首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
ABSTRACT Researchers have suggested golden eagle (Aquila chrysaetos) populations may be declining in portions of their range. However, there are few baseline data describing golden eagle populations across their range in the western United States. We used aerial line transect distance methodology with a double-observer modification to estimate golden eagle population numbers in 4 bird conservation regions of the western United States. We conducted surveys from 16 August to 8 September 2003, after most golden eagles had fledged and before fall migration. The goal of our sampling strategy was to provide >80% power (α = 0.1) to detect an annual rate of total population change >3% per year over a 20-year period. We observed 172 golden eagles across 148 transects and estimated 27,392 golden eagles (90% CI: 21,352-35,140) occurred in the study area during the late summer and early fall of 2003. Following the surveys, we used Monte Carlo simulation to determine the statistical power to detect trends in the golden eagle populations if yearly surveys were continued over a 20-year monitoring period. The simulation indicated the desired power could be achieved under the current methodology and sample size. The methods utilized in this study can be implemented for other raptor species when population estimates that include nonbreeding members of a population are needed. The results of this study can be utilized by professionals to help manage golden eagle populations and to develop conservation strategies.  相似文献   

2.
Peronospora effusa is an obligate pathogen that causes downy mildew on spinach and is considered the most economically important disease of spinach. The objective of the current research was to assess genetic diversity of known historical races and isolates collected in 2014 from production fields in Yuma, Arizona and Salinas Valley, California. Candidate neutral single nucleotide polymorphisms (SNPs) were identified by comparing sequence data from reference isolates of known races of the pathogen collected in 2009 and 2010. Genotypes were assessed using targeted sequencing on genomic DNA extracted directly from infected plant tissue. Genotyping 26 historical and 167 contemporary samples at 46 SNP loci revealed 82 unique multi-locus genotypes. The unique genotypes clustered into five groups and the majority of isolates collected in 2014 were genetically closely related, regardless of source location. The historical samples, representing several races, showed greater genetic differentiation. Overall, the SNP data indicate much of the genotypic variation found within fields was produced during asexual development, whereas overall genetic diversity may be influenced by sexual recombination on broader geographical and temporal scales.  相似文献   

3.
4.
We present a gridded 8 km-resolution data product of the estimated composition of tree taxa at the time of Euro-American settlement of the northeastern United States and the statistical methodology used to produce the product from trees recorded by land surveyors. Composition is defined as the proportion of stems larger than approximately 20 cm diameter at breast height for 22 tree taxa, generally at the genus level. The data come from settlement-era public survey records that are transcribed and then aggregated spatially, giving count data. The domain is divided into two regions, eastern (Maine to Ohio) and midwestern (Indiana to Minnesota). Public Land Survey point data in the midwestern region (ca. 0.8-km resolution) are aggregated to a regular 8 km grid, while data in the eastern region, from Town Proprietor Surveys, are aggregated at the township level in irregularly-shaped local administrative units. The product is based on a Bayesian statistical model fit to the count data that estimates composition on the 8 km grid across the entire domain. The statistical model is designed to handle data from both the regular grid and the irregularly-shaped townships and allows us to estimate composition at locations with no data and to smooth over noise caused by limited counts in locations with data. Critically, the model also allows us to quantify uncertainty in our composition estimates, making the product suitable for applications employing data assimilation. We expect this data product to be useful for understanding the state of vegetation in the northeastern United States prior to large-scale Euro-American settlement. In addition to specific regional questions, the data product can also serve as a baseline against which to investigate how forests and ecosystems change after intensive settlement. The data product is being made available at the NIS data portal as version 1.0.  相似文献   

