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1.
Abstract: Phylogenetic diversity measures rank areas for biodiversity conservation priorities based on information encoded in phylogenies (cladograms). The goal of these ranks for conservation is to consider as many factors as possible that provide additional taxic information, such as taxa richness, taxa distributional patterns, area endemicity, and complementarity between areas. At present there are many measures that consider phylogenetic information, including node-based, genetic-distance, and feature-based measures. We devised a modified phylogenetic node-based index that we call "taxonomic endemicity standardized weight," which considers not only the taxonomic distinctness of the taxa that inhabit a given area but their endemicity as well. Once the standardized weight of the taxonomic endemicity identifies the area of highest priority, complementarity can be used to identify the second area and so on. We used this node-based index to rank priority areas for conservation in southern South America, and we compared the results of our rankings to results based on other node-based indexes. Our index identified Santiago district, in Central Chile province, as the highest priority area for conservation, followed by Maule, Malvinas, and districts of Subantarctic province. Malvinas exhibits greater complementarity relative to Santiago than Maule does, however, so Malvinas is ranked second in priority. Indexes based on phylogenetic information measure the evolutionary component of biodiversity and allow one to identify areas that will ensure the preservation of evolutionary potential and phylogenetically rare taxa. The modified index we propose is sensitive to taxic distinctness and endemicity as well and allows information from diverse taxa to be combined (i.e., different cladograms). The use of complementarity allows for preservation of the maximum quantity of taxa in a minimal number of protected areas.  相似文献   

2.
Surrogates, such as umbrella species, are commonly used to reduce the complexity of quantifying biodiversity for conservation purposes. The presence of umbrella species is often indicative of high taxonomic diversity; however, functional diversity is now recognized as an important metric for biodiversity and thus should be considered when choosing umbrella species. We identified umbrella species associated with high taxonomic and functional biodiversity in urban areas in Switzerland. We analyzed 39,752 individuals of 574 animal species from 96 study plots and 1397 presences of 262 plant species from 58 plots. Thirty‐one biodiversity measures of 7 taxonomic groups (plants, spiders, bees, ground beetles, lady bugs, weevils and birds) were included in within‐ and across‐taxa analyses. Sixteen measures were taxonomical (species richness and species diversity), whereas 15 were functional (species traits including mobility, resource use, and reproduction). We used indicator value analysis to identify umbrella species associated with single or multiple biodiversity measures. Many umbrella species were indicators of high biodiversity within their own taxonomic group (from 33.3% in weevils to 93.8% in birds), to a lesser extent they were indicators across taxa. Principal component analysis revealed that umbrella species for multiple measures of biodiversity represented different aspects of biodiversity, especially with respect to measures of taxonomic and functional diversity. Thus, even umbrella species for multiple measures of biodiversity were complementary in the biodiversity aspects they represented. Thus, the choice of umbrella species based solely on taxonomic diversity is questionable and may not represent biodiversity comprehensively. Our results suggest that, depending on conservation priorities, managers should choose multiple and complementary umbrella species to assess the state of biodiversity. Selección de Múltiples Especies Paraguas para la Diversidad Funcional y Taxonómica para Representar la Biodiversidad Urbana  相似文献   

3.
Abstract:  We are now entering a time of immense environmental upheaval in which, increasingly, experts are required to provide conservation assessments. Quantitative assessment of trends in species' range and abundance is costly, requiring extensive field studies over a long period of time. Unfortunately, many species are only known through a few "chance" sightings or a handful of specimens, and therefore extinction may be even harder to ascertain. Several methods have been proposed for estimating the probability of extinction. However, comparison within and between species is difficult because of variations in sighting rates. We applied a probabilistic method that incorporates sighting rate to the sighting record of Vietnamese slipper orchids ( Paphiopedilum ). The method generates a probability that another sighting will occur given the previous sighting rate and the time since last observation. This allows greater comparability between species discovered at different times. Its predictions were more highly correlated with the World Conservation Union criteria than previous methods. Trends in data collection and the political climate of a country, which affects access to material, are important potential sources of variation that affect sighting rates. A lack of understanding of the process by which data are generated makes inferring extinction from sighting records difficult because extinction status depends on how the sighting rate varies. However, such methods allow rapid conservation prioritization of taxa that are poorly known and would otherwise go unassessed.  相似文献   

