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1.
史亚琪  朱晓东  孙翔  李扬帆  魏婷 《生态学报》2010,30(15):4119-4128
经济与环境协调发展评价是发展中国家可持续发展领域研究的热点问题。目前协调评价的模型取得了新的进展,但在应用方面多集中在现状评价,预测的案例较少;另外现有的研究多以经济子系统的发展水平与环境子系统的发展水平进行协调性评价,忽略了发展潜力这一重要变量。以连云港为分析案例,把发展潜力作为重要变量与发展水平变量相结合计算得到的综合发展指数纳入经济与环境协调评价模型中,并尝试根据系统历史与现状协调发展的演变规律运用GM(1,1)灰色模型预测系统未来的协调发展状态。现状评价与未来的预测结果表明:(1)1996—1999年连云港经济与环境系统从低级共生向环境资源的粗放利用转变;(2)2000—2006年,经济与环境的关系进入快速调整期,经济-环境复合生态系统综合发展指数不断增强,协调程度较上一阶段变化稳定;(3)到2007—2009年,环境对经济的限制作用将又逐渐显现;(4)2010—2015年,经济-环境复合生态系统整体协调度和综合发展指数都相应处于快速上升阶段。综合来看,1999年以后连云港经济-环境复合生态系统的协调度均处于0°以下,说明连云港在经济快速发展的初期往往是以环境破坏为代价的,因此在以后的发展中应主要处理好经济发展与环境保护的速度和公平问题。  相似文献   

2.
We use artificial selection experiments targeted on egg size, development time or pupal mass within a single butterfly population followed by a common-garden experiment to explore the interactions among these life-history traits. Relationships were predicted to be negative between egg size and development time, but to be positive between development time and body size and between egg size and body size. Correlated responses to selection were in part inconsistent with these predictions. Although there was evidence for a positive genetic correlation between egg and body size, there was no support for genetic correlations between larval development time and either egg size or pupal mass. Phenotypic correlations among the three target traits of selection gave comparable results for the relationships between egg mass and development time (no association) as well as between egg mass and pupal mass (positive association), but not for the relation between development time and pupal mass (negative phenotypic correlation). In summary, correlated responses to selection as well as phenotypic correlations were rather unpredictable. The impact of variation in acquisition and allocation of energy as well as of the benign conditions used deserve further investigation.  相似文献   

3.
陕北安塞县生态与经济系统耦合协调发展   总被引:4,自引:0,他引:4  
马亚亚  刘国彬  张超  王杰 《生态学报》2019,39(18):6840-6849
协调生态环境与社会经济的均衡发展,是实现县域可持续发展的重要因素。以延安市安塞县为对象,基于社会经济与生态环境的数据,构建安塞县社会经济系统与生态环境系统的指标体系,利用熵权法计算社会-经济-环境综合评价指数,在此基础上利用耦合协调度模型、剪刀差方法和耦合度模型分析了社会经济系统与生态环境系统的耦合协调状态、发展速度差异以及耦合度演变趋势。结果表明:1996—2013年间,安塞县社会经济系统综合评价指数稳定上升,自然生态系统综合水平呈现波动下降趋势,前者发展速度总体上快于后者;耦合协调度指数由0.33增长至0.59,反映了该区域社会经济与生态环境的关系不断改善,较好地实现了二者的协调;剪刀差在0. 032水平范围内波动上升,说明二者发展趋势之间的差异逐渐增大;安塞县社会经济与生态环境的耦合度分布于45°β90°范围内,二者处于协调发展阶段,耦合度β表现为先下降后上升,说明经济与环境之间的矛盾开始显露。研究表明,安塞县应着力加强生态建设的固基和推进作用,缓解社会经济和生态环境的矛盾,实现二者的协调发展。  相似文献   

