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1.
The Himalayas are assumed to be undergoing rapid climate change, with serious environmental, social and economic consequences for more than two billion people. However, data on the extent of climate change or its impact on the region are meagre. Based on local knowledge, we report perceived changes in climate and consequences of such changes for biodiversity and agriculture. Our analyses are based on 250 household interviews administered in 18 villages, and focused group discussions conducted in 10 additional villages in Darjeeling Hills, West Bengal, India and Ilam district of Nepal. There is a widespread feeling that weather is getting warmer, the water sources are drying up, the onset of summer and monsoon has advanced during last 10 years and there is less snow on mountains than before. Local perceptions of the impact of climate change on biodiversity included early budburst and flowering, new agricultural pests and weeds and appearance of mosquitoes. People at high altitudes appear more sensitive to climate change than those at low altitudes. Most local perceptions conform to scientific data. Local knowledge can be rapidly and efficiently gathered using systematic tools. Such knowledge can allow scientists to test specific hypotheses, and policy makers to design mitigation and adaptation strategies for climate change, especially in an extraordinarily important part of our world that is experiencing considerable change.  相似文献   

2.
Summary The decision as to where to source seed is one of the most critical in restoration projects. Locally collected seed is often recommended, or even contractually required, because it is assumed to be adapted to local conditions and therefore result in superior survival and growth rates, conferring a greater probability of restoration success. The perceived advantages, which include retaining the genetic ‘integrity’ of the site, are centred around the avoidance of outbreeding depression and hybridization. These traditional reasons for using locally collected seed need to be reconsidered in the light of rapidly changing climatic and other environmental conditions; plants that are locally adapted now may not be locally adapted in future. Understanding the current usage of local provenance is pivotal to discussions on its appropriateness under climate change. We present the results of a survey of restoration practitioners in New South Wales on attitudes and practices in relation to the use of local provenance. We found that whilst the majority of practitioners preferentially use local provenance seeds, the actual definition of local provenance varied amongst respondents. Whilst 80% of participants believe that projections of future climate change are relevant to restoration projects, there is an apparent reluctance to actively manage for this eventuality. However, many respondents are in favour of a review of seed‐sourcing policy/guidelines to allow for the inclusion of non‐local provenance material. Implications of the survey for potential changes to guidelines to better prepare for anticipated changing conditions are discussed.  相似文献   

3.
In polygynous mammals, it is commonly observed that both sex ratios at birth and dispersal are male biased. This has been interpreted as resulting from low female dispersal causing high female local resource competition, which would select for male-biased sex ratios. However, a female-biased sex ratio can be selected despite lower female than male-biased dispersal. This will occur if the low female dispersal is close to the optimal dispersal rate, while the male dispersal is not close to the optimal dispersal rate. The actual outcome depends on the joint evolution of sex-biased dispersal and sex ratio. Earlier analyses of joint evolution imply that there will be no sex-ratio nor dispersal biases at the joint evolutionarily stable strategy, thus they do not explain the data. However, these earlier analyses assume no intersexual competition for resources. Here, we show that when males and females compete with each other for access to resources, male-biased dispersal will be associated with male-biased birth sex ratio, as is commonly observed. A trend toward male-biased birth sex ratios is also expected if there is intersexual local resource competition and if birth sex ratio is constrained so that it cannot depart from balanced sex ratio.  相似文献   

4.
Sex allocation is a crucial life-history parameter in all sexual organisms. Over the last decades a body of evolutionary theory, sex allocation theory, was developed, which has yielded capital insight into the evolution of optimal sex allocation patterns and adaptive evolution in general. Most empirical work, however, has focused on species with separate sexes. Here I review sex allocation theory for simultaneous hermaphrodites and summarize over 50 empirical studies, which have aimed at evaluating this theory in a diversity of simultaneous hermaphrodites spanning nine animal phyla. These studies have yielded considerable qualitative support for several predictions of sex allocation theory, such as a female-biased sex allocation when the number of mates is limited, and a shift toward a more male-biased sex allocation with increasing numbers of mates. In contrast, many fundamental assumptions, such as the trade-off between male and female allocation, and numerous predictions, such as brooding limiting the returns from female allocation, are still poorly supported. Measuring sex allocation in simultaneously hermaphroditic animals remains experimentally demanding, which renders evaluation of more quantitative predictions a challenging task. I identify the main questions that need to be addressed and point to promising avenues for future research.  相似文献   