4.
崖爬藤属在中国物种分化特别多样。文中列出的国产种类是在对中国、印度支那半岛、印度半岛和喜马拉雅地区等植物种类的研究基础之上确定的。通过对上述不同地区存放在中国和法国巴黎自然历史博物馆(P)、英国邱园(K)及爱丁堡(E)皇家植物园等标本馆藏植物种类的比较研究,提出了本属植物的一个新分类系统,发表了国产的一些新分类群,也作了一些新组合。  相似文献   

5.
Abstract: The level of endemism at a site may indicate species richness of the site. Nevertheless, assessing endemism levels in taxonomic groups such as plants may be difficult because the species richness of plants is high relative to species richness of other taxonomic groups (e.g., vertebrates). A major problem in determining whether plant species are endemic is the lack of standardization of the geographic extent of endemism: species are considered endemic to, for example, countries, continents, or states. We compiled a history of the concept of endemism as it applies to plants. The application of the concept to geographic distribution dates from the 19th century, when European explorers discovered many taxa exclusive to regions outside Europe. Two types of endemism, paleoendemism and neoendemism, were then acknowledged, according to evolutionary age, and these categories are still in use. In the 20th century, most of the research on endemism focused on explaining range restriction on the basis of cytological data, edaphic and geological factors, and phylogeny. This research led to a vast number of concepts, of which only edaphic endemism remains relatively well accepted. More recently, researchers suggest that competition may determine endemism in some cases. We suggest that plants be labeled as endemic only if their distribution occurs in a distinct ecological unit, such as a biome. On the basis of a literature review of the factors that cause range restriction, we categorized endemic taxa as paleoendemic, neoendemic, edaphically endemic, or suppressed endemic. For example, Schlechtendalia luzulifolia, is a rare forb that is a paleoendemic species of the granite and sandstone‐based grasslands of the Pampa. Levels of endemism in southern Brazilian grasslands are poorly known. We emphasize the importance of recognizing these grasslands as a single transnational biome so that levels of endemism of species therein can be assessed correctly.  相似文献   

6.
Establishing protected areas has long been an effective conservation strategy and is often based on readily surveyed species. The potential of any freshwater taxa to be a surrogate for other aquatic groups has not been explored fully. We compiled occurrence data on 72 species of freshwater fishes, amphibians, mussels, and aquatic reptiles for the Great Plains, Wyoming (U.S.A.). We used hierarchical Bayesian multispecies mixture models and MaxEnt models to describe species’ distributions and the program Zonation to identify areas of conservation priority for each aquatic group. The landscape‐scale factors that best characterized aquatic species’ distributions differed among groups. There was low agreement and congruence among taxa‐specific conservation priorities (<20%), meaning no surrogate priority areas would include or protect the best habitats of other aquatic taxa. Common, wideranging aquatic species were included in taxa‐specific priority areas, but rare freshwater species were not included. Thus, the development of conservation priorities based on a single freshwater aquatic group would not protect all species in the other aquatic groups.  相似文献   

7.
Conservation planning based on the occurrence of rare species has been criticized as being too limited in scope to conserve biodiversity as a whole. Conversely, planning based on indicator taxa may lack sufficient focus to conserve those species in greatest need of conservation. An alternative approach is to identify a variety of species at risk that are associated with areas of conservation value, which is defined based on species-independent characteristics. We identified potential indicators of conservation value using occurrence data on species at risk and independent information on conservation value that incorporated indices of ecosystem integrity. We propose a taxonomically diverse group of indicator species that are strongly associated with areas of exceptional ecosystem integrity, to serve as a focus for further research and in planning for biodiversity conservation. We identify potential indicator species by defining a null model in which species at risk are equally associated with areas of high ecosystem integrity, then by conducting randomization tests to identify noncompliant species in the state of Michigan, USA. Areas of high ecosystem integrity are selected using criteria to flag (1) secure biotic communities with structural integrity and few exotic species, (2) natural areas subjected to expert review, (3) contiguous relict areas of forest interior, (4) contiguous areas of unmodified wetland, and (5) all these areas combined. We determine the spatial occurrence of species at risk using data from Michigan's statewide Natural Heritage database. The potential indicators include plants, insects, and birds. Their species identity and distribution of occurrences varies with the five scenarios, and together the species broadly cover the entire state. These species at risk, many of which occur throughout the Great Lakes region, may be used to identify additional areas potentially high in conservation value and to monitor their conservation. The ecological criteria and numerical methods we employ may be broadly applicable as Heritage Program databases in North America and parts of Latin America grow to become representative of species distributions.  相似文献   

