Geographic Rarity Research Articles

Spatial extent drives patterns of relative climate change sensitivity for freshwater fishes of the United States

AbstractAssessing the sensitivity of freshwater species to climate change is an essential component of prioritizing conservation efforts for threatened freshwater ecosystems and organisms. Sensitivity to climate change can be systematically evaluated for multiple species using geographic attributes such as range size and climate niche breadth, and using species traits associated with climate change sensitivity. These systematic evaluations produce relative rankings of species sensitivity to aid conservation prioritization and to identify relatively sensitive species that may otherwise be understudied or overlooked. Due in part to biogeographic constraints, species assemblages change across regions and spatial extents; yet, the degree to which spatial factors influence relative rankings of species sensitivity is unclear. The spatial extent of multispecies analyses may alter relative rankings of species climate sensitivity; alternatively, relative climate sensitivity may be conserved among spatial scales, resulting in consistent identification of sensitive species among regions and spatial extents. We investigated how spatial extent influences our understanding of relative climate sensitivity for 137 native freshwater fishes of the United States that were representative of taxonomic, trait, and geographic diversity. Using publicly available occurrence data from the Global Biodiversity Information Facility, we calculated a systematic, geographically derived index of climate change sensitivity for study species at national and regional extents, including within four major hydrologic subregions of the United States. We examined the effects of spatial extent on the relative ranking of climate sensitivity among species, and we explored relationships among climate sensitivity, species traits, and conservation status at regional and national extents. We found that climate sensitivity rankings of species were influenced by spatial extent in some specific instances, but that relative rankings were largely conserved across spatial scales. However, correlations among geographically derived climate sensitivity rankings and species traits associated with climate sensitivity were variable across scales and regions, suggesting that links between geographic rarity and species traits may be scale‐dependent in some cases. Finally, we found few associations between climate sensitivity and current conservation status among species. Systematic approaches to quantifying climate sensitivity may offer an opportunity to identify sensitive but overlooked species for pre‐listing actions such as monitoring or conservation agreements.

A dark side of conservation biology: Protected areas fail in representing subterranean biodiversity

Abstract Biodiversity conservation is a central imperative of the 21st century. Subterranean ecosystems deliver critical nature's contributions to people and harbour a broad diversity of poorly understood specialised organisms. However, the subterranean biome is still largely overlooked in global biodiversity targets. We assessed how well subterranean biodiversity is represented in protected areas (Natura 2000 and Emerald networks) in two global hotspots of subterranean biodiversity (the Pyrenees and the Alps). For this, we used two comprehensive databases of terrestrial subterranean taxa, that is, leiodids (beetles) from the Pyrenees and spiders from the Alps, and identified priority areas in each region using both species richness and geographic rarity patterns. Our results show the incapacity of surface‐protected area networks to represent subterranean biodiversity, as more than 70% and 90% of the identified priority areas (and 40% and 22% of the species) are not effectively covered by protected areas in the Pyrenees and the Alps, respectively. These findings call for developing an urgent plan for subterranean biodiversity conservation within the European Biodiversity Strategy for 2030.

The contribution of geographically common and rare species to the spatial distribution of biodiversity

AbstractMotivation and aimMapping the spatial distribution of biodiversity is critical for understanding its fundamental drivers (e.g. speciation, environmental filtering) as well as for conservation assessment. An important dimension of this topic is how the distributions of subsets of species contribute to the overall distribution of biodiversity. Although studies have previously investigated the role of geographically common and rare species in determining these patterns, their respective contributions appear to vary between studies. Knowing which species contribute disproportionately to the spatial distribution of biodiversity enables the identification of key indicator species for biodiversity assessments across large areas and is important for prioritising areas for conservation actions. An extensive review of the literature was carried out to synthesise research on how geographic rarity contributes to spatial patterns of biodiversity. We identify potential explanations for the discrepancies in findings between studies and identify opportunities for further research.ResultsMany studies on the contribution of geographic commonness and rarity to the spatial distribution of biodiversity focus on species richness. A prevalent view is that common (widespread) species contribute disproportionately, although this is not ubiquitous across studies due to factors such as the geographic extent from which relative rarity is quantified. We identify research pathways that will further improve our knowledge of how geographically common and rare species shape the spatial distribution of biodiversity including the impact of spatial scale on species contributions and the incorporation of biodiversity components beyond taxonomic alpha diversity, that is functional and phylogenetic diversity.Main conclusionsFuture research should incorporate multiple biodiversity components and model scale dependency. This will further our knowledge on the underlying processes that shape the spatial variation of biodiversity across the planet and help inform biological surveys and conservation activities.

