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1.
Franz Essl Markus Staudinger Oliver Sthr Luise Schratt-Ehrendorfer Wolfgang Rabitsch Harald Niklfeld 《Biological conservation》2009,142(11):2547-2558
Endemic species are not a uniform group in terms of range size, habitat preferences, and ecological plasticity. Based on a recent inventory of endemic vascular plant species in Austria, we analysed distribution patterns, altitudinal distribution and habitat preferences of endemic species and analysed the correlation of range size and niche breadth. The inventory includes 103 vascular plant taxa (species and subspecies) endemic to Austria.Grid cells (cell size ca. 35 km2) with highest taxon numbers (max. 25 taxa) are limited to the Northeastern Calcareous Alps, whereas highest numbers of acidophilous endemics occur in the easternmost high-mountain chains of the Central Alps. The majority of endemics (61 taxa; 59.2%) are found on calcareous bedrock, 6 taxa (5.8%) on intermediate substrates, and 29 (28.2%) on siliceous bedrock. The range size of endemic vascular plant taxa is strongly skewed towards very narrow distributions – 45 taxa are restricted to <20 grid cells. Average range sizes differ markedly between endemics of different broad habitat types, endemics of habitats with limited and patchy distribution (serpentine vegetation, dry grassland) having the smallest ranges.The altitudinal distribution of endemic plant taxa peaks at high altitudes, in the subalpine and lower alpine altitude belt. Below the tree line, endemics predominantly colonize extra- and azonal dry or wet habitats, whereas above the tree line, zonal alpine grassland and azonal vegetation types (scree, rocks, snowbeds) are equally essential to the endemic flora. Niche breadth of endemics is positively, however moderately, correlated with range size. This correlation is stronger for the altitudinal distribution than for the number of habitats colonized.The distribution patterns and ecology of endemics differ considerably from overall biodiversity patterns and must be addressed appropriately in conservation strategies. Small niche-breadths and the specific habitat requirements of endemics of very localized distribution render these taxa highly vulnerable to climate change. 相似文献
2.
Víctor Sánchez-Cordero Patricia Illoldi-Rangel Sahotra Sarkar 《Biological conservation》2005,126(4):465-473
Deforestation threatens biodiversity conservation worldwide, but little quantitative information is available on how it affects individual species’ distributions. We modeled potential distributions of 85 continental endemic Mexican mammal species using ecological niche modeling, and produced testable predictions of species’ extant distributions by limiting ecological niches to remnant untransformed habitat based on the Inventario Nacional Forestal 2000. We included point occurrence data for all endemics only from collecting localities prior to 1970, before wide areas of habitat transformation occurred nationwide. Most endemics (61 of 85, 72%) showed a high proportion of transformed habitat (34.5%) at the national level. More than one-fourth of the endemics (23 out of 85, 27%) lost more than 50% of untransformed habitat within their potential distributions; two showed drastic areal loss of more than 90%; another two showed a loss of more than 80%. Only 34 of the endemics are listed as endangered or threatened in the Mexican Norma Oficial Mexicana (NOM). No significant association existed between proportional loss and conservation status as assigned in the NOM, nor are correlations significant between original distributional area and area of remnant untransformed habitat. Both findings suggest that geographic location determines extinction risks rather than area per se. Endemics in the state of Veracruz and in the Transvolcanic Belt suffered the most drastic niche reductions and thus appear to be at high extinction risk from further deforestation. 相似文献
3.
