to preserve this charismatic animal but it should not release us from aiming to discover new sites. [ABSTRACT FROM AUTHOR]

Fires in northern Patagonia are very frequent events, especially in summer seasons, affecting a large percentage of the area each year. Its consequences on biodiversity are variable according to the intensity, permanence and environments that are affected. Fire in ecosystems appears with a dual behavior, as a catastrophic disturbance and as an agent capable of opening environments and allowing the colonization of new sites by rare species, that are considered poor competitors. Through the analysis of measurements in marked plants in the pre-fire season in the Lihué Calel National Park, it was possible to evaluate the response to this phenomenon of Gaillardia cabrerae Covas (Asteraceae), a rarity in the south-central of La Pampa province. The resprouting capacity allowed the recovery of the affected populations and the production of flower heads was recorded in a greater number than in the pre-fire season. These results suggest a positive response of the species to these particular events at the end of 2003. However, given the intrinsic vulnerability of species with such a limited distribution, fire continues to be a high-impact factor for populations and their effect remains uncertain. Considering its rare condition, it is necessary to take precautionary measures to ensure the survival of the species in a context of climate change that defines a near-future scenario characterized by a high degree of unpredictability. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The establishment of protected areas to face global diversity declines has mainly prioritized taxonomic diversity, leaving aside phylogenetic and functional diversities, which determine ecosystem functioning and resilience. Furthermore, the assessment of protected areas' effectiveness is mainly done using short‐duration surveys (<2 h), which may undermine the detection of rare species.Through a long‐duration video approach, reef fish taxonomic, phylogenetic and functional facets of diversity were assessed for 3 days within a fully protected area and a nearby poorly protected area in Mayotte Island (Western Indian Ocean).We found that temporally rare species contributed to more than 60% of the taxonomic facet and 85% of the functional facet of biodiversity found on each site. Those rare species, which harbour the most distinct trait values, also make reef fish diversity particularly vulnerable to their loss. Taxonomic, phylogenetic and functional richness were similar between the fully protected area and the poorly protected area, while the species, lineage and trait compositions were markedly different.These results pinpoint the importance of considering taxonomic, functional and phylogenetic dissimilarities while assessing protected areas' effectiveness, instead of using only richness. In addition, benefits of the fully protected area were detected only using more than 15 h of video survey, which emphasizes the importance of long‐duration remote approaches to capture the within‐ and between‐day temporal variations. [ABSTRACT FROM AUTHOR]

Copyright of Ornitologia Colombiana is the property of Asociacion Colombiana de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Species rarity is a common phenomenon across global ecosystems that is becoming increasingly more common under climate change. Although species rarity is often considered to be a stochastic response to environmental and ecological constraints, we examined the hypothesis that plant rarity is a consequence of natural selection acting on performance traits that affect a species range size, habitat specificity, and population aggregation; three primary descriptors of rarity. Using a common garden of 25 species of Tasmanian Eucalyptus, we find that the rarest species have 70% lower biomass than common species. Although rare species demonstrate lower biomass, rare species allocated proportionally more biomass aboveground than common species. There is also a negative phylogenetic autocorrelation underlying the biomass of rare and common species, indicating that traits associated with rarity have diverged within subgenera as a result of environmental factors to reach different associated optima. In support of our hypothesis, we found significant positive relationships between species biomass, range size and habitat specificity, but not population aggregation. These results demonstrate repeated convergent evolution of the trait‐based determinants of rarity across the phylogeny in Tasmanian eucalypts. Furthermore, the phylogenetically driven patterns in biomass and biomass allocation seen in rare species may be representative of a larger plant strategy, not yet considered, but offering a mechanism as to how rare species continue to persist despite inherent constraints of small, specialized ranges and populations. These results suggest that if rarity can evolve and is related to plant traits such as biomass, rather than a random outcome of environmental constraints, we may need to revise conservation efforts in these and other rare species to reconsider the abiotic and biotic factors that underlie the distributions of rare plant species.