Mismatch between conservation status and climate change sensitivity leaves some anurans in the United States unprotected

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.

SpORtI: The species originality and rarity index combines phylogenetic and functional originality with rarity metrics to provide a new perspective on species rarity

Methods used to assign rarity among species are fundamental to our ecological understanding and conservation of species that are most vulnerable to extinction or extirpation. Bees (Hymenoptera: Apoidea: Anthophila) are at the forefront of declines in pollinator diversity and a comprehensive understanding of their conservation requirements in any landscape is essential. Rarity is generally defined in terms of numerical abundance and geographical distribution, though aspects of species life history, such as degree of specialization and taxonomic relatedness, are also widely recognized as important. Incomplete information on the life histories of many taxa obliges ecologists to rely on species-level classifications of specialization provided by expert opinion or in published site- or region-specific studies. Descriptions of specialization are therefore rooted in characterization of the habitat and introduce subjectivity into rarity calculations through assumptions of how species perceive and use resources. An alternative approach that may reduce this level of subjectivity is to incorporate important life-history elements into species rarity assessments, which are traits of the organism itself and not its environment. Phylogenetic and functional originality are metrics which have been presented as useful for characterizing the uniqueness of species, and thus for developing a more informed index of species rarity. This study describes our Species Originality and Rarity Index (SpORtI) for bees that includes variables reflecting five rarity and originality metrics for each species: numeric rarity, geographic rarity, phenological rarity, phylogenetic originality, and functional originality. We compared species-specific rarity weights generated with this approach against other indices using a bee dataset collected over three years across the 520,000-km2 land area of the Great Lakes Basin and within the United States and found that rankings using our approach differed significantly from other indices. Our index represents an improvement on previous approaches since it incorporates key information identified by other researchers and avoids potential subjectivity associated with assigning habitat specialization. Importantly, SpORtI has the added advantage to incorporate updated species life-history traits reported in the literature to allow for the most comprehensive and timely rarity index. This new index will aid researchers and practitioners in determining what species to focus conservation efforts on, as well as which management treatments and environmental factors affect our most vulnerable species of bees, or other taxa, so that limited resources can be applied to focal areas of conservation concern more effectively and efficiently.

Anthropogenic pressures coincide with Neotropical biodiversity hotspots in a flagship butterfly group

AbstractAimThe biodiversity crisis has highlighted the need to assess and map biodiversity in order to prioritize conservation efforts. Clearwing butterflies (tribe Ithomiini) have been proposed as biological indicators for habitat quality in Neotropical forests, which contain the world's richest biological communities. Here, we provide maps of different facets of Ithomiini diversity across the Neotropics to identify areas of evolutionary and ecological importance for conservation and evaluate their overlap with current anthropogenic threats.LocationNeotropics.MethodsWe ran species distribution models on a data set based on 28,986 georeferenced occurrences representing 388 ithomiine species to generate maps of geographic rarity, taxonomic, phylogenetic and Müllerian mimetic wing pattern diversity. We quantified and mapped the overlap of diversity hotspots with areas threatened by or providing refuge from current anthropogenic pressures.ResultsThe eastern slopes of the Andes formed the primary hotspot of taxonomic, phylogenetic and mimetic diversity, with secondary hotspots in Central America and the Atlantic Forest. Most diversity indices were strongly spatially correlated. Nevertheless, species‐poor communities on the Pacific slopes of the Andes also sheltered some of the geographically rarest species. Overall, tropical montane forests that host high species and mimetic diversity as well as rare species and mimicry rings appeared particularly under threat.Main conclusionsRemote parts of the Upper Amazon may act as refuges against current anthropogenic pressures for a limited portion of Ithomiini diversity. Furthermore, it is likely that the current threat status may worsen with ongoing climate change and deforestation. In this context, the tropical Andes occupy a crucial position as the primary hotspot for multiple facets of biodiversity for ithomiine butterflies, as they do for angiosperms, tetrapods and other insect taxa. Our results support the role of ithomiine butterflies as a suitable flagship indicator group for Neotropical butterfly diversity and reinforce the position of the tropical Andes as a flagship region for biodiversity conservation in general, and insect and butterfly conservation in particular.

