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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]

• Rarity and composition metrics better measure land use impacts in tropical systems. • Land use intensification reduces biodiversity irrespective of the metric applied. • Agroforestry systems resemble forest diversity patterns across taxa. 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. [ABSTRACT FROM AUTHOR]

The decline and loss of biodiversity provoked by human activities have caused ecologists and conservationists to center their attention on the design of conservation priority areas (PAs), focusing mainly on species conservation in terms of richness, rarity and/or vulnerability. However, biodiversity has multiple dimensions, evolutionary processes have recently been labeled the 'missing component' of conservation strategies, and increasingly more authors are suggesting that the ecological, evolutionary and historical aspects of biodiversity are key components of conservation planning. In this study we develop a prioritization system to design conservation PAs using the wild terrestrial mammals of the Iberian Peninsula as an example. We aim to contribute to the design of more suitable PAs by integrating ecological components of biodiversity (species richness, vulnerability and rarity), evolutionary aspects (accumulated genetic diversification) and historical information relevant to the study area. After selecting a set of biodiversity indicators, we applied a multi-objective technique (extended goal programming) to construct a combined index, where values in the top 90th percentile were then used to select the PAs. According to our most efficient and satisfactory results, some areas highlighted for their conservation are currently categorized as PAs, however, we found that it would be necessary to reconsider their extent, especially in northern Spain, where the historical aspects of biodiversity (the missing component) are more widely present. The need to determine PAs is unquestionable. However, it should also be a priority to move towards a model of sustainable and fair development. [ABSTRACT FROM AUTHOR]

Highlights • At a regional scale, some populations of rare plant species are of doubtful origin. • Species composition of recipient plant communities can indicate this origin. • Associated local, geographical and historical site features provide further arguments. • The approach is tested with the cryptogenic Leucojum vernum in N France. • These ecological indicators can guide conservationists and nature managers. Abstract Regional lists of protected species commonly include rare plant species that are found in small, isolated populations at the range margin or disjunct. However, such populations often have suspicious origins and may have been historically introduced and now falsely viewed as native. Here I use a simple community ecology approach to assess whether plant community composition and site features can indicate whether local populations of a rare cryptogenic species are more likely of natural or introduced origin. I took the vernal geophyte Leucojum vernum L. in North France as a case study. Using multivariate analyses I show that L. vernum occurs in various plant communities, which correspond to different sets of environmental conditions. More specifically, several community types clearly reflect an introduced origin, with a discrepancy between L. vernum 's autecology and site features as well as a number of co-occurring anthropophilous species, including xenophytes. These populations are often associated with more or less ancient human artefacts, such as archaeological sites. In contrast, an equal number of community types likely correspond to natural populations, that are all located at the range margin and connected to the core range via a (former) west-flowing river corridor, pleading for a post-glacial recolonization. I conclude that a cryptogenic species, such as L. vernum in this case study, has a "socio-ecological signature" which can indicate whether a given population is more likely native or introduced, and thus informs conservationists on where to prioritize conservation efforts. [ABSTRACT FROM AUTHOR]

Abstract Rarity and life history traits inform multiple dimensions of intrinsic risk to climate and environmental change and can help systematically identify at-risk species. We quantified relative geographic rarity (area of occupancy), climate niche breadth, and life history traits for 114 freshwater fishes, amphibians, and reptiles in the U.S. Pacific Northwest. Our approach leveraged presence-only, publicly available data and traits-based inference to evaluate area of occupancy, climate sensitivity (i.e., climate niche breadth), and a Rarity and Climate Sensitivity (RCS) index of all species across multiple geographic extents, grain sizes, and data types. The RCS index was relatively stable across extents, grains, and data types, with climate sensitivity differentiating species with otherwise similar areas of occupancy. We also found that species with sensitivity-associated traits (e.g., long generation time, low fecundity) were not necessarily the same species identified as at-risk with geographical approaches (small range size, small climate niche breadth). Many multispecies assessments using coarse-scale data (e.g., entire range maps or convex-hull approaches) often focus on a single dimension of intrinsic risk; others rely on data-intensive models only applicable to a few well-studied species. What remains is a need for an approach that enables multispecies, multidimensional assessment efforts. This is particularly true at regional scales, where management needs require assessments that are intermediate to coarse- and fine-scale approaches. We demonstrate that by considering multiple dimensions of intrinsic risk to climate change (range size, climate sensitivity, and traits), site-specific locality data may offer a pathway for ensuring vulnerable, understudied species do not go overlooked in conservation. Highlights • Rarity and climate sensitivity enable direct comparison of species intrinsic risk. • A combined functional and geographic approach is robust across scales and data type. • Life history traits complement geographic rarity in understanding regional species risk. • This approach can identify potentially vulnerable, but understudied, species. [ABSTRACT FROM AUTHOR]

Abstract We collated data on the latitudinal, elevation and seasonality ranges, local densities, stature and dispersal mode of 514 evergreen tree species (≥10 cm girth at breast height), including 317 endemics, from the rain forests of the Western Ghats (WG) of India using two complementary databases, (i) 68 tree inventory plots, and (ii) the Atlas of Endemics. We tested the hypotheses that (i) regional rarity would be associated with local rarity and narrower ecological amplitudes, (ii) shorter and mechanically dispersed trees would be rarer, (iii) higher proportion of endemic species would be rare (iv) regionally wide ranging species would be locally rare, and localised species would be denser, (v) families with single species would be relicts in this biome, (vi) larger families would have a higher proportion of rare and endemic species. We used Atlas records in a generalised least square model acknowledging phylogenetic relationships, to test hypotheses (i) to (ii), and non parametric tests for (iii) to (vi). We identified rare species using binary cut-offs and compared these with IUCN threat status. Rarity was associated with (i) narrower ecological amplitudes and shorter stature, independent of phylogeny, (ii) 18 wide ranging and locally sparse, 41 narrow ranging and locally dense species, (iii) relict species and families, (iv) larger families. Rare species were more likely to be threatened, but 39% were not evaluated. We identified zones of rare endemics to help with conservation planning. The WG rain forests have a unique evolutionary history and potential that require increased conservation measures. Highlights • We examined multiple facets of rarity among 514 species including 317 endemics from the Western Ghats of India. • Rare species tend to have narrower ecological amplitudes, be short statured. • Rare endemics, rare non-endemics and rarity among families is examined. • The results highlight the importance of this limited biome for its unique biodiversity and evolutionary history. [ABSTRACT FROM AUTHOR]

The decline in biodiversity in freshwater ecosystems occurs at an alarming rate throughout the world. In Denmark, we know from historical records that several species within the plant genus Potamogeton , that were previously widespread in Danish freshwater ecosystems, are now under severe decline. In this study, we explore root development in two common and three declining Potamogeton species applying an experimental approach. Specifically, we examined if root development characteristics can contribute to explain the contrasting success of these species in the contemporary stream vegetation in Denmark. In accordance with our hypothesis, our results showed that common species of Potamogeton produced roots faster, had longer roots and produced more roots per growth node than declining Potamogeton species. This was particularly clear for P. crispus. Overall, our results expose a mechanism that is likely to affect the ability of these species to maintain populations in highly disturbed lowland streams in Denmark and therefore contribute to explain the contrasting success of these species. • Root development is faster in common compared to declining species of Potamogeton. • Common Potamogeton species produce longer roots and more roots per growth node. • Root traits likely affect colonization success of Potamogeton species in disturbed streams. [ABSTRACT FROM AUTHOR]