5.
This study was conducted to analyze the community structure of mayflies and stabilizing points for the local populations in relation to longitudinal changes in the Keumho River, Korea. A total of 22 ephemeropteran species occurred in the main riverine system during the sampling period of 3 years. The results indicated that Baetis fuscatus (mean density of 117.3 individuals/m2), Ecdyonurus levis (54.1), Uracanthella rufa (51.3) and Caenis KUa (49.9) comprised the major species group of the ephemeropteran community. The results of statistical analyses showed that these four species were distinguished from the others in terms of their mean densities. Longitudinal patterns based on total species numbers and numbers of individuals were characterized into three phases. A new approach was applied to analyze stabilized points for local populations based on the River Continuum Concept and density‐dependent mechanisms among local populations in a metapopulation. Stabilized local populations of B. fuscatus and E. levis occurred coincidentally at two points that were approximately 45 and 75 km away from the Youngchun Dam. Caenis KUa was locally stabilized at two points that were 40 and 60 km away from the dam. Uracanthella rufa showed only one stabilized local population at a point approximately 80 km away from the dam. The diversity index for the ephemeropteran community was compared with that calculated for the benthic macroinvertebrate community, and their similarity is discussed.  相似文献   

6.
It is clear that de novo protein synthesis has an important function in synaptic transmission and plasticity. A substantial amount of work has shown that mRNA translation in the hippocampus is spatially controlled and that dendritic protein synthesis is required for different forms of long‐term synaptic plasticity. More recently, several studies have highlighted a function for protein degradation by the ubiquitin proteasome system in synaptic plasticity. These observations suggest that changes in synaptic transmission involve extensive regulation of the synaptic proteome. Here, we review experimental data supporting the idea that protein homeostasis is a regulatory motif for synaptic plasticity.  相似文献   

7.
We studied Drosophila melanogaster populations from Europe (the Netherlands and France) and Africa (Rwanda and Zambia) to uncover genetic evidence of adaptation to cold. We present here four lines of evidence for genes involved in cold adaptation from four perspectives: (i) the frequency of SNPs at genes previously known to be associated with chill‐coma recovery time (CCRT), startle reflex (SR) and resistance to starvation stress (RSS) vary along environmental gradients and therefore among populations; (ii) SNPs of genes that correlate significantly with latitude and altitude in African and European populations overlap with SNPs that correlate with a latitudinal cline from North America; (iii) at the genomewide level, the top candidate genes are enriched in gene ontology (GO) terms that are related to cold tolerance; (iv) GO enriched terms from North American clinal genes overlap significantly with those from Africa and Europe. Each SNP was tested in 10 independent runs of Bayenv2, using the median Bayes factors to ascertain candidate genes. None of the candidate genes were found close to the breakpoints of cosmopolitan inversions, and only four candidate genes were linked to QTLs related to CCRT. To overcome the limitation that we used only four populations to test correlations with environmental gradients, we performed simulations to estimate the power of our approach for detecting selection. Based on our results, we propose a novel network of genes that is involved in cold adaptation.  相似文献   

8.
张林 《生物信息学》2014,12(3):179-184
为探索准确、高效、低成本、通用性并存的生物序列局部比对方法。将点阵图算法、启发式算法等各种序列局部比对算法中准确性最高的动态规划局部比对算法在计算机中实现,并通过流式模型将其映射到图形硬件上以实现算法加速,再通过实例比对搜索数据库完成比对时间和每秒百万次格点更新(MCUPS)性能值评测。结果表明,该加速算法在保证比对准确性的同时,能显著提升比对速度。与目前最快的启发式算法相比,比对平均加速为14.5倍,最高加速可达22.9倍。  相似文献   

