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1.
The conservation status of 24 threatened freshwater fishes and seven estuarine fishes from southern Africa is discussed against the background of natural and anthropogenic environmental factors. The majority of threatened species are endemic temperate forms with restricted ranges. Major threats include introduced alien fishes and a wide spectrum of environmentally destructive causes. Research on threatened species includes distribution surveys, biological and ecological studies and methods of artificial propagation. Long-term remedies based on ecosystem conservation are also being promoted. The perceptions and attitudes of nature conservation authorities are adjusting to the new challenges offish conservation. The number of threatened fishes in Africa is likely to increase in the face of escalating problems of habitat destruction and degradation. 相似文献
2.
ABSTRACT Background The genus Restrepia occurs throughout Central and South America in areas of montane forest heavily affected by deforestation. 相似文献
3.
The consequences of inbreeding in small isolated populations are well documented, yet populations are often managed in isolation to avoid irreversibly mixing genetic lineages and to maintain the historic integrity of each population. Three remaining populations of Whitaker's skink ( Cyclodina whitakeri ) in New Zealand, remnants of a once wider distribution, illustrate the conflict between this genetic goal (separate management of populations) with the more tangible and immediate threats of small population size and inbreeding. Middle and Castle Islands harbour populations of C. whitakeri and have been separated from each other and from the mainland for ∼10 000 years. The single mainland population at Pukerua Bay is extremely small, declining and deemed a high priority for management. We sequenced a 550 bp region of mitochondrial DNA (mtDNA,ND2) and genotyped animals from all three populations at 13 microsatellite loci. The population of C. whitakeri at Pukerua Bay showed marked differences from the island populations at both mtDNA (unique, fixed haplotype) and microsatellite loci ( F ST∼0.20), and private alleles were detected at a high frequency (24% of all alleles). However, we attribute this pattern to an historic genetic gradient coupled with rapid genetic drift. Further, animals in captivity show genetic signatures of both Pukerua Bay and island populations, despite the goal to maintain a pure Pukerua Bay stock. The mixed genetic stock in captivity provides an opportunity for the addition of skinks from Middle Island to evaluate the risks of further population hybridization, including the disruption of potential local adaptation, while mitigating the risks of inbreeding. 相似文献
4.
Conservation genetics and genomics are two independent disciplines that focus on using new techniques in genetics and genomics to solve problems in conservation biology. During the past two decades, conservation genetics and genomics have experienced rapid progress. Here, we summarize the research advances in the conservation genetics and genomics of threatened vertebrates (e.g., carnivorans, primates, ungulates, cetaceans, avians, amphibians and reptiles) in China. First, we introduce the concepts of conservation genetics and genomics and their development. Second, we review the recent advances in conservation genetics research, including noninvasive genetics and landscape genetics. Third, we summarize the progress in conservation genomics research, which mainly focuses on resolving genetic problems relevant to conservation such as genetic diversity, genetic structure, demographic history, and genomic evolution and adaptation. Finally, we discuss the future directions of conservation genetics and genomics. 相似文献
5.
The first step towards the preservation of endangered species is to establish an appropriate ranking system, which assigns different nature conservation priority scores to different taxa. The system developed by Millsap et al. (Wildlife Monograph 1990, 111: 1–57) has been modified and applied to the mammal, bird, reptile, and amphibian species of Hungary. Three variable groups have been compiled, including eight (measuring biological characteristics), three (features of the Hungarian population) and five (evaluation of research and conservation actions) variables, respectively. In cooperation with several experts, we gave scores to all 379 taxa considered. The most endangered taxon proved to be the Hungarian Meadow Viper ( Vipera ursinii rakosiensis), which occurs only in Hungary with just a few hundred individuals. The species rank depends on the availability and quality of data, so it is urgent to devote more effort to survey and monitoring projects. We present a possible application of the species list, where the taxa are grouped according to their legal status in Hungary (strictly protected, protected, partly protected and not protected), and the validity of this categorisation was tested by applying multivariate discriminant analysis. Only 58.36% of the species were correctly classified. The reasons for stronger than expected protection include popularity, attractiveness, and local rarity, while reasons for lower protection include preference for hunting and control of predators and pests. 相似文献
6.