Serpentine soils represent a stressful growing environment for most plants due to a number of edaphic factors, including low concentrations of plant nutrients and high concentrations of heavy metals. Plants in these environments range from weakly resistant to strictly endemic, yet it remains unclear whether serpentine habitat affinity affects plant chemistry, including elemental distribution among various organs. We address this knowledge gap using three confamilial pairs of endemic and non‐endemic plants. First, we determined total and phytoavailable soil concentrations of four nutrients (Ca, Mg, P, K) and three heavy metals (Co, Cr, Ni) across 11 serpentine study sites. Next, we determined the concentrations of these elements in leaves, flowers, and seeds in plants of each species growing on serpentine soil. Soils at the study sites were characteristically high in concentrations of Mg, Ni, Co and Cr, and low in K, P and Ca relative to non‐serpentine soils. Habitat affinity was critical in determining the organ concentrations of Ca, Mg, K, and Co, although concentration often varied by organ type. Relative to non‐endemics, endemics had higher concentrations of Mg and K across all organ types, whereas Ca concentrations were higher for non‐endemics in the leaves but equal for the two reproductive organs. While no difference was observed in Ni or Cr concentrations, endemics contained 56% less Co than non‐endemics across all organ types. These results suggest that serpentine endemics are more effective at acquiring potentially limiting nutrients compared to non‐endemic species, but both endemic and non‐endemic plants exclude most phytotoxic heavy metals. Therefore, growth on serpentine requires common physiological responses of all plants, though high variation in uptake of some key nutrients and exclusion of some metals may reflect differential adaptation to serpentines by non‐endemic and endemic plants. 相似文献
4.
Significant changes in the climates of Central America are expected over the next century. Lowland rainforests harbor high alpha diversity on local scales (<1 km2), yet montane landscapes often support higher beta diversity on 10-100 km2 scales. Climate change will likely disrupt the altitudinal zonation of montane communities that produces such landscape diversity. Projections of biotic response to climate change have often used broad-scale modelling of geographical ranges, but understanding likely impacts on population viability is also necessary for anticipating local and global extinctions. We model species’ abundances and estimate range shifts for birds in the Tilarán Mountains of Costa Rica, asking whether projected changes in temperature and rainfall could be sufficient to imperil high-elevation endemics and whether these variables will likely impact communities similarly. We find that nearly half of 77 forest bird species can be expected to decline in the next century. Almost half of species projected to decline are endemic to Central America, and seven of eight species projected to become locally extinct are endemic to the highlands of Costa Rica and Panamá. Logistic-regression modelling of distributions and similarity in projections produced by temperature and rainfall models suggest that changes in both variables will be important. Although these projections are probably conservative because they do not explicitly incorporate biological or climate variable interactions, they provide a starting point for incorporating more realistic biological complexity into community-change models. Prudent conservation planning for tropical mountains should focus on regions with room for altitudinal reorganization of communities comprised of ecological specialists. 相似文献
5.
Biodiversity in Africa, Madagascar and smaller surrounding islands is both globally extraordinary and increasingly threatened. However, to date no analyses have effectively integrated species values (e.g., richness, endemism) ‘non-species’ values (e.g., migrations, intact assemblages), and threats into a single assessment of conservation priorities. We present such an analysis for the 119 ecoregions of Africa, Madagascar and smaller islands. Biodiversity is not evenly distributed across Africa and patterns vary somewhat among taxonomic groups. Analyses of most vertebrates (i.e., birds, mammals, amphibians) tend to identify one set of priority ecoregions, while plants, reptiles, and invertebrates highlight additional areas. ‘Non-species’ biological values are not correlated with species measures and thus indicate another set of ecoregions. Combining species and non-species values is therefore crucial for assembling a comprehensive portfolio of conservation priorities across Africa. Threats to biodiversity are also unevenly distributed across Africa. We calculate a synthetic threat index using remaining habitat, habitat block size, degree of habitat fragmentation, coverage within protected areas, human population density, and the extinction risk of species. This threat index is positively correlated with all three measures of biological value (i.e., richness, endemism, non-species values), indicating that threats tend to be focused on the region’s most important areas for biodiversity. Integrating biological values with threats allows identification of two distinct sets of ecoregion priority. First, highly imperilled ecoregions with many narrow endemic species that require focused actions to prevent the loss of further habitat leading to the extinction of narrowly distributed endemics. Second, less threatened ecoregions that require maintenance of large and well-connected habitats that will support large-scale habitat processes and associated area-demanding species. By bringing these data together we can be much more confident that our set of conservation recommendations serves the needs of biodiversity across Africa, and that the contribution of different agencies to achieving African conservation can be firmly measured against these priorities. 相似文献
6.
