扬子鳄种群的微卫星DNA多态及其遗传多样性保护对策分析

扬子鳄(Alligator sinensis)是中国特有的珍稀保护动物,为保护这一濒危物种,我国于80年代初在安徽宣州先后建立了扬子鳄繁殖研究中心和国家级扬子鳄自然保护区,现饲养种群存鳄数量已达10000余头。为了揭示扬子鳄种群的遗传结构,共采集了39个个体的样品,其中包括6件剥制标本,按代系不同,分为野生群、F1代饲养群及F1代饲养群,用微卫星DNA分子标记对其进行研究。分析结果显示：扬子鳄种群在微卫星水平表现出很低的遗传多样性,平均等位基因数A=2．38,平均有效等位基因数Ne=1．60,平均观察杂合度He=0．374,平均期望杂合度He=0．350,平均多态信息含量PIG=0．327,3个群体间A、Ne、Ho、He、PIC及各微卫星位点等位基因频率分布无显著差异,但F1代饲养群在Ami-μ-6和Ami-μ-222两个位点表现出极显著的遗传不平衡。扬子鳄种群遗传多样性水平低下的主要原因是近几十年来种群数量大幅减少造成,现阶段应将全部现存的扬子鳄作为一个整体加以保护。     

室内饲养的小菜蛾种群近交衰退分析

【目的】分析近交繁殖对小菜蛾Plutella xylostella种群的影响,为室内繁殖小菜蛾种群提供依据。【方法】在室内条件下,连续饲养6代小菜蛾种群,比较近交种群和杂交种群在交配行为、繁殖能力、蛹重、成虫寿命及形态等方面的差异。【结果】近交繁殖各代蛹重达极显著差异,尤其第3代后,蛹重显著下降;近交各代的雌雄成虫在交配次数和交配持续时间上显著减小,尤其是第4代后,下降幅度极其明显,F6代雌(雄)成虫的交配次数和交配持续时间分别是F0代的12.9%(13.8%)和8.3%(8.9%),表明自F4代后,近交小菜蛾种群已呈现出明显的衰退现象。同样,F4代后近交种群的产卵前期、产卵期、产卵量、卵孵化率、成虫寿命等均极显著下降,但世代历期显著延长。同时,近交对雌雄成虫体长有显著影响,F6代雌雄成虫体长是F0代的60%左右。【结论】自近交繁殖3代始,会导致小菜蛾种群交配行为、繁殖及形态的变化,尤其是近交繁殖4代以后变化更为明显,使种群出现明显的衰退现象。因此,在小菜蛾室内繁殖时,隔一段时间(至多3代)采集远源虫源,避免种群衰退。     

影响扬子鳄产蛋量的因素分析

1997～2006年对安徽省扬子鳄繁殖研究中心内的扬子鳄亲本、F1代和F2代繁殖鳄群体在冬眠环境条件、采食量、年龄等方面进行观察,对各代繁殖鳄的年产蛋数量进行统计。用SPSS11.0软件中的one-way ANOVA方法分析比较人工饲养鳄各代群体之间及人工饲养鳄与野生鳄群体之间年产蛋数量的变化关系,结果显示区域内扬子鳄所建造的洞穴数量和其所建造洞穴的质量决定着圈养鳄的冬眠质量,鳄的冬眠质量影响到鳄体内的性腺系统正常发育,最终影响扬子鳄次年能否参加产蛋;年采食量影响鳄的产蛋数量。通过第1、2、5年间产蛋量F值检验(F值=4.866,P=0.009<0.05),得出圈养条件下扬子鳄的产蛋数量是随着产龄的增加而呈增长的趋势。     

