Aims: To understand the effects of providing supplementary food on the movement ecology of vultures.
Methods: We used Global Positioning System tracking devices to monitor the movements of 28 Cape Vultures Gyps coprotheres using feeding stations in South Africa. We calculated home range values and then performed a habitat selection analysis.
Results: We show that aside from roost sites, vulture feeding stations are the most important environmental variable that explains vulture movements. However, we found that the birds ranged over areas without supplementary food and their mean home range values were comparable to those measured before the inception of feeding stations.
Conclusion: Our findings suggest that the use of supplementary feeding sites did not significantly impact on the natural foraging behaviour of the species. 相似文献
Aims: Data on five tree species (Pinus taeda L., Pinus virginiana Mill., Liquidambar styraciflua L., Liriodendron tulipifera L., and Pinus palustris Mill.) were used to test the predictions from MST on the scaling of height–diameter and also diameter growth.
Methods: Data on tree height and diameter for five tree species from both natural forests and plantations were collected to study two types of scaling relationships: tree height–diameter and stem diameter growth. A reduced major axis of regression analysis model type II was used to determine scaling exponents from each species under different environmental conditions.
Results: No universal invariant scaling exponent was found in height–diameter and diameter growth for the five species. The scaling varied across natural forests, plantations and scales (e.g., time and number of measured trees). However, in some situations the scaling exponents failed to show significant difference with the predicted values (e.g., 2/3 or 1).
Conclusions: Diverse scaling exponents were observed for the five tree species with the scaling relationships varying with environmental settings. 相似文献
Aims: Here we examine whether post-fire seedling recruitment of three widespread Californian chaparral shrubs is affected by local adaptation within an edaphically and topographically complex landscape.
Methods: We reciprocally transplanted 6-month-old seedlings of Adenostema fasciculatum, Ceanothus cuneatus and Eriodictyon californicum to serpentine and sandstone soils, and cool northerly and warm southerly slopes.
Results: At the age of 2 years, none of the species manifested higher survival or growth on ‘home’ compared with ‘away’ soils or slopes, indicating an absence of local adaptation with respect to seedling recruitment in these environments. Seedlings of all species manifested lower survival and relative growth on serpentine soils regardless of seedling source, as well as a variety of other destination and source effects.
Conclusions: The ability of these three species to recruit in new environments, such as in restoration settings or in response to shifting climates, is unlikely to be impeded by a need for seeds from sources that closely match their edaphic or topographic destination. 相似文献
Aims: We compared four groups of plants: large trees, shrubs and saplings, herbs and ferns in a forest recovering from disturbance. We quantified the relative importance of disturbance history and local environmental conditions in determining species richness and community composition of these groups and assessed whether the groups could act as surrogate indicators for one another.
Methods: Vegetation was surveyed on a gradient of disturbance intensity and recovery time (20–60 years) in Mabira Forest, Uganda. We looked for correlations between species groups in richness or composition across sites and used constrained ordinations to identify important environmental variables.
Results: Neither species richness nor composition patterns were correlated between groups. All groups were weakly related to disturbance history; trees and shrubs were related to soil, herbs to microhabitat and ferns to microclimate.
Conclusions: No group acted as an indicator for another. The relative influence of disturbance and local environmental effects varied in the manner predicted, with disturbance stronger for trees and environment stronger for ferns. 相似文献
Aims: To investigate the genetic diversity and population structure of Macqueen’s Bustard in Iran, using two mitochondrial DNA loci.
Methods: Molecular diversity of the mitochondrial cytochrome oxidase c subunit I (COI) gene and part of the mitochondrial control region D-loop (in total 1183 base pairs) were analysed from 26 individual Macqueen’s Bustards from three regions of Iran.
Results: There was little variation in nucleotides and haplotypes in the populations for genes of both CR and COI. The population had free breeding and gene flow between the three study regions in Iran: Petregan, Ferdows and Yazd.
