共查询到20条相似文献,搜索用时 0 毫秒
1.
Louise H. Emmons 《Biotropica》2009,41(4):493-502
Small mammals were trapped annually in two savanna and two forest plots in cerrado habitats of Noel Kempff Mercado National Park, Santa Cruz, Bolivia, for 5–10 yr. Eighteen species were captured in forest and seven species in savanna. Species numbers and total number of individuals captured were tightly correlated. In forest, species and abundance varied interannually by up to fourfold in one plot and to 100-fold in the other, and showed alternating highs and lows as is typical for small mammals. The largest faunal differences were due not to site differences, but to year differences, with markedly different patterns in forests and savannas. Abundance was not correlated with rainfall overall, but showed correlation in exceptional years of rainfall and ENSO drought. In savanna, species and overall abundance declined without recovery during 3 yr after reaching minimum numbers in 2004. One species, Cavia aperea , became extinct on both plots, and subsequently, apparently on the entire savanna. Both herbivorous and insectivorous species declined together. Rainfall, fire, and flooding do not seem to account for savanna rodent declines. I propose the novel hypothesis that smoke from anthropogenic burning raises nocturnal temperatures and prevents dew formation, and that a decrease in nightly dry season dewfall has been instrumental in rodent declines. Anecdotal and climatic data are consistent with this hypothesis, but it cannot yet be tested. 相似文献
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Patterns of vascular plant species diversity in high‐altitude Ecuadorian ecosystems (‘páramos’) are examined. Data from two independent surveys were used: the first from 12 different locations and 192 samples, the other from 18 locations and 243 samples. These surveys included 348 and 284 species, respectively. The data confirmed the occurrence of two main zones in terms of vascular plant species diversity. The grass páramo and superpáramo were distinguished by differences in plant cover, species richness, α‐diversity and β‐diversity. The transition between these two zones begins at around 4000 m. Grass páramo samples comprised more species but the strong dominance of tussock grasses resulted in low equitability compared with the superpáramo, where safe sites for plant survival are limited and the environment does not permit continuous grass cover. Turnover of species across the altitudinal gradient is higher in the grass páramo than in the superpáramo. This is due largely to agricultural fires at lower altitudes, which create a fine‐scale mosaic of burned patches that enhances variability at this scale. Despite the loss of equitability, intermediate levels of fire disturbance appear to promote species richness within the samples. It is suggested that the complex patterns of páramo diversity in the Ecuadorian Andes are largely the outcome of three interrelated factors: altitude, disturbance and the availability of safe sites at the highest altitudes. 相似文献
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Karen R. Lips Patricia A. Burrowes Joseph R. Mendelson Gabriela Parra‐Olea 《Biotropica》2005,37(2):163-165
Amphibian populations are in decline throughout Latin America; all families of frogs have experienced declines, but the species associated with aquatic habitats in upland areas have been most affected. Declines in Latin America were most common during the 1980s, but new declines continue to be reported. The causes of declines are varied, but they have most often been associated with habitat loss, a pathogenic fungus, and climate change. Scientists are just beginning to grasp the ethical and biological implications of losses of this magnitude. In this Special Section, we provide a general summary of the phenomenon and introduce five contributed papers that provide new data and new insights into Latin American declines. 相似文献
4.
Charles W. Heckman 《International Review of Hydrobiology》1983,68(2):207-226