稀有鮈鲫封闭群Ihb:IHB生长和繁殖性能的监测

目的监测稀有鮈鲫野生型封闭群(Ihb:IHB)建群过程中的生长、繁殖性能,为品种管理和应用提供基础资料。方法对原代(P0)至F4代各50对传代亲鱼的产卵量、产卵间隔、卵膜径、受精率、孵化率进行监测,并对封闭群建群过程中各代(F1~F4)初孵仔鱼全长、7日龄仔鱼全长以及30、60、90日龄时的个体大小进行了监测。结果建群过程中各代间生长呈现一定的差异,F1代初孵仔鱼全长、7日龄全长较F2至F4代大,但30日龄后F2至F4代的生长指标高于F1代。培育封闭群过程中各代的受精率、孵化率有一定波动,但均维持在较高水平;各代间的产卵间隔差异并无显著性,P0代的产卵量和卵膜径大于F1至F4代。结论各代的生长差异可能与饲养条件有关,原代产卵量较大与其亲本个体较大有关;世代更替过程中封闭群保持了较高的生长和繁殖性能,未发现随世代更替而出现逐渐增大或者减小的现象,符合实验动物封闭群的要求。     

我国扬子鳄种群及栖息地保护现状

扬子鳄(Alligator sinensis)是我国特有的古老而珍稀的爬行动物,现阶段野生扬子鳄的分布区域进一步萎缩,成为彼此孤立的点状,残存栖息地的生态环境趋于恶化,野生鳄数量估计为120～150条,老年化程度高。扬子鳄的保护管理依据现实状况及时加以调整,加大了野外保护力度,逐步改善野生鳄的栖息生境,实施野外放归工程,初步遏制了野生鳄数量迅速下滑的局面。人工饲养种群数量已逾10 000条,当前人工饲养繁殖的重点是管理好有限的遗传多样性资源。扬子鳄的研究主要涉及形态学、解剖学、组织胚胎学、生态学、生理生化、细胞及分子生物学,人工饲养繁殖技术等方面。营养生理和保护遗传学的应用研究有待加强。     

母代性比对甜菜夜蛾实验种群繁殖潜力的影响

【目的】探明母代性比对甜菜夜蛾Spodoptera exigua(Hübner)实验种群繁殖及后代发展趋势的影响,为短期预测预报提供科学指导。【方法】在人工气候培养箱中(设置条件:温度28±1℃,光周期为16L:8D,相对湿度为70%±5%),研究甜菜夜蛾实验种群不同母代性比结构(♀:♂=1:1,1:2,1:3)对主要繁殖参数的影响。【结果】甜菜夜蛾成虫产卵历期随母代性比下降而缩短;种群产卵量随母代性比降低而减少;孵化率随母代性比降低而升高;每雌产卵量无差异,但雄蛾对卵及后代的贡献量却随着雌蛾比例的加大而显著提高;后代性比和雌蛹蛹重有随母代性比下降而上升的趋势。【结论】母代性比除对甜菜夜蛾雌蛾个体生殖能力影响较小,对雌蛾产卵历期、种群产卵量和孵化率、后代性比、后代雌蛹蛹重及母代雄蛾生殖贡献率均有显著影响。当以性诱剂诱集的雄虫数量为依据进行短期预测预报时,除了考虑雄虫的数量外,还有必要了解此时种群的性比结构,才能做出更准确的判断。     

稀有鮈鲫封闭群 Ihb: IHB 生长和繁殖性能的监测简

目的 监测稀有鮈鲫野生型封闭群（Ihb：IHB）建群过程中的生长、繁殖性能,为品种管理和应用提供基础资料.方法 对原代（P0）至F4代各50对传代亲鱼的产卵量、产卵间隔、卵膜径、受精率、孵化率进行监测,并对封闭群建群过程中各代（F1~F4）初孵仔鱼全长、7日龄仔鱼全长以及30、60、90日龄时的个体大小进行了监测.结果 建群过程中各代间生长呈现一定的差异,F1代初孵仔鱼全长、7日龄全长较F2至F4代大,但30日龄后F2至F4代的生长指标高于F1代.培育封闭群过程中各代的受精率、孵化率有一定波动,但均维持在较高水平;各代间的产卵间隔差异并无显著性,P0代的产卵量和卵膜径大于F1至F4代.结论 各代的生长差异可能与饲养条件有关,原代产卵量较大与其亲本个体较大有关;世代更替过程中封闭群保持了较高的生长和繁殖性能,未发现随世代更替而出现逐渐增大或者减小的现象,符合实验动物封闭群的要求.     