Conclusion: The use of molecular and genetic studies is essential to strengthen the protection of genetic diversity of the Macqueen’s Bustard. 相似文献
Aims: Investigating a range of hypotheses for the role of biotic and abiotic factors as determinants of the global variation in animal vs. wind pollination.
Methods: We analysed 67 plant communities ranging from 70º north to 34º south. For these we determined habitat type, species richness, insularity, topographic heterogeneity, current climate and late-quaternary climate change. The predictive effects of these factors on the proportion of wind- and animal-pollinated plants were tested using correlations, ordinary least squares (OLS) and logistic regression analyses with information-theoretic model selection.
Results: The proportion of animal-pollinated plant species was positively associated with plant species richness and current temperature. Furthermore, in forest, animal pollination was positively related to precipitation. Historical climate was only weakly and idiosyncratically correlated with animal pollination.
Conclusion: Results were consistent with the hypothesised reduced chance for wind-transported pollen reaching conspecific flowers in species-rich communities, fewer constraints on nectar production in warm and wet habitats, and reduced relative effectiveness of wind dispersal in humid areas. There was little evidence of a legacy of historical climate change affecting these patterns. 相似文献
Aims: Creating a baseline data set of epiphyte diversity in human settlements and assessing differences with assemblages of less disturbed habitats.
Methods: We surveyed the vascular epiphyte assemblages in 25 settlements of south-west Panama along a rainfall gradient. We tested how epiphyte assemblages were affected by human disturbance and climate by comparing our data to that of pastures and forest.
Results: Almost half (238 of 499) of all studied trees hosted at least one epiphyte. Altogether, 10,700 epiphytes of 56 species were found. Rainfall strongly affected both composition and diversity of epiphyte assemblages, whereas geographic proximity did not. In settlements, the species pool was considerably smaller than in pastures and undisturbed forest; however, settlements’ diversity was only significantly lower compared to pastures.
Conclusions: Epiphyte assemblages in settlements had a diminished species pool but diversity per tree was comparable to less disturbed habitats. Unsurprisingly, rainfall seems to be the main determinant of epiphyte diversity in rural settlements. 相似文献
Aims: To determine how litter and standing vegetation affected seedling recruitment in plant communities in Tibetan alpine grasslands.
Methods: Seedling recruitment was quantified in response to experimental treatments: (1) removal of standing vegetation and litter; (2) removal of standing vegetation with litter intact; (3) intact standing vegetation and removal of litter and (4) control: intact standing vegetation and litter.
Results: Litter removal increased seedling numbers, while standing vegetation removal had no effect. An interaction between litter and standing vegetation removal marginally increased seedling number. Species richness of seedlings was not related to either litter removal or standing vegetation removal. Species composition of seedling differed significantly between removal of both litter and standing vegetation and control.
Conclusions: Litter and its interaction with standing vegetation has an important role in affecting plant species recruitment in this alpine plant community. In contrast, biotic interactions, such as competition or facilitation from standing vegetation, appear to have only minor effects on recruitment. 相似文献
Objective: To compare the reliability of urine lactate between controlled hydration and no hydration after maximal exercise.
Material and methods: Athletes performed swimming exercise four times: two followed by consumption of 1?L of water and two followed by no water intake. Blood and urine lactate was measured.
Results: The reliability of urine lactate was good and similar to that in blood only after controlled hydration. Blood and urine lactate were correlated under both hydration conditions.
Discussion and conclusion: Controlled hydration after exercise provides satisfactory reliability of urine lactate. 相似文献
Objective: This review has focused on the most recent investigations, which has suggested potential epigenetic biomarkers in colorectal cancer.
Methods: Evidences were achieved by searching online medical databases including Google scholar, Pubmed, Scopus and Science Direct.
Results: Extensive studies have indicated that aberrant epigenetic modifications could serve as potential biomarkers for diagnosis, prognosis and prediction of colorectal cancer.
Conclusion: Advances in aberrant epigenetic modifications can open new avenues for exploration of reliable and robust biomarkers to improve the management of CRC patients. 相似文献
Objective: To examine effects of nickel exposure on plasma oxidative and anti-oxidative biomarkers.