Global determinants and conservation of evolutionary and geographic rarity in land vertebrates.

Deciphering global trends in phylogenetic endemism is crucial for understanding broad-scale evolutionary patterns and the conservation of key elements of biodiversity. However, knowledge to date on global phylogenetic endemism and its determinants has been lacking. Here, we conduct the first global analysis of phylogenetic endemism patterns of land vertebrates (>30,000 species), their environmental correlates, and threats. We found that low temperature seasonality and high topographic heterogeneity were the main global determinants of phylogenetic endemism. While phylogenetic endemism hotspots cover 22% of Earth, these regions currently have a high human footprint, low natural land cover, minimal protection, and will be greatly affected by climate change. Evolutionarily unique, narrow-range species are crucial for sustaining biodiversity in the face of environmental change. Our global study advances the current understanding of this imperilled yet previously overlooked facet of biodiversity.

The power, potential, and pitfalls of open access biodiversity data in range size assessments: Lessons from the fishes

Abstract Geographic rarity is a driver of a species’ intrinsic risk of extinction. It encompasses multiple key components including range size, which is one of the most commonly measured estimates of geographic rarity. Range size estimates are often used to prioritize conservation efforts when there are multiple candidate species, because data for other components of rarity such as population size are sparse, or do not exist for species of interest. Range size estimates can provide rankings of species vulnerability to changing environments or threats, identifying rare species for future study or conservation initiatives. However, range sizes can be estimated by several different metrics, and the degree of overlap in the identification of the rarest or most common species across methodologies is not well understood. This knowledge gap compromises our ability to prioritize correctly rare species, and presents a particularly difficult challenge for stream-dwelling organisms with distributions constrained to river networks. We evaluated the relationship of multiple range size estimates of a subset of freshwater fishes native to the United States to determine the degree of overlap in rarity rankings using different data sources and grain sizes. We used publicly available, open access data from the Global Biodiversity Information Facility (GBIF) to calculate extent of occurrence (minimum convex polygons) and area of occupancy (total area occupied, measured across various grain sizes). We compared range sizes estimated using GBIF data with the best available estimates of current distributions described by publicly available digital maps (NatureServe) to evaluate the efficacy of GBIF data in assessments of range size. We found strong correlations between range size estimates across analytical approaches and data sources with no detectable bias of taxonomy. We found that variation among rarity rankings was highest for species with intermediate range sizes indicating that the approaches considered here generally converge when used to identify the rarest or the most common species. Importantly, our results show that the rarest, and perhaps the most vulnerable, species are consistently identified across common methodological approaches. More broadly, our results support the use of open access biodiversity data that include opportunistically collated and collected point occurrence records as a complement to coarse-grain (e.g., whole range map) approaches, as we observed no systematic bias or deviation across data sources in our analyses. This indicates databases such as the GBIF may help fill important fundamental and applied knowledge gaps for many poorly understood species, particularly in a broad-scale, multispecies framework.

Application of multiple-population viability analysis to evaluate species recovery alternatives.