Abstract Description of spatial structure is in the focus of community ecology. Multifractal analysis is a prospective method because it connects fractal geometry tools with the conventional methodology of diversity analysis. The current version is based on a power-law scaling in the form of species-area relation. It is well suited for the description of self-similar communities. However, it is well known that many natural communities and theoretical models deviate from power-law diversity scaling. We propose to relax the requirement of self-similarity and introduce local multifractal analysis. This new method is based on a local approximation of the relation of effective diversity to scale. It is a fractal analysis in the sense of dealing with power-law approximations and estimation of scaling exponents within the framework of multifractal analysis. However, the multifractal spectra that resulted from this analysis do not characterize global scale-invariant properties but reflect details of diversity scaling specific for a given scale. In that sense, the analysis proposed is local. We present the results of analysis in theoretical and empirical contexts. Classical Fisher model of species abundance distribution deviate from power-law scaling and may be described with local multifractal spectra. We illustrate an empirical application in a case study of spatial structure of two temperate deciduous forests in different landscapes. Our approach provides new perspectives in the investigation of community spatial structure because it widens the scope of fractal analysis beyond self-similar communities. It may be adapted for other versions of multifractal analysis applied in community ecology. Highlights • The current version of multifractal analysis is restricted to self-similar communities. • We propose to relax the requirement of self-similarity and introduce local multifractal analysis. • We analyze the classic Fisher log-series SAD model. • We perform a case study of a spatial structure of two temperate forests. • Our approach provides new perspectives in the investigation of community spatial structure. [ABSTRACT FROM AUTHOR]

1. Species richness is unrivalled as the most reported biodiversity metric in ecological and conservation research. Unfortunately, species richness ignores the scale-dependency of biodiversity. 2. We propose the metric uniquity , a quantitative and spatially scalable measure of uniqueness of a site based on a species-by-site matrix and a site-by-habitat type classification with area weights for habitat types correcting for sampling biases. 3. An example of uniquity is presented using vascular plant data from 130 sites representing a larger region (Denmark). We demonstrate the importance of the scale parameter of uniquity for the prediction of independent uniqueness indices calculated from species distribution data and the number of recorded red listed species. 4. We compare the performance of uniquity with the performance of the indices Local Contribution to Beta Diversity (LCBD) and Range Rarity Richness (RRR), and we investigate its sensitivity to small sample size and poorly resolved habitat classification. 5. We assess the performance of the uniquity metric applied to DNA metabarcoding data for plants, fungi and eukaryotes from the same set of study sites. 6. Uniquity is a strong predictor of site uniqueness based on national distribution data and also correlates neatly with the observed number of red listed species. Uniquity based on DNA metabarcoding corresponds well with the number of red listed species observed. 7. Perspective: Uniquity is generally applicable to biotas sampled with comparable effort, including field inventories, trap sampling, and DNA metabarcoding data. To our knowledge uniquity is the first index of uniqueness that explicitly considers spatial scale and sampling biases, while simultaneously accepting non-annotated DNA-data as input. Based on our study we offer general recommendations for further use and testing of uniquity as conservation value metric. [ABSTRACT FROM AUTHOR]

Understanding the factors responsible for species rarity is key for designing effective management strategies aimed at long-term conservation of species. Most such studies investigate plant size, competitive vigour or habitat requirements, but studies that explore more complex characteristics of species directly related to different stages of the plant life cycle are much less common. Germination is the most critical stage in the life cycle of many plants and is the primary source of variation in the regeneration niche. However, only a few authors have studied differences in germination requirements between common and rare congeners, and none have studied these requirements for large sets of species. The aim of this study was to compare seed mass, germination requirements and proportions of germinated seeds of rare and common congeners across a large set of species. We analysed seed mass, proportions of germinated seeds in specific conditions and total proportions of germinated seeds of 18 congeneric pairs of rare and common plant species. We tested different lengths of cold stratification, constant or alternating temperatures, and different light conditions. Seed mass of rare and common congeners was not significantly different. The results indicated that after cold stratification, the proportions of germinated seeds were higher in rare than in common species. In common species, the proportions of germinated seeds were significantly higher during cold stratification than those of rare species. Rare species had higher proportions of germinated seeds than those of their common congeners, and total proportions of germinated seeds were influenced by seed mass and species rarity. Rare species were apparently well adapted to local conditions in the mountains and the inability to germinate was clearly not a cause for their rarity. The study provides unique data on proportions of germinated seeds over a wide spectrum of species and conditions. [ABSTRACT FROM AUTHOR]

There is no single diversity index that adequately summarises species diversity, since this is a multidimensional concept and hence should be quantified using a compound statistical measure. Here, we present the DER algorithm, available as an R package on CRAN and as an RWizard application on http://www.ipez.es/RWizard . This algorithm provides tools for differentiating assemblages on the basis of five compounds of diversity: rarity, heterogeneity, evenness, taxonomic/phylogenetic diversity and functional diversity. For all the samples, the algorithm calculates a total of 39 of the indices most often used. All indices of all samples are transformed to a scale range of between 0 and 1, and the algorithm calculates the polar coordinates of all samples with all possible combinations for all five groups of indices. Thus, for each combination, an index of rarity, heterogeneity (species richness is included in this group), evenness, taxonomic/phylogenetic diversity and functional diversity is used for each group to calculate the polar coordinates of all samples. When the polar coordinates of the samples are obtained for each combination, the convex hull and the mean Euclidean distance between samples are calculated. The algorithm selects the combination of indices with the highest value of the mean between convex hull and mean Euclidean distance between samples; priority is therefore given to maximising dispersion between the samples. The polar coordinates of the selected combination are depicted using a diagram from which it is possible to determine the differences in terms of rarity, heterogeneity, evenness, taxonomic/phylogenetic diversity and functional diversity between assemblages. [ABSTRACT FROM AUTHOR]

Calymperaceae is an acrocarpous moss family widely distributed in tropical and subtropical regions of the world. The main goal of this research was to study the distribution of species of the genera Calymperes and Syrrhopodon in the Atlantic Forest in northeastern Brazil to determine how environmental factors influence the distribution of these taxa. We compiled a list of species based on literature review, analysis of herbarium specimens and samples taken from forest remnants. This information was complemented with environmental factors compiled for each locality. We registered 13 Calymperes and Syrrhopodon species, five of which had a regionally and/or locally abundant pattern of distribution, while eight had regionally and/or locally sparse distributions. Altitude and annual temperature ranges were the most influential factors for the distribution of C. tenerum , S. incompletus , S. prolifer and S. gaudichaudii . Potential distribution models were developed for taxa with restricted distributions, which were found to be informative. According to the potential distribution models, it is very likely that investment in fieldwork will increase the known distributions of the rare species (e.g., C. erosum , C. tenerum , S. africanus and S. brasiliensis ). In the case of other species (e.g., S. cryptocarpus and S. gaudichaudii) , rarity may be due to the decline of populations in face of current limited suitable microhabitats as a consequence of alteration and destruction processes of the northeastern Atlantic Forest. [ABSTRACT FROM AUTHOR]