5.
ABSTRACT Determining population size and long-term trends in population size for species of high concern is a priority of international, national, and regional conservation plans. Long-billed curlews (Numenius americanus) are a species of special concern in North America due to apparent declines in their population. Because long-billed curlews are not adequately monitored by existing programs, we undertook a 2-year study with the goals of 1) determining present long-billed curlew distribution and breeding population size in the United States and 2) providing recommendations for a long-term long-billed curlew monitoring protocol. We selected a stratified random sample of survey routes in 16 western states for sampling in 2004 and 2005, and we analyzed count data from these routes to estimate detection probabilities and abundance. In addition, we evaluated habitat along roadsides to determine how well roadsides represented habitat throughout the sampling units. We estimated there were 164,515 (SE=42,047) breeding long-billed curlews in 2004, and 109,533 (SE=31,060) breeding individuals in 2005. These estimates far exceed currently accepted estimates based on expert opinion. We found that habitat along roadsides was representative of long-billed curlew habitat in general. We make recommendations for improving sampling methodology, and we present power curves to provide guidance on minimum sample sizes required to detect trends in abundance.  相似文献   

6.
Objective: Mis‐reporting dietary intake is a substantial barrier to understanding the role of dietary behavior in disease. Work with adults indicates that heavier individuals under‐report dietary intake and that under‐reporting may be macronutrient‐specific. Whether weight status and macronutrient intake influence the accuracy of dietary reports among children, however, is less clear. This research evaluated children's dietary reporting accuracy as a function of their relative weight, body composition, and macronutrient intake. Research Methods and Procedures: Participants included 146 4‐ to 11‐year‐old children. Reported energy intake was determined by interviewing children in the presence of parents, using three multiple pass, 24‐hour recalls. Children were classified as having had an under‐reported, accurately reported, or over‐reported dietary intake relative to total energy expenditure, as measured by doubly labeled water. Reporting accuracy was examined as a function of children's body weight, body composition (using dual energy x‐ray absorptiometry), and macronutrient intake. Results: Average reported intake was, on average, 14% greater than children's estimated expenditure (p < 0.01). Reporting accuracy varied as a function of children's relative weight and body composition; under‐reporting tended to occur among heavier children, having the highest body fat content (p < 0.0001) and relative weight (p < 0.0001). Discussion: These findings suggest that weight status influences the accuracy of dietary reports made by children and their parents. More research is needed to address possible psychological and social factors that introduce bias in reporting children's dietary data.  相似文献   

7.
8.
ABSTRACT We used recent developments in theoretical population ecology to construct basic models of common loon (Gavia immer) demography and population dynamics. We parameterized these models using existing survival estimates and data from long-term monitoring of loon productivity and abundance. Our models include deterministic, 2-stage, density-independent matrix models, yielding population growth-rate estimates (λ) of 0.99 and 1.01 for intensively studied populations in our Wisconsin, USA, and New Hampshire, USA, study areas, respectively. Perturbation analysis of these models indicated that estimated growth rate is extremely sensitive to adult survival, as expected for this long-lived species. Also, we examined 20 years of count data for the 2 areas and evaluated support for a set of count-based models of population growth. We detected no temporal trend in Wisconsin, which would be consistent with fluctuation around an average equilibrium state but could also result from data limitations. For New Hampshire, the model set included varying formulations of density dependence and partitioning of stochasticity that were enabled by the annual sampling resolution. The best model for New Hampshire included density regulation of population growth and, along with the demographic analyses for both areas, provided insight into the possible importance of breeding habitat availability and the abundance of nonbreeding adults. Based on these results, we recommend that conservation organizations include nonbreeder abundance in common loon monitoring efforts and that additional emphasis be placed on identifying and managing human influences on adult loon survival.  相似文献   