The analysis and comparison of endemic plants in southeast France (215 taxa representing 7.2% of the flora) and in Corsica (240 taxa, 11% of the flora) exhibit similar ecological preferences and life strategies (sensu Grime). Both show a clear altitudinal zonation, a predominance of stress-tolerant taxa and an ability to colonize harsh habitats (with low competition and disturbance). The particular characteristics of these endemics primarily reflect the richness, topography and history of the specialized habitats of the regions involved. However, the degree of isolation and the intensity of competition probably helps to explain the contraction of some endemic species' niches in southeast France, and conversely the expansion of these niches in Corsica. The analysis of data related to comparable territories in the Mediterranean and throughout southern Europe, seems to show that: (1) mountain isolation has generally been more favourable to endemism than insularity; and (2) the degree of endemism often decreases as floristic richness increases. Finally, 32% of endemic plants are threatened in Corsica, and 28% in southeast France. The low altitude zones are most affected, particularly coastal areas, rocky grasslands and damp ecosystems, but the risks now extend throughout all sectors due to the increase of human activities. Faced with these major threats, in situ protective action must be taken immediately through appropriate management of indigenous populations, and scientific studies undertaken to analyse population viability. 相似文献
7.
Lyubov E. Burlakova Alexander Y. Karatayev Vadim A. Karatayev Marsha E. May Daniel L. Bennett Michael J. Cook 《Biological conservation》2011,(1):155-165
The biodiversity crisis, particularly dramatic in freshwaters, has prompted further setting of global and regional conservation priorities. Species rarity and endemism are among the most fundamental criteria for establishing these priorities. We studied the patterns of rarity and the role of rare species in community uniqueness using data on freshwater bivalve molluscs (family Unionidae) in Texas. Due to the large size and gradients in landscape and climate, Texas has diverse and distinct unionid communities, including numerous regional and state endemic species. Analysis of the state-wide distribution and abundance of Unionidae allowed us to develop a non-arbitrary method to classify species rarity based on their range size and relative density. Of the 46 Unionidae species currently present in Texas, 65% were classified as rare and very rare, including all state and regional endemics. We found that endemic species were a critical component in defining the uniqueness of unionid communities. Almost all endemics were found exclusively in streams and rivers, where diversity was almost double that of lentic waters. Man’s ongoing alteration of lotic with lentic waterbodies favors common species, and dramatically reduces habitat for endemics, contributing to homogenization of unionid fauna. We identified hotspots of endemism, prioritized species in need of protection, estimated their population size, and recommended changes to their current conservation status. 相似文献
8.
Hilary Crusz 《Biological conservation》1973,5(3):199-208
Sri Lanka (Ceylon) was once part of an Indo-Malayan and Afro-Madgascan complex, and has three peneplains. These circumtances are reflected in her fauna and flora, of which 28·5 per cent of the vascular plants and 16 per cent of the land vertebrates are endemic, inhabiting mostly the central montane and southwestern regions. Such figures could provide indices or coefficients of insularity of islands of the nature of Sri Lanka and Madagascar. The parasites of the endemics and relicts could also point to the relationships of the hosts and the antiquity of the geographical regions. Nearly all the wildlife reserves are in the dry northern and eastern halves of the island, in areas of monsoon scrub-jungle, monsoon forest, or grassland. Further strict natural reserves are urgently needed in the montane and southwestern rain-forest and grassland areas. Significant conservation measures have been taken since 1885 by the Government and by what in 1971 was renamed the Wildlife and Nature Protection Society of Ceylon. Constitutional changes have also had their impact, while human population increase has affected land utilization and the extents of nature reserves. Twenty-seven mammal, 340 bird, 7 reptile, and 9 plant, species are absolutely protected. Despute such efforts, conservation science and practice, based on ecological studies, have lagged behind, but some progress is being made through the work of foreign and local scientists, and the new interest taken by Government and the universities. That Sri Lanka is well suited to effective nature conservation is shown also by the ethos of her people, as shaped by Buddhist teachings and by the concern of kings during her long history. 相似文献
9.