8.
Abstract:  The Natura 2000 network is the most important conservation effort being implemented in Europe. Nevertheless, no comprehensive and systematic region—or nationwide evaluation of the effectiveness of the network has been conducted. We used habitat suitability models and extent of occurrence of 468 species of vertebrates to evaluate the contribution of the Natura 2000 network to biodiversity conservation in Italy. We also estimated the population size of 101 species inside the Natura 2000 network to assess its capacity to maintain or improve the population status of listed species. In general the Italian Natura 2000 did not seem to integrate existing protected areas well. The Natura 2000 network increased from 11% to 20% the area devoted to conservation in Italy and the coverage provided to areas with high biodiversity. Nevertheless, some areas with high numbers of species were devoid of conservation areas, and more than 50% of the highly irreplaceable areas were not considered in the system. Moreover, the Natura 2000 network cannot maintain 44–80% (depending on the taxa considered) of the species in a "favorable conservation status" under World Conservation Union Red List criteria. The Natura 2000 network is probably stronger than the results of our analyses suggest. The system is based on a site-specific expert-based strategy and is driven by direct and detailed knowledge of local diversity. Nevertheless, if Natura 2000 is taken to represent the final point of all the EU conservation policies, it will inevitably fail. Its role in conservation could be enhanced by integrating the Natura 2000 system into a more general strategy that considers natural processes and the ecological and evolutionary mechanisms underlying these processes.  相似文献   

9.
Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. We quantified extinctions among the vascular flora of the continental United States and Canada since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching the literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an index of taxonomic uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest that 51 species and 14 infraspecific taxa, representing 33 families and 49 genera of vascular plants, have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. Most extinctions occurred in the west, but this outcome may reflect the timing of botanical exploration relative to settlement. Sixty-four percent of extinct plants were single-site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here.  相似文献   

10.
Abstract: Analysis of geographic concentrations of endemic taxa is often used to determine priorities for conservation action; nevertheless, assumptions inherent in the taxonomic authority list used as the basis for analysis are not always considered. We analyzed foci of avian endemism in Mexico under two alternate species concepts. Under the biological species concept, 101 bird species are endemic to Mexico and are concentrated in the mountains of the western and southern portions of the country. Under the phylogenetic species concept, however, total endemic species rises to 249, which are concentrated in the mountains and lowlands of western Mexico. Twenty-four narrow endemic biological species are concentrated on offshore islands, but 97 narrow endemic phylogenetic species show a concentration in the Transvolcanic Belt of the mainland and on several offshore islands. Our study demonstrates that conservation priorities based on concentrations of endemic taxa depend critically on the particular taxonomic authority employed and that biodiversity evaluations need to be developed in collaboration or consultation with practicing systematic specialists.  相似文献   

11.
Assessing species’ extinction risk is vital to setting conservation priorities. However, assessment endeavors, such as those used to produce the IUCN Red List of Threatened Species, have significant gaps in taxonomic coverage. Automated assessment (AA) methods are gaining popularity to fill these gaps. Choices made in developing, using, and reporting results of AA methods could hinder their successful adoption or lead to poor allocation of conservation resources. We explored how choice of data cleaning type and level, taxonomic group, training sample, and automation method affect performance of threat status predictions for plant species. We used occurrences from the Global Biodiversity Information Facility (GBIF) to generate assessments for species in 3 taxonomic groups based on 6 different occurrence-based AA methods. We measured each method's performance and coverage following increasingly stringent occurrence cleaning. Automatically cleaned data from GBIF performed comparably to occurrence records cleaned manually by experts. However, all types of data cleaning limited the coverage of AAs. Overall, machine-learning-based methods performed well across taxa, even with minimal data cleaning. Results suggest a machine-learning-based method applied to minimally cleaned data offers the best compromise between performance and species coverage. However, optimal data cleaning, training sample, and automation methods depend on the study group, intended applications, and expertise.  相似文献   

