共查询到20条相似文献,搜索用时 0 毫秒
1.
Prasanna Venkatesh Sampath Hua-Sheng Liao Zachary Kristopher Curtis Patrick J. Doran Matthew E. Herbert Christopher A. May Shu-Guang Li 《PloS one》2015,10(10)
The sources of water and corresponding delivery mechanisms to groundwater-fed fens are not well understood due to the multi-scale geo-morphologic variability of the glacial landscape in which they occur. This lack of understanding limits the ability to effectively conserve these systems and the ecosystem services they provide, including biodiversity and water provisioning. While fens tend to occur in clusters around regional groundwater mounds, Ives Road Fen in southern Michigan is an example of a geographically-isolated fen. In this paper, we apply a multi-scale groundwater modeling approach to understand the groundwater sources for Ives Road fen. We apply Transition Probability geo-statistics on more than 3000 well logs from a state-wide water well database to characterize the complex geology using conditional simulations. We subsequently implement a 3-dimensional reverse particle tracking to delineate groundwater contribution areas to the fen. The fen receives water from multiple sources: local recharge, regional recharge from an extensive till plain, a regional groundwater mound, and a nearby pond. The regional sources deliver water through a tortuous, 3-dimensional “pipeline” consisting of a confined aquifer lying beneath an extensive clay layer. Water in this pipeline reaches the fen by upwelling through openings in the clay layer. The pipeline connects the geographically-isolated fen to the same regional mound that provides water to other fen clusters in southern Michigan. The major implication of these findings is that fen conservation efforts must be expanded from focusing on individual fens and their immediate surroundings, to studying the much larger and inter-connected hydrologic network that sustains multiple fens. 相似文献
2.
Antoni Margalida Martina Carrete Daniel Hegglin David Serrano Rafael Arenas José A. Donázar 《PloS one》2013,8(6)
After the quasi-extinction of much of the European vertebrate megafauna during the last few centuries, many reintroduction projects seek to restore decimated populations. However, the future of numerous species depends on the management scenarios of metapopulations where the flow of individuals can be critical to ensure their viability. This is the case of the bearded vulture Gypaetus barbatus, an Old World, large body-sized and long-lived scavenger living in mountain ranges. Although persecution in Western Europe restrained it to the Pyrenees, the species is nowadays present in other mountains thanks to reintroduction projects. We examined the movement patterns of pre-adult non-breeding individuals born in the wild population of the Pyrenees (n = 9) and in the reintroduced populations of the Alps (n = 24) and Andalusia (n = 13). Most birds were equipped with GPS-GSM radio transmitters, which allowed accurate determination of individual dispersal patterns. Two estimators were considered: i) step length (i.e., the distance travelled per day by each individual, calculated considering only successive days); and ii) total dispersal distance (i.e., the distance travelled between each mean daily location and the point of release). Both dispersal estimators showed a positive relationship with age but were also highly dependent on the source population, birds in Andalusia and Alps moving farther than in Pyrenees. Future research should confirm if differences in dispersal distances are the rule, in which case the dynamics of future populations would be strongly influenced. In summary, our findings highlight that inter-population differences can affect the flow of individuals among patches (a key aspect to ensure the viability of the European metapopulation of the endangered bearded vulture), and thus should be taken into account when planning reintroduction programs. This result also raises questions about whether similar scenarios may occur in other restoration projects of European megafauna. 相似文献
3.
Pythons are harvested for the international leather industry and pet trade. We analyzed the CITES export records (1999–2008) of the most intensively commercialized wild pythons (Python regius, Python sebae, Python reticulatus, Python molurus, Python curtus species complex) from African and Asian countries where reliable data on trade rates and ecology are available. Mean declared annual numbers of exported pythons were 30,000 in five African countries and 164,000 in Indonesia. Trade intensity tripled in Indonesia over the last decade, but declined in Africa. African international trade is exclusively associated with the pet market (mainly United States and Europe), whereas Asian pythons are sold mostly for luxury leather, albeit more recently also for the pet trade. A negative correlation between the annual numbers of pythons traded in Africa vs. Asia suggests a rapid and recent shift of the pressure exerted on wild populations in the two main exporting continents. We also found a strong effect of the currency exchange rate (i.e., U.S.$/€, the currencies used by the major importing countries) on African python exports: when the cost per African python increased, importers relied increasingly on Asian providers for pet trade. Overall, our data indicate that Asian pythons (especially P. reticulatus) might be threatened due to the rapidly increasing pressure, whereas the decreasing international trade in African pythons is likely more sustainable. 相似文献
4.