Non-fungible token (NFT) is a digital asset whose ownership can be validated and controlled via blockchain technology. The NFT market is a rapidly growing field, and the rarity of NFT is an essential factor that affects its price, as scarcity leads to higher demand. This study focuses on the BAYC NFT collection, which is a successful and representative collection of profile picture NFT, and analyzes how rarity affects NFT prices. This paper investigates the relationship between the rarity and price of the BAYC NFT collection using formal concept analysis (FCA) method. The results show that rarity is a major factor influencing the price of NFT and the effect is more apparent in the medium rarity range. When rarity is very high or very low, other factors become significant determinants, such as the uniqueness and appeal of NFT, and even the naturalness of NFT images. This research highlights the importance of considering rarity when assessing NFT and underscores the need for a comprehensive evaluation of NFT rarity. This study also provides valuable insights into the NFT market and can be useful for NFT investors, creators, and collectors. Furthermore, the usefulness of FCA as a tool for quantifying NFT rarity and evaluating NFT price was demonstrated.

Northern bog lemmings, Mictomys (Synaptomys) borealis, are currently being assessed for protections under the U.S. Endangered Species Act. A major impediment to comprehensive evaluation is a deficiency of data towards understanding the biology of these rodents. Inherent rarity and scarce specimen sampling, despite a continent-wide distribution, has precluded our ability to implement modern methods for resolving taxonomy, evolutionary history, and investigating multiple other species traits. Here we use a maternally inherited locus (mitochondrial cytochrome b) and between 5939 and 11 513 nuclear loci from reduced representation sequencing (ddRADseq) to investigate the evolutionary history of northern bog lemmings. We (1) qualify evidence based on morphological and early molecular studies for the genus assignment of Mictomys, (2) test the validity of multiple sub-species designations, (3) provide spatial and temporal historical biogeographic perspectives, and (4) discuss how incomplete sampling might influence conservation efforts. Both mitochondrial and nuclear datasets exhibit deep divergence and paraphyly between two recognized species, the northern (Mictomys borealis) and southern (Synaptomys cooperi) bog lemmings. Based on mtDNA, the geographically isolated subspecies (M. b. sphagnicola) was found to be divergent from all other specimens. The remainder of the species exhibited shallow intra-specific differentiation in mtDNA, however, nuclear data supports genetic distinction consistent with four geographic subspecies. Recent coalescence of all northern bog lemmings (except for M. b. sphagnicola) reflects divergence in multiple refugia through the last glacial cycle, including a well-known coastal center of endemism and multiple regions south of continental ice sheets. Regional lineages across North America suggest strong latitudinal displacement with global climate change, coupled with isolation-reconnection dynamics. This taxon suffers from a lack of modern samples through most of its distribution, severely limiting the interpretation of ongoing evolutionary processes, particularly in southern portions of the species' range. Limited voucher specimen sampling of vulnerable populations could aid in rigorous conservation decision-making. [ABSTRACT FROM AUTHOR]

The emergence of the Covid-19 pandemic and the constant changes in the expectations and needs of employees have accelerated the implementation of labour flexibility policies by companies. Currently, there is some uncertainty in the literature about the real benefits of adopting these policies, hence the relevance of this research, which aims to assess whether they represent a source of sustainable competitive advantage. This research used a qualitative approach involving in-depth interviews with human resource managers to analyse the impact of labour flexibility policies on a firm's competitive advantage using the VRIO framework. The study found that while employees view labour flexibility as beneficial to their work-life balance and job satisfaction, from the perspective of firms, these policies may be valuable but do not provide a distinct competitive advantage. Consequently, companies need to consider these policies when developing strategies to maintain their competitiveness and market position. [ABSTRACT FROM AUTHOR]