Population viability analysis (PVA) is a powerful conservation tool, but it remains impractical for many species, particularly species with multiple, broadly distributed populations for which collecting suitable data can be challenging. A recently developed method of multiple-population viability analysis (MPVA), however, addresses many limitations of traditional PVA. We built on previous development of MPVA for Lahontan cutthroat trout (LCT) (Oncorhynchus clarkii henshawi), a species listed under the U.S. Endangered Species Act, that is distributed broadly across habitat fragments in the Great Basin (U.S.A.). We simulated potential management scenarios and assessed their effects on population sizes and extinction risks in 211 streams, where LCT exist or may be reintroduced. Conservation populations (those managed for recovery) tended to have lower extinction risks than nonconservation populations (mean = 19.8% vs. 52.7%), but not always. Active management or reprioritization may be warranted in some cases. Eliminating non-native trout had a strong positive effect on overall carrying capacities for LCT populations but often did not translate into lower extinction risks unless simulations also reduced associated stochasticity (to the mean for populations without non-native trout). Sixty fish or 5-10 fish/km was the minimum reintroduction number and density, respectively, that provided near-maximum reintroduction success. This modeling framework provided crucial insights and empirical justification for conservation planning and specific adaptive management actions for this threatened species. More broadly, MPVA is applicable to a wide range of species exhibiting geographic rarity and limited availability of abundance data and greatly extends the potential use of empirical PVA for conservation assessment and planning.

A multicriteria decision making approach to prioritise vascular plants for species-based conservation

There is a growing demand for species-based conservation to be strategic and deliver the greatest possible benefits for the money and resources invested. There is no global consensus on what constitutes an important species, but many biodiversity conservation initiatives prioritise the most rare, unique, vulnerable and/or useful as deserving attention. Currently, a wide range of prioritisation methods using varied criteria are available, but it can be difficult for conservation managers to choose the appropriate protocol best suited to their conservation purposes, and to combine the protocols that are available.The prioritisation process proposed here is integrative, adaptable, straightforward and transparent, and open to refinement by interested parties. Based on the availability of taxon level data, from an initial list of 337,137 accepted scientific names, we produced a conservation priority list for 25,025 vascular plant taxa (pteridophytes, gymnosperms and angiosperms) that accounts for their geographic rarity or endemism, taxonomic rarity or uniqueness, vulnerability to extinction and natural capital value by means of a multicriteria decision making approach. This list represents about 4.47% of pteridophyte, 36.12% of gymnosperm and 7.41% of angiosperm global diversity. The list consisted of a high percentage of taxa from South America (30%), Africa (23%) and North America (22%) followed by Asia-Temperate and Europe (each 15%) and Asia-Tropical (14%) with a low percentage from Australasia (6%), the Pacific (5%) and Antarctic (~2%). The occurrence of some taxa was reported from more than one geographic continent.We found 573 taxa (2%) had a high priority status, 21,707 taxa (87%) had a medium priority status and 2745 taxa (11%) had a low priority status for conservation. Results were validated against existing prioritisation schemes with a global or continental focus. The resulting list of plants with priority status along with their geographical distribution patterns should complement, not replace, existing conservation plans. Our method can be used as a rapid and preliminary assessment technique in prioritising vascular plants and has the scope to be used globally across various conservation activities.

Terrestrial vertebrates as surrogates for selecting conservation areas in a biodiversity hotspot in Mexico

Systematic conservation planning (SCP) identifies priority areas for biodiversity conservation using surrogates for adequate representation of biodiversity content. The use of multiple well‐known taxonomic groups rather than single ones as a surrogate set is expected to enable a better representation of most important biodiversity constituents in prioritizing conservation areas. We quantitatively analyzed if single‐ or multitaxa groups of terrestrial vertebrates serve best as surrogates for representing biodiversity constituents in the state of Oaxaca, a biodiversity hotspot in southern Mexico. We produced species distribution models for 1,063 terrestrial vertebrate species using a maximum entropy algorithm. To determine which fraction of each terrestrial vertebrate group best represented the remaining groups, we produced solutions requiring different proportions of species to be represented with a 10% target of the species' potential distribution in conservation area networks. Precedence to geographical rarity, minimizing area, and enhancing compactness in shape of the selected priority areas was established using ConsNet. We further evaluated performance with surrogacy graphs for determining the representation of each group of terrestrial vertebrates treated as biodiversity constituents. Inclusion of multiple terrestrial vertebrate groups as surrogates performed best for the representation of biodiversity constituents compared to a single terrestrial vertebrate group, in all solutions with different proportions of species in these conservation areas. Terrestrial vertebrate species were poorly represented in the few protected areas (<2% of species), but representation increased significantly (99% of species) when complemented with other established conservation initiatives. SCP should include multitaxa surrogate sets and all established conservation initiatives to ensure priority areas for conservation with an adequate biodiversity representation.