在确定中国东北地区受威胁植物的基础上,依据植物优先保护值确定受威胁植物的优先保护区域.结果表明:中国东北地区共有受威胁植物25科42属60种.在东北地区219个县(市)中,共119个县(市)分布有受威胁植物.吉林省安图县是东北地区拥有受威胁植物最多的县,有受威胁植物42种.确定吉林省安图县、辽宁省桓仁满族自治县等16县(市)为东北地区受威胁植物优先保护县(市).根据受威胁植物的优先保护区域值,划分出中国东北地区的5个优先保护区域,分别为长白山优先保护区、辽东优先保护区、辽南优先保护区、张广才岭优先保护区和小兴安岭优先保护区,并对各优先保护区的主要受威胁植物进行了分析. 相似文献
7.
Statistical predictions of the impact of climate change on biodiversity assume that the environmental and spatial characteristics of contemporary species’ distributions reflect the conditions needed for their continued and prolonged existence. Here we explore this assumption by testing whether a species’ threatened status is associated with the amount of variation in its distribution range attributable to environmental and spatial patterns. Using a variation partitioning approach, we decomposed variation in the distribution ranges of 4423 vertebrate species in sub-Saharan Africa into components attributable exclusively to environmental variables (E|S), exclusively to spatial variables (S|E) or to the collinearity between environmental and spatial variables (E∩S). We found that species’ threatened status was unrelated to E|S, S|E or E∩S variation components, but that unexplained variation was higher for species threatened with extinction. This suggests that spatio-environmental patterns in species’ ranges likely underestimate the overall extinction threat caused by climate change. We also found clear geographic patterns in the strength of E|S, S|E or E∩S that differed amongst biogeographical regions, but no component was over- or underrepresented in the present-day protected area network. While there may be benefits to tailoring protected area expansion to differences between biogeographical regions, this should aim to incorporate species-specific information wherever possible. 相似文献
8.
One hundred and twenty-seven threatened species listed in the ChinaPlant Red Data Book were found in the Yangtze valley. One-third of them belongedto four families with high economic value, including Pinaceae, Magnoliaceae,Lauraceae and Ranuculaceae. Of all the plants, 66.9% grew in forests and 71.7%were threatened with damage to habitats. The threatened plants in the studiedregion formed a geographical pattern with two large and six small distributioncenters. The two large centers were in the high mountains in western Sichuan andnorthern Yunnan or around the Sichuan Basin. The six small centers were situatedin fragmented montane forests in the eastern part of the Yangtze valley. Todetermine a plant's threat category, the number of populations 10 wasused as the basic criterion as accorded with the China Plant Red Data Book. Thethreatened plants in the valley could be divided into five ranks of priority forconservation. The plants in the first rank comprised eight species endemic tothe valley, with only one population, which should be first preserved. It wasconcluded that human activity was the main factor threatening the survival ofplants, and protecting forests had been the most effective approach in savingthe threatened plants in the valley. 相似文献
9.
In this study, the aquatic monocot Baldellia (Alismataceae) is used as a model for evaluating the general hindrances and shortfalls in the global conservation status
assessment of a threatened taxon. Our study clearly shows that Linnean shortfalls (uncertainty in the number of species and
taxonomy) and the Wallacean shortfall (fragmentary knowledge regarding distribution) form the basis for all other hindrances.