Colombia boasts extensive geodiversity thanks to complex geological processes that have shaped its landscape over geological time. The eastern region of the country is characterized by ancient rock formations, covered by a substantial layer of sediments, influenced by tectonic and erosive forces. These forces have given rise to unique geoforms that qualify as geosites. Thirteen sites were identified based on their geological context, accessibility, visibility, and tourism potential, by assessing their geoscientific and scenic interest. A methodology was applied, drawing from various experts in Geological Heritage both in Colombia and globally. Geosites in the east of Colombia encompass geological outcrops, structures, mountain ranges, reservoirs, karst formations, waterfalls, and archaeological and mining sites, all of significant geoscientific, educational, and scenic value. Each site was rated on a scale of 1 (low) to 3 (high), resulting in an average scientific value of 2.42, indicating a moderate to high geoconservation value. Geosites with the highest geoconservation rating (3) include the Structural Slopes of Guateque, El Encanto Hot Springs, Upín Salt Flats, Cerro Azul and the Orión Gate. The Mountain Ranges of San Luis de Gaceno, karstic dissolution sinkholes, and the Pink Plants of Tranquilandia fall into the moderate to high-value category (rated at 2.5). Other sites, such as the Eroded and Stepped Escarpments of Las Juntas, La Esmeralda Reservoir (Chivor), Sedimentary Slabs of Guejar River, Sandstone Tables, and the Love's Waterfall, also hold geological importance. We recommend implementing geoconservation policies for these geosites to preserve and develop them, taking into account their considerable geotourism potential. These efforts should be carried out with a keen awareness of the current resource usage and land management practices to ensure a sustainable strategy. [ABSTRACT FROM AUTHOR]

Climate change is modifying plant communities and ecosystems around the world. Alpine ecosystems are of special concern on oceanic islands, due to their characteristic higher endemicity percentage, small area and undergoing severe climate change impact in the last few decades. During recent decades there has been increasing interest in the effects of climate change on biodiversity and a range of methods have been developed to assess species vulnerability. However, some new insights are necessary to obtain useful information for species management on oceanic islands. Here in the alpine area of two oceanic islands (Tenerife and La Palma) we evaluate the drivers that best explain the vulnerability of 63 endemic species along three scenarios, covering recent past to present and two future projections (2041–2060 and 2061–2080). The selected drivers were: loss of potential area, mismatch index between potential and occupied areas in different scenarios, and adaptive capacity constraints. We assess the influence of potential area size and whether the drivers of risk and the vulnerability for common, restricted and rare species are significantly different. Our results indicate that management must be widely distributed over the species, and not only focus on restricted species. Evidence for this was that drivers directly deriving from climate change showed no significant differences in their impact on the rarity groups identified. Vulnerability depends partially on the potential area size, showing a more complex picture where constraints on the adaptive capacity of the species have a strong enough influence to modify the effects of the characteristic drivers of climate change. [ABSTRACT FROM AUTHOR]

Variations in the Dolivo-Dobrovol’sky symmetry index for minerals through time reveal several factors that influence the emergence of crystalline symmetry in natural processes. Of special interest in this regard are the numerous paragenetic modes—different processes of mineral genesis that reflect changes in physical, chemical, and ultimately biological environments that foster the emergence of new mineral species. Here, we consider the roles of hydrogen content, rarity, formation temperature and pressure, and age on the average symmetry of minerals from 57 different modes of formation (i.e., paragenetic modes). We find four significant trends in the average mineral symmetry index for all minerals in each paragenetic mode: specifically, this average index is (1) lower for minerals with greater hydrogen content; (2) greater for minerals formed at higher pressure; (3) lower for minerals of greater rarity; and (4) greater for older paragenetic modes. These findings elucidate some of the intricate relationships among paragenetic modes, average mineral attributes, and the Dolivo-Dobrovol’sky symmetry index, providing insights into the geological processes governing mineral formation.

Land-use change is a primary driver of biodiversity loss. Tropical ecosystems face rapid conversion rates due to the encroachment of agricultural lands and supply needs for goods and services from an increasing population and changing market demands. Measuring the effect of land conversion on species diversity is challenging due to incomplete and uneven knowledge of different taxonomical groups. Here, we contrast different metrics for measuring biodiversity loss across three land-use typologies: secondary forest, agroforestry, and monoculture for five taxonomic groups: birds, frogs, fish, dung beetles, and macroinvertebrates in the Andean piedmont forests of the western equatorial Andes. Albeit our limited and uneven sample in space and time, we found that rarity, Non-Metric Multidimensional Scaling, and Multinomial Classification Model (i.e., classifications of habitat specialists and generalists) constitute a more sensitive set of indicators to assess land-use change impacts on tropical mountain biodiversity compared to classical metrics. Likewise, our results showed that land-use intensification influenced community assemblages in the five taxonomic groups. These non-classical biodiversity metrics can provide better insight into the effect of land conversion on these highly biodiverse ecosystems composed of many rare species.