Terrestrial vertebrates as surrogates for selecting conservation areas in a biodiversity hotspot in Mexico

Systematic conservation planning (SCP) identifies priority areas for biodiversity conservation using surrogates for adequate representation of biodiversity content. The use of multiple well‐known taxonomic groups rather than single ones as a surrogate set is expected to enable a better representation of most important biodiversity constituents in prioritizing conservation areas. We quantitatively analyzed if single‐ or multitaxa groups of terrestrial vertebrates serve best as surrogates for representing biodiversity constituents in the state of Oaxaca, a biodiversity hotspot in southern Mexico. We produced species distribution models for 1,063 terrestrial vertebrate species using a maximum entropy algorithm. To determine which fraction of each terrestrial vertebrate group best represented the remaining groups, we produced solutions requiring different proportions of species to be represented with a 10% target of the species' potential distribution in conservation area networks. Precedence to geographical rarity, minimizing area, and enhancing compactness in shape of the selected priority areas was established using ConsNet. We further evaluated performance with surrogacy graphs for determining the representation of each group of terrestrial vertebrates treated as biodiversity constituents. Inclusion of multiple terrestrial vertebrate groups as surrogates performed best for the representation of biodiversity constituents compared to a single terrestrial vertebrate group, in all solutions with different proportions of species in these conservation areas. Terrestrial vertebrate species were poorly represented in the few protected areas (<2% of species), but representation increased significantly (99% of species) when complemented with other established conservation initiatives. SCP should include multitaxa surrogate sets and all established conservation initiatives to ensure priority areas for conservation with an adequate biodiversity representation.

Functional and geographic components of risk for climate sensitive vertebrates in the Pacific Northwest, USA

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.

Anthropogenic landscapes support fewer rare bee species

The response of rare species to human land use is poorly known because rarity is difficult to study; however, it is also important because rare species compose most of biodiversity, and are disproportionately vulnerable. Regional bee pollinator faunas have not been assessed for rarity outside of Europe. Therefore, we do not know to what extent anthropogenic landscapes support rare North American bee biodiversity. We ask how richness and abundance of bee species respond to land use, within quartiles of species defined by their numerical, phenological, and geographical rarity. We conducted a field study to sample bee communities in forested, agricultural, and urban landscapes replicated across a large spatial extent of the northeastern United States. We used large independent data sets to classify observed bee species according to three forms of rarity: their numerical rarity (low regional frequency in a museum-based data set), phenological rarity (short flight season length) and geographical rarity (small range size). For all three forms of rarity, we found half as many rare bee species in agricultural landscapes compared to forest. We found half as many phenologically rare species in urban landscapes. Bees that had both shorter flight seasons and smaller range sizes were between one-third and one-half as rich in both types of anthropogenic landscapes, regardless of regional frequency. Although a minority of rare bee species were found in anthropogenic landscapes, our overall conclusion is that the native vegetation of our region, forest, is critical for supporting rare bee biodiversity.

Designating conservation priorities for Southeast European hoverflies (Diptera: Syrphidae) based on species distribution models and species vulnerability

Abstract Information on the distribution and vulnerability of invertebrates is often scarce and, as a consequence, this group of organisms is usually neglected in conservation studies. Yet it is possible to reasonably infer ranges and vulnerabilities of species and establish spatial conservation priorities, even with incomplete information. We investigated conservation priorities of hoverflies in Southeast Europe based on species distribution models (SDM) and vulnerability indices. Species distribution models were used to compensate for the lack of knowledge on species ranges. Measures related to geographical rarity, endemism and habitat specialisation were used to assess species vulnerability. Potential distribution and three alternative vulnerability indices were used to calculate two spatial conservation indices: potential Biodiversity Conservation Concern index (pBCC) and potential Biodiversity Conservation Weight (pBCW). pBCC highlighted areas with a large proportion of highly vulnerable species, even where species richness was low, such as the Danube delta and mid‐Aegean islands. It also identified potentially important areas yet‐to‐be surveyed (e.g. Carpathian mountains), which might deserve future conservation measures. pBCW emphasised areas hosting high richness of both vulnerable and resilient species, such as the eastern Aegean Islands and the eastern part of Crete. We demonstrate that: (i) it is possible to establish conservation priorities at large scales if SDM and simple vulnerability measures are combined; (ii) complementary approaches are necessary to emphasise the importance of areas with different characteristics; and (iii) several understudied areas should be targets of future sampling schemes to confirm their importance for the conservation of hoverfly diversity in Southeast Europe.