4.
变温促进昆虫发育的酶学解释   总被引:1,自引:0,他引:1  
王智翔  陈永林 《生态学报》1989,9(2):106-114
本文关于如何评价变温对昆虫发育速率影响的讨论表明,在比较两点(T_1,T_2)变温与恒温下的发育速率时,相应恒温下的发育速率为R_(con)(T_1,T_2)=(R_(con)(T_1) R_(con)(T_2))/2,而不是T_1、T_2平均值所对应的发育速率R_(con)(T_1,T_2)=R_(con)(T_1 T_2/2)。 在探讨发育速率与温度关系时,认为,(1)发育速率实际上是代谢速率的表现,从本质上说是由昆虫体内无数生化反应所决定的。每步生化反应所需酶不同。(2)不同酶,其活力与温度的关系不同。即使同种昆虫,体内不同种类酶的最大活力温度不同。因此,在不同温度下,代谢链中起限速作用的酶不同。发育速率与温度的关系实质上是代谢链中所有酶与温度关系的综合表现。  相似文献   

5.
Development rate early in the ontogeny is believed to correlate positively with fitness. Geographic variation in intrinsic development rate suggests the existence of trade-offs between development rate and other fitness related traits. We investigated whether these trade-offs exist between intrinsic larval development rate and post-metamorphic traits in an organism with a complex life cycle. In laboratory, we measured if the tadpoles of the frog Rana latastei with fast intrinsic development rate have a suboptimal post-metamorphic morphology, by comparing froglets from five populations. Then, we evaluated the relationship between age at metamorphosis, hindlimb length and jumping performance for frogs grown in nature in two populations. Under laboratory conditions, froglets with fast intrinsic development had shorter absolute and shorter size-adjusted tibiofibulas. We observed a strong, positive relationship between tibiofibula length and jumping performance. In nature, froglets from the last metamorphosing population had longer absolute and size-adjusted tibiofibulas, and were able to jump further. The cost of fast development could be the shorter legs of early metamorphosing frogs, and their poor jumping performance. Thus, a fast intrinsic development rate may not always be positively related to lifetime fitness, since delayed effects of larval development persist also across life history stages. Co-ordinating editor: V. Jormalainen  相似文献   

6.
Early coelomic development in the abbreviated development of the sea urchin Holopneustes purpurescens is described and then used in a comparison with coelomic development in chordate embryos to support homology between a single arm of the five-armed radial body plan of an echinoderm and the single bilateral axis of a chordate. The homology depends on a positional similarity between the origin of the hydrocoele in echinoderm development and the origin of the notochord in chordate development, and a positional similarity between the respective origins of the coelomic mesoderm and chordate mesoderm in echinoderm and chordate development. The hydrocoele is homologous with the notochord and the secondary podia are homologous with the somites. The homology between a single echinoderm arm and the chordate axis becomes clear when the aboral to oral growth from the archenteron in the echinoderm larva is turned anteriorly, more in line with the anterior–posterior axis of the early zygote. A dorsoventral axis inversion in chordates is not required in the proposed homology.  相似文献   

7.
A positive genetic correlation between periods of circadian rhythm and developmental time supports the hypothesis that circadian clocks are implicated in the timing of development. Empirical evidence for this genetic correlation in insects has been documented in two fly species. In contrast, here we show that there is no evidence of genetic correlation between circadian rhythm and development time in the adzuki bean beetle, Callosobruchus chinensis. This species has variation that is explained by a major gene in the expression and period length of circadian rhythm between strains. In this study, we found genetic variation in development time between the strains. The development time was not covaried with either the incidence or the period length of circadian rhythm among the strains. Crosses between strains suggest that development time is controlled by a polygene. In the F2 individuals from the crosses, the circadian rhythm is attributable to allelic variation in the major gene. Across the F2 individuals, development time was not correlated with either the expression or the period length of circadian rhythm. Thus, we found no effects of major genes responsible for variation in the circadian rhythm on development time in C. chinensis. Our findings collectively give no support to the hypothesis that the circadian clock is involved in the regulation of development time in this species.  相似文献   