自然条件下人工辅助扬子鳄卵孵化的研究

提高自然条件下扬子鳄卵的孵化率 ,不仅可以节省人工室内孵化所需的大量人力、物力 ,还有助于野外扬子鳄自然种群的恢复和扩大 ,具有重要的现实意义。我们于 1 990年 7月～ 9月对此进行了探索 ,并初获成效 ,现报道如下。1　材料和方法1 1　扬子鳄卵的获得　取安徽省扬子鳄繁殖研究中心饲养的繁殖鳄当年所产的全部鳄卵作实验研究对象。1 .2　实验方法⑴孵化用窝巢的准备　选择野外阳光充足、靠近水源的一平坦处 ,人工筑成 1× 1 的窝巢。巢底垫以杂草 ,其上放置厚约 1 0～ 1 4ｃｍ的苔藓 ,再堆放约 5ｃｍ杂草。窝巢上方搭一活动木棚 ,棚顶…     

北戴河朱鹮野化训练种群的繁殖和婚外配北大核心CSCD

为了扩大朱鹮(Nipponia nippon)种群的数量和分布区,于2018年7月从洋县引进20只朱鹮在北戴河建立了朱鹮野化种群。2020年繁殖期,北戴河共有22只朱鹮,其中成年朱鹮17只,雌雄性比为1.1;实际繁殖密度为37.8只/hm2;人工巢的密度为40.0巢/hm2,人工巢筐内径为50 cm。2020年繁殖期,北戴河朱鹮共配对8对,其中6对繁殖成功,营巢成功率为75%;共产卵33枚,平均窝卵数为(4.1±1.8)枚;出壳18只,孵化率54.5%;出飞13只,出飞率72.2%,繁殖成功率为39.4%,繁殖生产力为2.2±1.2。与洋县饲养种群相比,北戴河种群首枚卵的产卵时间晚17 d,与两地温差相吻合。北戴河朱鹮的窝卵数显著高于洋县种群,这可能是由种内巢寄生所致。监控录像表明,北戴河1巢朱鹮的窝卵数高达6枚,超过野生种群平均窝卵数(2或3枚)的2倍,推测发生了种内巢寄生行为。此外,还观察到8号巢朱鹮同时发生了婚外配和种内巢寄生行为,婚外配雌鸟将卵产在该雄鸟的巢中,使得窝卵数高达7枚。此后在该巢中发现3只朱鹮轮流孵卵,以及2只雌性朱鹮并排孵于同一巢中的异常情况。北戴河朱鹮的种内巢寄生行为可能是因网笼内人工巢址密度较高但隐蔽性较低所致,而婚外配行为可能与种群密度和繁殖密度过高有关。本文有关朱鹮异常繁殖行为的研究结果可为野化网笼内人工巢筐的设置和野化种源的选择提供参考,并提示我们进一步关注朱鹮在环境压力下的表型可塑性和生态适应能力。     

人工条件下越冬扬子鳄的繁殖

2003年11月~2004年9月在安徽省扬子鳄繁殖研究中心,观察了人工养殖的成年扬子鳄(Alligatorsinensis)在饲养池和模拟自然生态环境的繁殖区中越冬后的繁殖行为。结果表明,在与扬子鳄自然洞穴的温度和水分条件相似但其他条件相差很大的人工环境中冬眠的扬子鳄具有繁殖能力。越冬后,这些鳄只能在具备其栖息地环境特点的场地成功繁殖,但不能在不具备这种环境特点的场地成功繁殖。本研究拓展了扬子鳄的人工繁殖技术,为扬子鳄人工繁殖场地的兴建提供参考资料。     