The consumption of cetacean meat is geographically common and often of undetermined sustainability. Besides, it can expose humans to contaminants and zoonotic pathogens. The illegality of possessing cetacean meat was likely under-reported in some countries due to lack of attention paid by the officials although DNA analysis of market products helped to show such practices. We developed two monoclonal antibodies against synthetic peptides of myoglobin (Mb) for constructing a rapid immune colloidal gold strip. Only cetacean Mb is capable of binding to both antibodies and presents positive signal while the Mb from other animals can bind only 1 of the antibodies and presents negative result. The strip for cetacean meat would be an applicable and cost-effective test for field inspectors and even the general public. It contributes to increase the reporting capacity and coverage of illegal cetacean meat possession, which has implications for global cetacean conservation and public health. 相似文献
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María-Angeles Arevalo María Santos-Galindo María-José Bellini Iñigo Azcoitia Luis M. Garcia-Segura 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Glial cells are directly or indirectly affected by estradiol and by different estrogenic compounds, such as selective estrogen receptor modulators. Acting on oligodendrocytes, astrocytes and microglia, estrogens regulate remyelination, edema formation, extracellular glutamate levels and the inflammatory response after brain injury. In addition, estradiol induces the expression and release of growth factors by glial cells that promote neuronal survival. Therefore, glial cells are important players in the neuroprotective and reparative mechanisms of estrogenic compounds. 相似文献
6.
Thomas T. Struhsaker 《International journal of primatology》2008,29(1):19-34
Demographic parameters of nonhuman primates, like those of all other organisms, vary over time and space. However, many contemporary
models comparing multiple species treat these parameters as if they were static. Population density, group size, age-sex composition,
natality, and juvenile recruitment all vary considerably within populations that researchers have studied for many years.
It is important to describe and to understand the variance not only for the development of more realistic models but also
to clarify the status and trends of the populations in order to develop effective conservation management plans. A critical
issue is to distinguish real demographic trends from the natural demographic variation that occurs both between sites and
within specific sites over time. With few exceptions, demographic data for most nonhuman primates are not amenable to life-table
analyses because observation conditions typically prevent collection of the data required and generation time is long. Instead,
one must evaluate demographic indices that serve as surrogates for more detailed and accurate data, such as that derived from
life-time observations of recognizable individuals of known parentage. Long-term monitoring is essential to understand the
extent of and trends in demographic variation. These points are exemplified with case studies from vervets, red howlers, and
red colobus as they relate to the likely causal factors of habitat quality, disease, predator-prey imbalance, population compression,
and intragroup competition for food. 相似文献
7.
Javier Francisco-Ortega Zhong-Sheng Wang Fa-Guo Wang Fu-Wu Xing Hong Liu Han Xu Wei-Xiang Xu Yi-Bo Luo Xi-Qiang Song Stephan Gale David E. Boufford Mike Maunder Shu-Qing An 《The Botanical review》2010,76(3):346-376
Hainan, the second largest island of China, has the most extensive and best preserved tropical forests of this country. A network of 68 protected areas (54 of them are terrestrial) provides in situ conservation for the unique ecosystems of the island. We: (1) discuss an updated check-list of seed-plant species that are endemic to Hainan, (2) evaluate the extent to which the endemic flora has been the subject of molecular studies, and (3) investigate the conservation status of these species. We recognize 397 endemic species on the island, 271 of which are reported in the protected areas, and 144 of which have been Red-Listed (85 assigned to the Critically Endangered (40) or Endangered (45) IUCN categories). The families with the highest number of endemics are Rubiaceae (33 species), Lauraceae (27 species), and Poaceae (26 species). The island has only seven endemic genera, all of which are unispecific. Compared with other tropical islands, Hainan has a low number of endemics but our preliminary observations suggest that the island has a highly disharmonic flora when compared with that from the mainland. Nevertheless, most of the major clades of the seed-plant tree of life with representatives in China also have endemic species on the island. We argue that the low levels of endemism reflect the continental nature of Hainan and the fact that several areas of the island have not been fully inventoried. We were unable to find a single molecular systematic study focusing exclusively on the Hainan endemics; however, 24 of the endemic species have been included in phylogenetic studies targeting particular genera or families. Future research/conservation actions for the endemic flora of Hainan should focus in developing: (1) a red-list that assesses all 397 endemic species, (2) comprehensive floristic studies for the protected areas, (3) molecular phylogenetic and conservation genetic studies with a primary focus on the endemics, (4) studies to understand what ecological interactions are important in the biology of the endemic species, and (5) eco-geographical studies to identify Important Biodiversity Zones of endemism within Hainan and therefore potential new protected areas. 相似文献
8.