The apparent prevalence of rare species (rarity) in the deep sea is a concern for environmental management and conservation of biodiversity. Rare species are often considered at risk of extinction and, in terrestrial and shallow water environments, have been shown to play key roles within an ecosystem. In the deep-sea environment, current research focuses primarily on abundant species and deep-sea stakeholders are questioning the importance of rare species in ecosystem functioning. This study asks whether deep-sea stakeholders (primarily scientists) view rare-species research as a priority in guiding environmental management. Delphi methodology (i.e., an iterative survey approach) was used to understand views about whether or not ‘deep-sea scientists should allocate more resources to research on rare species in the deep sea, even if this means less resources might be available for abundant-species research.’ Results suggest little consensus regarding the prioritization of resources for rare-species research. From Survey 1 to Survey 3, the average participant response shifted toward a view that rare-species research is not a priority if it comes at a cost to research on abundant species. Participants pointed to the need for a balanced approach and highlighted knowledge gaps about even the most fundamental questions, including whether rare species are truly ‘rare’ or simply under-sampled. Participants emphasized the lack of basic biological knowledge for rare and abundant species, particularly abundant meio- and microscopic species, as well as uncertainty in the roles rare and abundant species play in ecosystem processes. Approaches that jointly consider the role of rare and abundant species in ecosystem functioning (e.g., biological trait analysis) may help to clarify the extent to which rare species need to be incorporated into deep-sea environment management in order to maintain ecosystem functioning. [ABSTRACT FROM AUTHOR]

Intensive land use is a major cause of biodiversity loss, but most studies comparing the response of multiple taxa rely on simple diversity measures while analyses of other community attributes are only recently gaining attention. Species-abundance distributions (SADs) are a community attribute that can be used to study changes in the overall abundance structure of species groups, and whether these changes are driven by abundant or rare species. We evaluated the effect of grassland management intensity for three land-use modes (fertilization, mowing, grazing) and their combination on species richness and SADs for three belowground (arbuscular mycorrhizal fungi, prokaryotes and insect larvae) and seven aboveground groups (vascular plants, bryophytes and lichens; arthropod herbivores; arthropod pollinators; bats and birds). Three descriptors of SADs were evaluated: general shape (abundance decay rate), proportion of rare species (rarity) and proportional abundance of the commonest species (dominance). Across groups, taxonomic richness was largely unaffected by land-use intensity and only decreased with increasing mowing intensity. Of the three SAD descriptors, abundance decay rate became steeper with increasing combined land-use intensity across groups. This reflected a decrease in rarity among plants, herbivores and vertebrates. Effects of fertilization on the three descriptors were similar to the combined land-use intensity effects. Mowing intensity only affected the SAD descriptors of insect larvae and vertebrates, while grazing intensity produced a range of effects on different descriptors in distinct groups. Overall, belowground groups had more even abundance distributions than aboveground groups. Strong differences among aboveground groups and between above- and belowground groups indicate that no single taxonomic group can serve as an indicator for effects in other groups. In the past, the use of SADs has been hampered by concerns over theoretical models underlying specific forms of SADs. Our study shows that SAD descriptors that are not connected to a particular model are suitable to assess the effect of land use on community structure. [ABSTRACT FROM AUTHOR]

Understanding drivers of demand for exotic pets may help inform adequate conservation strategies to address unsustainable trade. Here, we used a best-worst scaling approach to understand the variety of preferences and motivations for owning exotic pets. Respondents (316 from 33 countries) preferred exotic pets that were captive-bred, had rare aesthetic features, and were common in the wild and abundant in the market. Species that were at risk of extinction, in short supply, sourced from the wild, and under trade restrictions were the least favoured by respondents. Feelings of care, such as attachment, affection, nurture, as well as curiosity and being passionate about the species, were dominant motivations for pet keepers. Respondents were willing to support the conservation of species in the wild. Our findings highlight that relational dimensions are among the most important aspects influencing decisions to own exotic pets. Certification systems of origin that supports animal welfare and conservation may help consumers support sustainable trade in exotic pet species. However, attention should be paid to challenges throughout the supply chain and not to incentivize consumers' preferences for rare genetic features as this may pose a risk to the conservation of species in the wild. When planning conservation initiatives and policies, considering relational dimensions may provide novel insights to better foster meaningful expressions of care with animals in the wild, as opposed to animals as exotic pets. Fostering care, as a normative human sense of kinship with non-humans, could help channeling "demand for ownership" towards "stewardship relations" with nature. [ABSTRACT FROM AUTHOR]

• Philodryas livida suffered a decrease of Extent of Occurrence and Area of Habitat in the last 30 years (5.7% and 19.1% remaining, respectively). • Most recent records have come exclusively from within or around protected areas. • Not considering the date of records and land-use change throughout time might underestimate species range reduction and thus threat status. • We encourage the inclusion of the date of each occurrence record in conservation assessments, especially in highly dynamic and threatened landscapes. Documenting species distribution is essential to extinction risk asessments and subsequent conservation actions. Historical records are thus essential to understand how species are distributed and how their range has changed over time. However, using historical records might contribute to overestimating the species current range and misrepresent their conservation status. Here, we illustrate the pitfalls of this approach using a widespread but elusive Neotropical snake species, Philodryas livida (Dipsadidae Bonaparte, 1838). We mapped occurrences of this species over time and calculated its Extent of Occurrence and Area of Habitat. Our results show that due to the intense, widespread anthropic land-use transformation since the discovery of P. livida in 1920, most historical localities are now likely unsuitable for its occurrence and both its current Extent of Occurrence and Area of Habitat become remarkably smaller (5.7% and 19.1% remaining, respectively) if only localities from the last 30 years are considered. Apart from the natural elusiveness of the species, intense habitat loss and fragmentation may also explain the low number of recent records of P. livida, all concentrated within or near protected areas, indicating a putative decline in range relevant to its conservation status. We thus highlight how failing to consider the date of records and the associated land-use change over time might underestimate species range reduction and thus threat status. We strongly encourage the inclusion of the date of each occurrence record in conservation assessments, as suggested by the IUCN's mapping standards, such that historical records are carefully considered, especially in highly dynamic and threatened biomes such as the Cerrado savannas in Brazil. [ABSTRACT FROM AUTHOR]

Species vulnerable to climate change face increased extinction risk, but many sensitive species may be overlooked due to limited data and exclusion from vulnerability assessments. Intrinsic sensitivity, or the inherent risk of species to environmental change due to biological factors, can be assessed with widely available data and may address gaps in multispecies vulnerability assessments. Species that exist in few places (geographically rare) and in fewer climates (smaller realized climate niche breadth) have high intrinsic sensitivity to environmental change. Using point occurrences, we systematically evaluated intrinsic sensitivity based on geographic rarity and realized climate niche breadth for 90 species of frogs and toads native to the United States using over 140,000 occurrence records. To relate sensitivity to perceived extinction risk, we compared intrinsic sensitivity to conservation status at state, federal, and international levels. We found no relationship between intrinsic sensitivity and federal or state conservation status, and some intrinsically sensitive species (i.e., those with small areas of occurrence and narrow climate specificity) were not listed as at risk at any level. Intrinsic sensitivity analysis can serve as an early warning system for species that may be currently at risk and overlooked. [ABSTRACT FROM AUTHOR]