The population dynamics of the bushfly: the elucidation of population events in the field

At three well differentiated sites and over three seasons bushfly abundance at first increased rapidly, but then stabilized or fell slowly through the apparently favourable periods of summer and early autumn, before a rapid end of season decline. Analysis of the characteristics of flies taken regularly in a sampling programme allowed the sequence of population events involved to be elucidated. Adult flies immigrated in spring. They and their first progeny were comparatively large but in the subsequent locally bred generations a progressive decrease in fly size was associated with a gradual decline in the levels of natality and a gradual increase in the levels of mortality. Between site differences could be traced to variation in the balance of these changes. Climate may have a large role in the population dynamics of the bushfly but its effects are largely indirect. Fuller understanding of the bushfly life system requires some way of synthesizing the effects and interactions between the many factors involved.     

Forensic and population genetic analyses of the GlobalFiler STR loci in the Mongolian population

We have analyzed 24 loci including autosomal and Y-chromosomal short tandem repeats (STRs), Y-indel, and sex-determining marker in a sample of 267 unrelated individuals from the Mongolian population using the GlobalFiler? PCR Amplification Kit to provide an expanded and more reliable forensic database. Khalkh among 15 Mongolian minor-groups accounts for about 80% of the entire Mongolian population. A total of 267 different DNA profiles were found in this work. The highest gene diversity was observed in the SE33 (0.9376) locus, and the lowest value was found in the TPOX (0.6142) locus. Although individual power of discrimination estimates varied at the studied loci, combined probability of match from the 21 STR loci was estimated to be 1.139?×?10^?24, which is highly informative. Based on the results of pairwise F _ST genetic distances and multi-dimensional scaling plot showed that Mongolians were clustered into Europeans and Asians, although Mongolia is geographically located in Northeastern Asia. Thus, the present survey of the Mongolian population may help establish a comprehensive reference database for forensic and population genetic analyses.     

Rate of population change in voles from different phases of the population cycle

Factors involved in causing cyclic vole populations to decline, and in preventing populations from recovering during the subsequent low density phase have long remained unidentified. The traditional view of self-regulation assumes that an increase in population density is prevented by a change in the quality of individuals within the population itself, but this is still inadequately tested in the field. We compared the population growth of wild field voles ( Microtus agrestis ) from the low phase (conducted in 1998) with that of voles from the increase phase (conducted in 1999) in predator-proof enclosures (each 0.5 ha) in western Finland. Within a few months, enclosed vole populations increased to high density, and the realised per capita rate of change over the breeding season did not differ between the populations from different cycle phases. This implies that the recovery of populations from the low phase was not hindered by an impoverishment in quality of individual voles. Accordingly, we suggest that population intrinsic factors (irrespective of the mechanisms they are based on) are unlikely to play a significant role in the generation of cyclic density fluctuations of voles. Instead, we discovered direct density-dependent regulation in the vole populations. Accurate estimates of population growth and the observed density dependence provide important information for empirically based models on population dynamics of rodents.     

Genetic evidence of recent population contraction in the southernmost population of giant pandas

Anthropogenic habitat loss and fragmentation have been implicated in the endangerment and extinction of many species. Here we assess genetic variation and demographic history in the southernmost population of giant pandas (Ailuropoda melanoleuca) that continues to be threatened by habitat degradation and fragmentation, using noninvasive genetic sampling, mitochondrial control region sequence and 12 microsatellite loci. Compared to other giant panda populations, this population has medium-level genetic diversity based on the measure of both mitochondrial and nuclear markers. Mitochondrial DNA-based demographic analyses revealed that no historical population expansion or contraction has occurred, indicating a relatively stable population size. However, a Bayesian-coalescent method based on the observed allele distribution and allele frequencies of microsatellite clearly did detect, quantify and date a recent decrease in population size. Overall, the results indicate that a population contraction in the order of 95-96% has taken place over the last 910-999 years and is most likely due to anthropogenic habitat loss. These findings highlight the need for a greater focus on habitat protection and restoration for the long-term survival of this giant panda population.     