We demonstrate that even in Europe, which has traditionally been very well investigated, between 60 and 75% of regions or
countries possess no detailed distribution maps and/or data banks for Baldellia spp. Furthermore, between 50 and 60% of regions do not have any published red list category. Thus, only general conclusions
concerning the global conservation status of the three Baldellia taxa are possible—a global assessment of conservation status for B. ranunculoides subsp. repens is nearly impossible. Baldellia ranunculoides s.str. shows a strong decline in practically all regions of its natural range, and thus it is probably the most threatened
species in the genus. Baldellia alpestris is the least threatened species in the genus, even though it is a narrow endemic. Our case study clearly shows the need for
reinforced coordination of research and conservation activities as well as an urgent need for data accessibility regarding
taxonomic, chorological and conservation studies of endangered species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
The GATA, Friend of GATA, and Runt homology domain protein families function during hematopoiesis to promote progenitor cell development and regulate lineage commitment and differentiation. The hematopoietic functions of these factors have been remarkably conserved across taxonomic groups, ranging from flies to humans. Furthermore, aspects of hematopoiesis and hemocyte function appear to be conserved. Thus, comparative studies using Drosophila and vertebrate models should enhance our understanding of blood cell development. 相似文献
11.
Conservation planning analyses show a striking progression from endeavors targeted at single species or at individual sites, to the systematic assessment of entire taxa at large scales. These, in turn, inform wide-reaching conservation policies and financial investments. The latter are epitomized by global-scale prioritization frameworks, such as the Biodiversity Hotspots. We examine the entire Neotropical region to identify sets of areas of high conservation priority according to terrestrial vertebrate distribution patterns. We identified a set of 49 ecoregions in which 90, 82 and 83%, respectively of total, endemic and threatened vertebrates are represented. A core subset of 11 ecoregions captured 55, 27 and 38% of these groups. The Neotropics hold the largest remaining wilderness areas in the world, and encompass most of the tropical ecosystems still offering significant options for successful broad-scale conservation action. Our analysis helps to elucidate where conservation is likely to yield best returns at the ecoregion scale. 相似文献
13.
中国拥有丰富的两栖类资源,共321种,其中特有种236种,这些特有种是我国生物资源独特而重要的组成部分.但受人为和自然等因素的影响,中国特有两栖类出现了较快的种群数量下降,部分物种已经面临濒危状况而很少被人们关注.本文将对中国特有两栖类的数量、分布、受胁原因作简要阐述,以制定相应的保护对策. 相似文献
14.
The Pantanal is a 140,000 km 2 sedimentary floodplain in western Brazil and one of the largest wetlands in the world. The main landscapes and phytophysiognomies, according to flood origin, are briefly described and some of the characteristic plant species are mentioned: (a) river flood (1–5 m) on clayey eutrophic soils with gallery forests, pioneer forests and scrub, Tabebuia and Copernicia parks, seasonal swamps, grasslands and oxbow lakes; and (b) rain flood (10–80 cm) mainly on dystrophic sandy soils (72% of the total area) with savanna (cerrado) grasslands and woodlands, with or without ponds. Regulating factors of the vegetation such as wet-and-dry cycle and management are considered. Dynamics of the vegetation, in particular the aquatic types, are shortly depicted. The role of grazing for conservation is discussed, and we suggest that 200 years of cattle ranching apparently did not cause major changes in the vegetation, except turning tall grass into short swards, as the domestic herd found a nearly empty niche. However, severe threats to the flora and fauna of the Pantanal originate outside the floodplain. Siltation of the Taquari river is pointed out as the worst environmental problem, changing the hydrology (wet-and-dry to wet), fauna and flora, e.g. eliminating riparian forest.This revised version was published online in March 2005 with corrections to the issue cover date. 相似文献
16.
In this study, we combine species distribution models with a reserve selection approach to assess the degree of representation
of xenarthrans in the existing protected area network of Argentina, and to identify conservation priority areas that may help
expand the current system. Species distribution models were developed from species’ occurrence records using a maximum entropy
algorithm. Maps of species distributions were produced for 15 of the 16 species currently present in the country. To assess
the performance of the existing protected area network in representing all modeled species, and to identify priority areas
to expand the current reserve system, we used the software Zonation. Overall, all species modeled are represented in the existing
protected area network. However, the percentage of their ranges covered by protected areas is very low (average = 6.7%; range = 1.7–17.6%).
