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311.
Sean R. Brennan Diego P. Fernandez Jennifer M. Burns Stephanie Aswad Daniel E. Schindler Thure E. Cerling 《Conservation biology》2019,33(6):1415-1425
Human activities threaten the biodiversity of aquatic mammals across the globe. Conservation of these species hinges on the ability to delineate movements and foraging behaviors of animals, but gaining such insights is hampered by difficulties in tracing individuals over their lives. We determined isotope ratios in teeth (87Sr/86Sr, 13C/12C, and 18O/16O) to examine lifelong movement and resource-use patterns of a unique freshwater population of a wide-ranging pinniped species (harbor seal [Phoca vitulina]) that resides in Iliamna Lake, Alaska (U.S.A.). This population's potentially unique migratory behavior and use of different trophic resources are unknown. The isotope ratios we measured in teeth showed that seals were born in the lake, remained lifelong residents, and relied principally on resources produced from in the lake, even when seasonally abundant and nutrient-dense spawning anadromous fish (i.e., sockeye salmon [Oncorhynchus nerka]) were available in the lake. Our results illustrate how serial isotope records in teeth, particularly 87Sr/86Sr ratios, can be used to quantify how coastal mammal populations exploit both freshwater and marine ecosystems. Understanding lifelong patterns of habitat and resource use is essential information when designing effective conservation plans for threatened coastal mammals. We present the Iliamna Lake harbor seals as a unique case study into how isotope records within teeth can help reveal the cryptic ecology of such a population residing in an intact ecosystem. The results also provide critical baseline information for the Kvichak River system, which is facing an uncertain future due to proposed large-scale industrial development and a rapidly changing climate. 相似文献
312.
J. Cnaani G. E. Robinson G. Bloch D. Borst A. Hefetz 《Behavioral ecology and sociobiology》2000,47(5):346-352
Endocrine analyses were used to investigate the well-known association between queen production and the onset of worker reproduction
(termed the competition phase, CPh) in Bombus terrestris. Larvae that reached the age of 5 days before the CPh had a worker-like profile: low juvenile hormone (JH) biosynthesis rates
and low JH hemolymph titers. In contrast, larvae that reached the age of 5 days during the CPh had a queen-like profile: high
JH biosynthesis rates and high hemolymph JH levels. Larval fate could be manipulated by transplanting egg cells into host
colonies with different social structures. There was a steep rise in JH production in larvae transplanted into colonies near
or during the CPh. This indicates that during colony development, larvae switch from the ”worker developmental pathway” to
the ”queen developmental pathway,” and that the switch is socially regulated. In small rearing groups, larvae reared with
queens before the CPh developed into workers, whereas those reared with queens after the CPh developed into queens. Variation
in worker type (naive or experienced) did not affect caste determination. Therefore, we hypothesize that queens produce a
pheromone that directly inhibits queen differentiation by larvae. We also present two alternative scenarios that explain the
timing of gyne production in B. terrestris, one based on ecological constraints and the other based on queen-worker competition.
Received: 20 October 1999 / Received in revised form: 18 December 1999 / Accepted: 23 January 2000 相似文献
313.
314.
FISH-NanoSIMS技术在环境微生物生态学上的应用研究 总被引:2,自引:1,他引:1
微生物分子生态学技术的不断发展,使得同时分析复杂生态系统中微生物的分布和功能特征成为可能.为了研究荧光原位杂交-纳米二次离子质谱技术(fluorescence in situ hybridization-Nano secondary ion mass spectroscopy,FISH-Nano SIMS)在环境微生物生态学上的应用,本研究采用稳定同位素标记的化合物13C-C6H12O6、15N-NH4Cl作为C源和N源,分别对纯培养锰氧化细菌假单胞菌Pseudomonas sp.QJX-1(培养基加锰及不加锰两种条件下),以及浅层土壤及厌氧污泥两种环境样品进行培养.利用FISH-NanoSIMS技术检测培养后样品中微生物体内12C-、13C-、12C14N-、12C15N-的分布特征及其丰度值,进而探讨纯菌及环境样品中微生物利用同位素碳氮源的情况.结果显示所有样品细菌分布区域对应的同位素碳氮(13C、15N)的含量均显著大于其自然丰度值,这表明Pseudomonas sp.QJX-1及环境样品中的微生物均能代谢13C-C6H12O6和15N-NH4Cl.研究进一步发现,Pseudomonas sp.QJX-1在碳氮源消耗至较低浓度时才进行锰氧化;浅层土壤和厌氧污泥中可能都存在同步硝化反硝化细菌群落.FISH和Nano SIMS技术联用能同时分析环境样品中特定微生物的分布特征及代谢功能,进而能更好地掌握环境样品中微生物群落的生理生态学特征. 相似文献
315.
