城市化对鸟类分布的影响

随着世界各地经济的迅速发展,城市化进程正以前所未有的速度推进.城市生态系统所具有的片断化和严重干扰等特征均会对野生动物的分布产生限制性影响.城市生物多样性研究及生态学理论在城市规划中的应用对维护城市生态系统的平衡具有重要意义.本文从城市化程度、城市绿地斑块特征以及城市类型3个方面介绍了城市化与鸟类分布的关系,提出从局域和景观2个尺度综合分析城市结构特征对鸟类分布的影响并加强种群水平的研究将更有利于制定合理的城市鸟类保护方案.     

城市化对鸟类分布的影响

随着世界各地经济的迅速发展, 城市化进程正以前所未有的速度推进。城市生态系统所具有的片断化和严重干扰等特征均会对野生动物的分布产生限制性影响。城市生物多样性研究及生态学理论在城市规划中的应用对维护城市生态系统的平衡具有重要意义。本文从城市化程度、城市绿地斑块特征以及城市类型3个方面介绍了城市化与鸟类分布的关系,提出从局域和景观2个尺度综合分析城市结构特征对鸟类分布的影响并加强种群水平的研究将更有利于制定合理的城市鸟类保护方案。     

城市化对杭州市鸟类营巢集团的影响

为了了解城市化对鸟类营巢集团的影响,2007年3月至2007年8月,沿城市化梯度在杭州地区的城区、城乡结合区、农田区、农林交错区和自然林区等类型栖息地内设置3 000 m长、100 m宽的样线各18条,共计90条;并对其鸟类物种与群落营巢集团进行调查。调查共记录到繁殖鸟类96种,根据鸟类营巢位置可将其分为林冠枝干营巢集团、灌草丛营巢集团、林冠枝干/灌草丛营巢集团、自然洞穴营巢集团、人工建筑营巢集团、自然洞穴/人工建筑营巢集团地面营巢集团、水面营巢集团和寄生集团共9种。进一步分析显示,随城市化程度提高,鸟类营巢集团的数目呈整体下降趋势,而各集团的物种数也基本呈下降趋势。但是,不同的营巢集团对城市化的反应存在差异,导致其物种组成在群落中比例的明显变化。城市化程度的提高使树冠筑巢鸟、灌丛筑巢鸟、地面筑巢鸟及自然洞穴筑巢鸟在群落中所占的比例明显下降,其中地面筑巢鸟最为敏感,灌丛筑巢鸟次之。同时,自然洞穴/人工建筑集团的鸟类在群落中的比例却随着城市化程度的提高明显上升。各营巢集团之所以对城市化做出不同反应,是因为它们对筑巢地资源利用方式不同。此外,还发现植被盖度、人工设施面积、至市中心距离以及人为干扰等因素均可对鸟类营巢集团结构产生影响,但不同类型的营巢集团对上述因素的反应各异。     

鸟类的食物多样性及其取食适应

介绍了鸟类为取食各种不同的食物而在进化中形成的形态、生理和行为以及这几种类型鸟类的取食适应。     

城市化对鸟类的影响：从群落到个体

世界范围急剧的城市化进程所带来的生态问题,尤其是城市化对鸟类的影响引起了生态学家越来越多的关注。关注点从最初的群落水平,逐渐向种群水平和个体水平深入。在群落水平上,现有的研究展示了城市化对鸟类群落组成、物种的丰富度、多度、生物量和多样性等多方面存在的不同程度的影响;而物种水平的研究探讨了城市化影响鸟类群落格局的内在原因:不同的鸟类物种对城市化具有不同的反应;而个体水平的研究,更是进一步从鸟类行为、生活史特征等方面揭示城市化压力和鸟类的适应对策。大量的证据说明,城市化所带来的土地使用的改变、人为干扰、热岛效应、食物资源改变、巢捕食、夜间灯光等,不同程度地对城市鸟类产生了影响。     

城市化对鸟类筑巢的影响研究综述

繁殖期筑巢是鸟类生活史的重要阶段, 是鸟类繁殖成功的关键保障。全球范围的城市化加速推进, 使城市中筑巢繁殖的鸟类面临挑战的同时又为其提供了特殊机遇。本文通过搜索现有文献, 利用Biblioshiny程序提取并整合关键词, 得到城市鸟类生态研究的热点领域, 分析了城市气候、食物资源、巢址资源、捕食压力、污染和人为干扰对鸟类筑巢的影响, 并对今后城市化对鸟类筑巢影响研究中亟需解决的问题进行了展望。城市化对鸟类筑巢期、巢址选择及巢材选择产生显著影响, 与栖息在村镇生境的鸟类相比, 在城市中繁殖的鸟类在筑巢时间、空间和巢材使用上出现变化。在城市中筑巢的鸟类到底是通过调整行为策略作出积极适应, 还是被动接受城市环境中的诸多负面干扰, 需要针对研究对象和特定的城市栖息生境进行及时评估, 而非泛泛之谈。要在研究结论基础上, 深入思考并提出城市化建设过程中有利于鸟类种群和群落保护的具体措施, 高效发挥公民科学作用以解决城市中的鸟类保护实践问题。     

