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We surveyed slender lorises (Loris lydekkerianus) in Karnataka, south India intermittently during November 2001–July 2004 and estimated their relative abundance via direct sightings. Two subspecies, Loris lydekkerianus lydekkerianus and L. l. malabaricus, with different morphological traits, occur in the eastern drier region and the western wet region of the state, respectively. The distribution of Loris lydekkerianus lydekkerianus is patchy in a small region in the southeast, which contradicts earlier reports of its abundance throughout the state. Loris lydekkerianus malabaricus occurs throughout the Western Ghats as a contiguous population. The encounter rates of Loris lydekkerianus lydekkerianus and L. l. malabaricus are 0.41 individuals/km and 0.21 individuals/km, respectively. Whereas several forest tracts in the distributional range of Loris lydekkerianus malabaricus are protected areas, no such area exists in the distributional range of L. l. lydekkerianus. Loris lydekkerianus faces serious challenges of conservation because it largely occurs in commercial plantations, which can be relatively unstable habitats as harvesting can take place at any time.
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Mewa SinghEmail: |
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Behavioral traits are likely to influence species vulnerability to anthropogenic threats and in consequence, their risk of extinction. Several studies have addressed this question and have highlighted a correlation between reproductive strategies and different viability proxies, such as introduction success and local extinction risk. Yet, very few studies have investigated the effective impact of social behaviour, and evidence regarding global extinction risk remains scant. Here we examined the effects of three main behavioral factors: the group size, the social and reproductive system, and the strength of sexual selection on global extinction risk. Using Primates as biological model, we performed comparative analysis on 93 species. The conservation status as described by the IUCN Red List was considered as a proxy for extinction risk. In addition, we added previously identified intrinsic factors of vulnerability to extinction, and a measure of the strength of the human impact for each species, described by the human footprint. Our analysis highlighted a significant effect of two of the three studied behavioral traits, group size and social and reproductive system. Extinction risk is negatively correlated with mean group size, which may be due to an Allee effect resulting from the difficulties for solitary and monogamous species to find a partner at low densities. Our results also indicate that species with a flexible mating system are less vulnerable. Taking into account these behavioral variables is thus of high importance when establishing conservation plans, particularly when assessing species relative vulnerability. 相似文献
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J. López-Pujol M. R. Orellana M. Bosch J. Simon C. Blanché 《Plant biology (Stuttgart, Germany)》2003,5(5):504-512
Abstract: Allozyme electrophoresis was used to evaluate levels and distribution of genetic diversity in Iberian populations of the threatened coastal sand dune plant Stachys maritima (Lamiaceae). During the last century, this species was subjected to severe habitat fragmentation, mainly as a consequence of tourism activities and urban pressures, with a decreasing of area up to 99 % in the Iberian Peninsula and a remaining total population size of ca. 250 individuals. Extremely low levels of genetic variation were detected ( P = 14.0, A = 1.16 and H e = 0.066). From the 20 interpretable loci found, only 4 were polymorphic and another one, the Idh-2 locus, showed a fixed heterozygous banding pattern, which may be attributed to gene duplication. Low values of diversity can be related to small population size and isolation of populations. The degree of threat has been increased from vulnerable (VU) to critically endangered (CR), according to the IUCN criteria. Conservation policies should be focused on maintaining population size and gene flow, in addition to preserving its habitat, although reintroductions and reinforcements appear to be necessary to ensure long-term viability of populations. 相似文献
