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排序方式: 共有995条查询结果,搜索用时 15 毫秒
941.
Spencer J. Ingley Eric J. Billman Chelsey Hancock Jerald B. Johnson 《Behavioral ecology and sociobiology》2014,68(10):1577-1587
Environmental effects on behavior have long been a focus of behavioral ecologists. Among the important drivers of behavior is predation environment, which can include the presence/absence of predators, differences in resource availability, and variation in individual density. Environments with predators are often more ecologically complex and “risky” than those without predators. Populations from these environments are sometimes more active and explorative than populations from low-risk, less complex environments. To date, most comparative studies of behavior are limited to within-species comparisons of populations from divergent environments, but neglect comparisons between species following speciation, thus limiting our understanding of post-speciation behavioral evolution. Brachyrhaphis fishes provide an ideal system for studying correlations between divergent environments and behavior within and between species. Here, we test for differences in two behavioral traits—activity and exploration —between sister species Brachyrhaphis roseni and Brachyrhaphis terrabensis that occur in divergent predation environments. Species differed in activity and exploration, with higher activity and exploration levels in populations that co-occur with predators. Furthermore, we found drainage-by-species interactions, indicating that the nature of divergence varied geographically. Using the recently developed phenotypic trajectory analysis (PTA), we quantified this difference and found that, while the geographically isolated populations of sister species tended to evolve in parallel, the magnitude of divergence between species differed between drainages. Our results highlight the utility of PTA for multivariate behavioral data and corroborate past predictions that complex and risky environments are correlated with increased activity and exploration levels and that divergence continues post-speciation. 相似文献
942.
Nishant Pandya Nadine Gabas Eric Marsden 《Journal of Loss Prevention in the Process Industries》2012,25(1):20-32
We present the results of a parametric sensitivity analysis of a widely used model for atmospheric dispersion of toxic gases, in order better to understand the influence of user-adjustable parameters on model outputs. We have studied 60 min continuous release scenarios for three different products (nitric oxide, ammonia and chlorine), chosen to cover a range of physical characteristics and storage conditions. For each product, we have broken down base-case scenarios into a number of sub-scenarios corresponding to different release conditions which determine physical phenomena (flow rate, release angle, release elevation and atmospheric stability class). The use of statistical tools to analyze the results of a large number of model executions allows us to rank model parameters according to their influence on the variability of a number of model outputs (distances and concentrations), on a per-scenario and per-product basis. Analysis of the results allows us to verify our understanding of the modeling of cloud dispersion. 相似文献
943.
944.
Fu-Lin Evelyn Chu Eric D. Lund Paul R. Littreal Kate E. Ruck Ellen Harvey Jean-René Le Coz Yanic Marty Jeanne Moal Philippe Soudant 《Marine Biology》2009,156(2):155-169
The kinetics and efficiency of sterol production and bioconversion of phytosterols in two heterotrophic protists Oxyrrhis marina and Gyrodinium dominans were examined by feeding them two different algal species (Rhodomonas salina and Dunaliella tertiolecta) differing in sterol profiles. R. salina contains predominantly brassicasterol (≅99%) and <2% cholesterol. The major sterols in D. tertiolecta are ergosterol (45–49%), 7-dehydroporiferasterol (29–31%) and fungisterol (21–26%). O. marina fed R. salina metabolized dietary brassicasterol to produce 22-dehydrocholesterol and cholesterol. O. marina fed D. tertiolecta metabolized dietary sterols to produce cholesterol, 22-dehydrocholesterol, brassicasterol and stigmasterol. G. dominans fed either R. salina or D. tertiolecta metabolized dietary sterols to make cholesterol, brassicasterol and a series of unknown sterols. When protists were fed R. salina, which contains cholesterol, the levels of cholesterol were increased to a magnitude of nearly 5- to 30-fold at the phytoplankton-heterotrophic
protist interface, equivalent to a production of 172.5 ± 16.2 and 987.7 ± 377.7 ng cholesterol per mg R. salina carbon consumed by O. marina and G. dominans, respectively. When protists were fed D. tertiolecta, which contains no cholesterol, a net production of cholesterol by the protists ranged from 123.2 ± 30.6 to 871.8 ± 130.8 ng
per mg algal C consumed. Cholesterol is not only the dominant sterol, but a critical precursor for many physiologically functional
biochemicals in higher animal. As intermediates, these heterotrophic protists increase the amount of cholesterol at the phytoplankton–zooplankton
interface available to higher trophic levels relative to zooplankton feeding on algae directly. 相似文献
945.
Crini Grégorio Torri Giangiacomo Lichtfouse Eric Kyzas George Z. Wilson Lee D. Morin-Crini Nadia 《Environmental Chemistry Letters》2019,17(4):1645-1666
Environmental Chemistry Letters - Synthetic dyes are an important class of recalcitrant organic compounds that are often found in the environment as a result of their wide industrial use.... 相似文献
946.
Wu Yujie Wang Peng Yu Shaocai Wang Liqiang Li Pengfei Li Zhen Mehmood Khalid Liu Weiping Wu Jian Lichtfouse Eric Rosenfeld Daniel Seinfeld John H. 《Environmental Chemistry Letters》2018,16(3):1117-1127
Environmental Chemistry Letters - Air pollution is an increasingly critical health issue responsible for numerous diseases and deaths worldwide. In China, to address severe air pollution in the... 相似文献
947.