高度城市化区域中铁岗水库鸟类多样性研究

深圳市最大的水库铁岗水库的鸟类资源调查结果表明,库区拥有18目42科74属98种鸟类,其中非雀形目鸟类占全部鸟类总种数的39.8%,雀形目鸟类占60.2%。水库内的鸟类包括留鸟52种、冬候鸟34种、夏候鸟10种,旅鸟2种;国家二级保护鸟类8种、省级保护鸟类9种、中国濒危鸟类1种、濒危野生动植物种国际贸易公约收录鸟类8种、中日协定保护鸟类32种、中澳协定保护鸟类8种。在高度城市化过程中保留下来的部分大型水库及周边的水源保护区域可提供多样的栖息地,有助于增加城市区域的生物多样性。     

城市化鸟类群落变化及其与城市植被的关系

持续而快速的城市化进程正在助长全球生物多样性的丧失,其中鸟类是城市生态系统的重要环节和城市生物多样性保护的重点目标,同时也是研究的热点内容。从城市环境变化压力下,鸟类群落组成与结构、空间分布和繁殖营巢方式的改变分析,重点介绍了支持城市地区鸟类多样性的植物环境因素与影响机制的最新研究成果。结果表明：1）城市中的植被和绿色空间为城市鸟类提供生存空间和食物资源,是城市鸟类最主要的栖息地。2）保留原生乡土植物和大型树木的地区能支持更丰富的鸟类物种。3）植被的结构和盖度对鸟类群落有显著影响。林冠覆盖率增加,复杂的垂直空间和多样的植物种类的组合产生各种不同类型的植物空间和栖息地类型,吸引不同的鸟类物种,相应地也会导致更丰富的鸟类群落。总之,保持和加强城市中植物环境良好和稳定是保护城市生物多样性的有效手段。据此,提出城市环境与鸟类群落关系研究的未来发展方向,指出了其在鸟类多样性保护和城市可持续发展等领域的应用前景。     

环境噪音对鸟类鸣声的影响及鸟类的适应对策

在高噪音环境中生存的动物,发出的声信号会与噪声的频率、振幅和时间等重叠,使动物声信号的传播效率降低.鸟类主要靠鸣声通讯,鸣声传播效率下降会影响鸟类个体间识别、配偶关系、领域防卫、种群密度、群落结构等.本文综述了城市噪音、自然噪音等环境噪声对鸟类鸣声的影响以及鸟类的适应对策,提出在城市化进程中要关注噪音对鸟类的影响,并展望了本领域今后可能的研究热点.     

城市鸟类群落生态学研究展望

城市鸟类群落生态学是一个重要的但未引起足够重视的研究领域。城市化的后果和城市栖息地的特征已引起了部分生态学家的关注,同时也决定了它在研究内容和方法上的特殊性。城市化对野生动物的泛化影响以及城市鸟类群落生态学研究的潜在理论价值应该引起足够的重视。本文在总结国内外城市鸟类群落生态学研究现状的基础上,重点论述和探讨了目前的研究热点和今后的发展趋势,介绍了一些国外新的理论和方法在此领域研究上的应用状况,这     

Urban flight: understanding individual and population-level responses of Nearctic-Neotropical migratory birds to urbanization

1. Despite the fact that studies of urban ecology have become commonplace in the literature, ecologists still lack empirical evidence of the underlying mechanisms responsible for relationships between urbanization and animal community structure. In an effort to understand the processes that govern an apparent avoidance of urban landscapes by many Nearctic-Neotropical migratory birds, we examined population- and individual-level responses of the Acadian flycatcher (Empidonax virescens) to urbanization within the landscapes surrounding 35 riparian forest stands in Ohio, USA. 2. From May to August 2001-06 we surveyed birds, banded 175 territorial flycatchers to estimate both condition and survival, tracked nest initiation dates, monitored success of 387 nests and estimated annual reproductive productivity of 163 breeding pairs. 3. Neither apparent annual survival of males (phi = 0.53 +/- 0.056 SE) nor females (phi = 0.23 +/- 0.064 SE) was related to the amount of urban development within the landscape. Similarly, daily survival rates of nests, which ranged from 0.92 to 0.98 across sites, was not associated significantly with urbanization. In contrast, reproductive productivity was related negatively to the amount of urbanization surrounding riparian forests, perhaps due in part to the greater incidence of brood parasitism and fewer numbers of nesting attempts made by pairs in urban compared to rural forests. 4. Forests within urban landscapes experienced higher levels of turnover in site occupancy, and birds settling in urban areas initiated nests later, had marginally smaller body sizes and exhibited lower return rates following nest predation than birds in more rural landscapes. In this way, behavioural processes governing habitat selection, settlement patterns and site fidelity probably contributed to the lower levels of reproductive productivity achieved by pairs nesting in urban landscapes. 5. This study provides evidence that the negative association between Acadian flycatchers and urbanization results from both population- and individual-level responses to urbanizing landscapes surrounding their riparian forest habitats.     