Materials and methods: Biomarker data were collected from 154 workers with various levels of nickel exposure and from 73 controls. Correlations between nickel exposure and oxidative and anti-oxidative biomarkers were determined using linear regression models.
Results: Workers with a exposure to high nickel levels had significantly lower levels of anti-oxidants (glutathione and catalase) than those with a lower exposure to nickel; however, only glutathione showed an independent association after multivariable adjustment.
Discussion and conclusion: Exposure to high levels of nickel may reduce serum anti-oxidative capacity. 相似文献
Objective: To establish a panel of protein biomarkers incorporated in a multiplexed microarray (BCa chip) and a classifier for diagnosing recurrent NMIBC.
Materials and methods: Urine samples from 45 patients were tested. Diagnostic performance was evaluated by receiver operating characteristic (ROC) analysis.
Results: A multi biomarker panel (ECadh, IL8, MMP9, EN2, VEGF, past recurrences, BCG therapies and stage at diagnosis) was identified yielding an area under the curve of 0.96.
Discussion and conclusion: This biomarker panel represents a potential diagnostic tool for noninvasive diagnosis of recurrent NMIBC. 相似文献
Objective: Ascertain the utility of measurements of single-strand breaks (SSB) in DNA for assessment of breast cancer risk.
Methods: Fine-needle aspirates of the breast, SSB by nick translation, percent breast density (PBD), Gail model risk, cumulative methylation index (CMI), enzymes of DNA repair and tissue antioxidants.
Results: DNA repair enzymes and 4-hydroxyestradiol were negatively associated with SSB; CMI and PBD were positively associated.
Conclusions: Quantitative measurement of SSBs by this procedure indicates the relative number of SSBs and is related to promoter methylation, antioxidant availability and percent breast density. 相似文献
Aims: We tested the hypothesis that habitat used during spring stopovers in Spain differed from habitat use during the breeding period in Switzerland in a year of exceptional abundance as a result of persistent easterly winds in the Mediterranean.
Methods: Habitat use during spring migration 2015 was compared by using bootstrapping resampling techniques on citizen science data from Spain and Switzerland, comparing the land-cover categories between locations of observations with random pseudo-absences.
Results: Wood Warblers showed no preference for habitat features during migration and covered practically all available habitat types from urbanized areas to wetlands and forests, whereas in the breeding range birds showed an increasing tendency to be present in forest habitats.
Conclusions: Habitat use during spring migration covered most available habitat types from urbanized areas to wetlands and forests. Breeding habitat use was restricted to forested areas. Citizen science allowed a quick collection of biological data over a wide area to potentially identify large-scale biological patterns. This is essential to potentially manage international conservation efforts for declining species. 相似文献
Aims: To estimate the age-specific survival and reporting rate from an internationally important population of Northern Gannets M. bassanus breeding at one of the southernmost colonies for this species.
Methods: We use 28 years of ringing and recovery data in order to estimate age-specific survival and reporting rates.
Results: Adult and juvenile survival rates differ, and both survival and reporting rates are considerably lower in first-year birds than older birds. Additionally there is an increasing linear trend in survival rates over time, and a decreasing trend in reporting rates.
Conclusion: Threats to Gannets from anthropogenic disturbance are likely to be age and population specific. While these rates point towards continued growth of this population, the confidence intervals around our estimates are large, highlighting the need for improved resighting efforts in long-term studies of this nature. 相似文献
Aims: To investigate the breeding biology of Western Bonelli’s Warbler P. bonelli, focusing on possible altitude effects and potential reproductive problems.
Methods: Three Western Bonelli’s Warbler populations were monitored during the 2012 and 2013 breeding seasons in the massif range of Sierra Nevada, Spain. We determined all the breeding parameters and calculated daily survival and success rates for each reproductive period.
Results: The three studied populations did not differ in any breeding parameters. Altitude showed a positive relationship with clutch size and duration of incubation period, but a negative relationship with nestling tarsus growth and body mass gain. Daily survival rates during incubation and nestling periods were similar to those of common warblers, but the species presented a low breeding success of 25%.