9.
10.
Documenting local ecological knowledge (LEK) has recently become a topic of considerable interest within the social research, development, and indigenous rights communities. For instance, LEK is thought to offer a substantial alternative to existing, largely top–down, natural resource management regimes. LEK informed resource management systems would acknowledge peoples' experiences and priorities, while also providing people with additional means of empowerment. Given these qualities, one might reasonably expect that rigorous design and methodological attributes will characterize LEK research, particularly respecting the procedures employed to identify and to select local knowledge experts. Our review of the recent social research literature suggests that insufficient attention is given both to reporting the methods employed and to employing systematic approaches, especially with regard to the critical issue of how local experts are identified. We detail a research design that systematically solicited peer recommendations of fisheries local knowledge experts in a study focused on two northeast Nova Scotian embayments. Finally, we argue that in order to achieve the stated purposes and potentials of LEK research, researchers need to become more attentive to reporting on the methods employed and to employing systematic approaches than is currently the case.  相似文献   

11.
Local search behaviour of the housefly, Musca domestica, released by ingestion of sucrose, was recorded on a bitpad digitizer. Local search is characterized by an initial increase in turning rate and a decrease in locomotory rate followed by an exponential return to control (unfed) levels for both functions. Greater variation in the slope of the exponential return to control levels was observed between runs of different flies than between runs of an individual fly, suggesting a possible internal basis for locomotory and turning functions. The local search pattern, based on decrease in relative turning rate generates a spiral configuration. A zig-zag component increases path width and increases the chances of a fly relocating the drop residue. Looping patterns correlate with successive recontacts with the drop residue and associated changes in turn direction and stopping. The results are discussed with respect to sources of internal and external orientation information controlling local search.  相似文献   

12.
Recent studies on the effect of local mate competition (LMC) on sex ratios have focused on the effect of post-dispersal mating success by males. A higher proportion of males is expected to be produced as the potential for outbreeding increases. Here we demonstrate that males of a haplodiploid ambrosia beetle with LMC disperse to seek additional matings, and brood sex ratios increase with outbreeding opportunities in the field. Manipulations in the laboratory confirm that females produce more sons when the post-dispersal mating prospects of their sons are experimentally increased. This is the first study showing that male dispersal options may influence individual female sex allocation decisions in species with strong LMC.  相似文献   

13.
太湖流域晚粳稻地方种资源的表型遗传多样性   总被引:3,自引:0,他引:3  
对368份太湖地区晚粳稻地方种材料的植株及品质性状进行分析与测定,结果表明种质问的性状均有极显著差异。植株形态及穗粒特性中,株高的变化从120.5~160.5cm,每穗总粒数变化在69.9~144.0粒/穗,千粒重的极差达10.7g。在品质性状上,整精米率变化在50.05%~77.05%间,垩白率、垩白度平均48.31%、5.36%,直链淀粉含量、蛋白质含量分别变化在12.8%~25.8%、7.55%~14.55%,平均分别为17.5%、9.42%,总体加工、蒸煮品质较优,外观品质较差。不同级分的种质资源数量的分布总体上亦呈正态分布的特征,如株高主要集中在137cm左右,占41.7%,每穗总粒数主要分布在92.3~110.0粒/穗间,占57.2%,千粒重主要在27.0~28.0g间,占41.7%。种质材料的植株及品质性状均具有较高的遗传多样性,穗粒性状、品质性状、植株形态性状的遗传多样性指数分别为2.02、1.87、1.54。种质资源材料中共有15个大穗型种质,穗粒数超过了140粒/穗,如天下第一种、千斤稻、晚慢种等,还有一些穗粒数低于70粒/穗的小穗型品种,如白叠谷、硬头颈、绿种等,直链淀粉含量≤15%的种质有22个,如来自吴江的田鸡青、野凤凰,也有一些高直链淀粉含量的种质材料,如矮土种、红芒种、木樨球和野稻。优质加工、外观品质的种质资源数量较少,吴江的晚洋稻、野凤凰两个材料属于低直链淀粉含量并且加工、外观品质为优质的种质资源。  相似文献   

