Impacts of a global climate cycle on population dynamics of a migratory songbird

Progress toward understanding factors that limit abundances of migratory birds, including climate change, has been difficult because these species move between diverse locations, often on different continents. For black-throated blue warblers (Dendroica caerulescens), demographic rates in both tropical winter quarters and north temperate breeding grounds varied with fluctuations in the El Ni?o Southern Oscillation. Adult survival and fecundity were lower in El Ni?o years and higher in La Ni?a years. Fecundity, in turn, was positively correlated with subsequent recruitment of new individuals into winter and breeding populations. These findings demonstrate that migratory birds can be affected by shifts in global climate patterns and emphasize the need to know how events throughout the annual cycle interact to determine population size.     

扎龙湿地游禽类数量变动及原因分析

2006-2009年对扎龙湿地内的游禽类种群动态进行了研究,并将结果与1983年研究结果进行了比较.调查共记录到游禽鸟类3目3科24种,夏季游禽类繁殖鸟种类少、繁殖种群数量低,春秋季节迁徙鸟类种类多、数量高.在调查期间内游禽鸟类年际间的数量变动略呈下降趋势.1983年记录的37种游禽中有13种在本调查中未见.本研究6-...     

Declining amphibian populations: the problem of separating human impacts from natural fluctuations

Reports of declining amphibian populations in many parts of the world are numerous, but supporting long-term census data are generally unavailable. Census data from 1979 to 1990 for three salamander species and one frog species at a breeding pond in South Carolina showed fluctuations of substantial magnitude in both the size of breeding populations and in recruitment of juveniles. Breeding population sizes exhibited no overall trend in three species and increased in the fourth. Recent droughts account satisfactorily for an increase in recruitment failures. These data illustrate that to distinguish between natural population fluctuations and declines with anthropogenic causes may require long-term studies.     

Edge effects and the extinction of populations inside protected areas

Theory predicts that small populations may be driven to extinction by random fluctuations in demography and loss of genetic diversity through drift. However, population size is a poor predictor of extinction in large carnivores inhabiting protected areas. Conflict with people on reserve borders is the major cause of mortality in such populations, so that border areas represent population sinks. The species most likely to disappear from small reserves are those that range widely-and are therefore most exposed to threats on reserve borders-irrespective of population size. Conservation efforts that combat only stochastic processes are therefore unlikely to avert extinction.     

Age, sex, density, winter weather, and population crashes in Soay sheep

Quantifying the impact of density, extrinsic climatic fluctuations, and demography on population fluctuations is a persistent challenge in ecology. We analyzed the effect of these processes on the irregular pattern of population crashes of Soay sheep on the St. Kilda archipelago, United Kingdom. Because the age and sex structure of the population fluctuates independently of population size, and because animals of different age and sex respond in different ways to density and weather, identical weather conditions can result in different dynamics in populations of equal size. In addition, the strength of density-dependent processes is a function of the distribution of weather events. Incorporating demographic heterogeneities into population models can influence dynamics and their response to climate change.     

Linking breeding and wintering ranges of a migratory songbird using stable isotopes

We used the natural abundance of stable isotopes (carbon and hydrogen) in the feathers of a neotropical migrant songbird to determine where birds from particular breeding areas spend the winter and the extent to which breeding populations mix in winter quarters. We show that most birds wintering on western Caribbean islands come from the northern portion of the species' North American breeding range, whereas those on more easterly islands are primarily from southern breeding areas. Although segregated by breeding latitude, birds within local wintering areas derive from a wide range of breeding longitudes, indicating considerable population mixing with respect to breeding longitude. These results are useful for assessing the effects of wintering habitat loss on breeding population abundances and for predicting whether the demographic consequences will be concentrated or diffuse.     