自然种群中混沌的检测及其在种群动态研究中的意义

混沌现象广泛地存在于自然界,20世纪70年代以来,通过大量的生物模型模拟说明混沌也存在于生物系统中。几十年来生态学家一直在努力寻找混沌在自然生态系统存在的证据,但所获不多,这是源于自然的现实还是由于检测方法的不当和数据的局限?一直困扰着生态学家,自然界中对混沌的检测成为一个要点,也是一个难点。在概述混沌概念和性质的基础上,着重介绍目前在自然生态系统检测混沌的方法,对各种方法的应用条件和范围进行了概述。这些方法包括功率谱法、时间序列的自相关函数分析、模型参数估计、庞加莱截面法、全局和局域李雅普若夫特征指数的估计、吸引子关联维的确定、非线性预测。大量研究结果显示,虽然在自然界检测到的混沌的例子还不多,但其存在却是不容怀疑的。问题是什么样的系统在什么样的条件下会出现混沌?研究表明食物链的结构、种群的迁入和迁出、环境噪音都会对种群的复杂性动态特征产生影响。混沌动态可能对产生系统的多样性和适应性有利,它比随机系统对外界干扰的抵抗能力更强。自然界的变化和系统的维持是持续性和混沌相互矛盾统一的结果。害虫种群复杂性动态的研究为害虫的管理提供了更多的理论依据。混沌控制的理论和方法有可能为害虫管理提供新的思路和途径。在孤立的种群中,混沌会增加种群的灭绝概率,而在集合种群中,混沌动态降低了各局域种群的同步性和同时灭绝的倾向,所以混沌虽然能增加局域种群灭绝的概率,但却能减少整个集合种群灭绝的概率。系统结构及其时空动态与混沌及种群灭绝之间的关系,是保护生物学及生物多样性保护研究的一个重要方面。今后的研究应更多地从种群、群落、生态系统及景观不同层次上的时空动态入手,利用3S等信息技术和空间动态分析方法,研究复杂性动态产生的条件及其在系统调控中的作用机制。     

On the action of population density in the population fluctuation of the flour moth,Ephestia cautella

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Contributions from the Entomological Laboratory, Kyoto University, No. 228.     

Within-host population dynamics and the evolution of microparasites in a heterogeneous host population

Abstract Why do parasites harm their hosts? The general understanding is that if the transmission rate and virulence of a parasite are linked, then the parasite must harm its host to maximize its transmission. The exact nature of such trade‐offs remains largely unclear, but for vertebrate hosts it probably involves interactions between a microparasite and the host immune system. Previous results have suggested that in a homogeneous host population in the absence of super‐ or coinfection, within‐host dynamics lead to selection of the parasite with an intermediate growth rate that is just being controlled by the immune system before it kills the host (Antia et al. 1994). In this paper, we examine how this result changes when heterogeneity is introduced to the host population. We incorporate the simplest form of heterogeneity–random heterogeneity in the parameters describing the size of the initial parasite inoculum, the immune response of the host, and the lethal density at which the parasite kills the host. We find that the general conclusion of the previous model holds: parasites evolve some intermediate growth rate. However, in contrast with the generally accepted view, we find that virulence (measured by the case mortality or the rate of parasite‐induced host mortality) increases with heterogeneity. Finally, we link the within‐host and between‐host dynamics of parasites. We show how the parameters for epidemiological spread of the disease can be estimated from the within‐host dynamics, and in doing so examine the way in which trade‐offs between these epidemiological parameters arise as a consequence of the interaction of the parasite and the immune response of the host.     