8.
Isometric rate of torque development examines how quickly force can be exerted and may resemble everyday task demands more closely than isometric strength. Rate of torque development may provide further insight into the relationship between muscle function and gait following stroke. Aims of this study were to examine the test-retest reliability of hand-held dynamometry to measure isometric rate of torque development following stroke, to examine associations between strength and rate of torque development, and to compare the relationships of strength and rate of torque development to gait velocity. Sixty-three post-stroke adults participated (60 years, 34 male). Gait velocity was assessed using the fast-paced 10 m walk test. Isometric strength and rate of torque development of seven lower-limb muscle groups were assessed with hand-held dynamometry. Intraclass correlation coefficients were calculated for reliability and Spearman’s rho correlations were calculated for associations. Regression analyses using partial F-tests were used to compare strength and rate of torque development in their relationship with gait velocity. Good to excellent reliability was shown for strength and rate of torque development (0.82–0.97). Strong associations were found between strength and rate of torque development (0.71–0.94). Despite high correlations between strength and rate of torque development, rate of torque development failed to provide significant value to regression models that already contained strength. Assessment of isometric rate of torque development with hand-held dynamometry is reliable following stroke, however isometric strength demonstrated greater relationships with gait velocity. Further research should examine the relationship between dynamic measures of muscle strength/torque and gait after stroke.  相似文献   

9.
RONSE DECRAENE, L.-P. & SMETS, E., 1991. The impact of receptacular growth on polyandry in the Myrtales. The androecium of the Myrtales shows a wide variation in structure and development, linked with an original diplostemony. The difference between a centrifugal stamen inception in Lythraceae against a centripetal inception in other families has been a major issue in discussing the internal relationships of the Myrtales. The first stamens usually arise as pairs opposite the petals on primary androecial primordia. It is shown that the number of stamens that are initiated and the difference between the direction of development of more stamens are based on the extent of growth of the receptacle after the inception of the primary androecial primordia. In Lagerstroemia indica , receptacular growth takes place between stamens and petals providing room for a centrifugal development. In the Punicaceae and Myrtaceae growth of the receptacle occurs between the androecium and gynoecium, leading to a centripetal development of the stamens. The development of a ring-wall is discussed and a comparison is made with other types of complex polyandry.  相似文献   

10.
草鱼和鲤杂交的细胞学研究—鱼类远缘杂交核质不同步现象   总被引:27,自引:4,他引:23  
以草鱼(Ctenopharyngodon idellus)为母本、鲤(Cyprinus carpio)为父本进行人工杂交,杂种胚胎发育至孵化期全部死亡;同时获得了少数雌核发育草鱼和雄核发育的鲤。分析比较了草鲤杂种胚胎染色体变化及胚胎发育情况。发现杂种胚胎染色体数目变化较大,一般在24—73之间,绝大部分细胞染色体在发育过程中不断丢失而出现非整倍体;极少数细胞在受精后雌性原核和雄性原核不结合而引起雌核发育和雄核发育;草鱼和鲤胚胎发育时序有较大差别;因此细胞分裂不能同步。可能是杂种胚胎染色体不断丢失的主要原因。  相似文献   

11.
The assumption of a trade‐off between development time and fecundity, resulting from a positive correlation between body size and fecundity and between body size and development time, is a common feature of life history models. The present paper examines the evidence for such a trade‐off as indicated by genetic correlations between traits. The genetic covariances between traits are derived using a model in which maturation occurs when the organism achieves a genetically variable size threshold, and fecundity is an allometric function of body size with one genetically variable parameter (excluding body size itself). This model predicts that the heritabilities of the life history traits (growth rate, development time, fecundity) will not necessarily be less than the heritability of adult size (i.e. morphological traits). It is shown that if growth rate is genetically correlated with adult size then it is not possible, in general, to predict the sign of the genetic correlation between development time and fecundity. For particular cases the signs of the covariances between traits can be predicted. These predictions are tested using data drawn from the literature.  相似文献   