Seagrass habitats are declining worldwide, placing several seagrass‐associated animals at risk of extinction. The Critically Endangered limpet Siphonaria compressa is one of the rarest molluscs in Africa, and has been reported from only two disjunctive lagoons in South Africa. Being a highly specialized grazer that lives exclusively on the narrow blades of Cape eelgrass, Zostera capensis, which is itself listed as Endangered in the South African Red List and has decreased in abundance, conservation initiatives are urgently needed to ensure the long‐term survival of S. compressa.Molecular data (sequence data from the mitochondrial genome and single nucleotide polymorphism data of the nuclear genome) and morphological data were analysed to determine whether the two populations are conspecific, with implications for whether translocation between localities could be a viable management strategy to restore either population in the event of a collapse, or to maintain the genetic diversity of each population.Strong evidence emerged for the distinctness of the two populations, including a lack of shared mtDNA haplotypes that indicate an absence of contemporary gene flow, a divergence time that dates to the late Pleistocene, and a number of morphological characters that distinguish their shells. These findings indicate that the two populations are distinct cryptic subspecies.As the two populations occur in different temperature‐defined marine biogeographical regions, they are probably adapted to different thermal environments. Translocations are not recommended, as this management strategy has considerable potential to result in outbreeding depression and exacerbate the extinction risk. Instead, each population should be managed separately, and several alternative conservation measures are discussed, including the protection and restoration of seagrass beds. [ABSTRACT FROM AUTHOR]

Conservation policies and environmental impact assessments commonly target threatened species and habitats. Nevertheless, macroecological research provides reasons why also common species should be considered. We investigate the consequences of focussing solely on legally protected species and habitats in a spatial conservation planning context using a comprehensive, benthic marine data set from the northern Baltic Sea. Using spatial prioritization and surrogacy analysis, we show that the common approach in conservation planning, where legally listed threatened species and habitats are the focus of conservation efforts, could lead to poor outcomes for common species (and therefore biodiversity as a whole), allowing them to decline in the future. If conservation efforts were aimed solely at threatened species, common species would experience a loss of 62% coverage. In contrast, if conservation plans were based only on common species, threatened species would suffer a loss of 1%. Threatened species are rare and their ecological niches distinct, making them poor surrogates for biodiversity. The best results are achieved by unified planning for all species and habitats. The minimal step towards acknowledging common species in conservation planning would be the inclusion of the richness of common species, complemented by information on indicator species or species of high importance for ecosystem functioning. The trade‐off between planning for rare and common species should be evaluated, to minimize losses to biodiversity. [ABSTRACT FROM AUTHOR]

Meighan watershed habitats, located in central Iran (Markazi Province), have undergone considerable changes in recent years. Landsat satellite images of the year 2020 were used to produce digital land use maps for the present study. Ecological quality, rarity and risk assessment analyses were performed using the Sub-Watershed-scale Ecosystem Service Modeler according to the InVEST (SWESMI) toolkit, HQR and HRA models. The images were classified into three classes including Agriculture, Rangeland, and Human-made (industrial-residential regions) impacts. The results indicated that there are three important habitats in the Meighan watershed: mountains, plains, and wetlands. Human-made changes, agriculture, and road developments were among the biggest threats and most devastating stressors in the Meighan watershed. There was an increased cumulative risk in the plain habitat of the Kharahrod (31.44%), Amanabad (27.75%) and Sarogh (26.87%) sub-watersheds. A decreased cumulative risk was identified in the mountain habitat of the Kheirabad (7.62%) sub-watershed in the Haftad-Gholleh National Park, and wetland habitat of the Meighan (4.30%) sub-watersheds. The plain habitat (with high cumulative consequence) and the wetland habitat (with high accumulative exposure) are at the highest risk from Human-made activities. Stressors related to roads and agriculture-livestock were the main stressors in the mountain habitat and wetland habitat, respectively, whereas both stressors were considerably high in the plain habitat. Due to being located in a protected area, the Kheirabad sub-watershed was found to have suitable quality and rarity compared to other sub-watersheds in central Iran. The results highlight the significance of land conservation and protected areas in maintaining the habitat quality and reducing the risks associated with habitat degradation and biodiversity. [ABSTRACT FROM AUTHOR]