Geospatial data of freshwater habitats for macroecological studies: an example with freshwater fishes

Global data sets are essential in macroecological studies. File formats of the few available data sets of freshwater ecosystems, however, are either incompatible with most macroecological software packages, incomplete, or of coarse spatial resolutions. We integrated more than 460 million geographical coordinates for freshwater habitats in the FRWater data set, partitioned into seven different habitats (lentic, wetlands, reservoirs, small rivers, large rivers, small ditches, large ditches, small channels, large channels, small drains and large drains) in ModestR (http://www.ipez.es/ModestR). A comprehensive collection of geospatial rasters was assembled, one for each of the seven freshwater habitats, with the area in km2 occupied by each habitat presented in cells of 5 arc-minute resolution. The utility of FRWater was evaluated using hierarchical partitioning via the identification of the contribution of the seven different freshwater habitats to both species richness and rarity. To this end, we used a data set of 836,123 geographical records of the 16,216 species of freshwater fishes recognized as valid by systematists at the end of 2014. Areas in North America and Europe are the most detailed in the FRWater data set, evidencing the higher quality of data sources in those regions. The number of geographical coordinates is much lower for Africa, Asia, Australia, and South America where many water bodies remain unmapped. In light of the variation in information quality at continental levels, we performed and present comparative analyses for Europe versus South America at local (5ʹ × 5ʹ grid cells) and regional (5° × 5° grid cells) scales. The relative contribution of small rivers to both species richness and rarity was highest under almost all analyses, followed by lentic habitats and large rivers. The areas of different habitats moreover explained a relatively high proportion of the observed variance in geographic rarity. Our findings corroborate previous findings that the greater contribution of small rivers to species richness is probably due to these habitats promoting geographical rarity. Hence, species richness is favored by the isolation resultant from, and the refuges associated with, small river basins and via the diversification processes promoted by such isolation.

Global diversity patterns of freshwater fishes – potential victims of their own success

AbstractAimTo examine the pattern and cumulative curve of descriptions of freshwater fishes world‐wide, the geographical biases in the available information on that fauna, the relationship between species richness and geographical rarity of such fishes, as well as to assess the relative contributions of different environmental factors on these variables.LocationGlobal.MethodsModestR was used to summarize the geographical distribution of freshwater fish species using information available from data‐based geographical records. The first‐order jackknife richness estimator was used to estimate the completeness of such data in all terrestrial 1‐degree cells world‐wide. An α‐shape procedure was used to build range maps capable of providing relatively accurate species richness and geographical rarity values for each grid cell. We also examined the explanatory capacity of a high number of environmental variables using multiple regressions and Support Vector Machine.ResultsCumulative species description curves show that a high number of species of freshwater fishes remain to be discovered. Completeness values indicate that only 199 one‐degree grid cells, mainly located in eastern North America and Europe, could be considered as having relatively accurate inventories. Range maps provide species richness values that are positively and significantly related to those resulting from the first‐order jackknife richness estimator. The relationship between species richness and geographical rarity is triangular, so that these species‐rich cells are those with a higher proportion of distributionally rare species. Species richness is predicted by climatic and/or productivity variables but geographical rarity is not.Main conclusionsIn general, species‐rich tropical areas harbour a higher number of narrowly distributed species although comparatively species‐poor subtropical cells may also contain narrowly distributed species. Historical factors may help to explain the faunistic composition of these latter areas; a supposition also supported by the low predictive capacity of climatic and productivity variables on geographical rarity values.