中国美利奴羊群体规模对育种成效的影响

在考虑后裔测验与配母羊比例及测验公羊数量的条件下,按群体规模进行了中国美利奴羊育种方案最优化的模型计算,探索规划模型计算结果在我国细毛羊育种实践中应用和推广的可能性。结果表明:随着群体规模的扩大,多性状综合选育的育种进展及育种效益均较大幅度地提高;根据中国美利奴羊群的现状,后裔测验与配母羊在核心群中的比例应相应提高,最好达到50%以上;在一个2～4万只母羊的群体中,每年选留20～30只测验公羊进行后裔测验,就可以获得理想的遗传进展。对于一个大的育种单位,测验公羊数应每年选留50～70只。     

山西临汾灯诱地下害虫种类组成及优势种群发生动态

[目的]为明确对山西省临汾小麦玉米造成严重为害的地下害虫优势种群的种类组成及其年发生动态。[方法]利用在农田设置虫情测报灯诱捕的方法进行了山西临汾小麦和玉米一年两熟区农田地下害虫的虫口调查,通过室内鉴定、数据分析、查阅文献等对所诱集到的成虫进行结果分析。[结果]铜绿丽金龟,毛黄鳃金龟等7种为山西临汾小麦玉米一年两熟区农田地下害虫的主要优势种群,且不同优势种群年发生量和发生期均有所差异,对黑光灯的敏感度也不同。[结论]绝对优势种铜绿丽金龟成虫的发生期较为集中,一般在6月下旬至7月中旬,且其对灯光敏感度较高,可利用黑光灯对其进行监测和防治。     

Chaos versus noisy periodicity: alternative hypotheses for childhood epidemics

Whereas case rates for some childhood diseases (chickenpox) often vary according to an almost regular annual cycle, the incidence of more efficiently transmitted infections such as measles is more variable. Three hypotheses have been proposed to account for such fluctuations. (i) Irregular dynamics result from random shocks to systems with stable equilibria. (ii) The intrinsic dynamics correspond to biennial cycles that are subject to stochastic forcing. (iii) Aperiodic fluctuations are intrinsic to the epidemiology. Comparison of real world data and epidemiological models suggests that measles epidemics are inherently chaotic. Conversely, the extent to which chickenpox outbreaks approximate a yearly cycle depends inversely on the population size.     

红锥天然群体和栽培群体的遗传多样性研究(英文)

[目的]调查红锥天然群体和栽培群体的遗传分化状况。[方法]以广东、广西、福建、云南、海南的5个红锥天然群体和广西的3个种源的红锥栽培群体为供试材料,用筛选出的9对ISSR引物,对8个群体共计151个个体进行ISSR分析。[结果]每对ISSR引物扩增出7～20条条带,共得到122条多态带。红锥天然群体在种群水平的多态带百分率P为59.84%,Nei基因多样性指数Hpop为0.1827,Shannon多样性指数(I)为0.2856,高于红锥栽培群体(P=54.87%,HPOP=0.1366,I=0.2198)。群体特异带及群体间共有带的差异与分布揭示了群体间的遗传差异及相似性,红锥天然群体遗传多样性主要存在于群体内,群体间的遗传分化系数Gst为0.99。在红锥的3个栽培群体中发现了类似的群体遗传结构(GST=0.1275)。UPGMA聚类分析结果表明,红锥天然群体间的遗传距离有随地理距离跨度增加而递增的趋势。[结论]红锥遗传多样性偏低可能与人为干预和环境破坏导致的种群缩小及生境片段化等因素有关;红锥种群遗传结构的形成则与其自身繁育机制密切相关。     