CATHERINE WORKMAN 《American anthropologist》2004,106(2):346-352
Vietnam is home to a considerable diversity of primates: Indeed, five of the world's top 25 most endangered primate species are found within Vietnam. To understand and ultimately address Vietnam's conservation crisis, the complex interplay of history, demography, economics, international relations, and culture must be analyzed within Vietnam's specific context. Conducting a holistic analysis with the example of hunting represents how seemingly disparate factors such as the U.S. war, increased tourism and globalization, population density, and cultural traditions converge to significantly impact wildlife. 相似文献
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Natália Carolina de Almeida Silva Rafael Vidal Flaviane Malaquias Costa Magdalena Vaio Juliana Bernardi Ogliari 《PloS one》2015,10(10)
Records of the occurrence of wild relatives of maize in South American lowlands are unprecedented, especially in sympatric coexistence with landraces. This fact is relevant, because regions of occurrence of wild relatives of cultivated plants should be a priority for conservation, even if they do not correspond to the center of origin of the species. The aim of this study was to identify and characterize the wild relatives of maize in the Far West of Santa Catarina, southern Brazil. Therefore, phenotypic characterization was performed for five populations, based on 22 morphological traits deemed as fundamental for classifying the species of the genus Zea, and validated through the characterization of chromosomal knobs of two populations. The occurrence and distribution of teosinte populations were described through semi-structured interviews applied to a sample of 305 farmers. A total of 136 teosinte populations were identified; 75% of them occur spontaneously, 17% are cultivated populations, and 8% occur both ways, for the same farm. Populations that were characterized morphologically had trapezoidal fruits mostly, upright tassel branch (4–18), non-prominent main branch and glabrous glumes, with two protruding outer ribs and 8 inner ribs, on average. Cytogenetic analysis identified 10 pairs of homologous chromosomes (2n = 20) with 26 knobs, located in the terminal region of all chromosomes. The similarity of these results with the information reported in the literature indicates that the five populations of wild relatives of maize in this region of Santa Catarina belong to the botanical species Zea luxurians. 相似文献
11.
Mostafa A Borahay Ayman Al-Hendy Gokhan S Kilic Darren Boehning 《Molecular medicine (Cambridge, Mass.)》2015,21(1):242-256
Uterine leiomyomas are the most common tumors of the female genital tract, affecting 50% to 70% of females by the age of 50. Despite their prevalence and enormous medical and economic impact, no effective medical treatment is currently available. This is, in part, due to the poor understanding of their underlying pathobiology. Although they are thought to start as a clonal proliferation of a single myometrial smooth muscle cell, these early cytogenetic alterations are considered insufficient for tumor development and additional complex signaling pathway alterations are crucial. These include steroids, growth factors, transforming growth factor-beta (TGF-β)/Smad; wingless-type (Wnt)/β-catenin, retinoic acid, vitamin D, and peroxisome proliferator-activated receptor γ (PPARγ). An important finding is that several of these pathways converge in a summative way. For example, mitogen-activated protein kinase (MAPK) and Akt pathways seem to act as signal integrators, incorporating input from several signaling pathways, including growth factors, estrogen and vitamin D. This underlines the multifactorial origin and complex nature of these tumors. In this review, we aim to dissect these pathways and discuss their interconnections, aberrations and role in leiomyoma pathobiology. We also aim to identify potential targets for development of novel therapeutics. 相似文献
12.