A través de este documento, el Comité de Rarezas de Euskadi (CRE) recopila la homologación de citas de aves raras en 2022 en Euskadi. Este Comité, creado al amparo del Comité Ornitológico de Euskadi (COE), ejerce su actividad para recopilar, estudiar y publicar todas las citas de especies o subespecies cuya presencia en Euskadi es accidental o irregular. A lo largo de 2022 se evaluaron un total de 173 citas. De todas ellas, 78 fueron homologadas, 9 se asignaron a categoría D, 1 a categoría E, 69 fueron rechazadas (no homologadas) y 16 quedaron pendientes de evaluación. Por otro lado, dado el alto número de citas registradas durante los últimos años, se eliminan de la lista de aves raras, desde el 1 de enero de 2023, el vencejo pálido Apus pallidus y el bisbita costero Anthus petrosus. Se añade como nueva especie el alzacola rojizo Cercotrichas galactotes, al producirse la primera cita para Euskadi en 2022.

Motivated by accelerating anthropogenic extinctions, decades of biodiversity–ecosystem function (BEF) experiments show that ecosystem function declines with species loss from local communities. Yet, at the local scale, changes in species' total and relative abundances are more common than species loss. The consensus best biodiversity measures are Hill numbers, which use a scaling parameter, ℓ, to emphasize rarer versus more common species. Shifting that emphasis captures distinct, function-relevant biodiversity gradients beyond species richness. Here, we hypothesized that Hill numbers that emphasize rare species more than richness does may distinguish large, complex and presumably higher-functioning assemblages from smaller and simpler ones. In this study, we tested which values of ℓ produce the strongest BEF relationships in community datasets of ecosystem functions provided by wild, free-living organisms. We found that ℓ values that emphasized rare species more than richness does most often correlated most strongly with ecosystem functions. As emphasis shifted to more common species, BEF correlations were often weak and/or negative. We argue that unconventional Hill diversities that shift emphasis towards rarer species may be useful for describing biodiversity change, and that employing a wide spectrum of Hill numbers can clarify mechanisms underlying BEF relationships. This article is part of the theme issue 'Detecting and attributing the causes of biodiversity change: needs, gaps and solutions'. [ABSTRACT FROM AUTHOR]

Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. We quantified extinctions among the vascular flora of the continental United States and Canada since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching the literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an index of taxonomic uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest that 51 species and 14 infraspecific taxa, representing 33 families and 49 genera of vascular plants, have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. Most extinctions occurred in the west, but this outcome may reflect the timing of botanical exploration relative to settlement. Sixty-four percent of extinct plants were single-site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here.

People trade thousands of non-fungible tokens (NFT) daily. The NFT prices are expressed in cryptocurrency, and it is volatile. As the interest in the NFTs changes, their prices vary with time too. Is there an immanent meter to order NFTs by their value? Within a single collection, a vector of features–traits–characterizes NFT. People construct rarity meters based on the assumed value of the trait vector rarity. But this process lacks formalism. In this paper, we formulate the optimal rarity meter problem and provide a pipeline for optimal rarity meter design. A proposed tournament score function is an essential part of the construction. We demonstrate the approach for the Kanaria NFT collection.

Three species of the tropical hydrocoral genus Millepora were common and abundant in the Maldives before 1998, characterizing extensive shallow reef areas known as ‘Millepora zones’. The 1998 heat wave resulted in mass mortality of all the Millepora species, the characteristic Millepora zones disappeared, and only a few observations of isolated colonies were reported in the years ahead. A recent expedition (January 2024) to the northernmost region of the Maldives (Ihavandhippolhu Atoll) revealed new Millepora zones at 7–13 m depth, suggesting a potential repopulation of a vulnerable genus considered regionally extinct.