Global Distribution and Conservation of Evolutionary Distinctness in Birds

Integrated, efficient, and global prioritization approaches are necessary to manage the ongoing loss of species and their associated function. "Evolutionary distinctness" measures a species' contribution to the total evolutionary history of its clade and is expected to capture uniquely divergent genomes and functions. Here we demonstrate how such a metric identifies species and regions of particular value for safeguarding evolutionary diversity. Among the world's 9,993 recognized bird species, evolutionary distinctness is very heterogeneously distributed on the phylogenetic tree and varies little with range size or threat level. Species representing the most evolutionary history over the smallest area (those with greatest "evolutionary distinctness rarity") as well as some of the most imperiled distinct species are often concentrated outside the species-rich regions and countries, suggesting they may not be well captured by current conservation planning. We perform global cross-species and spatial analyses and generate minimum conservation sets to assess the benefits of the presented species-level metrics. We find that prioritizing imperiled species by their evolutionary distinctness and geographic rarity is a surprisingly effective and spatially economical way to maintain the total evolutionary information encompassing the world's birds. We identify potential conservation gaps in relation to the existing reserve network that in particular highlight islands as effective priority areas. The presented distinctness metrics are effective yet easily communicable and versatile tools to assist objective global conservation decision making. Given that most species will remain ecologically understudied, combining growing phylogenetic and spatial data may be an efficient way to retain vital aspects of biodiversity.

Priority setting by sites and by species using rarity, richness and phylogenetic diversity: the case of neotropical glassfrogs (Anura: Centrolenidae)

The identification of priority areas and species for conservation is an urgent endeavor in view of environmental changes threatening biological diversity. New macroecological tools that take advantage of the rapid accumulation of distribution and phylogenetic data have been developed recently to tackle that challenge. Here we use the novel concept of the diversity and dispersion fields, complemented with phylogenetic information, to identify priorities for the conservation of neotropical glass frogs (Centrolenidae), both from the perspective of sites and of species. Through the novel approach used here, the priority level of species and sites could be determined by combinations of different traits based both on diversity (species richness and phylogenetic diversity) and distribution (geographic rarity and phylogenetic endemism). Patterns of diversity and distribution for Centrolenidae, such as extreme level of restrictedness, high levels of rarity and high segregation among species, were readily revealed by the use of range-diversity plots. Results were in some cases consistent with studies based on traditional analyses, but the inclusion of phylogenetic information added a historical-evolutionary perspective that further enhanced the analyses. We identified priority species (such as Rulyrana susatamai and Nymphargus griffithsi) and sites (such as the Guiana Shield) that harbor the evolutionary history of the group but that had been overlooked in prior studies. We suggest that for priority setting and gap analysis, phylogenetic information should not be treated as a full substitute for traditional measures of diversity but as a complementary tool.

Incorporating Geographical and Evolutionary Rarity into Conservation Prioritization

Key goals of conservation are to protect both species and the functional and genetic diversity they represent. A strictly species-based approach may underrepresent rare, threatened, or genetically distinct species and overrepresent widespread species. Although reserves are created for a number of reasons, including economic, cultural, and ecological reasons, their efficacy has been measured primarily in terms of how well species richness is protected, and it is useful to compare how well they protect other measures of diversity. We used Proteaceae species-occurrence data in the Cape Floristic Region of South Africa to illustrate differences in the spatial distribution of species and evolutionary diversity estimated from a new maximum-likelihood molecular phylogeny. We calculated species richness, phylogenetic diversity (i.e., summed phylogenetic branch lengths in a site), and a site-aggregated measure of biogeographically weighted evolutionary distinctiveness (i.e., an abundance weighted measure that captures the unique proportion of the phylogenetic tree a species represents) for sites throughout the Cape Floristic Region. Species richness and phylogenetic diversity values were highly correlated for sites in the region, but species richness was concentrated at a few sites that underrepresented the much more spatially extensive distribution of phylogenetic diversity. Biogeographically weighted evolutionary diversity produced a scheme of prioritization distinct from the other 2 metrics and highlighted southern sites as conservation priorities. In these sites, the high values of biogeographically weighted evolutionary distinctiveness were the result of a nonrandom relation between evolutionary distinctiveness and geographical rarity, where rare species also tended to have high levels of evolutionary distinctiveness. Such distinct and rare species are of particular concern, but are not captured by conservation schemes that focus on species richness or phylogenetic diversity alone.