The recovery of a temperate zone biotic community in a lotic freshwater habitat after acute chlorine poisoning was nearly completed in four months (May to September). This was facilitated by the water flow, which rapidly removed the toxic residues of the chlorine and transported organisms from the intact community upstream into the impoverished habitat. The first aggregation in the ditch after the chlorine was eliminated consisted of survivors, including members of species that failed to produce new generations. These were joined by pioneer species of the families Simuliidae and Chironomidae, the larvae of which appeared in massive numbers. This aggregation was displaced by a more diverse fauna as the macroflora and microbiota re-established themselves, providing food and anchorage for the invertebrates. The populations of large fishes are slowest to return because a considerable amount of time is required for the migration and growth of the recruits. While the chronic intoxication of a habitat produces changes in community structure, an acute poisoning is followed by a nearly complete restoration of the original biota, the recovery time being determined by the proximity of recruits for resettlement. 相似文献
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Enrique La Marca Karen R. Lips Stefan Ltters Robert Puschendorf Roberto Ibez Jos Vicente Rueda‐Almonacid Rainer Schulte Christian Marty Fernando Castro Jesús Manzanilla‐Puppo Juan Elías García‐Prez Federico Bolaos Gerardo Chaves J. Alan Pounds Eduardo Toral Bruce E. Young 《Biotropica》2005,37(2):190-201
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参考两栖爬行动物分类学和分子系统学的最新研究成果,收集近年来甘肃省两栖爬行类相关研究文献,结合2018—2019年的野外调查,对甘肃两栖爬行动物名录进行了整理与修订,结果表明,甘肃现分布有两栖动物2目10科20属36种,爬行动物2目17科38属70种;与《甘肃脊椎动物志》相比,增加20种,删除10种;与《甘肃两栖爬行动物》相比,增加16种,删除7种;并对20个物种的归属或学名进行了修订。动物区系分析表明,古北界物种28种(26.42%),东洋界物种56种(52.83%),广布种22种(20.75%);在动物地理省级分布区中,陇南南部山地省物种最多(69.81%),陇南北部山地省次之(29.24%),祁连山地省最少(5.66%)。国家Ⅱ级重点保护野生动物2种;被《中国脊椎动物红色名录》列为受威胁种40种;中国特有种42种。本文对甘肃分布的两栖爬行动物进行了梳理和探讨,旨在更新及完善甘肃本土生物多样性名录,为甘肃两栖爬行动物物种多样性保护与研究提供基础资料。 相似文献
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Hctor Zumbado‐Ulate Adrin García‐Rodríguez Vance T. Vredenburg Catherine Searle 《Ecology and evolution》2019,9(8):4917-4930
Numerous species of amphibians declined in Central America during the 1980s and 1990s. These declines mostly affected highland stream amphibians and have been primarily linked to chytridiomycosis, a deadly disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd). Since then, the majority of field studies on Bd in the Tropics have been conducted in midland and highland environments (>800 m) mainly because the environmental conditions of mountain ranges match the range of ideal abiotic conditions for Bd in the laboratory. This unbalanced sampling has led researchers to largely overlook host–pathogen dynamics in lowlands, where other amphibian species declined during the same period. We conducted a survey testing for Bd in 47 species (n = 348) in four lowland sites in Costa Rica to identify local host–pathogen dynamics and to describe the abiotic environment of these sites. We detected Bd in three sampling sites and 70% of the surveyed species. We found evidence that lowland study sites exhibit enzootic dynamics with low infection intensity and moderate to high prevalence (55% overall prevalence). Additionally, we found evidence that every study site represents an independent climatic zone, where local climatic differences may explain variations in Bd disease dynamics. We recommend more detection surveys across lowlands and other sites that have been historically considered unsuitable for Bd occurrence. These data can be used to identify sites for potential disease outbreaks and amphibian rediscoveries. 相似文献
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广东梧桐山国家级风景名胜区两栖爬行动物多样性研究 总被引:1,自引:0,他引:1
唐跃琳;陶青;陈永锋;张雄芳;崔平越;王英永;林石狮 《四川动物》2015,34(5):767-772
2012年对广东梧桐山国家级风景名胜区内的两栖爬行动物进行本底普查,共记录两栖动物2目7科18种,包括中国特有种5种,国家Ⅱ级重点保护野生动物1种,CITES公约附录Ⅱ1种,IUCN濒危物种红色名录列为易危(VU)1种、近危(NT)1种。爬行动物共记录3目(含亚目)11科35种,其中,中国特有种5种,受保护和受胁物种6种,国家Ⅰ级重点保护野生动物1种——蟒蛇Python molurus。区系分析结果显示,梧桐山国家级风景名胜区内的两栖爬行动物具有明显的南亚热带区系的过渡特征。另外,调查发现掌突蟾属1种、湍蛙属1种分别与已知同属物种存在分化,颈槽蛇属有1新种。 相似文献
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Bird censuses were taken by routing in the central part of the Prilenskoe plateau, a region poorly explored by ornithologists. The summer population of birds in different habitats at watersheds, in valleys and along riverbanks has been characterized on the basis of the original data obtained. 相似文献
11.