Howard W. Mielke Chris R. Gonzales Elise Cahn Jessica Brumfield Eric T. Powell Paul W. MielkeJr 《Environmental geochemistry and health》2010,32(5):431-440
Arsenic (As) ranks first on the 2005 and 2007 hazardous substances priority lists compiled for the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA). This study describes two New Orleans soil As surveys: (1) a survey of
composite soil samples from 286 census tracts and (2) a field survey of soil As at 38 play areas associated with the presence
of chromated-copper-arsenate (CCA)-treated wood on residential and public properties. The survey of metropolitan New Orleans
soils revealed a median As content of 1.5 mg/kg (range <0.2–16.4) and no distinctive differences between the soils of the
city core and outlying areas. Play area accessible soils associated with CCA-treated wood (N = 32) had a median As of 57 mg/kg and 78% of the samples were ≥12 mg/kg, the Louisiana soil As standard. The field survey
of play areas for CCA-treated wood (N = 132 samples at 38 sites) was conducted with a portable energy-dispersive X-ray fluorescence (XRF) analyzer. Seventy-five
of 132 wood samples (56.8%) were deemed CCA-treated wood. Of the 38 play areas surveyed, 14 (36.8%) had CCA-treated wood.
A significant association (Fisher’s exact p-value = 0.348 × 10−6) was found between CCA-treated wood and soil As (N = 75). At one elementary school CCA-treated woodchips (As range 813–1,654 mg As/kg) covered the playgrounds. The situation
in New Orleans probably exists in play areas across the nation. These findings support a precautionary program for testing
soils and wood for hazardous substances at all play areas intended for children. 相似文献
948.
Breininger DR Nichols JD Duncan BW Stolen ED Carter GM Hunt DK Drese JH 《Ecology》2010,91(11):3354-3364
Many ecosystems are influenced by disturbances that create specific successional states and habitat structures that species need to persist. Estimating transition probabilities between habitat states and modeling the factors that influence such transitions have many applications for investigating and managing disturbance-prone ecosystems. We identify the correspondence between multistate capture-recapture models and Markov models of habitat dynamics. We exploit this correspondence by fitting and comparing competing models of different ecological covariates affecting habitat transition probabilities in Florida scrub and flatwoods, a habitat important to many unique plants and animals. We subdivided a large scrub and flatwoods ecosystem along central Florida's Atlantic coast into 10-ha grid cells, which approximated average territory size of the threatened Florida Scrub-Jay (Aphelocoma coerulescens), a management indicator species. We used 1.0-m resolution aerial imagery for 1994, 1999, and 2004 to classify grid cells into four habitat quality states that were directly related to Florida Scrub-Jay source-sink dynamics and management decision making. Results showed that static site features related to fire propagation (vegetation type, edges) and temporally varying disturbances (fires, mechanical cutting) best explained transition probabilities. Results indicated that much of the scrub and flatwoods ecosystem was resistant to moving from a degraded state to a desired state without mechanical cutting, an expensive restoration tool. We used habitat models parameterized with the estimated transition probabilities to investigate the consequences of alternative management scenarios on future habitat dynamics. We recommend this multistate modeling approach as being broadly applicable for studying ecosystem, land cover, or habitat dynamics. The approach provides maximum-likelihood estimates of transition parameters, including precision measures, and can be used to assess evidence among competing ecological models that describe system dynamics. 相似文献
949.
Geospatial analysis of vulnerable beach-foredune systems from decadal time series of lidar data 总被引:1,自引:0,他引:1
Helena Mitasova Eric Hardin Margery F. Overton Mustafa Onur Kurum 《Journal of Coastal Conservation》2010,14(3):161-172
Time series of lidar data, acquired over the past decade along the North American East Coast, provide opportunities to gain
new insights into 3D evolution of barrier islands and their beach and dune systems. GIS-based per grid cell statistics and
map algebra was applied to time series of Digital Surface Models representing two sections of North Carolina barrier islands
to quantify elevation change trends, map dynamic and stable locations, identify new and lost buildings, measure relative volume
evolution in the beach and foredune systems and analyze shoreline dynamics. Results show a relatively small stable core in
both study areas, with beaches and the ocean side of the dunes exhibiting systematic high rates of elevation loss while areas
landward from the dunes increase slightly in elevation. Significant number of new homes have been built at locations with
very small core surface elevation, and homes built within the shoreline dynamics band have already been lost. The raster-based
methodology used in this study can be applied to perform similar analyses in other coastal areas where time series of lidar
data are available. 相似文献
950.
With the discovery of previously unreported populations of hemoglobin-possessing Ophiactis from the Texas coast in the Gulf of Mexico, an investigation into its population structure, including populations of O. simplex from the Pacific coast of California and O. rubropoda from the Atlantic coast of Florida, was undertaken using DNA sequence data from the mitochondrial COI gene. The reconstructed
haplotype network suggests that California populations contain the ancestral source of mtDNA variation, and there is no evidence
of recent introductions into Texas. Population genetic analyses reveal the California, Florida, and Texas Ophiactis populations to each be significantly differentiated from one another. Sequence divergence among the three areas is shallower
than would be predicted given biogeographic history. Texas and Florida populations are equally genetically diverged from California
populations as they are to one another, despite the greater potential for gene flow between these areas. The genetic distinctiveness
of the Texas populations and the concordance of this pattern with phylogeographic patterns in other brittle star systems indicate
an isolated and independent evolutionary history and we hypothesize that the three geographic regions included in this study
each serve as hypotheses of population-level lineages that remain to be tested with independent sources of data. 相似文献