Adaptation to local ultraviolet radiation conditions among neighbouring Daphnia populations

Understanding the historical processes that generated current patterns of phenotypic diversity in nature is particularly challenging in subdivided populations. Populations often exhibit heritable genetic differences that correlate with environmental variables, but the non-independence among neighbouring populations complicates statistical inference of adaptation. To understand the relative influence of adaptive and non-adaptive processes in generating phenotypes requires joint evaluation of genetic and phenotypic divergence in an integrated and statistically appropriate analysis. We investigated phenotypic divergence, population-genetic structure and potential fitness trade-offs in populations of Daphnia melanica inhabiting neighbouring subalpine ponds of widely differing transparency to ultraviolet radiation (UVR). Using a combination of experimental, population-genetic and statistical techniques, we separated the effects of shared population ancestry and environmental variables in predicting phenotypic divergence among populations. We found that native water transparency significantly predicted divergence in phenotypes among populations even after accounting for significant population structure. This result demonstrates that environmental factors such as UVR can at least partially account for phenotypic divergence. However, a lack of evidence for a hypothesized trade-off between UVR tolerance and growth rates in the absence of UVR prevents us from ruling out the possibility that non-adaptive processes are partially responsible for phenotypic differentiation in this system.     

Winter feeding of birds increases productivity in the subsequent breeding season

Supplementary food given to birds can have contemporary effects by reducing the risk of starvation, increasing survival and altering movements and reproductive performance. There is, however, a widely held perception that birds benefit from extra food over winter, but that it is better that they 'look after themselves' during breeding. Here we describe a landscape-scale experiment showing for the first time that the effects of increasing food availability only during the winter can be carried over to the subsequent breeding season. Even though food supplementation stopped six weeks prior to breeding, birds living on sites provisioned over winter had advanced laying dates and increased fledging success compared with birds living on unprovisioned sites. Thus, supplemental feeding of wild birds during winter, in a manner mimicking householders provisioning in gardens and backyards, has the potential to alter bird population dynamics by altering future reproductive performance. With levels of bird feeding by the public continuing to increase, the impacts of this additional food supply on wild bird populations may be considerable.     

Adaptation to the laboratory environment in Drosophila subobscura

Adaptation to a novel environment is expected to have a number of features. Among these is a temporal increase in fitness and some or all of its components. It is also expected that additive genetic variances for these fitness characters will fall. Finally, it is expected that at least some additive genetic correlations will decrease, from positive toward negative values. In a study of several life‐history variables in a Drosophila subobscura population sampled from the wild and then cultured in the laboratory, we did not find any such longitudinal trends over the first 29 generations. However, a temporal comparison (over 14 generations) of the later generations of this laboratory‐adapted population with a new population, derived from a more recent wild‐caught sample, indicated clearly that laboratory adaptation was nonetheless occurring. This study suggests the need for extensive replication and control in studies of the features of adaptation to a novel environment.     

Feather function and the evolution of birds

The ability of feathers to perform many functions either simultaneously or at different times throughout the year or life of a bird is integral to the evolutionary history of birds. Many studies focus on single functions of feathers, but any given feather performs many functions over its lifetime. These functions necessarily interact with each other throughout the evolution and development of birds, so our knowledge of avian evolution is incomplete without understanding the multifunctionality of feathers, and how different functions may act synergistically or antagonistically during natural selection. Here, we review how feather functions interact with avian evolution, with a focus on recent technological and discovery-based advances. By synthesising research into feather functions over hierarchical scales (pattern, arrangement, macrostructure, microstructure, nanostructure, molecules), we aim to provide a broad context for how the adaptability and multifunctionality of feathers have allowed birds to diversify into an astounding array of environments and life-history strategies. We suggest that future research into avian evolution involving feather function should consider multiple aspects of a feather, including multiple functions, seasonal wear and renewal, and ecological or mechanical interactions. With this more holistic view, processes such as the evolution of avian coloration and flight can be understood in a broader and more nuanced context.     