Redundancy in the population code of the retina

We have explored the manner in which the population of retinal ganglion cells collectively represent the visual world. Ganglion cells in the salamander were recorded simultaneously with a multielectrode array during stimulation with both artificial and natural visual stimuli, and the mutual information that single cells and pairs of cells conveyed about the stimulus was estimated. We found significant redundancy between cells spaced as far as 500 mum apart. When we used standard methods for defining functional types, only ON-type and OFF-type cells emerged as truly independent information channels. Although the average redundancy between nearby cell pairs was moderate, each ganglion cell shared information with many neighbors, so that visual information was represented approximately 10-fold within the ganglion cell population. This high degree of retinal redundancy suggests that design principles beyond coding efficiency may be important at the population level.     

Prevention of influenza in the general population

Background

Although all jurisdictions in Canada offer annual influenza immunization to people at high risk of complications, only Ontario has provided universal annual immunization of healthy adults and children. Use of chemotherapy (amantidine, neuraminidase inhibitors) to prevent influenza varies among provinces. We sought to systematically review the evidence for the prevention of influenza infection in the general population.

Methods

The interventions reviewed were influenza vaccination and prophylactic use of neuraminidase inhibitors. The health outcomes of interest were rates of laboratory-confirmed influenza infection, clinical definitions of influenza-like illness and work absenteeism. MEDLINE and Cochrane databases were searched for relevant articles published between 1966 and March 2003. Only randomized controlled trials (RCTs) were selected. Evidence was appraised using the methodology of the Canadian Task Force on Preventive Health Care.

Results

Eighteen trials involving more than 33 000 healthy adults were identified that met the inclusion criteria; of these, 15 showed that influenza vaccination with either live-attenuated and inactivated vaccines was efficacious. Eleven trials were considered to be of “good” quality, and 7 were considered to be of “fair” quality. The relative risk reduction (RRR) associated with influenza immunization in adults ranged from 0% to 91%. Fifteen RCTs involving more than 45 000 healthy children aged 6 months to 19 years were identified, of which 9 were considered to contain “good” evidence and 6 “fair” evidence. Results from 12 of these trials showed protection against influenza. The RRR ranged from 0% to 93%. There were 6 RCTs of “good” quality showing that neuraminidase inhibitors are effective in preventing influenza infection. Side effects from both influenza vaccination and neuraminidase inhibitor administration were mild.

Interpretation

There are numerous RCTs of good quality in large populations that have consistently shown that influenza vaccination, using inactivated or live-attenuated vaccines, is moderately effective in preventing influenza in the general population (healthy adults and children over 6 months of age). There is good evidence that neuraminidase inhibitor prophylaxis in contacts given within 36 to 48 hours of symptom onset of the household index case is effective; appropriate use of this prevention method requires access to rapid diagnostic methods. Decisions about introduction of routine immunization programs must take into account the cost and cost-effectiveness of a universal program and the burden of illness associated with influenza in each jurisdiction.Influenza virus causes yearly epidemics of respiratory illness of varying severity worldwide in people of all ages, and it may be the most important cause of medically attended acute respiratory illness.¹ In Canada influenza and pneumonia are the leading cause of death from infection and the sixth cause of death overall.² Rates of complications and death from influenza are high among adults over 65 years of age and people with cardiac or pulmonary disease or chronic medical conditions, and annual influenza immunization in this population is associated with lower frequency of hospital admissions because of respiratory disease, congestive heart failure and death from any cause.^3,4 Previously healthy young children are increasingly recognized as having hospital admission rates comparable to those among elderly people during influenza epidemics⁵ and up to 12-fold greater than rates among older children.⁶ Because influenza occurs yearly and because re-infections occur throughout the lifespan and affect up to 20% of the population each year, considerable attention has been directed to the prevention of influenza in healthy people. Although annual immunization programs are routinely offered to high-risk groups, only the province of Ontario routinely offers influenza immunization to healthy adults and children.We performed a systematic review of the literature to answer the following question: how effective are the influenza vaccine and prophylactic neuraminidase inhibitor antiviral agents for the prevention of influenza in healthy adults and children?