Transovarial transmission of dengue virus has been studied in 33 districts of Rajasthan, India. Small proportion (1.09%) of breeding containers positive for the virus and their elimination has been demonstrated as a possible intervention method of disease control. Dengue virus was isolated from individual mosquitoes employing Indirect Fluorescence Antibody Test and Reverse Transcriptase Polymerase Chain Reaction. Out of 1,30,525 containers examined only 1432(1.09%) showed transovarially transmitted virus activity. Elimination of larvae from all the 1432 virus positive containers resulted in substantial control over prospective transmission of dengue. The study highlights rarity of transovarial transmission under natural conditions and sensitizes whether elimination of vertically infected foci could be used as a new intervention method. [ABSTRACT FROM AUTHOR]

The 231 habitat types included in the European Environmental Agency (EEA) database of the Natura 2000 Network are distributed throughout more than 22 thousand Sites of Community Importance (SCI) covering around 128 million hectares in Europe. However, individual habitat areas have different conservation relevance according to the Rarity of the habitat type and their Representativeness in relation to the whole type. We propose a Relevance Index and evaluate it for each area of each habitat type, taking into account the Rarity of the habitat type, assessed by the extent of its occurrence in the Natura 2000 Network, and the Representativeness of the area, as the contribution of that area to the total extent of that habitat type in the Network. Results allow for an objective analysis of the Natura 2000 Network indicating, for example, that rarity of a habitat type in Natura 2000 Network does not necessarily correlate with its priority status, suggesting the need for reevaluation of the situation. The Relevance Index proposed for a given habitat area is the product of the Rarity Index of its habitat type and the Representativeness of the area. We demonstrate the application of the Index for the areas of three different Natura 2000 Sites. The Relevance Index of one Site (SRI) will be the sum of the Relevance Indices of its corresponding habitat areas (HRI). The same approach is applicable to regions, countries or for any habitat cluster allowing for the quantification of their contribution to the whole Natura 2000 Network. It is suggested that the Relevance index can also be applied in monitoring the components of the Natura 2000 Network, and is useful to support management decisions for conservation in Europe. [ABSTRACT FROM AUTHOR]

Human preferences may generate purely anthropogenic positive feedback loops reinforcing either declines of overexploited populations or expansions of prized introduced species, potentially leading to species substitutions. I illustrate this process based on a content analysis of 20th century Spanish newspapers that document a rapid, country-wide substitution of an originally exploited crayfish ( Austropotamobius italicus ) by two North American species ( Procambarus clarkii and Pacifastacus leniusculus ). The substitution was driven by anthropogenic positive feedbacks acting over a short period, coinciding with an exponential increase of crayfish market value, high numbers of crayfish-related articles and a rapid change in the thematic content of those articles. Similar substitutions involving economic or socially valued organisms occur in other regions and concerning other taxa. Human preferences and choices may constitute relevant drivers of several species declines and invasions, which can be very quick due to positive feedback loops. Conservation biology in general and invasion biology in particular have been traditionally focused on biological aspects, but, as shown here, would largely benefit from social perspectives dealing with human motivations and preferences. [ABSTRACT FROM AUTHOR]

Beneath the hot debate about the tempo and mode of the first human colonization of Europe is the perception that the record of human presence in the Early Pleistocene is sparse and fragmented. As a result, it is often implicitly assumed that hominins, if present, were scarce in the Early Pleistocene European ecosystems. Here we present a quantitative assessment of the rarity and commonness of the European large mammal species during the 1.4–0.8 Ma period, including hominins. Considering the palaeontological record only, Homo was not one of the most common species in Europe, but it may not be considered a rare species. In contrast, taking into consideration the archaeological record, hominins exhibit a wide geographical distribution and a high frequency of occurrence (occupancy) in comparison with other large mammals. It is speculated that hominins were frequent but not abundant in Europe during the late Early Pleistocene. [ABSTRACT FROM AUTHOR]

The demand for wildlife products drives an illegal trade estimated to be worth up to $10 billion per year, ranking it amongst the top transnational crimes in terms of value. Orchids are one of the best-selling plants in the legal horticultural trade but are also traded illegally and make up 70% of all species listed by the Convention on the International Trade in Endangered Species (CITES). To study consumer preferences for horticultural orchids we use choice experiments to survey 522 orchid buyers online and at large international orchid shows. Using latent class modelling we show that different groups of consumers in our sample have distinct preferences, and that these groups are based on gender, genera grown, online purchasing and type of grower. Over half of our sample, likely to be buyers of mass-produced orchids, prefer white, multi-flowered plants. Of greater conservation interest were a smaller group consisting of male hobbyist growers who buy their orchids online, and who were willing to pay significantly more for species that are rare in trade. This is the first in-depth study of consumer preferences in the international orchid trade and our findings confirm the importance of rarity as a driver of hobbyist trade. We show that market-research methods are a new tool for conservationists that could provide evidence for more effective conservation of species threatened by trade, especially via campaigns that focus on demand reduction or behaviour change. [ABSTRACT FROM AUTHOR]

American hart's-tongue fern (AHTF) is one of the rarest ferns in the United States and concern over its conservation and management has highlighted the need for genetic analysis. Genetic analysis also provides insights into the species' mating system which contributes to our understanding of its rarity and persistence. We analyzed 88 individuals from 11 populations in NY and MI based on variations in 108 loci as revealed through ISSR markers using Nei's gene diversity index, percent polymorphic loci and other measures. Low genetic diversity predominates in the populations from NY, and even lower for the populations in MI. Our results also indicate that AHTF from NY and MI are genetically differentiated from each other, as well as the populations within them. There is no positive correlation between genetic and geographic distances, as well as between genetic distance and census population size. The significantly high among population genetic variation and low gene flow value are common indicators of a predominant inbreeding mating strategy within populations, limited spore dispersal, and genetic drift. Our results also indicate that each AHTF population is an important contributor to the overall genetic variation of the species and thus, represents a significant unit for conservation efforts. [ABSTRACT FROM AUTHOR]

Here we examine the distribution patterns, abundance, and species richness of tanaidacean peracarids in the abyssal-hadal transition zone. Material was collected in the region of Kuril–Kamchatka Trench during the German–Russian KuramBio Expedition with use of a giant boxcorer (GKG) of sampling area 0.25 m 2 . In the 23 samples collected from depths 4900 to 5800 m 48 species of Tanaidacea belonging to 11 families have been identified; most of the species (80%) are new to science. There was no evidence of a distribution pattern associated with depth or geographic location of stations in the nMDS analysis. Frequency of occurrence of twelve species was high (at 34–78% of stations) although the stations were distributed along a distance of about 1000 km. This observation is rationalized by the uniform environmental conditions of temperature, hydrostatic pressure, salinity, conductivity, and character of bottom deposits in the investigated area. Mean tanaidacean densities were 25.0±18.0 ind./0.25 m 2 , with mean values of species richness (number of species per sample) and diversity (Shannon Index) as high as 9.7±4.6 and 1.9±0.3 respectively. Singletons constituted about 20% of all species and more than one third of the species occurred as low counts per sample. The species accumulation curve did not reach the asymptotic level suggesting under-sampling of the studied area. [ABSTRACT FROM AUTHOR]