Phytoplankton guilds are commonly characterised by dominance effects, while the main contribution to biological diversity is given by rare species. Here, we analysed the influence of rare species on taxonomic and functional diversity, which is described by taxa richness and composition, cell size, and size–abundance relationships in phytoplankton guilds. We explore these relationships at global and regional scales by analysing phytoplankton guilds from five biogeographical regions: the Northern Atlantic Ocean (Scotland), the South-Western Atlantic Ocean (Brazil), the South-Western Pacific Ocean (Australia), the Indo-Pacific Ocean (Maldives), and the Mediterranean Sea (Greece and Turkey). We have comparatively analysed the phytoplankton taxonomic diversity of the whole dataset and with the datasets obtained by progressively subtracting taxa occurring in the last 1%, 5%, 10%, and 25% of both numerical abundance and overall biomass. Globally, 306 taxa were identified across five ecoregions with only 27 taxa accounting for 75% of overall numerical abundance and biomass; almost 50% of taxa were lost on every step. The removal of 1% of most rare taxa significantly affected the phytoplankton size–abundance relationships and body-size structure, strongly impacting on small taxa. The progressive removal of additional rare taxa did not further affect phytoplankton size–abundance relationships and size structure.

This article aims to understand why medical actors recently published lists of rare and very rare cancers. It studies four lists of rare and very rare cancers based on interviews with the main actors on these lists and an analysis of medical articles in which these lists were published. It argues that these lists constitute boundary objects whose aim is to deal with the organizational challenges raised by precision medicine, which imply increasing the coordination work between various types of actors. Our work therefore allows a better understanding of the functioning of the recursive standardization process of a boundary object and, by analyzing how the category of rarity is built at the intersection of both professional and nosographic principles, shows the intertwining of the biomedical, organizational, and political aspects on which rests the practice of contemporary precision medicine.

Aim: Support for different underlying mechanisms of species occupancy is inconsistent, yet this could be related to spatial scale. Since abiotic filtering typically acts at broader scales than biotic interactions, we hypothesise that occupancy could be more driven by species' abiotic niche (i.e. tolerance and preference of abiotic conditions) at broad scales, whereas species' traits affecting competitive ability could be more important at fine scales. Here, we test these hypotheses by assessing relationships of occupancy to niche and trait metrics across spatial scales. Location: Four study areas located north of Arctic Circle. Taxon: Vascular plants. Methods: We derived occupancy for 106 species at four spatial scales (micro‐scale with plot size of 0.04 m2 and extent of 2 km, local‐scale with plot size of 4 m2 and extent of 40 km, regional‐scale with plot size of 4 ha and extent of 800 km, and polar‐scale with plot size of 4 km2 and extent of 5200 km). We then assessed using generalized additive models whether the relationships between occupancy and species' niche breadth, niche marginality, intraspecific trait variability (ITV) and trait distinctiveness vary across the scales. Results: At the finer scales, ITV (especially of specific leaf area) had the highest contribution with positive relationship in explaining occupancy. At the broader scales, occupancy was better explained by niche metrics. Especially at the broadest scale, the occupancy had a positive relationship with species' climatic tolerance. Main Conclusions: Abiotic filtering, especially related to macro‐climate, drives species occupancy at broader spatial scales while biotic interactions are relatively more important at local scales. This scale‐dependency of factors behind species occupancy should be accounted for when, for example, planning conservation of rare species, forecasting invasions or anticipating the effects of changing climate on biota at local versus global scales. [ABSTRACT FROM AUTHOR]

The bryophyte flora of Hungary was relatively well studied during the twentieth century, but data on the present-day frequency and geographical distribution of Hungarian bryophytes are lacking. We present here our preliminary results based on recent fieldwork and herbarium studies. We recorded bryophyte occurrences in grid cells (quadrants) of approximately 5.5 × 6 km. Frequency was determined based on the number of quadrants, and geographical distribution evaluated in terms of the 19 administrative units (counties) of the country. To investigate correlations between species richness and relevant environmental drivers, statistical analyses were carried out. A total of 698 bryophyte taxa (2 hornworts, 151 liverworts and 545 mosses) have been found in the territory of Hungary. For each of the 637 taxa that have been observed since 1973, one of five frequency classes (very common, common, sporadic to frequent, rare, and very rare) has been assigned based on the relevant number of field records or herbarium specimens. Additionally, tabular distributional information (occurrence in each of the 19 counties) is presented for each taxon. In the statistical evaluation of the geographical distribution data, the elevational range and the size of the surveyed area were positively correlated with bryophyte richness, whereas arable land cover was negatively correlated. Although the survey was not uniform or complete across the different counties, the results support some robust bryogeographical theories. We hope to have the opportunity in the near future to compile a new Hungarian bryophyte Red List, partly based on these national frequency data. [ABSTRACT FROM AUTHOR]