To represent at least 5% of the distribution of each species, 8.8% of the country’s area would be needed, and species with
restricted ranges have the greatest increase in representation in this scenario. When 10% of the country is set aside for
conservation, species representation increases considerably, again favoring range-restricted species. Most of the areas identified
as conservation priorities are under strong anthropogenic pressures, including deforestation, agricultural expansion, and
hunting. Our analysis provides a preliminary assessment of conservation priorities for the xenarthrans of Argentina, and we
hope will serve as guideline to focus future conservation assessments at more refined scales. 相似文献
17.
The geochronology and taphonomy of internationally important fossil bearing cave deposits were studied, both in the semi-arid Northern Bahia area and the subtropical southeastern Lagoa Santa area of Brazil. Taphonomic analysis suggests that the processes responsible for bone accumulation in the Brazilian caves vary between sites, and taphonomic bias can therefore be significant in causing differences in faunal composition. In the Toca da Boa Vista caves the presence of single articulated skeletons, and the entrance-related distribution indicate that random penetration of animals is the main mechanism of fossil accumulation, a process that biases the assemblage to smaller species, and takes place over extended time periods. In nearby Toca dos Ossos cave transport by runoff in the cave river is predominant, and biases the fauna remains to larger more robust bones and species. Deposition probably also occurred only at times of enhanced runoff giving a more contemporaneous assemblage. Similar processes were responsible for emplacement of the copious fossil remains in the more humid Lagoa Santa area, where terrigenous fossil deposits are found intercalated by massive speleothem calcite layers. In this area runoff under a drier climate probably accounts for the sediment emplacement inside caves. In both areas the mode of emplacement implies bias in the fossil record, resulting in fossil assemblages that do not mirror surface faunas, limiting palaeoenvironmental reconstruction. Mass spectrometric U-series analysis of speleothem calcite overlaying fossil remains gives minimum ages for fossil deposition. These ages confirm the previous view that many of the deposits derive from the late glacial, but also show that much older material (some > 350,000 yr) is also present. The habitat requirements of critical fossil species such as bats and monkeys strongly suggest that they derive from much wetter periods when forest cover was present in the currently semi-arid Northern Bahia area. Taphonomy exerts a major control on the diversity and mode of emplacement of cave fossil deposits in eastern Brazil and thus detailed sedimentological and hydrological studies coupled with a sound geochronological approach are essential in quantifying the relative importance of each taphonomic processes before faunal and palaeoecological interpretations can be attempted. 相似文献
19.
We present a case study of the relationship between spatial genetic structure (SGS) and age structure in Protium spruceanum (Burseraceae), an insect-pollinated, mass-fruiting, and secondary bird-dispersed tree, as determined through variation in allozyme loci. Using ten polymorphic loci, we investigated spatial and temporal patterns of a genetic structure within a 40?m?×?60?m plot in a small (1.0?ha) fragment of Atlantic Rainforest to investigate the processes shaping the distribution of genetic diversity. Individuals ( n?=?345) from seedlings to adults were grouped and analyzed in four diameter classes. The results showed a high average level of genetic diversity ( H e?=?0.438), but genetic diversity parameters did not vary significantly among cohorts. The spatial distribution pattern analysis of individuals showed significant levels of aggregation among small- and medium-diameter classes and random distribution among the highest diameter class, likely due to processes of competitive thinning. There was an association between demographic and SGS at short distances (less than 10?m) which is likely the consequence of restricted seed dispersal. The degree of SGS decreased across small- to large-diameter classes. We inferred that limited seed dispersal and subsequent density-dependent mortality from the family clusters are responsible for the observed changes in fine-scale SGS across different demographic classes. 相似文献
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