Patterns of rarity in the context of species richness gradients have intrigued researchers for decades, but the same patterns have only rarely been considered in the context of community composition. There is thus a need to combine the classical rarity theory with expectations from metacommunity research. We studied the responses of assemblages of common and rare lake macrophytes to ecological gradients across various spatial extents. Based on the ideas of metacommunity research, we first hypothesised that the communities of common species are mainly affected by environmental factors and rare species are mainly controlled by spatial processes. Alternatively, following the classical theory of rarity, we expected that common species are environmental generalists (their assemblages are controlled by the spatial processes) and rare species are environmental specialists (their assemblages are controlled by the environment). We used two criteria to define common and rare species: the inflection point criterion and the 50th quartile criterion. Partial redundancy analysis was employed to decompose variation in the assemblage composition of common and rare macrophytes between environmental and spatial variables at each spatial extent and geographical region. Both criteria defined similar sets of common and rare macrophytes across spatial extents. As found in previous studies, the amount of explained variation in the composition of the macrophyte communities along ecological gradients was low overall. However, most of the explained variation, was related to the responses of common species. Assemblage composition of common and rare species was similarly explained by environmental factors. We did not find clear support for current ecological theories with regard to variation in the assemblage composition of common and rare macrophytes. In contrast, our findings suggested that species sorting is collectively structuring the assemblages of both common and rare macrophytes. Spatial variation in metacommunity structuring, however, hinders our ability to draw general conclusions on how common and rare species respond to specific ecological gradients in different regions and at various spatial extents. [ABSTRACT FROM AUTHOR]

A systematic approach for prioritization of protected areas is the use of artificial intelligence. This approach employs computer algorithms based on an objective function to identify the best network of areas to be protected. Site selection algorithms are commonly used to identify areas of high conservation value. This study used three types of heuristic algorithms (simulated annealing, greedy, rarity) to prioritize areas for protection in Mazandaran Province of Iran using Marxan software. The goal was to select a conservation network with the smallest possible area in which maximum protection targets are achievable. The effects of spatial scale, algorithm, and zone compactness were also examined. We found that the existing network of protected areas is inadequate to achieve conservation targets. The algorithm results provided the best areas for supplementation of the current network. The simulated annealing algorithm provided the most plausible results for all scenarios. These results can be used to modify the existing boundaries of the protected areas network and introduce new sites for protection of plant and animal species. [ABSTRACT FROM AUTHOR]

Abstract: Inselbergs support highly specialized vegetation with many endemic species. Here we studied by an integrated approach a rare and threatened species from Brazilian inselbergs. Pitcairnia encholirioides (Bromeliaceae) is included in the Red Book of Brazilian Flora, in the ‘Endangered’ category. Only one single population on unprotected private property was known at the beginning of our study. We studied several life-history traits including clonal growth, reproductive biology, seed germination and cryopreservation, and genetic diversity. Pitcairnia encholirioides has the phalanx type of clonal growth strategy. Its self-incompatible flowers are successfully pollinated by hummingbirds. However, less than 5% of clonal fragments produced flowers. Seeds can be wind-dispersed, but most of them are dispersed by gravity and fall close to the mother plant. The percentage and speed of germination were significantly affected by different temperatures, water potential, and red:far-red light ratios, although more than 80% of seeds germinated under optimal physiological conditions. The genetic diversity was very low (H sp =0.09) and the population was highly structured (ΦST =0.51). The combination of dispersal mode and environmental conditions seems to be the main factor leading to the rarity of P. encholiroides. Low genetic diversity combined with small population size and low reproductive capacity suggest that the species is highly susceptible to environmental disturbance. Similarly to P. encholiroides, many species from Brazilian inselbergs are restricted to only a few localities. For more widely distributed species, a higher genetic diversity among populations has been consistently detected. The pattern of low gene flow of many species with small distributions highlight the importance of population-based conservation strategies for such taxa the areas of occurrence of which being naturally fragmented at inselberg sites. We discuss some strategies that may help in conservation of such species. [Copyright &y& Elsevier]

Abstract: Butterfly decline in Northern Europe is a cause of concern and it has been hypothesised that this is due to nitrogen deposition inducing excess early growth of plants. It has also been changing the quality of the food available to larvae. We tested these hypotheses by linking butterfly biodiversity quality indices (species richness, population, biomass, conservation value, evenness (Simpson's Index) and modelled species richness (Chao 1 and 2)) with nitrogen Critical Load Exceedence (nCLE) data. An index of butterfly sensitivity to nitrogen was also created (Species Nitrogen Value Index (SNVI)). Using PCA, datasets were tested for associations and relationships. The results included multiple biodiversity quality indices based on 17 years of data (aggregated into three periods of six, six and five years to give 287 datasets) in four habitat types (grassland, heathland, woodland and farmland). With the exception of heathland the analysis showed that nitrogen deposition and all other indices (except SNVI) were in decline. For heathland the last 11 years did not show any significant decline. Heathland also showed an anomalous biodiversity quality profile for these last 11 years, suggesting that the sensitivity of heathland to nitrogen deposition will require further considerable efforts to achieve a nitrogen deposition that is not in exceedence of the critical load. Habitat restoration will take time due to the multiple hindrances to colonisation, which in the case of heathland might prevent successful butterfly colonisation for the foreseeable future. These results indicate the efficacy of butterfly biodiversity quality and nCLE as indicators for the SEBI 2020 process (Streamlining European Biodiversity Indicators) by showing the relationship between them. [Copyright &y& Elsevier]

Abstract: Forensic identification is the task of determining whether or not observed evidence arose from a known source. It is useful to associate probabilities with identification/exclusion opinions, either for presentation in court or to evaluate the discriminative power of a given set of attributes. At present, in most forensic domains outside of DNA evidence, it is not possible to make such a statement since the necessary probability distributions cannot be computed with reasonable accuracy, although the probabilistic approach itself is well-understood. In principle, it involves determining a likelihood ratio (LR) – the ratio of the joint probability of the evidence and source under the identification hypothesis (that the evidence came from the source) and under the exclusion hypothesis (that the evidence did not arise from the source). Evaluating the joint probability is computationally intractable when the number of variables is even moderately large. It is also statistically infeasible since the number of parameters to be determined from the data is exponential with the number of variables. An approximate method is to replace the joint probability by another probability: that of distance (or similarity) between evidence and object under the two hypotheses. While this reduces to linear complexity with the number of variables, it is an oversimplification leading to errors. We consider a third method which decomposes the LR into a product of two factors, one based on distance and the other on rarity. This result, which is exact for the univariate Gaussian case, has an intuitive appeal – forensic examiners assign higher importance to rare feature values in the evidence and low importance to common feature values. We generalize this approach to more complex data such as vectors and graphs, which makes LR estimation computationally tractable. Empirical evaluations of the three methods, done with several data types (continuous features, binary features, multinomial and graph) and several modalities (handwriting with binary features, handwriting with multinomial features and footwear impressions with continuous features), show that the distance and rarity method is significantly better than the distance only method. [Copyright &y& Elsevier]