Tarrant AM 《Integrative and comparative biology》2005,45(1):201-214
The vertebrate endocrine system is well-characterized, with many reports of disruption by environmental chemicals. In contrast, cnidarians are less compartmentalized, physiological regulation is poorly understood, and the potential for disruption is unknown. Endocrine-like activity has not been systematically studied in cnidarians, but several classical vertebrate hormones (e.g., steroids, iodinated organic compounds, neuropeptides, and indoleamines) have been identified in cnidarian tissues. Investigators have made progress in identifying putative bioregulatory molecules in cnidarians, and testing the effects of these individual compounds. Less progress has been made in elucidating signaling pathways. For example, putative gonadotropin-releasing hormone and sex steroids have been identified in cnidarian tissues, but it is unknown whether these compounds are components of a larger signal cascade comparable to the vertebrate hypothalamic-pituitary-gonadal axis. Further, while sex steroids and iodinated organic compounds may help to regulate cnidarian physiology, the mechanisms of action are unknown. Homologs to the vertebrate steroid and thyroid receptors have not been identified in cnidarians, so more research is needed to understand the mechanisms of endocrine-like signaling in cnidarians. Elucidation of cnidarian regulatory pathways will provide insight into evolution of hormonal signaling. These studies will also improve understanding of how cnidarians respond to environmental cues and will provide a basis to investigate disruption of physiological processes by physical and chemical stressors. 相似文献
13.
Rafael Dias Loyola Sofia-Luiza Brito Rodrigo Lopes Ferreira 《Biodiversity and Conservation》2006,15(1):25-42
The Pantanal is one of the faunistic provinces considered as a priority area for invertebrate conservation. However, it is
one of the areas in Brazil where the local fauna is less assessed, thus needing more scientific information that could allow
political decisions to be made regarding conservation. The continuous pressure for new pasture areas leads to improper habitat
occupation and destruction, like fragmentation of forest areas in the region. Such alterations can cause different impacts
on the local fauna, including the soil arthropods. The main objective of this work was to compare the morphospecies composition,
diversity and density of the soil arthropod fauna between a secondary single species forest (Cambarazal) and a cultivated
pasture with exotic and native grass species, using only pitfall traps as sampling method. We found a great variation on the
vegetal cover among environments. A higher humidity in the forest soil was observed, as well as a greater compaction of the
soil in the cultivated pasture. A total of 3635 individuals were collected, belonging to 214 different morphospecies. 139
morphospecies were collected in the forest (37% exclusive to this environment), while 134 morphospecies were collected in
the cultivated pasture (35% exclusive). The diversity was higher in the forest (H′ = 1.634) than in the cultivated pasture (H′ = 1.253). However, considering the area as a whole (forest and pasture) the global diversity was increased. In this paper
we discuss about the effects of environmental changes on soil arthropod diversity and propose a hypothetical model for invertebrate
management in mosaic ecosystems. 相似文献
14.
Gabriele Cozzi Dominik M. Behr Hugh S. Webster Megan Claase Caleb M. Bryce Boitshepho Modise John W. Mcnutt Arpat Ozgul 《The Journal of wildlife management》2020,84(4):614-621
Successful conservation of species that roam and disperse over large areas requires detailed understanding of their movement patterns and connectivity between subpopulations. But empirical information on movement, space use, and connectivity is lacking for many species, and data acquisition is often hindered when study animals cross international borders. The African wild dog (Lycaon pictus) exemplifies such species that require vast undisturbed areas to support viable, self-sustaining populations. To study wild dog dispersal and investigate potential barriers to movements and causes of mortality during dispersal, between 2016 and 2019 we followed the fate of 16 dispersing coalitions (i.e., same-sex group of ≥1 dispersing African wild dogs) in northern Botswana through global positioning system (GPS)-satellite telemetry. Dispersing wild dogs covered ≤54 km in 24 hours and traveled 150 km to Namibia and 360 km to Zimbabwe within 10 days. Wild dogs were little hindered in their movements by natural landscape features, whereas medium to densely human-populated landscapes represented obstacles to dispersal. Human-caused mortality was responsible for >90% of the recorded deaths. Our results suggest that a holistic approach to the management and conservation of highly mobile species is necessary to develop effective research and evidence-based conservation programs across transfrontier protected areas, including the need for coordinated research efforts through collaboration between national and international conservation authorities. © 2020 The Wildlife Society. 相似文献
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城市野境是城市内部或周边区域中自然过程占主导的土地,其中人类开发和控制程度相对较低,允许在一定程度上发生自然演替和生态过程,各类野生生物能够与人类繁荣共存。城市野境在重新连接人与自然、促进人类身心健康、保护生物多样性、维持生态系统服务方面具有重要和独特的价值。基于文献综述与案例研究,提出并阐释了保护与营造城市野境的 4 种途径,包括保护、修复、设计与融合,即在城市保护地中保护野性自然、再野化部分城市区域、在城市公园中营造类荒野景观以及在城市空间中系统性融入野性自然。建议在中国城市规划与城市设计中,融入野性自然保护与修复的理念,进一步探索城市野境保护与营造的理论与方法。 相似文献
18.