Between the 1930s and the 1990s, as art museums across the USA began contending with what place photography might hold within their programmes, key individuals framed photography's value in language that itself deserves consideration. Amid this museological reckoning with the medium, at the National Gallery of Art, which was established in the 1930s as a national public repository for Western art of the highest standards, the question of whether and how photography might fit into that lineage presented new questions. How would the greatness of photography be defined? What would its presentation look like? Sarah Greenough joined the National Gallery of Art in 1978 with a PhD in Art History and an expertise in the work of Alfred Stieglitz. I argue that as she aimed to integrate photography seamlessly into the set of values established by Andrew W. Mellon at the founding of the Gallery, she drew upon Stieglitz's own terminology for valuing the medium, modelling her own philosophy of its import on his notion of 'the idea photography'. [ABSTRACT FROM AUTHOR]

The slender racer, Orientocoluber spinalis, is a monotypic species found in northeast Asia. We collected 67 O. spinalis samples from the Republic of Korea (hereafter, South Korea) and 7 from China and Mongolia and investigated their genetic diversity and population structure. In South Korea, O. spinalis populations were mainly found on Oeyeondo, Uido, and Udo islands and Woraksan Mountain and showed low genetic diversity in the analysis of concatenated mitochondrial sequences of the cytochrome b (Cytb) and NADH dehydrogenase subunit 4 (ND4) genes. Orientocoluber spinalis populations in South Korea showed low differentiation and likely diverged recently. Orientocoluber spinalis may have colonized the Korean Peninsula from China and Mongolia, but this route is not confirmed due to the lack of samples from the Democratic People's Republic of Korea and middle eastern China. Considering its extreme rarity, low population density, and low genetic diversity, O. spinalis should be designated an endangered species in South Korea, as it is in Russia, Mongolia, and Kazakhstan. [ABSTRACT FROM AUTHOR]

Background and Aims The hart's tongue fern (HTF) complex is a monophyletic group composed of five geographically segregated members with divergent abundance patterns across its broad geographic range. We postulated hierarchical systems of environmental controls in which climatic and land-use change drive abundance patterns at the global scale, while various ecological conditions function as finer scale determinants that further increase geographic disparities at regional to local scales. Methods After quantifying the abundance patterns of the HTF complex, we estimated their correlations with global climate and land-use dynamics. Regional determinants were assessed using boosted regression tree models with 18 potential ecological variables. Moreover, we investigated long-term population trends in the USA to understand the interplay of climate change and anthropogenic activities on a temporal scale. Key Results Latitudinal climate shifts drove latitudinal abundance gradients, and regionally different levels of land-use change resulted in global geographic disparities in population abundance. At a regional scale, population isolation, which accounts for rescue effects, played an important role, particularly in Europe and East Asia where several hot spots occurred. Furthermore, the variables most strongly influencing abundance patterns greatly differed by region: precipitation seasonality in Europe; spatial heterogeneity of temperature and precipitation in East Asia; and magnitudes of past climate change, temperature seasonality and edaphic conditions in North America. In the USA, protected populations showed increasing trends compared with unprotected populations at the same latitude, highlighting the critical role of habitat protection in conservation measures. Conclusions Geographic disparities in the abundance patterns of the HTF complex were determined by hierarchical systems of environmental controls, wherein climatic and land-use dynamics act globally but are modulated by various regional and local determinants operating at increasingly finer scales. We highlighted that fern conservation must be tailored to particular geographic contexts and environmental conditions by incorporating a better understanding of the dynamics acting at different spatiotemporal scales. [ABSTRACT FROM AUTHOR]