Abstract: An important task in conservation biology is to assess the spatial scale pertinent for species protection since some species may require protection throughout their distribution, others in only part of their range. Once this is done, species can be correctly identified for listing at different administrative levels (e.g. continental, national, and local). Here, we propose an objective method to list taxa at nested administrative levels based on three criteria (responsibility, rarity and vulnerability). We tested the method using quantitative data on the distribution, abundance and decline of orchids in France. The proposed method enables increased protection status in regions where species’ abundance and diversity are higher, gives priority to species for which an individual administrative unit has high responsibility and allows objective integration of species decline at different administrative levels. The method also enables the integration of locally rare species at their distribution limits and avoids repetition of species listing across second-level administrative units. The use of an objective method such as this could contribute to a standardised system of priority setting that integrates the geographic scale of rarity in relation to different administrative levels for protection. [Copyright &y& Elsevier]

Highlights: [•] We tested if mycorrhizal and pollinator availability is associated with plant rarity. [•] All Drakaea formed a mycorrhizal association with the same widely distributed fungal species. [•] Despite relying on one pollinator species, pollination rates are high. [•] Rare Drakaea are associated with pollinators that are rare at the patch scale. [•] Understanding the ecological requirements of pollinators is critical for conservation. [Copyright &y& Elsevier]

Biodiverse communities have been shown to sustain high levels of multifunctionality and thus a loss of species likely negatively impacts ecosystem functions. For most taxa, however, roles of individual species are poorly known. Rare species, often most likely to go extinct, may have unique traits and functional roles. Alternatively, rare species may be functionally redundant, such that their loss would not disrupt ecosystem functions. We quantified the functional role of rare species by using captures of wood-living (saproxylic) beetle species, combined with recent databases of morphological and ecological traits, from three regions in central and northern Europe. Using a rarity index based on species' local abundance, geographic range, and habitat breadth, we used local and regional species removal simulations to examine the contributions of both the rarest and the most common beetle species to three measures of community functional structure: functional richness, functional specialization, and functional originality. Both regionally and locally, all three measures declined more rapidly when rare species were removed than under common (or random) species removal scenarios. These consistent patterns across scales and among forest types give evidence that rare species provide unique functional contributions, and their loss may disproportionately impact ecosystem functions. This implies that conservation measures targeting rare and endangered species, such as preserving intact forests with dead wood and mature trees, can provide broader ecosystem-level benefits. Experimental research linking functional structure to ecosystem processes should be prioritized to increase understanding of the functional consequences of species loss and to develop more effective conservation strategies. [ABSTRACT FROM AUTHOR]

Highlights: [•] Unimodal relationship is appeared between migration and local rare species number. [•] Unimodal relationship is appeared between migration and local species richness. [•] Rare species declines faster at large niche breadth than small niche breadth. [•] Species richness declines faster at large niche breadth than small niche breadth. [ABSTRACT FROM AUTHOR]

Abstract: INTRODUCTION: Tailgut cysts or retrorectal cystic hamartomas are rare developmental anomalies that are believed to arise from the embryonic hindgut. PRESENTATION OF CASE: 9 months old male infant was presented with swelling in the right gluteal region. MRI lumbo-sacral spine showed well defined round to oval lesion which is brightly hypertense on T2W1 and hypotense on T1W1 posterior to sacrum and coccyx with no evidence of connection to the thecal sac indicating cyst. Complete excision of the cyst was done. Histopathology report shows cyst wall partially lined with stratified squamous epithelium and cyst wall shows spaces lined by cuboidal epithelium and nerve bundles with no evidence of malignancy suggestive of tailgut cyst. DISCUSSION: Tailgut cysts are rare congenital anomalies. Most commonly located in the retrorectal space. They are thought to be derived from the remnants of the embryonic hindgut. Age ranges from 4 to 73 years but an average presentation is at 35 years. Female to male ratio is 3:1. MRI is a good diagnostic tool for diagnosis of tailgut cyst. Complete surgical excision is the treatment of choice as this provides a definite diagnosis and prevents possible complications such as infection, fistula formation and malignant degeneration. CONCLUSION: The aim of presenting this case is its rarity. Complete surgical excision is the treatment of choice. Preoperative imaging with MRI is essential to plan the most appropriate surgical approach. [Copyright &y& Elsevier]

Abstract: Empirical work assessing the maintenance of rare genotypes in natural populations is difficult over very long time scales. Skirting this problematic issue is possible with theory and simulations. Major theoretical constructs, including mutation-selection balance and balancing selection, explain the theoretical maintenance of rare genotypes, and the occurrence of multiple, rare genotypes over time. Additionally, numerical simulations are valuable tools for assessing evolving biological systems because they allow for monitoring systems over long time scales, as well as for controlling model parameters, thus contributing to the exploration of system dynamics that cannot be assessed in nature. Here we employed numerical simulations to explore the importance of several biological factors that contribute to the maintenance of a fish color-pattern polymorphism. We present a numerical model of a two-morph fish polymorphism that allowed us to test the sensitivity of the rare morph''s persistence and the population''s stability to multiple parameters. Our simulations ran over 10,000 years (where one year is approximately one generation) and demonstrated the maintenance of a stable polymorphism with a rare morph which persisted at a frequency of ∼10−2, which is in-fact the frequency of the rare, mottled black mosquitofish morph in natural populations. This pigmentation polymorphism is stable, independent of changes in population size, but can be destabilized with very high predation when coupled with very low birth rates. Employing models with empirical fitness estimates is a valuable tool for monitoring rare vertebrate morphs in nature, however few studies exist that have accomplished this task. Our approach can be adapted for modeling rare morphs (particularly in additional live-bearing fishes like sailfin mollies) that also harbor rare, pigmentation morphs within large populations. [Copyright &y& Elsevier]

Abstract: The distribution of species in their environment is largely defined by habitat characteristics. Both species and habitat distributions can be used to define conservation areas, especially in highly diversified ecosystems like coral reefs where biodiversity inventories are lacking. The main objective of this study was to test the relationship between multi-taxa community structure (defined by richness, species lists, and taxonomic distinctness) and habitat typology in the Man and Biosphere UNESCO Reserve of Baa Atoll (Maldives). Species richness per taxon was described at 18 stations located on different habitats mapped using high resolution satellite imagery. A total of 1012 species were described including 178 macroalgae, 173 corals, 121 hydroids, 351 fish and 189 (other) macro-invertebrates. Rarity was extremely high for macro-invertebrates, algae and hydrozoans. The results highlighted a marked difference in species composition between stations for macro-algae and corals but not for other groups (hydroids, fish and macro-invertebrates). These distribution patterns were not strongly correlated to differences in habitat characteristics, which created a weak spatial structure of communities between habitats probably caused by differential exposure of atolls to monsoons and the 1998 bleaching event. Community differences between stations were often due to rarity. Therefore, identifying a network of protected areas that includes occurrences of all species may pose challenges. This is overcome by conservation planning scenarios using medium-size (of the order of 1km2) management units. [Copyright &y& Elsevier]