David J. Lohman Krista K. Ingram Kevin Winker Robert G. Moyle Perry S. Ong Thomas M. Braile Dwi Astuti 《Biological conservation》2010,143(8):1885-1890
Mistakenly classifying morphologically cryptic endemic species as populations of widespread species potentially interferes with the conservation of biodiversity because undetected endemics that are imperilled may lack appropriate protection. It also impedes the reconstruction of the evolutionary history of a taxon by obscuring the number and distributional limits of species. Here, we present genetic and phylogenetic evidence corroborated by morphology that Philippine populations of seven widespread, non-migratory passerine birds might represent unrecognized, distinct species. An extrapolation based on this finding suggests that the proportion of endemic bird species in the Philippines could be much higher than currently estimated. This high degree of cryptic diversity in a well-studied, volant taxon implies that large numbers of unrecognized species can be expected in less thoroughly studied groups. We predict that genetic investigations of insular populations of widespread species will frequently reveal unrecognized island endemics, and because of the vulnerability of island habitats and their biota, these taxa may be particularly susceptible to extinction. 相似文献
10.
Christopher W. Hoagstrom James E. Brooks Stephen R. Davenport 《Biological conservation》2011,(1):21-34
Regions with unique habitats often harbor endemic taxa associated with temporally stable habitats. We identified such habitats that sustain endemic fishes in the plains of North America. We also summarized threats to their conservation and identified remnant habitats that still harbor endemic fishes (refuges) based on post-1989 surveys. Major springs, smaller, spring-fed streams, larger rivers, and euryhaline habitats were associated with a total of 49 endemics. Endemism was attributable to climatic refugia associated with each habitat type and dispersal limitation among major river drainages and springs. Forty-one endemic fishes (84%) were declining or extinct. Dewatering, habitat fragmentation, and habitat degradation were main causes of declines, often present together. Pollution and non-native species were also threats in many cases. Evidence for 53 existing refuges was found. We considered 34 refuges to be “high-quality” because they harbored three or more endemics. Twenty of these (those with available data) maintained consistent streamflow regimes for at least 50 years up to 2009. Case studies suggest high stream length, more natural flow regimes, and fewer direct human impacts are features of high-quality refuges, but extinction thresholds are unquantified and extinction debts of refuges are unknown. Limited information on past extinctions suggests drought, a natural feature of the plains, combines with other threats to eliminate remnant endemic populations. Long-term conservation planning requires identification, protection, and restoration of high-quality refuges to reduce extinction risk, especially during future drought periods. Planning should be integrated with regional water resource planning, given scarcity of water in the region. 相似文献
11.
Neil Cumberlidge Peter K.L. Ng Celio Magalhães Savel R. Daniels 《Biological conservation》2009,142(8):1665-2610
Freshwater ecosystems in the tropics host a diverse endemic fauna including freshwater crabs, but the rapid loss and deterioration of habitat means that many species are now under imminent threat. Studies on freshwater fish and amphibians suggest a third to half of the species in some tropical freshwaters is either extinct or endangered, but the status of the freshwater crabs is not known. Freshwater crabs, with 1280 species, represent one-fifth of all the World’s brachyurans. We therefore undertook a comprehensive IUCN Red List assessment of the freshwater crabs, which was the first time that such a study had been attempted on a global scale for any group of freshwater invertebrates. The conservation status of all known species from the Americas, Africa, Europe, Asia, and Australasia revealed unexpectedly high threat levels. Here we show that about one-sixth of all freshwater crab species have an elevated risk of extinction, only one-third are not at-risk, and although none are actually extinct, almost half are too poorly known to assess. Out of 122 countries that have populations of freshwater crabs, 43 have species in need of protection. The majority of threatened species are restricted-range semi-terrestrial endemics living in habitats subjected to deforestation, alteration of drainage patterns, and pollution. This is illustrated with a case study of one such species found in Singapore. This underlines the need to prioritize and develop conservation measures before species decline to levels from which they cannot recover. The proportion of freshwater crabs threatened with extinction is equal to that of reef-building corals, and exceeds that of all other groups that have been assessed except for amphibians. These results represent a baseline that can be used to design strategies to save the World’s threatened freshwater crab species. 相似文献
12.