12.
Abstract: Non‐native species can cause the loss of biological diversity (i.e., genetic, species, and ecosystem diversity) and threaten the well‐being of humans when they become invasive. In some cases, however, they can also provide conservation benefits. We examined the ways in which non‐native species currently contribute to conservation objectives. These include, for example, providing habitat or food resources to rare species, serving as functional substitutes for extinct taxa, and providing desirable ecosystem functions. We speculate that non‐native species might contribute to achieving conservation goals in the future because they may be more likely than native species to persist and provide ecosystem services in areas where climate and land use are changing rapidly and because they may evolve into new and endemic taxa. The management of non‐native species and their potential integration into conservation plans depends on how conservation goals are set in the future. A fraction of non‐native species will continue to cause biological and economic damage, and substantial uncertainty surrounds the potential future effects of all non‐native species. Nevertheless, we predict the proportion of non‐native species that are viewed as benign or even desirable will slowly increase over time as their potential contributions to society and to achieving conservation objectives become well recognized and realized.  相似文献   

13.
Effects of Economic Prosperity on Numbers of Threatened Species   总被引:2,自引:0,他引:2  
Abstract: We used data from over 100 countries to investigate the link between numbers of threatened species and per-capita gross national product. We corrected for factors that might otherwise confound such a relationship. Our study was motivated by the continuing debate over the relationship between environmental degradation and per-capita income. Proponents of the environmental Kuznets-curve hypothesis argue that although environmental degradation may increase initially, increases in per-capita income will eventually result in greater environmental quality. Theoretical objections and the lack of widespread empirical evidence recently have thrown doubt on the existence of such a pattern. Treating threat to biodiversity as one potential indicator of environmental degradation, we divided threatened species into seven taxonomic groups ( plants, mammals, birds, amphibians, reptiles, fishes, and invertebrates) and analyzed each group separately. Count-data regression analysis indicated that the number of threatened species was related to per-capita gross national product in five of seven taxonomic groups. Birds were the only taxonomic group in which numbers of threatened species decreased throughout the range of developed countries' per-capita gross national product. Plants, amphibians, reptiles, and invertebrates showed increasing numbers of threatened species throughout this same range. If these relationships hold, increasing numbers of species from several taxonomic groups are likely to be threatened with extinction as countries increase in prosperity. A key challenge is to understand the interactions among consumer preferences, biology, and institutions that lead to the relationship observed for birds and to see whether this knowledge can be applied to conservation of other taxa.  相似文献   

14.
Terrestrial animals are negatively affected by habitat loss, which is assessed on a landscape scale, whereas secondary effects of habitat loss, such as crowding, are usually disregarded. Such impacts are inherently hard to address and poorly understood, and there is a growing concern that they could have dire consequences. We sampled birds throughout a deforestation process to assess crowding stress in an adjacent habitat remnant in the southern Brazilian Atlantic Forest. Crowding is expected of highly mobile taxa, especially given the microhabitat heterogeneity of Neotropical forests, and we hypothesized that the arrival of new individuals or species in refuges shifts assemblage patterns. We used point counts to obtain bird abundances in a before-after-control-impact design sampling of a deforestation event. Temporal changes in taxonomic and functional diversity were examined with metrics used to assess alpha and beta diversity, turnover of taxonomic and functional similarity, and taxonomic and functional composition. Over time increased abundance of some species altered the Simpson index and affected the abundance-distribution of traits in the habitat remnant. Taxonomic composition and functional composition changed in the remnant, and thus bird assemblages changed over time. Taxonomic and functional metrics indicated that fugitives affected resident assemblages in refuges, and effects endured >2 years after the deforestation processes had ceased. Dissimilarity of taxonomic composition between pre- and postdeforestation assemblages increased, whereas functional composition reverted to preimpact conditions. We found that ecological disruptions resulted from crowding and escalated into disruptions of species’ assemblages and potentially compromising ecosystem functioning. It is important to consider crowding effects of highly mobile taxa during impact assessments, especially in large-scale infrastructure projects that may affect larger areas than is assumed.  相似文献   