Abstract: While the business value of IT (BVIT) is central to the IS discipline, only recently a possible chain of causation from IT assets (i.e., fungible, widely available, commodity-like, technology-based products) to firm performance has been conceptually specified. Furthermore, little empirical evidence exists regarding IT assets’ business value. In light of this paucity, this paper makes several contributions to IS research and practice. First, it advances the BVIT literature by empirically testing a model that traces a path from IT assets through IT-enabled resources to firm performance. Second, it extends the BVIT and resource-based view (RBV) literatures by explicating and testing the impact of a firm’s external environment on its IT-enabled resources. Third, it builds on recent literature to argue for, and test, two distinct forms of firm-level outcome: operational and strategic benefits. Finally, the paper contributes to managers’ and IS practitioners’ knowledge by demonstrating the transformative capacity of IT assets on the strategic potential of organizational resources. Empirically, the paper develops and employs valid and reliable scales to test the research model using survey data on IT-enabled customer service departments. The findings demonstrate that when an IT asset is combined with an organizational resource, the extent of synergy borne out of the resulting relationship can positively impact the strategic potential of the ensuing IT-enabled resource. This IT-enabled resource, in turn, is positively associated with firm-level benefits. Further, the external environment is shown to exert a positive effect on the strategic potential of outside-in IT-enabled resources. In sum, this paper offers several important conceptual and empirical contributions to a stream of research that is at the core of the IS discipline. [Copyright &y& Elsevier]

Abstract: Wildlife viewing recreation offers conservationists opportunities for education and generating revenue but can also have detrimental ecological impacts. To manage these opportunities and impacts effectively, a better understanding is needed of what people value in wildlife viewing events. We examine the relationship between species rarity and value for wildlife viewing recreation. We undertook visitor counts of birdwatchers attending rare (vagrant) bird sightings and collected home postcodes to assess the distances these individuals travelled to achieve these sightings. We also undertook visitor counts at common bird viewing locations for comparison. We regressed birdwatcher numbers against rarity, site protection status, time the bird had been on site and day of the week when the count took place. We undertook these analyses for rare bird sightings only, using a continuous measure of rarity, and for both rare and common species combined, using a categorical rarity index. Species rarity was the clearest predictor of visitor numbers in both the analyses. When studying rare birds only, we found the functional form of the relationship between rarity and visitor numbers to be inverse and asymptotic. Individuals also travelled further to see rarer species. However, while exceptional numbers of visitors attended exceptionally rare bird sightings, the marginal value of rarity appeared to be relatively low. Despite the opportunity for revenue raising and education provided by rare bird sightings, a comparison of visitor numbers at sightings inside and outside protected areas showed no evidence that managers of protected areas capitalise on these opportunities. [Copyright &y& Elsevier]

Abstract: Data on the occurrence of weed species in 1463 German oilseed rape (OSR) fields were used to multivariately investigate the interactions of management practices and ecological processes with weed species composition. Partial canonical correspondence analysis (pCCA) served to quantify the relative contribution of 25 characteristics of climate, site and crop to weed species composition. According to pCCA the considerable differences in weed species composition of OSR fields were mainly associated with the crop preceding OSR, the tillage intensity and soil quality. Longitude and precipitation were the most important environmental parameters. Factors driving the occurrence of weed species differed for the categories ‘common’, ‘frequent’ and ‘rare’ weed species. Common weed species showed the strongest response to factors acting at the field scale such as crop sowing date or soil quality, while only frequent species were affected by local environment, and the occurrence of rare weeds more than the other groups depended on large-scale geographical position variables as well as cropping intensity. Cluster analyses of thematically grouped explanatory variables resulted in the identification of four farming systems with different soil properties and management, two farming systems differing in the occurrence of OSR cropping, and five ecoregions, each with characteristic and statistically verified OSR weed communities. [Copyright &y& Elsevier]

Abstract: A traditional focus in conservation biology has been on rare species as they are often those most at risk of decline or extinction. However, we argue in this paper that some kinds of currently common species also can be susceptible to decline. Those at particular risk are species that are specialized on widespread environmental conditions. Such specialization may make such species vulnerable to a range of drivers of environmental change, placing them at risk of significant decline or even local extinction. We illustrate this with a case study of the arboreal marsupial the Greater Glider (Petauroides volans) in south-eastern Australia. The Greater Glider was formerly common in two large-scale studies but in one it suffered rapid extinction (within a 3 year period) and in another it is declining at an annual rate of 8.8%. We therefore argue for more research to better predict those kinds of currently common species which might be at risk of future rapid decline or extinction. In addition, we suggest there will often be a need to take pro-active conservation and management action to reduce the number of potential environmental stressors on populations of common species to ensure they do not become uncommon or rare. We also argue that conserving common species will ensure the retention of their key ecological and functional roles in ecosystems. Finally, we believe there is a need to develop better monitoring programs that can detect changes in the population trajectories of common species, help identify the reasons for temporal changes in such populations, and underpin timely management interventions. Despite these good intentions, we acknowledge that in one of our own long-term investigations we: (1) failed to anticipate the extremely rapid decline (and likely local extinction) of the Greater Glider, (2) were unable to diagnose the reason/s underpinning the population collapse, and (3) nor were we able to instigate a timely intervention program of management to prevent this from occurring. The key lesson from this sobering result is that common species can sometimes be at risk of rapid decline and it is wise to avoid complacency in conservation. [Copyright &y& Elsevier]

Abstract: Proneness to extinction varies naturally and continuously according to the ecological phenomena that compound rarity even before anthropogenic effects may play a role. This is particularly obvious in islands, where populations are often (and naturally) small and fragmented and, consequently, conservation priority lists may have a large number of species clustered unhelpfully in the higher threat categories. In this study we propose a simple model of threat based on natural descriptors of rarity and taxonomic distinctiveness (area of occupancy, population abundance and trend, and endemicity), assess its correlation with ecological features of the species (habitat preferences and body size) and check whether the Spanish Red data Book and a normative conservation priority list (the Canary Islands Catalogue of Threatened Species and its administrative revision) includes these ecological bases for birds. We found that a large variation in threat (48.2%) was explained by phylogeny, habitat breadth and preference for urban areas (with a negative effect), and preference for agricultural environments (a positive effect). The Spanish Red data Book and the administrative lists tested are poorly related to descriptors ordering the extinction risk and loss of taxonomic singularity, so some changes would make their categories more coherent. We contend that the ecological bases of rarity should be taken into account to understand why some populations/species are at higher extinction risk whereas others remain relatively safe, as this would provide firmer grounds on which to base conservation priorities. [Copyright &y& Elsevier]

Abstract: Conservation of rare species is frequently complicated by their narrow niches and poor competitive abilities which limit their distribution to a few small populations. We studied how population size and structure of an endemic cycad of northwestern Mexico, Dioon sonorense, known to be threatened by widespread land conversion and plant extraction by humans, varied with 21 environmental variables. We also used matrix population models to show how population structure may affect its long-term persistence. Slope and soil exchangeable potassium explained a moderate proportion of the variance in the abundance of adult individuals, while abundance of adults and slope explained a large proportion of the variance in the abundance of seedlings. The strong non-linear relationships of seedling abundance with slope and adult abundance suggest threshold effects that may limit D. sonorense regeneration in less suitable environments. Modeling suggests that most of the study populations will not be viable in the long-term, except for the largest population. Modeling scenarios with large increments in fecundity and seedling survival produced modest gains in population growth. The long-term persistence of D. sonorense is shown in our study to be further threatened by: (a) small size of adult populations, (b) low-quality habitat in which most populations occur, and potentially, (c) the combined effect of low fecundity and recruitment. [ABSTRACT FROM AUTHOR]