We ask whether oceanic islands and equivalent-sized continental blocks, which we call here ‘land islands’, are similar or not in their species richness, number of range-restricted species, and in number of threatened species. We used sites in southern Africa and islands in the Western Indian Ocean. We chose dragonflies as they are taxonomically tractable, well surveyed, and provide a range of characteristics from narrow-range endemics to widely-spread and vagile opportunists. We then selected as many oceanic islands as possible where there were sufficient data to make comparisons with land islands of a similar area in African savanna, grassland and mountains rich in endemic species. Generalized Linear Mixed Models were used to analyse the overall, range-restricted and threatened species richness for all islands (both oceanic and land) and then for the two types of island separately. Species richness increased with island size, with oceanic and land island size relationships being similar. Land islands overall had significantly more range-restricted species. Species on land islands were as threatened as those on oceanic islands. However, the land islands of the Western Cape were under a higher level of threat than oceanic islands of comparative size. The large islands of Madagascar and Sri Lanka were outliers with very high levels of threat. Translated into conservation, the results illustrate that over-generalizations about island faunas being more threatened than continental ones are not necessarily valid. While not wishing to draw attention away from the urgent conservation action needed on many tropical islands, we argue that comparisons of oceanic versus land islands detract from the more urgent task of local conservation action based on the special needs of any particular area, whether land or oceanic. It is more meaningful to establish how threats operate and how to mitigate them on small populations rather than focusing purely on any particular island type per se. 相似文献
13.
The conservation of rare species on islands is a special challenge, especially when the islands are faced with increasing human impact. Two endangered wild felids in Japan provide a contrast that is useful for examining conservation strategies. The Iriomote cat (Prionailurus bengalensis iriomotensis) is endemic to Iriomotejima Island in Okinawa, and the Tsushima leopard cat (Prionailurus bengalensis euptilurus) occurs in the Tsushima islands in Japan, although a related subspecies found in the Korean Peninsula. Population size was approximately 100 individuals for each subspecies. While the population of Iriomote cat appears relatively stable, the population and abundance of the Tsushima leopard cat has decreased in recent decades. Because of their small population sizes and restricted habitats both are listed as endangered species/subspecies in Japan’s Red List, and the Iriomote cat is listed as an endangered subspecies in the IUCN Red List. Although both are similar-sized felids living on small islands, their ecological characteristics such as food habit, habitat selection, and density differ. These differences seem to be caused by the climate, the biological environment (the species composition of fauna in each island, and the presence of competitors), and the artificial background. The threats facing these two felids are also similar. Habitat destruction, traffic accidents, and negative influences by introduced species are the principal threats to be addressed for their conservation. At the same time, there are differences in the degree of impact by each threat, in each species’ conservation programs in practice, and in the stages of progress and operation of programs. These differences are partly because they have different ecological features and partly because the social background of each island, such as human population, main industry, and historical relationship between human and wildlife, are quite different. We will compare the ecology and state of these two wild felids and discuss the different conservational situations in relation to felid ecology and human society. 相似文献
14.