Conclusion: The absence of differences among the three populations suggests that the information provided here could be representative of its distribution in the woodlands of Sierra Nevada. The novel and detailed information reported is crucial not only for expanding our understanding of this species but also to draw attention to the potential risks that it might face in the near future, considering the reduction that this species has suffered in Sierra Nevada during recent decades. 相似文献
Aim: To assess size and competitive ability of the exotic non-invasive weed Centaurea sulphurea, and of inter-regional hybrids between native and non-native populations.
Methods: We experimentally produced a cohort of C. sulphurea individuals from the native range of the species in Spain, from its non-native range in California, as well as hybrids between the two regions. We grew these plants in pots in competition with the grass Bromus hordeaceus, or alone in control pots.
Results: Individuals from California were larger and better competitors than individuals from Spain. Furthermore, inter-regional hybrids showed competitive responses similar to that of individuals from California.
Conclusions: Our results confirm that increased competitive ability might be more frequent than previously thought among introduced species, since it can be detected in at least some exotic non-invasive species. They also illustrate the importance of maternal effects, how locally adapted traits are conserved and spread in the non-native ranges of exotic species, and suggest that plant size and competitive ability are not directly associated in this species. 相似文献
Aims: We evaluated seed weight variation within and between Trichloris crinita and Trichloris pluriflora across their geographical ranges in Argentina.
Methods: Genetic variation in seed weight was evaluated through a common garden experiment. To examine the possible role of such variation in local adaptation, we compared the seed weight of plants of populations raised in the common garden with seed weight variation and ecogeographical variables across their original habitats. We also evaluated experimentally the effects of seed weight variation upon osmotic stress tolerance at germination.
Results: Variation in seed weight existed in both species. Such variation had a genetic basis in T. crinita related to several ecogeographical variables. Larger seeds of T. crinita were associated with more stressful environments and produced larger seedlings under both osmotic stress and non-stress conditions.
Conclusions: Our results suggest that seed weight variation in T. crinita is likely adaptive, with large seed having an advantage during early developmental stages, particularly under stressful conditions. Such knowledge should prove helpful in selecting the most suitable populations for restoration and plant breeding. 相似文献
Aims: To investigate effects of Eucalyptus saligna leaf litter on the colonisation and development of the ground layer by grassland species and if these effects were related to allelopathy.
Methods: We assessed the effects of Eucalyptus litter on the establishment of species of the native grassland community and on seeded test species (Paspalum notatum and Lotus corniculatus – introduced). We tested the impact of the addition of E. saligna leaf litter, artificial leaves (shading and mechanical impediment) and shading. We also tested the phytotoxicity of the soil from E. saligna plantations.
Results: Species richness, diversity, plant height, cover and biomass were lower in E. saligna leaves and artificial leaves treatments than in the control (absence of litter). The test species showed lower biomass and higher mortality in treatment plots with E. saligna leaves, artificial leaves and shading treatments than in the control. Allelochemicals did not accumulate in soil at phytotoxic levels.
Conclusions: Eucalyptus saligna leaf litter suppresses the establishment of grassland vegetation, but the effects are mainly physical. Field evaluations with appropriate controls should be more extensively used in allelopathy investigations. 相似文献
Objective: To characterize by in vitro biochemical and in silico studies the NBDHEX analogues named MC2752 and MC2753.
Materials and methods: Synthesis of MC2752 and MC2753, biochemical assays and in silico docking and normal-mode analyses.
Results: The presence of a hydrophobic moiety in the side chain of MC2753 confers unique features to this molecule. Unlike its parent drug NBDHEX, MC2753 does not require GSH to trigger the dissociation of the complex between GSTP1-1 and TRAF2, and displays high stability towards the nucleophilic attack of the tripeptide under physiological conditions.
Discussion and conclusion: MC2753 may represent a lead compound for the development of novel GSTP1-1 inhibitors not affected in their anticancer action by fluctuations of cellular GSH levels, and characterized by an increased half-life in vivo. 相似文献