红壳色文蛤选育群体遗传多样性的微卫星分析

【目的】了解群体选育过程中红壳色文蛤（Meretrix meretrix）选育群体的遗传多样性变化及世代遗传分化情况,为文蛤育种计划的可持续性提供理论依据。【方法】以江苏黄文蛤原种（SY）、江苏红文蛤原种（SR）及5个红壳色文蛤选育群体（SRF₁~SR5F₅）为研究对象,利用15对微卫星引物对各文蛤群体基因组DNA进行PCR扩增,然后通过Gel-Pro32 4.0、PopGen 32和MEGA 6.0等在线软件分析7个文蛤群体的遗传多样性。【结果】从7个文蛤群体中共检测出766个等位基因,每个微卫星位点在每个群体中检测出3~18个等位基因,且等位基因数（Na）随选育世代增加呈下降趋势。15个微卫星位点的平均多态信息含量（PIC）在0.575~0.630,均属于高度多态性位点。7个文蛤群体的平均观测杂合度（Ho）为0.442~0.502,平均期望杂合度（He）为0.629~0.680,群体中63.81%的微卫星位点偏离Hardy-Weinberg平衡,表明各微卫星位点存在一定程度的杂合子缺失;群体内近交系数（F_is）范围为-0.0157~0.7409,平均为0.2777,表明文蛤群体内存在一定程度的近交水平;群体间遗传分化系数（F_st）平均为0.0455,即文蛤群体变异中仅有4.55%是由不同群体间的基因差异所产生,而95.45%的变异来源于群体内部;各群体的基因流（Nm）为0.9002~18.9478,平均为8.8065,说明7个文蛤群体间的遗传分化较低。UPMGA聚类分析发现7个文蛤群体聚类呈两大支,江苏红文蛤原种及其选育群体聚为一支,而江苏黄文蛤原种（SY）独自聚为一支。【结论】经过5代人工选育的红壳色文蛤选育群体虽然较基础群体其遗传多样性指数略有下降,但并未导致各选育群体的遗传结构发生改变,仍具有较高的遗传多样性。在连续的选择育种计划中,应增加亲本养殖环境多样化,避免因人工繁育的亲本和养殖群体规模较小引起遗传漂移或近交衰退而致使某些等位基因缺失,导致后代的遗传结构发生改变。     

Energetic and fitness costs of mismatching resource supply and demand in seasonally breeding birds

By advancing spring leaf flush and ensuing food availability, climatic warming results in a mismatch between the timing of peak food supply and nestling demand, shifting the optimal time for reproduction in birds. Two populations of blue tits (Parus caeruleus) that breed at different dates in similar, but spatially distinct, habitat types in Corsica and southern France provide a unique opportunity to quantify the energetic and fitness consequences when breeding is mismatched with local productivity. As food supply and demand become progressively mismatched, the increased cost of rearing young pushes the metabolic effort of adults beyond their apparent sustainable limit, drastically reducing the persistence of adults in the breeding population. We provide evidence that the economics of parental foraging and limits to sustainable metabolic effort are key selective forces underlying synchronized seasonal breeding and long-term shifts in breeding date in response to climatic change.     

Tracking the long-term decline and recovery of an isolated population

Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens.     

西藏光核桃果实表型性状变异分析与种质资源筛选

  目的  本研究是探究西藏野生光核桃果实表型性状种群变异规律,结合主成分分析筛选优良种质资源,探明生态因子对果实表型性状的影响,为光核桃良种选育和推广提供参考。  方法  根据西藏野生光核桃的集中分布区,兼顾种群生长海拔、气候和成熟期的差异,对5个地级市18个种群（SYD、AR、LD、JT、DB、QD、MX、LK、BM、GY、SZ、BJ、ZR、PZ、QN、BH、LZ、CN）进行实地调查采样,每个种群选取13株长势良好的光核桃,各单株间距大于50 m,每株分阴面、阳面和上、下4个方位采集成熟果实,从每方位的果实中随机选择5枚,共20枚,测量其表型性状。  结果  光核桃果实表型性状种群间和种群内均存在极显著差异;种群间表型分化系数均值为67.99%,表型变异主要来源于种群间;根据PCA分析结合利用部位果肉和果核,筛选出果实大、果核小、果肉厚、出核率低的果用型光核桃,代表种群为山南贡嘎县江塘镇、林芝米林县羌纳乡、林芝朗县朗镇;果实小、果核大、果肉薄、高出核率的核用型光核桃,代表种群有林芝察隅县古玉乡、日喀则亚东县上亚东乡、昌都芒康县曲登乡。RDA分析5个生态因子共解释56.00%的果实性状变异,仅年均温对果实性状的总体变异影响显著（P = 0.049）;两个特征性状果肉厚和出核率与生态因子的多元回归方程均回归显著（P < 0.01）,调整后判定系数分别为0.599 3、0.798 1。果肉厚与经度、海拔、年均降雨量呈负相关,与纬度和年均温呈正相关;出核率与经度、海拔、年均降雨量和年均温呈正相关,与纬度呈负相关;5个生态因子中经度、纬度、海拔对果肉厚和出核率的影响极显著。  结论  光核桃果实表型性状变异主要来源于种群间;根据表型性状筛选出了果用型和核用型光核桃及其代表种群,其特征性状主要受经纬度、海拔的影响。      