低于最小存活种群(Minimum Viable Population,简称:MVP)界线而濒临灭绝的极小种群野生植物是需要最优先保护的物种。“近地保护”是云南省林业厅在近年提出的对极小种群野生植物进行保护的一种新方法,它已成为国家林业局的野生植物六大拯救措施之一。根据近年来云南省对极小种群野生植物近地保护的实践和所取得的成果,以及经笔者对若干种国家重点保护植物在迁地保护与就地保护条件下的生长与适应性的比较研究,认为对包括极小种群在内的受严重威胁植物的近地保护的有效性远高于对它们的迁地保护。因而,笔者建议,应该尽快建立和完善野生植物近地保护体系,进一步加强极小种群野生植物高风险灭绝机制的研究,才能有的放矢地选择恰当的保护方法和科学的措施,以及在近地保护的实践中还必须遵循气候相似、生境相似和群落相似的生态学原则,以减少投入和提高其保护的有效性。 相似文献
19.
Budgets for species conservation limit actions. Expending resources in areas of high human density is costly and generally considered less likely to succeed. Yet, coastal California contains both a large fraction of narrowly endemic at-risk plant species as well as the state''s three largest metropolitan regions. Hence understanding the capacity to protect species along the highly urbanized coast is a conservation priority. We examine at-risk plant populations along California''s coastline from San Diego to north of San Francisco to better understand whether there is a relationship between human population density and: i) performance of at-risk plant populations; and ii) conservation spending. Answering these questions can help focus appropriate strategic conservation investment. Rare plant performance was measured using the annualized growth rate estimate between census periods using the California Natural Diversity Database. Human density was estimated using Census Bureau statistics from the year 2000. We found strong evidence for a lack of a relationship between human population density and plant population performance in California''s coastal counties. Analyzing US Endangered Species expenditure reports, we found large differences in expenditures among counties, with plants in San Diego County receiving much higher expenditures than other locations. We found a slight positive relationship between expenditures on behalf of endangered species and human density. Together these data support the argument that conservation efforts by protecting habitats within urban environments are not less likely to be successful than in rural areas. Expenditures on behalf of federally listed endangered and threatened plants do not appear to be related to proximity to human populations. Given the evidence of sufficient performance in urban environments, along with a high potential to leverage public support for nature in urban environments, expenditures in these areas appear to be an appropriate use of conservation funds. 相似文献
20.
Positive Feedbacks in Seagrass Ecosystems: Implications for Success in Conservation and Restoration 总被引:1,自引:0,他引:1
Tjisse van der Heide Egbert H. van Nes Gertjan W. Geerling Alfons J. P. Smolders Tjeerd J. Bouma Marieke M. van Katwijk 《Ecosystems》2007,10(8):1311-1322
Abstract
Seagrasses are threatened by human activity in many locations around the world. Their decline is often characterized by sudden
ecosystem collapse from a vegetated to a bare state. In the 1930s, such a dramatic event happened in the Dutch Wadden Sea.
Before the shift, large seagrass beds (Zostera marina) were present in this area. After the construction of a large dam and an incidence of the “wasting disease” in the early
1930s, these meadows became virtually extinct and never recovered despite restoration attempts. We investigated whether this
shift could be explained as a critical transition between alternative stable states, and whether the lack of recovery could
be due to the high resilience of the new turbid state. We analyzed the depth distribution of the historical meadows, a long-term
dataset of key factors determining turbidity and a minimal model based on these data. Results demonstrate that recovery was
impossible because turbidity related to suspended sediment was too high, probably because turbidity was no longer reduced
by seagrass itself. Model simulations on the positive feedback suggest indeed the robust occurrence of alternative stable
states and a high resilience of the current turbid state. As positive feedbacks are common in seagrasses, our findings may
explain both the worldwide observed collapses and the low success rate of restoration attempts of seagrass habitats. Therefore,
appreciation of ecosystem resilience may be crucial in seagrass ecosystem management. 相似文献