9.
Using ∼60,000 SNPs selected for minimal linkage disequilibrium, we perform population structure analysis of 1,374 unrelated Hispanic individuals from the Multi-Ethnic Study of Atherosclerosis (MESA), with self-identification corresponding to Central America (n = 93), Cuba (n = 50), the Dominican Republic (n = 203), Mexico (n = 708), Puerto Rico (n = 192), and South America (n = 111). By projection of principal components (PCs) of ancestry to samples from the HapMap phase III and the Human Genome Diversity Panel (HGDP), we show the first two PCs quantify the Caucasian, African, and Native American origins, while the third and fourth PCs bring out an axis that aligns with known South-to-North geographic location of HGDP Native American samples and further separates MESA Mexican versus Central/South American samples along the same axis. Using k-means clustering computed from the first four PCs, we define four subgroups of the MESA Hispanic cohort that show close agreement with self-identification, labeling the clusters as primarily Dominican/Cuban, Mexican, Central/South American, and Puerto Rican. To demonstrate our recommendations for genetic analysis in the MESA Hispanic cohort, we present pooled and stratified association analysis of triglycerides for selected SNPs in the LPL and TRIB1 gene regions, previously reported in GWAS of triglycerides in Caucasians but as yet unconfirmed in Hispanic populations. We report statistically significant evidence for genetic association in both genes, and we further demonstrate the importance of considering population substructure and genetic heterogeneity in genetic association studies performed in the United States Hispanic population.  相似文献   

10.
《Endocrine practice》2021,27(5):419-425
ObjectiveTo explore the body composition of pediatric patients referred for endocrine evaluation.MethodsThis real-life observational study conducted between January 2018 and January 2020 included 10 001 clinic visits of 3500 children and adolescents; first visits of 5 to 18-year-old patients were included. Anthropometric data, blood pressure levels, pubertal status, and bioelectrical impedance analysis (BIA, Tanita MC-780 MA) were extracted from medical files. Excluded from the analysis were patients participating in other studies.ResultsA total of 1001 patients (48% boys, mean age 11.3 ± 3.4 years, 33.5% prepubertal) were included. Mean anthropometric z-scores were normal and similar for boys and girls. Sex differences in body composition were as follows: boys had lower fat percentage, lower truncal fat percentage, higher appendicular skeletal muscle mass, and a higher muscle-to-fat ratio (MFR) than girls (P < .001 for all). MFR correlated with body mass index-standard deviation scores (BMI-SDS) in overweight/obese patients (r = −0.558, P < .001), although not in underweight patients. Systolic blood pressure (SBP) correlated with BMI-SDS in overweight/obese patients (r = 0.262, P < .001), although not in underweight patients. Diastolic blood pressure (DBP) did not correlate with BMI-SDS in either group of extreme weight status. MFR correlated with SBP and DBP in overweight/obese patients (r = −0.230, P < .001 and r = −0.141, P = .018, respectively) as well as in underweight patients (r = 0.331, P < .001 and r = 0.264, P = .005, respectively).ConclusionsOur findings support BIA for a more refined characterization of patients referred for endocrine evaluation than BMI-SDS. MFR may be a better surrogate marker of blood pressure levels than BMI-SDS in both underweight and overweight/obese pediatric patients.  相似文献   

11.
美国流域生态健康评价体系的发展和实践   总被引:4,自引:0,他引:4  
张华  骆永明 《应用生态学报》2013,24(7):2063-2072
为了达到《清洁水法》规定的水质目标,美国环境部门在过去20多年的实践中逐步发展形成了涵盖整个流域,包括水文、化学、生物等多重指标在内的全国性流域综合生态健康评价体系.该体系已经成为美国流域水质管理系统的重要组成部分,为水环境保护和水生生态系统恢复提供了有力支持.本文从法律行政框架、生态功能分析、生态健康指标、综合评价体系和流域监测系统等方面系统总结了美国环境管理部门,特别是联邦环境保护局在流域生态健康评价方面的发展和实践;并介绍了美国水生资源调查采用的河流、湖泊、河口、海湾、湿地流域健康评价系统.在此基础上,根据我国水环境保护和治理的实际情况,提出了建立流域生态健康科学评价和决策支持体系建议.  相似文献   