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We surveyed the diversity of soil Archaea across a large scale elevational gradient of ecosystem types, from foothills forest to alpine tundra in the Front Range of the Rocky Mountains. We used a dilution technique to sequence the single most abundant archaeal 16S rDNA sequence in each of the 40 soil cores distributed across the gradient to compare our results to those of typical 16S clone library studies.We found a greater diversity of sequences than has typically been found in clone library studies from a single site or core, identifying sequences both from the Terrestrial Group and the FFSB Group at several sites. We did not observe any significant environmental correlates with the dominant sequence type, nor was there any relationship between the spatial distance between samples and the phylogenetic similarity of the dominant sequence types. Despite using a very different methodology, our collective results are in remarkably good agreement with other studies of soil Crenarchaeota in terms of the diversity and relative abundance of sequence types identified. We are able to identify two instances of very tightly clustered sequences which we suggest are the results of global selective sweeps—one closely related to SCA1145, an abundant globally distributed group within the Terrestrial Group of Crenarchaeota, and another nested within the more basal FFSB group of sequences. We replicated our sequence results at two levels: first, by repeating the dilution and PCR processes from the same soil core DNA extraction, and second, by performing a replicate DNA extraction from the same homogenized soil core sample. Pairs of sequences produced by the dilution replicates were significantly more similar than the pairs of sequences produced by the extraction replicates, suggesting that soil Crenarchaeota exists in highly localized and discrete clonal populations. 相似文献
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Ethnic Diversity and Its Environmental Determinants: Effects of Climate, Pathogens, and Habitat Diversity 总被引:4,自引:1,他引:3
This article documents, and seeks to explain, the geographical patterning in ethnic group distributions. Some areas, chiefly equatorial regions and areas of high habitat diversity, are crowded with a large number of named groups. Elsewhere, people over a large area consider themselves members of a single group. Using three new codes for the Standard Cross-Cultural Sample (ethnic diversity, habitat diversity, and rainfall variation), I show that regions with relatively few ethnic groups (low ethnic diversity) have unpredictable and highly variable climates and low pathogen loads. In most areas there was no relationship between ethnic diversity and ecosystem productivity, and there was little or none with the chief determinants of productivity, mean annual rainfall and temperature. Habitat diversity was also associated with ethnic diversity, particularly among nonstratified societies. Habitat diversity is correlated with degree of topographic relief, but the effect of habitat diversity on ethnic diversity is larger than, and independent of, the effect of topography. [ ethnic diversity, ecological anthropology, spatial organization, cross-cultural research ] 相似文献
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There is increasing concern about the conservation of dung beetles which are threatened by several peculiar dangers world-wide, both at the population and community level. A noticeable threat in Europe is the dramatic reduction in the number of cattle and sheep grazing in the open, which is associated with both intensive agriculture and the progressive reforestation of previously pastured areas. We studied dung beetle habitat and resource preferences at La Mandria Park (north-west Italy) which is a mosaic of open and wooded patches where domestic (cows and horses) and wild ungulates (deer and wild boar) co-exist. Scarabaeidae were numerically dominant, accounting for 61.5% of the approximately 3000 individuals sampled (Aphodiidae accounted for 32.5% and Geotrupidae for only 6%). However, when species richness was considered, Aphodiidae were dominant, with 17 of the 27 species found (Scarabaeidae with eight and Geotrupidae with two). Assuming a null hypothesis of equal probability of colonizing any habitat or faeces, we found that most species were significantly associated with one of the four dung types or with one of the two habitats considered. On average, Scarabaeidae preferred cattle dung