15.
Conservation Biology of Caecilian Amphibians   总被引:2,自引:0,他引:2  
Abstract:  Most of the available data on declining populations of amphibians pertain to frogs and, to a lesser extent, salamanders. In keeping with their generally less understood biology, the population trends and conservation status of caecilian amphibians (Gymnophiona) are also much less known. We reviewed reports of threats to and declines of populations of caecilians. Despite a lack of field-study details (e.g., localities, dates, and sampling methods) and quantitative data, there are several recent reports of threats to and declines and extinctions of caecilians. A range of causal explanations (habitat loss, pollution, chytridiomycosis, and scientific collecting) for these perceived declines have been proposed but little or no associated evidence has been given. Although caecilians are often considered rare and thought to require pristine habitat, published, quantitative data demonstrate that at least some species can occur in high abundance in disturbed, synanthropic environments. Few estimates of caecilian population parameters have been made and very few field methods have been tested, so the assumed rarity of any taxa remains inadequately demonstrated. Distribution and taxonomic data are also inadequate. Because they are generally poorly known and often cryptic, caecilians can be overlooked in standard faunal surveys, meaning that lack of opportunistic collection over several years might not represent evidence of decline. The conservation status of most species must be considered data deficient. More precise assessments will require a substantial increase in all areas of caecilian research, especially those involving new fieldwork. Future reports of caecilian conservation biology need to be explicit and more quantitative.  相似文献   

16.
Owing to the lack of information about the distribution patterns of many taxonomic groups, biodiversity conservation strategies commonly rely on a surrogate taxa approach for identifying areas of maximum conservation potential. Macroinvertebrates or fish are the most likely candidates for such a role in many freshwater systems. The usefulness of the surrogate taxa depends largely on community concordance, i.e., the degree of similarity in community patterns among taxonomic groups across a set of sites. We examined the effect of the spatial scale of a. study on the strength of community concordance among macroinvertebrates, bryophytes, and fish by comparing the concordance between ordinations of these groups in 101 boreal stream sites. We specifically asked if communities spanning several drainages are more concordant than those originating from a single drainage system. Our results indicate that community concordance is affected by spatial extent, being variable and generally weak at the scale of individual drainages, but strong across multiple drainage systems and ecoregions. We attribute this finding to different taxonomic groups responding to similar environmental factors and sharing a similar latitudinal gradient of community structure when viewed across large spatial scales. We also identified a "gradient of concordance," with sites contributing disproportionately to community concordance being in relatively large streams with high microhabitat variability. Overall, our results suggest that the degree of community concordance among freshwater organism groups depends critically on the spatial extent of the study, and surrogate groups at the scale of single river systems should be used with caution.  相似文献   

17.
Abstract: Past and present pressures on forest resources have led to a drastic decrease in the surface area of unmanaged forests in Europe. Changes in forest structure, composition, and dynamics inevitably lead to changes in the biodiversity of forest‐dwelling species. The possible biodiversity gains and losses due to forest management (i.e., anthropogenic pressures related to direct forest resource use), however, have never been assessed at a pan‐European scale. We used meta‐analysis to review 49 published papers containing 120 individual comparisons of species richness between unmanaged and managed forests throughout Europe. We explored the response of different taxonomic groups and the variability of their response with respect to time since abandonment and intensity of forest management. Species richness was slightly higher in unmanaged than in managed forests. Species dependent on forest cover continuity, deadwood, and large trees (bryophytes, lichens, fungi, saproxylic beetles) and carabids were negatively affected by forest management. In contrast, vascular plant species were favored. The response for birds was heterogeneous and probably depended more on factors such as landscape patterns. The global difference in species richness between unmanaged and managed forests increased with time since abandonment and indicated a gradual recovery of biodiversity. Clearcut forests in which the composition of tree species changed had the strongest effect on species richness, but the effects of different types of management on taxa could not be assessed in a robust way because of low numbers of replications in the management‐intensity classes. Our results show that some taxa are more affected by forestry than others, but there is a need for research into poorly studied species groups in Europe and in particular locations. Our meta‐analysis supports the need for a coordinated European research network to study and monitor the biodiversity of different taxa in managed and unmanaged forests.  相似文献   