12.
A considerable number of institutions offer courses in restoration ecology and its application, ecological restoration. We quantified the scope and structure of introductory restoration courses at 67 post‐secondary institutions by reviewing institutional course catalogs and course syllabi. Most courses were available at Research‐level institutions. More than half of the courses were offered within departments that focused on natural resource management, and were required or optional in a degree program. Most courses were taught in classroom settings during the academic year and were geared toward advanced students. Course titles suggested an emphasis on the science of restoration ecology over the practice of ecological restoration, and learning objectives focused primarily on concepts and less on skills and attitudes. Assessment was largely via conventional methods, notably exams. Many courses assigned readings from the primary literature; there was little consensus in terms of text selection. We conclude that restoration is being presented to students as an advanced undertaking and in largely theoretical terms. Although we were unable to consider other important elements such as thematic content, class size, or pedagogical method, our study provides a baseline assessment of introductory restoration courses that can be used to evaluate changes in restoration education or opportunities for restoration education in other countries. These results can inform the development of new introductory restoration courses, and raise important considerations in light of the development of a Practitioners' Certification Program by the Society for Ecological Restoration.  相似文献   

13.
ObjectiveCounseling patients about nutrition significantly improves chronic disease outcomes. Endocrinologists are uniquely positioned to educate patients regarding nutrition. The purpose of this study was to define the current state of nutrition education in endocrinology fellowship programs in the United States and assess the needs for future nutrition training.MethodsEndocrinology program directors were surveyed via an online questionnaire between February and April 2021.ResultsThirty-eight program directors responded (25% response rate) to the survey. Twenty-two (58%) programs offered nutrition education. Existing nutrition education offerings were 1 to 5 total hours (13, 34%), primarily didactic (20, 53%), and often led by registered dietitian nutritionists (15, 39%). Only 3 (8%) programs rated their current nutrition education as extremely effective; 95% of respondents believed that further nutrition education was needed. According to respondents, the ideal nutrition education for endocrine trainees should be 1 to 5 total hours (19, 50%) over multiple sessions (25, 66%), be interactive (24, 63%), and be led by registered dietitian nutritionists (26, 68%). The most important topics for independent practice included diet-related behavior modification (21, 55%), components of a healthful diet (19, 50%), and energy expenditure/intake (18, 47%).ConclusionAlthough the majority of the program directors believe that further nutrition education is needed, almost half of the surveyed programs do not offer such training. Programs that offer nutrition education primarily rely on a didactic format. There is an unmet need for interactive, multidisciplinary nutrition education in these programs.  相似文献   

14.
15.
In some small, often unstable, streams of the Gila River drainage, New Mexico, Gila trout Oncorhynchus gilae populations fluctuated numerically seasonally and annually. Few differences were noted in length-weight and size-structure comparisons, but Fulton condition index varied significantly. Time of sample and time since disturbance (natural or human-caused) were often associated with differences in condition. Other factors may include availability of prey, cannibalism, and reproductive condition. The repeatedly sampled McKnight Creek population illustrated the resilience of Gila trout populations to natural disturbances. A scouring flood in 1988 caused a >90% reduction in numbers, but, by 1992, population structure was not substantially different from that of other streams. Likewise, juvenile/adult ratio, density, and per cent large specimens (≥ 200 mm total length) of most other samples were within the ranges for the McKnight Creek population. Gila trout density (no. fish min−1 electrofishing) tended to increase with higher elevation and greater drainage density (stream km catchment−1 km−2) but decreased with larger catchments. Information gained in this study demonstrates that a variety of factors must be considered when evaluating the relative well-being of Gila trout populations and illustrates the importance of larger, more hydrologically complex drainages to the long-term survival of Gila trout populations.  相似文献   