and open habitats whereas most Aphodiidae used deer lumps and wooded habitats. In spite of the precise ecological choices observed at La Mandria, surveys from other European areas suggest that both habitat and food selection are quite flexible. From a conservation viewpoint, the ability of coprophagous beetles to choose herbivore faeces according to their availability and to select habitats that satisfy their own microclimate requirements may certainly be useful in preserving biodiversity. Agroecology, which implies some woodland and hedgerow management practices associated with pastoralism, could be the right approach to the management of the agricultural landscape. Conversely, in reforested areas, while wild ungulate populations should be preserved, some form of human disturbance, particularly clearings used for pastoralism, should also be maintained. 相似文献
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WEI WANG GUOPENG REN YUANHUI HE JIANGUO ZHU 《The Journal of wildlife management》2008,72(6):1335-1341
Abstract: The greatest concentration of Chinese Galliformes occurs in the Trans-Himalayas. We selected 4 northwestern Yunnan counties (Lijiang, Shangri-la, Deqin, and Weixi) in the Trans-Himalayas to assess the conservation status of 9 gallinaceous forest birds. We developed maps depicting recent forest cover and modeled habitat availability of each gallinaceous forest bird based on 3 factors that restrict its distribution: geographic location, elevation range, and forest coverage. The conservation status of 4 species was inadequate, because <10% of their respective potential habitats were within existing nature reserves. To predict the historic habitats of the species we studied, we also delineated a forest map from the late 1950s. We calculated the loss and fragmentation of potential habitats within the past 40 years as degree of habitat degradation. Our results showed that all 9 species became reduced and fragmented of their potential habitats from the late 1950s to 2002. Assessing habitat degradation and conservation status of wild species could help identify the threatened species with poor protection and degraded habitats, thereby warranting more attention in future conservation strategies. To protect those threatened species, it is urgent that the government should design new nature reserves to fill the conservation gaps, and enlarge and strengthen the management of existing natural reserves to reduce effects of human activities on their habitats. 相似文献
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为探究不同种植方式对稻田中小型土壤动物多样性的影响,本研究选取上海市崇明岛常规、有机和生态(稻-渔共作)三种种植方式的稻田为研究样地,采用干漏斗法对其中的中小型土壤动物群落结构进行调查。结果表明,调查共捕获中小型土壤动物449头,分属2门5纲8目,优势类群为弹尾目(Collembola)物种,占总捕获量的82.18%。三种种植方式稻田的中小型土壤动物群落结构有明显差异,其中,有机种植模式稻田的中小型土壤动物密度明显高于另外两种种植模式。中小型土壤动物群落的垂直分布呈现表聚性特征,类群数和密度均表现为向下减小的趋势。生态种植稻田的中小型土壤动物丰富度指数、Shannon-Wiener指数和均匀度指数均为最高,有机种植稻田的中小型动物优势度指数最高。三种不同种植方式稻田的中小型动物呈中等程度相似。与常规和有机种植水稻方式相比,生态种植方式更有利于提高中小型土壤动物的多样性和均匀度水平,促进稻田生态系统的稳定与健康发展,对稻田种植的可持续性及农业面源污染的指示作用方面具有一定意义。 相似文献
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《新西兰生态学杂志》2011,16(2):83-90
The yellowhead, a forest-dwelling passerine endemic to the South Island of New Zealand, has declined in both abundance and range since the arrival of European settlers last century. In the last 30 years it has all but disappeared from the northern half of the South Island but remains widespread in the south. One possible explanation is that the yellowhead has declined in abundance throughout its range, disappearing from less suitable habitats in which it was never very abundant. To test this hypothesis a habitat suitability index was constructed and northern and southern forests compared. Yellowheads appear to be tall forest specialists and are most common in tall red beech dominated forests at low altitude on flat valley floors. No evidence was found that forests in the northern South Island are any less suitable for yellowheads than those in the south. Other explanations for the decline of yellowheads in the north of their range are discussed. 相似文献