14.
Provisioning in western bluebirds is not related to offspring sex   总被引:1,自引:1,他引:0  
Parents should invest more in one sex of offspring if the fitnessreturn per unit investment is higher for that sex. Sex-biasedprovisioning may occur when sons and daughters differ in theirneeds or when there is local resource competition or enhancement.We used feeding observations and sex-ratio manipulations todetermine if sex-biased provisioning occurs in western bluebirds(Sialia mexicana). The sex ratio of the brood had no effecton feeding rates by adults at unmanipulated nests over a 6-yearperiod. Adult males and females also did not differ in the numberof feedings made to sons and daughters in 13 videotaped nests.Likewise, adult feeding rates to nests experimentally biasedtoward sons or daughters did not differ significantly. Nesdingsthat were closest to the nest hole and that reached highestwere the most likely to be fed. Sons and daughters did not differin the begging behaviors most likely to result in a feeding.We conclude that sex-biased provisioning does not occur in thispopulation of western bluebirds and diat nesding behavior maybe a more important determinant of feeding.  相似文献   

15.
The introduction of integration tests on a pre-entry or post-arrival basis has drawn attention to changing national integration policies. Yet, at the local level, language and civic culture courses have often been implemented before the development of national programmes. The way these policies came into place and the extent to which they responded to similar challenges has often been overlooked. This article explores the development of these measures in four cities – Stuttgart, Vienna, Barcelona and Turin – to find out which mechanisms account for convergence in policymaking. Integration courses present traits of similarity in their contents and target groups; however, this does not imply a consistent process towards convergence. Local introduction initiatives are the product of local policy arenas, which display different policy frames of migrant integration. On the other hand, new legislation and changes in the available financial resources for integration appear to be crucial factors that trigger divergence.  相似文献   

16.
In species with polygynous mating systems, females are regarded as food-limited, while males are limited by access to mates. When local density increases, forage availability declines, while mate access for males may increase due to an increasingly female-biased sex ratio. Density dependence in emigration rates may consequently differ between sexes. Here, we investigate emigration using mark-recovery data from 468 young red deer Cervus elaphus marked in Snillfjord, Norway over a 20-year period when the population size has increased sixfold. We demonstrate a strong negative density-dependent emigration rate in males, while female emigration rates were lower and independent of density. Emigrating males leaving the natal range settled in areas with lower density than expected by chance. Dispersing males moved 42 per cent longer at high density in 1997 (37 km) than at low density in 1977 (26 km), possibly caused by increasing saturation of deer in areas surrounding the marking sites. Our study highlights that pattern of density dependence in dispersal rates may differ markedly between sexes in highly polygynous species. Contrasting patterns reported in small-scale studies are suggestive that spatial scale of density variation may affect the pattern of temporal density dependence in emigration rates and distances.  相似文献   

17.
Studies of sex allocation offer excellent opportunities for examining the constraints and limits on adaptation. A major topic of debate within this field concerns the extent to which the ability of individuals to adaptively manipulate their offspring sex ratio is determined by constraints such as the method of sex determination. We address this problem by comparing the extent of sex-ratio adjustment across taxa with different methods of sex determination, under the common selective scenario of interactions between relatives. These interactions comprise the following: local resource competition (LRC), local mate competition (LMC), and local resource enhancement (LRE). We found that: (1) species with supposedly constraining methods of sex determination showed consistent sex-ratio adjustment in the predicted direction; (2) vertebrates with chromosomal sex determination (CSD) showed less adjustment then haplodiploid invertebrates; (3) invertebrates with possibly constraining sex-determination mechanisms (CSD and pseudo-arrhenotoky) did not show less adjustment then haplodiploid invertebrates; (4) greater sex-ratio adjustment was seen in response to LRC and LMC than LRE; (5) greater sex-ratio adjustment was seen in response to interactions between relatives (LRC, LMC, and LRE) compared to responses to other environmental factors. Our results also illustrate the problem that sex-determination mechanism and selective pressure are confounded across taxa because vertebrates with CSD are influenced primarily by LRE whereas invertebrates are influenced by LRC and LMC. Overall, our analyses suggest that sex-allocation theory needs to consider simultaneously the influence of variable selection pressures and variable constraints when applying general theory to specific cases.  相似文献   