12.
《应用发育科学》2013,17(3):132-146
The purpose of the current investigation was to examine the associations between a variety of measures of extracurricular participation and indicators of youth development. We use data from the Childhood and Beyond Study, a larger longitudinal study of adolescent development. The sample is primarily White middle-class adolescents in Grades 7 through 12. First, we examined the relation between the duration of involvement in school clubs and in organized sports over a 3-year span and youth development. Second, the linear and nonlinear relations between the number of extracurricular activities and youth development 1 year later were examined. Finally, we tested the link between the breadth of participation and youth development 1 year later. In general, across all 3 sets of analyses, our findings indicate that greater involvement in extracurricular activities is associated with academic adjustment, psychological competencies, and a positive peer context. The results were strongest for the oldest group of youth.  相似文献   

13.
This article addresses the relation between the current proliferation of Information and Communication Technology (ICT) goods and services and the development of different kinds of risk assessments and policy documents. The ambition is to shed light on a, hithertho, less-discussed aspect of the development of risk assessments and policy documents, namely the time span between the development of new technologies and the development of regulatory frameworks. The concept of risk and danger can be seen as a potential means through which we can start to think about the consequences of the delay between the increased generation of electronic waste (e-waste) and the regulations to manage this increase. By using e-waste as a case study, this article provides the basis for a more general understanding of the relation between the development of new technologies and the development of regulatory frameworks. While it might be difficult to pin down the effects that this delay had/has for the subsequent development of ICTs, this article highlights the importance of taking into account not only how and by whom risk assessments and policy documents are developed, but also when they are developed in relation to the technologies that they serve to regulate.  相似文献   

14.
The life history of New Zealand flower thrips (Thrips obscuratus (Crawford), Thysanoptera: Thripidae) was studied using a simple laboratory rearing method. The effects of temperature and diet on oviposition rate and development time were examined. Oviposition rate increased with increasing temperature between 10°C and 25°C. Development time for individual instars and for total development decreased with increasing temperature between 10°C and 27°C. Total development time ranged from 50 days at 10°C (female) to 10 days at 27°C (male). The relationship between temperature and development rate was expressed as a straight line such that lower thresholds of development of between 4.2°C and 6.3°C were established for life stages. Adult lifespan increased with decreasing temperature between 10°C and 25°C and females lived longer than males. At 10°C and 25°C females lived for an average of 34 and 3 weeks respectively. Thrips supplied with pollen exhibited highest and sustained levels of egg production in comparison to other diets. Larval mortality was lowest and development time fastest on diets of pollen and sucrose or fruit juice in comparison to other plant tissues. Larval development time was similar on four species of pollen.  相似文献   

15.
The mane characteristics of lions Panthera leo in the greater Tsavo ecosystem (GTE) were compared with those of lions from the equatorial middle-elevation plains (EMEP). Contrary to popular belief, most full-grown GTE lions are not maneless; 87% had manes, with 49% possessing good manes. The manes of GTE lions, however, were poorer on average, relative to age, than the manes of EMEP lions. For both groups, there was a significant relationship between age and mane type. In EMEP lions, mane development started early and grew to a full mane by age 4–5. In GTE lions, mane development began later and developed more slowly. Delayed onset and a slower rate of development are correlated with the consistently hot Tsavo climate. Poorly maned but fully mature lions mated actively, showing dissociation between mane development and sexual maturity. The correlation between climate and mane development suggests that climatic adaptation results in the inhibition and/or delay in the development of a secondary sexual character without compromising reproductive viability.  相似文献   