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Ideas on the spatial variation of biodiversity often imply a causal link between the abundance and species richness of organisms. We investigated this ‘more individuals hypothesis’ using light‐trapping data of three unrelated groups of moths (Arctiidae, Geometridae and Pyraloidea) from the Ecuadorian Andes. We analyzed environmental correlates of specimen densities found in different habitats, finding effects of temperature, moonlight, forest succession, elevation and season. We corrected abundance data for light‐trapping artefacts, and we measured species diversity with various metrics known to be unbiased by undersampling. We found significant positive correlations between abundance and species diversity for all three taxonomic groups. We discuss implications for a general evaluation of species‐energy theory as well as for a better understanding of ecological processes in montane habitats of the Andes. 相似文献
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广州市园林植物多样性及其效应的调查研究 总被引:4,自引:0,他引:4
选取广州市信园为研究个案,同时先取市内有代表性的5个生态园林区作对比进行植物多样性调查,计算物种多样性指数(SW指数).并把计算结果分别与园区内其它生物多样性的调查结果和环境指标(温度、湿度、土壤含水量、有机质质量分数、含氮量)的检测结果进行分析.结果表明:①有机质质量百分比随植物SW指数上升呈增高趋势, 良好的土壤环境又会促进植物多样性发展;②鸟类、其他小型动物的种类数随植物SW指数上升呈现增高趋势,即植物多样性决定动物物种丰富程度.建议广州市园区的SW指数不应低于2.5. 相似文献
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论自然保护与资源开发的策略 总被引:7,自引:0,他引:7
物种保护的根本途径是保护其生境,生境的完整性遭到破坏则物种将趋于灭绝[1,2]。不少国家的政府及非政府组织正投入巨资设置保护区试图将至少部分生物多样性资源加以永久保存[3],但这些目标的达到往往是基于如下假设:即保护区将不受干扰、原封不动的加以保存并与经济活动及周围环境难以达成任何形式的妥协。然而越来越多的证据表明,在全球范围遭受人类干扰的背景下无论是保护区内还是保护区外的生境均将趋于退化,因此现行建立保护区的模式并不能有效阻止生物多样性灾难性的损失[4]。特别对于发展中国家,人口、资源、环境的… 相似文献
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Sphingid biodiversity was compared in a large number of light-trapping samples on Borneo and elsewhere in the Indo-Australian
tropics, using our own quantitative light-trapping samples supplemented by other collectors’ published and unpublished data.
No effects of anthropogenic habitat disturbance on the within-habitat diversity (measured as Fisher’s α) were observed, but
the faunal composition of assemblages differs significantly under varying degrees of disturbance. Altitude, year of sampling
and sampling regime (full night vs. part of the night) were identified as additional parameters that influence the composition
of local samples. The frequency of subfamilies in samples varies under different disturbance regimes: Smerinthinae decline
along a gradient from primary habitats to heavily disturbed sites, while Macroglossinae show the reverse trend. Connections
between the reactions of subfamilies to disturbance and altitude and potential life-history differences between the subfamilies
are discussed. Hypothetically, capital breeding Smerinthinae might be commoner and more speciose in stable primary habitats, whereas many income breeding Macroglossinae are probably adapted to thrive in ephemeral, disturbed habitats. Furthermore, we show that estimates from
local samples fall short of the total known species richness of Borneo by about 10%. 相似文献
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Charles A. Nock Alain Paquette Matt Follett David J. Nowak Christian Messier 《Ecosystems》2013,16(8):1487-1497
Urban forests provide ecosystem services for millions of people. Numerous introductions have elevated tree species richness in cities, which may enhance functional diversity. However, few studies have examined changes in tree community composition or functional diversity with urbanization, even though functional diversity, and not species number per se, is directly linked with ecosystem function and associated services. We combined tree abundance data from both urban and extra-urban forest inventory plots for seven metropolitan areas in eastern North America to analyze changes in species composition, Shannon’s diversity, and functional diversity with urbanization. As expected, urban tree diversity was reduced at local scales, and the effect varied with land use. Rarefaction analysis indicated that at large scales, urban tree species pools were equal with respect to species or functional diversity compared to extra-urban forests, but in urban areas at small scales this diversity is not realized because of low tree density. Ordination revealed that with urbanization, introduced species increased in importance, and regional variation in species composition became more homogenous. Increasing tree density and/or tree cover through changes in management practices and urban design could facilitate local scale urban tree diversity using existing species pools, which are functionally diverse. Monitoring of forests at large spatial scales that include urban areas, and the use of methods that account for abundance and functional trait variation can provide insights into the effects of urbanization on tree diversity at multiple scales. 相似文献