The Peninsula of Baja California, Mexico has long been recognized as a hotspot for plant richness and endemism. However, its extraordinary diversity is not adequately protected by the existing protected areas. We analyzed the distribution of the endemic vascular flora of the peninsula, and its presence or absence in protected areas. We also identified regions with greater numbers of endemic species not currently under protected status. The families Asteraceae, Cactaceae, and Fabaceae alone contain 40% of the endemic species. All the peninsular species within the Begoniaceae, Thymeliaceae, Araliaceae and Hippocastanaceae are endemic. Of the total number of endemic taxa in the region, 76.4% are present within protected areas. The endemic genera Adenothamnus, Carterothamnus, Faxonia, and Ornithostaphylos are entirely absent from protected areas. Of the 567 endemics found in protected areas 75 represent varieties or subspecies Of the 175 not found in protected areas 21 are varieties or subspecies. A gap analysis identified that the areas with the highest number of unprotected endemic species are in the Mediterranean-type ecosystems of the north-west part of the peninsula and in the deciduous dry tropical communities of the cape region at the southernmost tip of Baja California. Our findings suggest that it is necessary to create several protected areas along the peninsula for the successful conservation of rare and endemic taxa These new areas should encompass a latitudinal gradient of biogeographical units (including Mediterranean communities and montane habitats of the Sierras) along the peninsula. 相似文献
15.
Sergey Venevsky 《Biological conservation》2005,124(2):235-251
National conservation planning should operate with measures of biodiversity similar to those applied globally in order to harmonize national and international conservation strategies. Here we suggest quantitative measures which enable two criteria of the global biodiversity hotspots to be applied on a national level for 74 large countries, and show how these measures can be applied to map national biodiversity hotspots. The plant endemism criteria of global hotspots are captured by quantitative measures of endemism, which are approximately scale-independent and can be corrected to account for a country’s environmental conditions and conservation priorities. The flexible land use criteria for national biodiversity hotspots are defined from percentage of natural vegetation remaining in the global hotspots. The minimum-area-required approach is applied to define the borders of national biodiversity hotspots using data on vascular plants species richness. We show how national biodiversity hotspots can be mapped from the species-energy relationship for vascular plants using climate, topographical and land use data when spatial pattern of species richness is not known. This methodology to map national biodiversity hotspots from abiotic factors is applied to Russia as a case study. Three Russian biodiversity hotspots, North Caucasus, South Siberia and Far East were identified. The resulting hotspot maps cover national-scale environmental gradients across Russia and although they are also identified by Russian experts their actual geographical locations were hitherto unspecified. The large-scale national hotspots, identified for Russia, can be used for further fine scale and more detailed conservation planning. 相似文献
16.
Soon Leong Lee Kevin K.S. Ng Chai Ting Lee Naoki Tani Jarkko Koskela 《Biological conservation》2006,131(1):72-92
To conserve a rare plant, conservation programs must be guided by the biological attributes of the species. What constitutes the most critical biological information for plant conservation has been the issue of discussion for the last 30 years. Most scientists promote an approach that is either ecological or genetic in emphasis. Ecological and genetic processes will often interact synergistically to influence the population viability and to determine the persistence of populations in the long run. Consequently, conservation management of plant species, in addition to ecological information, requires a robust understanding of underlying genetic processes as well as the variation within and between populations. Conservation has a cost and the resources available for conservation programs are always limited. Therefore, conservation management strategies should not only be scientifically justified but also practical in terms of resource availability. Shorea lumutensis is a rare and endemic dipterocarp in Peninsular Malaysia. A comprehensive research activity was initiated to assess the population ecology and population genetics of S. lumutensis to elucidate specific ecological and genetic requirements and subsequently to set conservation strategies and priorities. This paper is apparently the first attempt at applying both the ecological and genetic approaches into conservation management of a rare dipterocarp. In addition, this paper also attempts to link the gaps between conservation research and conservation management in a realistic manner. It is our hope that this study will serve as a model for the study of other rare dipterocarps which should be given priority for conservation. 相似文献
17.