18.
Seed for restoration projects has traditionally been sourced locally to “preserve” the genetic integrity of the replanted site. Plants grown from locally sourced seeds are perceived to have the advantage of being adapted to local conditions, and the use of local provenance is a requirement of many restoration projects. However, the processes of climate change and habitat fragmentation, with the subsequent development of novel environments, are forcing us to reconsider this basic tenet of restoration ecology. We tested the “local provenance is best” paradigm, by comparing the performance of plants grown from local with non‐local seed sources within a common garden experiment. We selected six species representing a range of growth forms (Acacia falcata, Bursaria spinosa ssp. spinosa, Eucalyptus crebra, E. tereticornis, Hardenbergia violacea and Themeda australis) from an assemblage known as the Cumberland Plain Woodland, a threatened community in western Sydney. Multiple provenances were collected from within the range of each species and grown at two field sites on the Cumberland Plain. Growing time varied between species and ranged from 7 months to 2 years. With the exception of B. spinosa, and to a lesser extent T. australis, we found little evidence that local provenance plants were superior to distant provenances in terms of survival and establishment.  相似文献   

19.
ABSTRACT

While equal ratios of males and females are normal, crustacean sex ratios are frequently biased. Here I review potential reasons for sex ratio biases in animals, and evaluate how likely they apply to crustaceans. I introduce crustacean examples and highlight promising crustacean taxa for future studies where examples are lacking. I conclude that ecological differences between the sexes appear to be the dominant reason for sex ratio bias in crustaceans. Major life history patterns limit the importance of evolutionary drivers to sedentary taxa with limited dispersal. Still largely unresolved is the question whether females can bias their offspring sex ratio, and given the diversity of sex determining systems, answers will vary from case to case.

Abbreviations: LMC: local mate competition; LSC: local sperm competition.  相似文献   

20.
1. Thrips comprise the only order besides Hymenoptera where females are diploid and males are haploid. This makes them useful insects for studying the roles of kin selection and ecology in social evolution. 2. Kladothrips hamiltoni is one of six species of Australian gall-inducing thrips that have been identified as eusocial. Galls are initiated by a single foundress, who rears her brood and remains within the enclosed gall for life. The adults of both sexes of her first brood cohort are morphologically distinct from the second generation, comprising a nondispersing soldier caste. The foundress and sib-mated soldiers jointly produce a second, dispersing generation, approximately 60–80% of which are produced by the soldiers. Mean per capita egg production of female soldiers is less than 33% that of the foundress. 3. Adult eclosion of soldiers is protandrous but the overall sex ratio of the soldiers lacks bias (52% male). Protandry of soldiers increases the probability that female soldiers will be inseminated soon after their eclosion and therefore lay fertilised, female eggs. The lack of bias could be due to a balance between local resource competition and local mate competition. Gender-specific defensive behaviour of soldiers with their enemies may also be important in explaining this unexpected sex ratio. 4. The dispersing generation has an overall extreme female bias (5.6% male). Soldier incest increases relatedness between females more than between males, such that the foundress is more related to her granddaughters than her daughters, and female soldiers are more related to their daughters than their sons (assuming within-gall relatedness < 1). A female bias in the offspring of soldiers should be preferred by both the foundress and soldiers as they are more related to soldier-produced dispersing females than any other thrips in the gall. Female bias in the dispersing generation will also reduce local mate competition between males. Both soldier incest and local mate competition may therefore contribute to the extreme female bias in the dispersing generation. 5. Selection pressures for sociality in gall-inducing thrips appear to be more similar to those in gall-inducing aphids and naked mole rats than to those in Hymenoptera.  相似文献   

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