16.
Developing animals must resolve the conflicting demands of survival and growth, ensuring that they can function as infants or juveniles while developing toward their adult form. In the case of the mammalian skull, the cranium and mandible must maintain functional integrity to meet the feeding needs of a juvenile even as the relationship between parts must change to meet the demands imposed on adults. We examine growth and development of the cranium and mandible, using a unique ontogenetic series of known‐age coyotes (Canis latrans), analyzing ontogenetic changes in the shapes of each part, and the relationship between them, relative to key life‐history events. Both cranial and mandibular development conform to general mammalian patterns, but each also exhibits temporally and spatially localized maturational transformations, yielding a complex relationship between growth and development of each part as well as complex patterns of synchronous growth and asynchronous development between parts. One major difference between cranium and mandible is that the cranium changes dramatically in both size and shape over ontogeny, whereas the mandible undergoes only modest shape change. Cranium and mandible are synchronous in growth, reaching adult size at the same life‐history stage; growth and development are synchronous for the cranium but not for the mandible. This synchrony of growth between cranium and mandible, and asynchrony of mandibular development, is also characteristic of a highly specialized carnivore, the spotted hyena (Crocuta crocuta), but coyotes have a much less protracted development, being handicapped relative to adults for a much shorter time. Morphological development does not predict life‐history events in these two carnivores, which is contrary to what has been reported for two rodent species. The changes seen in skull shape in successive life‐history stages suggest that adult functional demands cannot be satisfied by the morphology characterizing earlier life‐history stages. J. Morphol. 2011. © 2011 Wiley‐Liss, Inc.  相似文献   

17.
Leaf development involves many complex genetic interactions,signals between adjacent cells or between more distant tissues and consequent changes in cell fate.This review describes three stages in leaf development where regulation by small RNAs have been used to modulate gene expression patterns.  相似文献   

18.
Certain correlations between spindling and delta-activity during slow-wave sleep (SWS) development have been studied in experiments on man and animals. Interaction between systems of delta-activity and spindling generation is discussed as a possible mechanism underlying development of SWS. Amplitude-modulated stimulation of non-specific thalamic structures has been shown to influence this interaction and development of sleep processes.  相似文献   

19.
R. K. Butlin  T. H. Day 《Oecologia》1984,63(1):122-127
Summary The effect of larval competition on adult size and egg to adult development time has been investigated in laboratory populations of the seaweed fly, Coelopa frigida. Increased larval density results in longer development times and smaller adults, suggesting a strong interference element to the competition. This may be due to a limiting rate of food supply rather than interactions between larvae. The relationship between development time and size suggests that both these characters are involved in control of the onset of pupation. C. frigida is polymorphic for an inversion on chromosome I. Differences in relative viability between the karyotypes are not related to the development time or size differences.  相似文献   

20.
城市绿地与经济发展的互动机制是社会-经济-自然复合生态系统和生态文明理论研究的重要内容。利用面板格兰杰因果关系检验和面板数据回归分析方法,对中国城市绿地与经济发展之间存在的因果互动关系开展实证研究。研究结果表明:(1)全国尺度上,城市建成区绿地率与人均GDP互为格兰杰原因,存在"正向循环反馈"的因果互动关系,即城市绿地水平的提高能够推动城市经济发展,而经济发展能够拉动城市绿地建设。城市绿地率与城市人均GDP的因果关系可以概括为"绿磁效应"(GME)和"需求效应"(GDE)。(2)区域尺度上,东部地区人均GDP与城市建成区绿地率存在单向格兰杰因果关系,人均GDP是城市绿地率增长的格兰杰原因,而城市绿地率不是人均GDP的格兰杰原因;(3)西部地区城市绿地率与人均GDP的交互强度最大,即西部"绿地-经济弹性"和"经济-绿地弹性"高于其他地区。东部地区通过扩大城市绿地率来提升经济发展的空间比较小,应着眼于提高城市绿地质量,中、西部地区城市绿地率较小,应在兼顾城市绿地质量的基础上提升城市建成区绿地率。本研究能够为城市绿地与经济发展的关系研究和城市生态规划与经济发展规划提供参考。  相似文献   

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