Abstract: Fire plays an important role in determining the structure of savannas, so that frequent fires tend to favor the herbaceous species in savannas. Functional diversity is a measure of the range of the species functional traits and is thought to be related to many functions and properties like community stability, nutrient cycling, and productivity, for example. We examined if functional diversity of herbaceous species was different along a fire gradient, and if observed functional diversity differed from a random assembly of species traits. We sampled three sites with different fire frequencies. According to the intermediate disturbance hypothesis, we expected the functional diversity to be higher in the intermediate fire frequency site. Subsequently, we excluded rare species from the analyses – species with less than ten individuals in each site – to verify their contribution to the observed patterns of functional diversity. We expected to find no difference with the exclusion of rare species. Functional diversity values, either considering all species or excluding the rare ones, were not different among sites, suggesting that (1) frequent fires may not affect overall functioning of the herbaceous community in savannas and (2) rare herbaceous species seem to present lower functional complementarity. According to the neutral theory, most of the herbaceous species may have evolved stochastically in niches more similar than competitive exclusion could allow. Also, functional diversity was not different from what one may expect by chance in any of the three sites. We also calculated the floristic similarity among sites. When we considered qualitative data, we found floristic differences between the sites of high and intermediate as well as between high and low fire frequency sites, but there was no difference between the intermediate and low fire frequency situation. Floristic similarities were different among all the three sites when the abundances of species were considered. Consequently, different fire conditions may change species composition without affecting the functional diversity of the herbaceous layer of savannas, corroborating the idea that savannas are more stable in functional than in floristic terms. [Copyright &y& Elsevier]

Reduced biological diversity in freshwater habitats situated in urban areas has been discussed in numerous studies. Certain municipal areas, however, can help save animal diversity of freshwater invertebrates. In the present study animals were collected or observed alive in 13 freshwater environments localized in Warsaw – the second largest city of Central Europe – in a densely populated, urban building complex close to the city, and also in suburban areas. Leech assemblages in all the environments under observation were numerically dominated by a few common species, but on the whole 19 species were collected or observed. The populations of six rare leech species inhabit both flowing and standing waters in Warsaw. Five of these species are on the Polish Red List of Species and one is strictly protected. The shallow Lake Powsinkowskie is the richest freshwater environment in the studied area in terms of species richness and rarity and also one of the richest lakes in Poland. Taxonomic diversity in the environments under study seems not to be directly related to the size of the water body or the level of degradation but rather to the habitat complexity, especially the diversity of the bottom in littoral zone. Certain freshwater habitats located inside this great urban complex still create good conditions for rare, highly specialized species. [Copyright &y& Elsevier]

Abstract: Freshwaters ecosystems continue to face pressures from pollution, flow regime alterations, habitat destruction and exotic species invasions despite their unique biodiversity. In Europe, National Parks and Special Areas of Conservation aim to provide protection of ‘aggregate’ biodiversity, yet inspection of priority species lists for these sites often reveals a focus towards terrestrial species. In regions such as the Alps and the Pyrénées, this is a particularly serious problem because climate change and other anthropogenic pressures (e.g. hydropower, tourism) are causing widespread hydrological modification which is likely to drive changes in aquatic species abundance, diversity and distribution. Improved understanding of the diversity of rare plants and animals is necessary so efforts can be cost-effectively targeted to conserve the maximum number of species, whilst a clearer picture of these species’ distributions is a precursor to targeting conservation efforts. This paper reports results of a study into the diversity and distribution of 17 endemic mayflies, stoneflies and caddisflies from 598 rivers sites across southern France. Endemic macroinvertebrates were found only at sites in the Pyrénées mountain range with richness peaking at 1500–1800m above sea level. Nine of these 17 species were recorded from <20 sites and two (Protonemura angelieri, Rhithrogena kimminsi) were found at only 10 sites. Despite both the rarity of these species and threats to their existence, none of them have any current conservation status. New conservation policies for freshwater ecosystems in the French Pyrénées need to be developed as a priority due to the rarity of many aquatic species in this area, growing threats to their existence (habitat modification, hydrological change), and to recognise their importance in food webs that may include other rare species of conservation value. [Copyright &y& Elsevier]

Abstract: “Turrids” are a group of small predatory gastropods that are highly diversified in shallow as well as deep water. They sing a hymn to specialisation and rarity. A dataset of 34,810 specimens collected through a quarter-century of qualitative exploration off New Caledonia reveals 1409 species of turrids at depths deeper than 100m. Much of this diversity is constituent of the “rare biosphere”: as many as 41% are singletons, and 73% of the species are represented by empty shells only. Species numbers vary with depth, reflecting both differences in sampling intensity and in actual species richness. The richest depth interval is 301–600m, with 831 species, and a moderately good saturation. By contrast, the 601–1000m interval, with 389 species, is still far from saturated. The overlap in species composition with other South Pacific tropical island groups (Vanuatu, Fiji, Tonga and the Marquesas) is only 17%, but we lack data to back up extrapolations at broader geographical scales (West Pacific, Indo-Pacific, World Ocean). These results champion the slopes of tropical islands, consisting mostly of highly heterogeneous hard bottoms, as a vast reservoir of biodiversity. However, the technological challenges associated with sampling hard bottoms and the geographical remoteness of these target areas combine in making these benthic communities among the least sampled and least studied in the world. [Copyright &y& Elsevier]

Abstract: Developmental variation in some Achnatherum species was evaluated for two kinds of groups, (1) species pairs that do or do not hybridize and (2) rare and common species. Variation was assessed in two different ways, one that captures developmental events expressed in an individual and one reflecting developmental events that are part of the information systems of a species. The former captures the effect of the environment on development; the latter expresses developmental variation without the information controlling ontogenetic events being filtered through the environment. Development variation is lower for species pair that hybridizes when the effect of development in an individual is expressed. When that variation is of the species information system, the non-hybridizing species pair shows a lower level of developmental variation, likely the effect of greater similarity between those species. It is lower for rare species when variation in development is that of the information system of a species. The lower level of developmental variation seen in species pairs that hybridize likely reflects the necessity of compatible developmental programs in order for a hybrid to appear. Lower variation in development in rare species is expected. Here, though, the lower variation is a property of the species and not of the environment. [Copyright &y& Elsevier]

We studied the patterns of commonness and rarity for one vertebrate (fish) and four freshwater insect taxa (Ephemeroptera, Plecoptera, Trichoptera and Coleoptera) in southwestern France (57,000km2), and we analysed the relationships between the location of sites and the contribution of commonness and rarity to species richness within a large stream system. Richness patterns in fish and aquatic insects were related to the location of sites within the stream system. The number of common and rare fish species increased from up- to downstream areas as a result of downstream additions of species. The number of common insect species peaked in the intermediate section of the river continuum, whereas rarity increased with decreasing elevation. In all taxa, common species gave a closer approximation to overall patterns of species richness than did rare ones. The biodiversity patterns of river animals emerged from convergence in the distributions of common and rare species (fish), or mostly from the distribution of common species (insects). However, in fish, Ephemeroptera and Plecoptera, the rarer species became almost equally, or more strongly correlated with overall species richness when increasing information along the common-to-rare and rare-to-common sequences. These patterns suggested that rarer species show a similar or stronger affinity, on a species-for-species basis, for high richness areas than do the commoner species. These schemes have implications for biodiversity assessments, as studies using common species richness to target important areas for monitoring or conservation efforts within stream systems will not necessarily identify areas important for rare species, and vice versa. [Copyright &y& Elsevier]