Linking genotypes to phenotypes and fitness: how mechanistic biology can inform molecular ecology

The accessibility of new genomic resources, high‐throughput molecular technologies and analytical approaches such as genome scans have made finding genes contributing to fitness variation in natural populations an increasingly feasible task. Once candidate genes are identified, we argue that it is necessary to take a mechanistic approach and work up through the levels of biological organization to fully understand the impacts of genetic variation at these candidate genes. We demonstrate how this approach provides testable hypotheses about the causal links among levels of biological organization, and assists in designing relevant experiments to test the effects of genetic variation on phenotype, whole‐organism performance capabilities and fitness. We review some of the research programs that have incorporated mechanistic approaches when examining naturally occurring genetic and phenotypic variation and use these examples to highlight the value of developing a comprehensive understanding of the relationship between genotype and fitness. We give suggestions to guide future research aimed at uncovering and understanding the genetic basis of adaptation and argue that further integration of mechanistic approaches will help molecular ecologists better understand the evolution of natural populations.     

Phenotypic Plasticity Contributes to Maize Adaptation and Heterosis

Plant phenotypic plasticity describes altered phenotypic performance of an individual when grown in different environments. Exploring genetic architecture underlying plant plasticity variation may help mitigate the detrimental effects of a rapidly changing climate on agriculture, but little research has been done in this area to date. In the present study, we established a population of 976 maize F₁ hybrids by crossing 488 diverse inbred lines with two elite testers. Genome-wide association study identified hundreds of quantitative trait loci associated with phenotypic plasticity variation across diverse F₁ hybrids, the majority of which contributed very little variance, in accordance with the polygenic nature of these traits. We identified several quantitative trait locus regions that may have been selected during the tropical-temperate adaptation process. We also observed heterosis in terms of phenotypic plasticity, in addition to the traditional genetic value differences measured between hybrid and inbred lines, and the pattern of which was affected by genetic background. Our results demonstrate a landscape of phenotypic plasticity in maize, which will aid in the understanding of its genetic architecture, its contribution to adaptation and heterosis, and how it may be exploited for future maize breeding in a rapidly changing environment.     

Manipulation of photoperiod perception advances gonadal growth but not laying date in the great tit

In seasonal environments, organisms use biotic and abiotic cues to time various biological processes that are crucial for growth, survival and reproductive success. Photoperiod is the best‐known cue used to regulate gonadal development, migration and moult of many animal species. In birds, the relationship between photoperiod and gonadal development is clearly established, but we have little understanding on whether photoperiod also regulates actual timing of egg laying under natural conditions. Elucidating the link between photoperiod and timing of breeding is however key to understand whether an evolutionary change in sensitivity to photoperiod is a possible mechanism through which organisms could adjust their seasonal timing in response to climate warming. Here, we investigated the causal relationship between photoperiod, gonadal growth and laying date in wild female great tits. We experimentally increased the photoperiod perceived by the birds in spring by clipping head feathers, and we subsequently monitored gonadal development in the lab and egg laying dates in the wild. We show that our manipulation increased the photoperiod perceived by the birds to a level that approximately corresponds to an advancement of ten calendar days. This increase in perceived photoperiod led to an acceleration of gonadal development, but not to an advancement of egg laying dates. Our results indicate that photoperiod sensitivity is not constraining the advancement of laying date under current environmental conditions and suggest that evolution of sensitivity to other supplementary cues is necessary to advance reproduction under global warming.     

Adaptation to a seasonally varying environment: a strong latitudinal cline in reproductive diapause combined with high gene flow in Drosophila montana

Adaptation to seasonal changes in the northern hemisphere includes an ability to predict the forthcoming cold season from gradual changes in environmental cues early enough to prepare for the harsh winter conditions. The magnitude and speed of changes in these cues vary between the latitudes, which induces strong selection pressures for local adaptation.We studied adaptation to seasonal changes in Drosophila montana, a northern maltfly, by defining the photoperiodic conditions leading to adult reproductive diapause along a latitudinal cline in Finland and by measuring genetic differentiation and the amount of gene flow between the sampling sites with microsatellites. Our data revealed a clear correlation between the latitude and the critical day length (CDL), in which half of the females of different cline populations enter photoperiodic reproductive diapause. There was no sign of limited gene flow between the cline populations, even though these populations showed isolation by distance. Our results show that local adaptation may occur even in the presence of high gene flow, when selection for locally adaptive life-history traits is strong. A wide range of variation in the CDLs of the fly strains within and between the cline populations may be partly due to gene flow and partly due to the opposing selection pressures for fly reproduction and overwinter survival. This variation in the timing of diapause will enhance populations' survival over the years that differ in the severity of the winter and in the length of the warm period and may also help them respond to long-term changes in environmental conditions.