Large flying-foxes in insular Southeast Asia are the most threatened of the Old World fruit bats due to high levels of deforestation and hunting and effectively little local conservation commitment. The forest at Subic Bay, Philippines, supports a rare, large colony of vulnerable Philippine giant fruit bats (Pteropus vampyrus lanensis) and endangered and endemic golden-crowned flying-foxes (Acerodon jubatus). These large flying-foxes are optimal for conservation focus, because in addition to being keystone, flagship, and umbrella species, the bats are important to Subic Bay’s economy and its indigenous cultures. Habitat selection information streamlines management’s efforts to protect and conserve these popular but threatened animals. We used radio telemetry to describe the bats’ nighttime use of habitat on two ecological scales: vegetation and microhabitat. The fruit bats used the entire 14,000 ha study area, including all of Subic Bay Watershed Reserve, as well as neighboring forests just outside the protected area boundaries. Their recorded foraging locations ranged between 0.4 and 12 km from the roost. We compared the bats’ use to the availability of vegetative habitat types, riparian areas, and bat trees. The fruit bats’ locations showed a preference for undisturbed forest types and selection against disturbed and agricultural areas. Bat locations also showed selection for particular fruiting/flowering bat trees. The bats showed strong preference for riparian areas; locations were in riparian areas over four times more than expected. From these results we recommend that management focus flying-fox conservation efforts on undisturbed forest and riparian areas. 相似文献
18.
José Antonio González-Oreja 《Biological conservation》2011,(1):234-242
Impacts of urbanization on ecological systems are expected to increase during the 21st century, and identifying which species may not survive under urban constraints is of practical importance to conservation biology. I study whether a species’ biogeographic origin might be a useful predictor of vulnerability to urban pressures, and if this depends on the geographic scale of the study. By means of multivariate ordination analyses and computer intensive, Monte Carlo simulation techniques, I study the patterns of zoogeographical affinity (a proxy for biogeographic origin) of passerine birds living in 14 non-urban (NU) and 11 urban (U) sites throughout Mexico, a biodiversity rich and urbanizing country between the Nearctic and Neotropical Regions; at a regional scale, I also study differences between NU and U sites in the state of Puebla, in the ‘Temperate Sierras’ ecoregion. Differences in zoogeographical affinities between NU and U sites were statistically significant, and were mainly caused by changes in the number of neotropical and nearctic species. In terms of the ‘equivalent number of zoogeographical classes’, a useful measure of zoogeographical diversity, bird assemblages in urban settings were less diverse than those simulated by random drawings from the corresponding species pools. In fact, urbanization seems to be provoking the selective removal of neotropical and endemic species from urban assemblages, whereas at the same time retaining more-than-expected nearctic (temperate) species; birds with nearctic affinities could be successful candidates to ‘urban exploiters’ in the study case. At a landscape scale, results suggest that urbanization is creating holes in the geographic range of both neotropical passerines and birds endemic to Mexico, which are selectively removed by the urban filter, and can be identified as those more heavily threatened by urbanization if proactive strategies to conserve biodiversity in urban ecosystems are not implemented. Among other reasons for the observed patterns, the tropical niche conservatism is invoked as an explanation. 相似文献
19.
Mitchell T. Irwin Patricia C. Wright Paul Loiselle Daniel Rakotondravony Jonah Ratsimbazafy 《Biological conservation》2010,143(10):2351-2362
Five main conclusions arise from this review of the responses of species to anthropogenic disturbance in Madagascar: First, species’ reactions to anthropogenic disturbance are generally negative, but remain poorly known. Our knowledge is patchy among and within higher taxonomic groups; we are still largely gathering case studies. Second, taxonomic groups vary considerably in which proximate factors are most important. Third, several groups show differing responses within different ecoregions. Whether these differences are consistent across groups requires further testing. Fourth, related species often have divergent reactions to disturbance, even within lower taxonomic groupings (families or genera). Thus, we cannot rely on phylogenetic relatedness or even ecological similarity to infer similarity in responses. Finally, disturbance typically reduces species diversity (especially of native and/or endemic species), but also causes species turnover, typically with forest specialists replaced by grassland generalists, and endemics replaced by non-endemics (including invasives). Given these knowledge gaps, we stress the urgency of applied studies that assess species’ ecology, behaviour and health across disturbance gradients, including purely anthropogenic landscapes. Remaining natural vegetation and protected areas will be unable to preserve Madagascar’s biodiversity under the impact of climatic change; we must understand responses of plants and animals to disturbance in order to create buffer zones and corridors combining secondary, degraded and natural habitats. 相似文献
20.