16.
Phytophthora infestans, the causal agent of late blight disease, has been reported in North America since the mid-nineteenth century. In the United States the lack of or very limited sexual reproduction has resulted in largely clonal populations of P. infestans. In 2010 and 2011, but not in 2012 or 2013, 20 rare and diverse genotypes of P. infestans were detected in a region that centered around central New York State. The ratio of A1 to A2 mating types among these genotypes was close to the 50∶50 ratio expected for sexual recombination. These genotypes were diverse at the glucose-6-phosphate isomerase locus, differed in their microsatellite profiles, showed different banding patterns in a restriction fragment length polymorphism assay using a moderately repetitive and highly polymorphic probe (RG57), were polymorphic for four different nuclear genes and differed in their sensitivity to the systemic fungicide mefenoxam. The null hypothesis of linkage equilibrium was not rejected, which suggests the population could be sexual. These new genotypes were monomorphic in their mitochondrial haplotype that was the same as US-22. Through parentage exclusion testing using microsatellite data and sequences of four nuclear genes, recent dominant lineages US-8, US-11, US-23, and US-24 were excluded as possible parents for these genotypes. Further analyses indicated that US-22 could not be eliminated as a possible parent for 14 of the 20 genotypes. We conclude that US-22 could be a parent of some, but not all, of the new genotypes found in 2010 and 2011. There were at least two other parents for this population and the genotypic characteristics of the other parents were identified.  相似文献   

17.
18.
Variability in edaphic factors such as clay content, organic matter, and nutrient availability within individual fields is a major obstacle confronting cotton producers. Adaptation of geospatial technologies such global positioning systems (GPS), yield monitors, autosteering, and the automated on-and-off technology required for site-specific nematicide application has provided growers with additional tools for managing nematodes. Multiple trials in several states were conducted to evaluate this technology in cotton. In a field infested with Meloidogyne spp., both shallow (0 to 0.3 m) and deep (0 to 0.91 m) apparent electrical conductivity (ECa) readings were highly correlated with sand content. Populations of Meloidogyne spp. were present when shallow and deep EC values were less than 30 and 90 mS/m, respectively. Across three years of trials in production fields in which verification strips (adjacent nematicide treated and untreated rows across all soil zones) were established to evaluate crop response to nematicide application, deep EC values from 27.4-m wide transects of verification strips were more predictive of yield response to application of 1,3-dichloropropene than were shallow EC values in one location and both ECa values equally effective at predicting responses at the second location. In 2006, yields from entire verification strips across three soil zones in four production fields showed that nematicide response was greatest in areas with the lowest EC values indicating highest content of sand. In 2008 in Ashley and Mississippi Counties, AR, nematicide treatment by soil zone resulted in 36% and 42% reductions in the amount of nematicide applied relative to whole-field application. In 2007 in Bamberg County, SC, there was a strong positive correlation between increasing population densities of Meloidogyne incognita and increasing sand content. Trials conducted during 2007 and 2009 in South Carolina against Hoplolaimus columbus showed a stepwise response to increasing rates of aldicarb in zone 1 but not in zones 2 and 3. Site-specific application of nematicides has been shown to be a viable option for producers as a potential management tool against several nematode pathogens of cotton.  相似文献   

19.
Married individuals tend to be heavier than those who are unmarried, particularly men, and individuals in different ethnic categories vary in their involvement in marriage and in their body weights. We examined gender and ethnic differences in relationships between marital status and body weight using cross‐sectional data from the 1999–2002 National Health and Nutrition Examination Survey (NHANES) for 3,947 women and 4,019 men. The findings revealed that compared to married men in the same ethnic category, white divorced men, black never‐married men, and all Hispanic men except for widows had lower odds of being overweight. Compared to married women in the same ethnic category, white women's weights did not significantly differ by marital status, black separated women had greater odds of being overweight, and Hispanic never‐married women had lower odds of being overweight. Associations of marriage with body weight appear to be at least partly contingent upon gender and ethnicity, which may reflect larger societal patterns of involvement in marriage, commitment to family, and body‐weight norms and expectations.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号