安徽河川沙塘鳢不同地理群体遗传多样性和遗传结构研究

为探究安徽河川沙塘鳢不同地理群体遗传多样性差异和遗传分化水平,研究采集了安徽长江、新安江流域的4个地理群体,共142个河川沙塘鳢样本。选择线粒体基因作为分子标记,进行测序与分析。结果显示,标记全长1 291 bp,包含52个变异位点,定义了15个单倍型。4个群体总体遗传多样性水平远高于群体内遗传多样性水平,分子变异主要来源于群体间。所有群体形成了3个反映物种的地理分布关系的支系,且未曾发生过扩张。河川沙塘鳢群体间的分化程度很高,具有较高的保护和选育价值。     

刺五加种群构件的数量统计（Ⅰ）─—刺五加种群地上部分构件的数量统计

植物种群构件数量统计是植物生态学的崭新领域，对种群结构与动态的研究具有重要的意义．本文以无性系灌木刺五加种群的地上部分构件枝、芽为对象，研究了三种天然次生林群落中及皆伐迹地上刺五加的平均枝长和分枝级数以及各级枝上着生的活芽数和分枝角度的变化规律，并从群落环境和刺五加的年龄状况对其进行了综合分析．结果表明．刺五加种群的枝、芽构筑型特征是由其本身的生物学特性决定的，但随年龄和环境状况而产生适应性变化     

水貂DNA指纹的研究：Ⅲ.群体遗传变异度估测的抽样统计分析

对在两个近交程度不同的水貂群体中利用小卫星ＤＮＡ指纹资料估测的群体内遗传变异度进行抽样统计分析的结果表明：在同一张ＤＮＡ指纹图谱中，随着样本含量的增加，群内遗传变异度估值的变异甚小，且无明显的上偏或下偏趋势，只是估计值的抽样误差呈持续下降的趋势，但当样本含量达到１０以后，下降幅度甚小（〈１０％）。遗传变异度较大的群体，其估计值的抽样误差相应较大，但两群体抽样误差的差异随样本含量的增加有逐渐缩小的趋     

鸟类对森林生境片断化的反应

森林生境片断化对生活在其中的鸟类产生着难以估量的影响,鸟类的种群动态、种群遗传和局部进化等都不同程度地受环境变化的影响。不同的鸟类对片断化的反应也不尽相同。边缘效应对物种具正负2种效应。片断化对鸟类基因库的影响也随种类而异,它取决于物种遗传变异的数量和性质。鸟类的森林栖息地片断化的反应不仅取决于栖息地及其质量,还取决于其本身所具有的行为的可塑性和内在的遗传变异。     

雷山县黑线姬鼠种群数量动态及繁殖参数变化

对贵州省雷山县1985～2011年黑线姬鼠种群数量动态及繁殖参数变化规律分析表明:黑线姬鼠多年平均捕获率达3.15%±1.37%,全年种群数量变动曲线呈单峰型,一年内种群数量在7月出现1个数量高峰期,平均捕获率达5.34%±2.25%,不同年度、不同月份、不同季节之间种群数量存在显著差异。黑线姬鼠种群繁殖参数具有明显的季节周期性波动,主要繁殖期在4～9月,一年中在春季4～5月和秋季8～9月出现2次怀孕高峰期,多年种群总性比为0.96,平均怀孕率为38.23%,平均胎仔数为6.12只,平均繁殖指数为1.15,平均睾丸下降率为59.55%,雄鼠睾丸下降率的季节变化与雌鼠怀孕率季节变化呈同步变动趋势。不同年度、不同月份、不同季节种群繁殖参数存在一定差异。     

Selection on heritable phenotypic plasticity in a wild bird population

Theoretical and laboratory research suggests that phenotypic plasticity can evolve under selection. However, evidence for its evolutionary potential from the wild is lacking. We present evidence from a Dutch population of great tits (Parus major) for variation in individual plasticity in the timing of reproduction, and we show that this variation is heritable. Selection favoring highly plastic individuals has intensified over a 32-year period. This temporal trend is concurrent with climate change causing a mismatch between the breeding times of the birds and their caterpillar prey. Continued selection on plasticity can act to alleviate this mismatch.