Phillipsen IC Funk WC Hoffman EA Monsen KJ Blouin MS 《Evolution; international journal of organic evolution》2011,65(10):2927-2945
It has recently become practicable to estimate the effective sizes (N(e) ) of multiple populations within species. Such efforts are valuable for estimating N(e) in evolutionary modeling and conservation planning. We used microsatellite loci to estimate N(e) of 90 populations of four ranid frog species (20-26 populations per species, mean n per population = 29). Our objectives were to determine typical values of N(e) for populations of each species, compare N(e) estimates among the species, and test for correlations between several geographic variables and N(e) within species. We used single-sample linkage disequilibrium (LD), approximate Bayesian computation (ABC), and sibship assignment (SA) methods to estimate contemporary N(e) for each population. Three of the species-Rana pretiosa, R. luteiventris, and R. cascadae- have consistently small effective population sizes (<50). N(e) in Lithobates pipiens spans a wider range, with some values in the hundreds or thousands. There is a strong east-to-west trend of decreasing N(e) in L. pipiens. The smaller effective sizes of western populations of this species may be related to habitat fragmentation and population bottlenecking. 相似文献
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Basing conservation interventions on evidence is important for justifying their associated cost and gauging their effectiveness. For amphibians, the number of studies available to support conservation action plans is limited. Here, we sought to determine the effect of invasive pine trees on the calling densities of a Critically Endangered frog species, endemic to the Western Cape province in South Africa. The Rough Moss frog, Arthroleptella rugosa, is an anuran restricted to a small patch of fire-driven fynbos habitat prone to invasion by Cluster Pines, Pinus pinaster. We use acoustic spatially explicit capture–recapture methods to estimate frog densities at multiple sites (n = 12) over ten years. Sites were classified as invaded or uninvaded by P. pinaster, and this information, along with the time since the last fire, were used as explanatory variables for frog density in a generalized linear mixed model. Frog densities were found to be significantly affected by P. pinaster invasion status. At invaded sites, there was a negative relationship between call densities and time since fire, while at uninvaded sites the same relationship was positive. These results confirm previous suggestions that invasive pine trees cause population declines in A. rugosa. Our findings can be used to support conservation interventions for A. rugosa, specifically the use of fire in an adaptive management context to control pine invasion across its range. 相似文献
13.
Shapcott A 《Molecular ecology》1999,8(10):1641-1654
This study investigated the effect of population density on the population genetic structure of five co-occurring congeneric understorey palm species: Pinanga aristata, P. sp. aff. brevipes, P. dumetosa, P. tenella var. tenella and P. veitchii, all endemic to northern Borneo. The average population densities of the study species varied across a wide spectrum, ranging from 343 (plants per ha) in P. tenella to 10 (plants per ha) in P. veitchii. All species of Pinanga palms studied had quite high levels of genetic diversity (HE: 0.379, 0.256, 0.294, 0.133, 0.352). Genetic diversity (HE) was correlated with population density (D; rs = - 0.433, P < 0.01) and the average distance to the nearest conspecific neighbour (NN; rs = 0.576, P < 0.001) such that the most-dense species had less genetic diversity and the less-dense species had greater genetic diversity. Gene flow (Nm) among populations approximately followed a gradient of increasing species density and abundance, such that the most common species P. dumestosa had the greatest gene flow (Nm = 2.268) between its populations and the rarest, most sparsely distributed species P. sp. aff. brevipes had the lowest (Nm = 0.698). All species of Pinanga were effectively inbred (F: 0.760, 0.856, 0.640, 0.753, 0.674). The amount of homozygosity and inbreeding (HO, F) were not correlated (P > 0.05) with population density (D) or the distance between nearest neighbouring plants of the same species (NN). 相似文献
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Luca Santini Nick J. B. Isaac Luigi Maiorano Gentile Francesco Ficetola Mark A. J. Huijbregts Chris Carbone Wilfried Thuiller 《Global Ecology and Biogeography》2018,27(8):968-979
Aim
Although the effects of life history traits on population density have been investigated widely, how spatial environmental variation influences population density for a large range of organisms and at a broad spatial scale is poorly known. Filling this knowledge gap is crucial for global species management and conservation planning and to understand the potential impact of environmental changes on multiple species.Location
Global.Time period
Present.Major taxa studied
Terrestrial amphibians, reptiles, birds and mammals.Methods
We collected population density estimates for a range of terrestrial vertebrates, including 364 estimates for amphibians, 850 for reptiles, 5,667 for birds and 7,651 for mammals. We contrasted the importance of life history traits and environmental predictors using mixed models and tested different hypotheses to explain the variation in population density for the four groups. We assessed the predictive accuracy of models through cross‐validation and mapped the partial response of vertebrate population density to environmental variables globally.Results
Amphibians were more abundant in wet areas with high productivity levels, whereas reptiles showed relatively higher densities in arid areas with low productivity and stable temperatures. The density of birds and mammals was typically high in temperate wet areas with intermediate levels of productivity. The models showed good predictive abilities, with pseudo‐R2 ranging between 0.68 (birds) and 0.83 (reptiles).Main conclusions
Traits determine most of the variation in population density across species, whereas environmental conditions explain the intraspecific variation across populations. Species traits, resource availability and climatic stability have a different influence on the population density of the four groups. These models can be used to predict the average species population density over large areas and be used to explore macroecological patterns and inform conservation analyses. 相似文献15.