18.
From Red Lists to Species of Conservation Concern   总被引:3,自引:0,他引:3  
Abstract:  National red lists of threatened animal and plant species prepared according to the criteria of the World Conservation Union (IUCN) adequately reflect the extinction risk of species within a country but cannot be used directly to set conservation priorities. In particular, the significance of national populations for the conservation of the species as a whole is not taken into account. We present a procedure that can be used to assess national responsibility based on the national red-list status of a species, the international importance of the national population, and the species' "historical rarity" status. We distinguished five responsibility classes for breeding birds: B1, threatened species with internationally important populations in Switzerland; B2, threatened species with internationally less important populations; B3, nonthreatened species with internationally important populations; B4, nonthreatened species with internationally less important populations; and B5, species that have never been common in Switzerland. Two responsibility classes were distinguished for birds occurring in Switzerland as visitors: G1, species with large concentrations in Switzerland and an unfavorable conservation status in Europe, and G2, species with large concentrations in Switzerland and a favorable conservation status in Europe. Two additional classes (G3 and G4) for visiting species occurring in internationally less important numbers are possible but were not analyzed in detail. Responsibility classes B1, B2, B3, G1, and G2 were defined as species of national conservation concern. We developed the method for birds in Switzerland, but it can be used in other countries and for other taxonomic groups as well. It is particularly suitable where national red lists are established according to IUCN guidelines.  相似文献   

19.
Indicator groups may be important tools with which to guide the selection of networks of areas for conservation. Nevertheless, the literature provides little guidance as to what makes some groups of species more suitable than others to guide area selection. Using distributional data on all sub-Saharan birds and mammals, we assessed factors that influence the effectiveness of indicator groups. We assessed the influence of threatened, endemic, range-restricted, widespread, and large-bodied species by systematically varying their number in indicator groups. We also assessed the influence of taxonomic diversity by systematically varying the number of distinct genera and families within the indicator groups. We selected area networks based on the indicator groups and tested their ability to represent a set of species, which, in terms of species composition, is independent of the indicator group. Increasing the proportion of threatened, endemic, and range-restricted species in the indicator groups improved effectiveness of the selected area networks; in particular it improved the effectiveness in representing other threatened and range-restricted species. In contrast increasing the proportion of widespread and large-bodied species decreased effectiveness. Changes in the number of genera and families only marginally affected the performance of indicator groups. Our results reveal that a focus on species of special conservation concern, which are legitimate conservation targets in their own right, also improves the effectiveness of indicator groups, in particular in representing other species of conservation concern.  相似文献   

20.
Establishing protected areas is the primary goal and tool for preventing irreversible biodiversity loss. However, the effectiveness of protected areas that target specific species has been questioned for some time because targeting key species for conservation may impair the integral regional pool of species diversity and phylogenetic and functional diversity are seldom considered. We assessed the efficacy of protected areas in China for the conservation of phylogenetic diversity based on the ranges and phylogenies of 2279 terrestrial vertebrates. Phylogenetic and taxonomic diversity were strongly and positively correlated, and only 12.1–43.8% of priority conservation areas are currently protected. However, the patterns and coverage of phylogenetic diversity were affected when weighted by species richness. These results indicated that in China, protected areas targeting high species richness protected phylogenetic diversity well overall but failed to do so in some regions with more unique or threatened communities (e.g., coastal areas of eastern China, where severely threatened avian communities were less protected). Our results suggest that the current distribution of protected areas could be improved, although most protected areas protect both taxonomic and phylogenetic diversity.  相似文献   

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