Rewards and employee creative performance: Moderating effects of creative self‐efficacy,reward importance,and locus of control 下载免费PDF全文
The effects of extrinsic rewards on creative performance have been controversial, and scholars have called for the examination of the boundary conditions of such effects. Drawing upon expectancy theory, we attend to both reinforcement and self‐determination pathways that reveal the informational and controlling functions of creativity‐related extrinsic rewards. We further identify the individual dispositions that moderate these two pathways. Specifically, we propose that extrinsic rewards for creativity positively predict creative performance only when employees have high creative self‐efficacy and regard such rewards as important. We likewise propose that extrinsic rewards positively affect the intrinsic motivation of employees with an internal locus of control, thus enhancing their creative performance. Results based on a sample of 181 employee–supervisor dyads largely supported these expectations. The current analysis enriches the creativity literature by combining different perspectives in a coherent framework, by demonstrating the positive effects of extrinsic rewards on intrinsic motivation, and by demonstrating that the rewards–creativity relationship varies across employees depending on their individual differences. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
316.
Using self‐determination theory to understand the relationship between calling enactment and daily well‐being 下载免费PDF全文
This paper contributes to the calling literature by using self‐determination theory—a theory that makes distinctions between different types of motivation—in order to gain a better understanding of how enacting a calling may relate both positively and negatively to well‐being. We use a daily diary method novel to the calling field and a sample with a distinctive calling, Church of England clergy. We expect daily calling enactment to relate positively to daily well‐being via more autonomous forms of motivation (intrinsic and identified motivation) and negatively via less autonomous forms (introjected motivation). Furthermore, we consider how the relationship between calling enactment and motivation may be moderated by perceived competence. The hypotheses were tested using multi‐level structural equation modeling. There was strong support for calling enactment relating positively to well‐being, and this relationship was fully mediated by intrinsic and identified motivation; the hypothesized negative pathway, from calling enactment, to introjected motivation, to well‐being, was not supported. However, perceived competence was found to moderate some of the relationships between calling and the motivation types, where calling enactment is linked to lower introjected motivation at high levels of competence. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
317.
对工业循环冷却水水垢中锌含量的测定方法进行了系统优化,主要考察了样品酸度、缓冲溶液添加量、试剂时效性、样品中铁离子量、掩蔽剂量和滴定剂浓度对锌含量检测效果的影响。结果表明:样品酸度控制在pH=4.9~5.1范围内,乙酸-乙酸钠缓冲溶液添加量为30 m L时,锌含量检出值最大,指示剂灵敏度最佳;试剂乙酸-乙酸钠在20 d内使用、二甲酚橙指示剂即配即用对滴定终点的判断效果较好;锌含量测定前应先检测样品中铁离子含量,若铁离子≥40%则应先沉淀过滤后方可进行测定;锌含量检出值随掩蔽剂添加量呈先升后降的趋势,并在3.2 g时滴定效果最佳;滴定剂浓度为0.010 mol/L时锌含量检出值最高;优化实验测定结果接近真实值,方法准确可靠。 相似文献
318.
环境水样中的甲基汞含量很低,但极易发生生物富集,且具有挥发性和高度的脂溶性,对神经系统造成不可逆的损害.而目前中国环境水样中的甲基汞检测标准滞后,且存在较大弊端,亟需更新.本文综述了前处理技术(液液萃取、固相萃取、固相微萃取、衍生化)和仪器技术(GC、GC-MS、HPLC-ICP-MS和CVAFS)等在检测环境水样中甲基汞的应用实例,论述了各种前处理技术和仪器分析方法的特点与不足,以期在分析环境水体中甲基汞的含量和前处理技术方面提供参考,并对未来的检测手段进行了展望. 相似文献
319.
氮是水体中的主要污染物之一。近几十年来,随着工农业的发展,使得水体中氮的污染呈上升趋势,并在今后可能会持续,最根本的解决方法是找到源头,从根本上切断污染途径以达到消除氮源的污染。在查阅相关文献的基础上,阐述了水中用同位素追踪研究氮的来源的研究进展和存在的问题,对于评价氮的污染现状、污染控制和环境管理具有十分重要的意义。 相似文献
320.