The keystone species concept was introduced in 1969 in reference to top‐down regulation of communities by predators, but has expanded to include myriad species at different trophic levels. Keystone species play disproportionately large, important roles in their ecosystems, but human‐wildlife conflicts often drive population declines. Population declines have resulted in the necessity of keystone species reintroduction; however, studies of such reintroductions are rare. We conducted a literature review and found only 30 peer‐reviewed journal articles that assessed reintroduced populations of keystone species, and only 11 of these assessed ecosystem‐level effects following reintroduction. Nine of 11 publications assessing ecosystem‐level effects found evidence of resumption of keystone roles; however, these publications focus on a narrow range of species. We highlight the deficit of peer‐reviewed literature on keystone species reintroductions, and draw attention to the need for assessment of ecosystem‐level effects so that the presence, extent, and rate of ecosystem restoration driven by keystone species can be better understood. 相似文献
16.
We will analyse the geographical and vertical distributions of Ecuadorian high páramo plants. Lists of species were prepared for six Ecuadorian mountains, and floristic relationships among them were expressed by means of Sørensen's index of similarity. A mantel test was employed to analyse the pattern of geographical distribution of the species to see if the distance between the mountains was sufficient to explain the differences discovered. Altitudinal range and mean altitude of species occurrence were tested against the number of mountains from which the species were recorded using a Kruskal–Wallis nonparametric test. We found that distance as a single factor can not fully explain the pattern of floristic similarity shared by the mountains. Other important factors are involved. Altitudinal range of the species examined was positively correlated with their distribution in Ecuador. Species with a broad altitudinal occurrence were found on several mountains, whereas species with narrow altitudinal distribution were found on fewer mountains. 相似文献
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H. Moller D. Fletcher P. N. Johnson Brian D. Bell D. Flack C. Bragg 《New Zealand journal of zoology.》2013,40(3):325-341
Abstract We estimated the change in abundance of sooty shearwater (titi, Puffinus griseus) at six Rakiura Titi Islands, New Zealand, by comparing historical and recent surveys of the density of entrances to breeding burrows. We found evidence that entrance density between 1994 and 2006 was lower than it was between 1961 and 1976. Our overall estimate of the annual rate of change in burrow entrance density is ‐1.0% (95% CI ‐2.3 to ‐ 0.1%). Declines have been slower on four islands where Rakiura Maori maintain a traditional harvest of sooty shearwater chicks (\"muttonbirding\") compared with three unharvested islands. Density‐dependent population processes may explain this difference: rates of decline have been faster in areas of relatively high initial entrance density, and historically the harvested islands have had lower initial density. There was a strong, apparently linear, relationship between entrance density and chick density on breeding colonies, so changes in entrance density probably do indicate a real population decline. The western side of Taukihepa, the largestof the Titi Islands, first became accessible for muttonbirding with the advent of helicopters in the 1970s, but it is unknown whether this has caused an increase in the number of sooty shearwaters harvested by Rakiura Maori. 相似文献
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Aim To integrate the effects of ecosystem engineers (organisms that create, maintain or destroy habitat for other species) sharing the same archetype on species diversity, and assess whether different engineer species have generalized or idiosyncratic effects across environmentally similar ecosystems.
Location High-Andean habitats of Chile and Argentina, from 23° S to 41° S.
Methods We measured and compared the effects of eight alpine plants with cushion growth-form on species richness, species diversity (measured as the Shannon–Wiener index) and evenness of vascular plant assemblages across four high-Andean ecosystems of Chile and Argentina.
Results The presence of cushion plants always increased the species richness, diversity (measured as the Shannon–Wiener index) and evenness of high-Andean plant assemblages. However, while the presence of different cushion species within the same ecosystem controlled species diversity in the same way, these effects varied between cushion species from different ecosystems.
Main conclusions Results consistently supported the idea that increases in habitat complexity due to the presence of ecosystem engineers, in this case cushion plants, would lead to higher community diversity. Results also indicate that effects of the presence of different cushion species within the same ecosystem could be generalized, while the effects of cushion species from different ecosystems should be considered idiosyncratic. 相似文献
Location High-Andean habitats of Chile and Argentina, from 23° S to 41° S.
Methods We measured and compared the effects of eight alpine plants with cushion growth-form on species richness, species diversity (measured as the Shannon–Wiener index) and evenness of vascular plant assemblages across four high-Andean ecosystems of Chile and Argentina.
Results The presence of cushion plants always increased the species richness, diversity (measured as the Shannon–Wiener index) and evenness of high-Andean plant assemblages. However, while the presence of different cushion species within the same ecosystem controlled species diversity in the same way, these effects varied between cushion species from different ecosystems.
Main conclusions Results consistently supported the idea that increases in habitat complexity due to the presence of ecosystem engineers, in this case cushion plants, would lead to higher community diversity. Results also indicate that effects of the presence of different cushion species within the same ecosystem could be generalized, while the effects of cushion species from different ecosystems should be considered idiosyncratic. 相似文献