贺兰山雄性岩羊种群两个时期生命表的比较

2004年4—5月,利用102架自然死亡的雄性岩羊角,分析了贺兰山雄性岩羊种群的生命表、年龄 结构和存活曲线,并与1995年的研究做了比较。结果表明,1．5-4．5龄的死亡率为0％～7．4％,5．5～10．5龄 的死亡率为14．9％～25．0％,11．5-15．5龄的死亡率为40．7％～100％;与1995年相比,第一死亡高峰出现的 年龄段基本相同,而第二死亡高峰出现的年龄段则明显推迟;有64．7％的个体可以活到8龄以上,有7．8％的 个体可以活到13龄以上,与1995年也存在一定差异;1．5～4．5龄的期望寿命与1995年基本一致,但从5．5龄 以后,期望寿命明显提高;与1995年相比,4．5龄以下的死亡率差异不显著;5．5～9．5龄的死亡率差异显著, 而10．5龄以上的死亡率差异极显著。贺兰山岩羊种群虽经10年发展变化,但雄性岩羊的存活曲线依然接近A 型。     

海南南湾猕猴种群增长的研究

对海南南湾猕猴１９６５～１９９４年间的种群动态和雌性猴生命表的研究表明,该种群年均增长率为９．７％,１９８７年后种群增长率和繁殖率有所下降,猴群中非成年猴比例已不足５０％。半驯化雌性猴的逐年存活率到１７岁仍达０．５８,通过对存活曲线和寿命期望曲线的分析,南湾雌猴寿命可达３３～３８岁。婴猴死亡率较低、成年猴死亡率较高,存活曲线属Ⅰ形即凸形。研究表明静态生命表编制方法不适于灵长类,在建立标准化存活曲线时应考虑种群综合死亡系数。猕猴通过存活率、繁殖率、群体结构变化等社群调节机制达到种群平衡。对南湾猕猴近年内每年可捕捉利用１００～１５０只左右,１０岁以上的猴应占５０％以上,在不影响种群遗传多样性水平上,可适当多捕一些成年雄猴。     

佛坪自然保护区羚牛的种群数量与结构特征

１９９６年对佛坪自然保护区内的羚牛种群进行了数量调查,结果表明,保护区内羚牛的数量为４３５～５２７只,种群密度达到１．２９～１．５６只／ｋｍ２。羚牛种群的成体雌雄个体之比约为１∶０．５,明显地偏向雌性。在羚牛种群中幼仔占１２．２４％,亚成体占３５．０３％,成年雄性个体占１７．３３％,成年雌性个体占３５．４０％。该羚牛种群在１９９１年至１９９６年间的年均增长率为１８．４８％,明显高于１９８４至１９９１年间羚牛种群的年均增长率。保护区周边地区的生境不断丧失,迫使羚牛向保护区境内迁移,是保护区内羚牛种群数量在短期内迅速升高的原因。     

盐城獐种群生存力的初步分析

本文采用Ｖｏｒｔｅｘ６．０计算机程序对盐城獐（Ｈｙｄｒｏｐｔｅｓｉｎｅｒｍｉｓ）种群的生存力进行了分析。结果表明：若无狩猎和海潮侵袭的影响,在能容纳５００头獐的栖息地中,盐城獐可长期生存。如狩猎死亡率达５％和１０％,拥有１００～２００头獐的种群分别在３２～５０年和１５～２７年内灭绝率超过５％;拥有３００～５００头的现存种群分别在９０～９５年和２９～４２年内灭绝率超过５％。在有海潮侵袭的栖息地中,不管现存种群多大,在未来２５年左右的时间内种群灭绝率大于５％,在５０年内种群绝灭的可能性超过５０％。根据该地的实际情况,建议在无海潮侵袭的堤内选择至少能容纳２００头獐的栖息地和在相临的堤外选择能容纳５００头獐的栖息地建立保护区,才能保证盐城獐种群长期生存。     

淮河野生鲇鱼线粒体Cyt b基因的序列变异与遗传结构分析

本研究利用线粒体DNA细胞色素b(Cyt b)基因序列分析淮河信阳段、淮滨段、蚌埠段、洪泽湖及其支流颍河、淠河和池河的野生鲇鱼(Silurus asotus)种群遗传结构及种群历史.结果表明,在841 bp的同源序列中,7个种群共检测到变异位点40个,占全部序列的4.76％,121个个体共检测到32种单倍型;7个种群的平均单倍型多样性(h)、核甘酸多样性(Pi)分别为0.884 8、0.003 8,表明淮河野生鲇鱼种群的遗传多样性水平较高.7个种群间的遗传分化指数Fst为0.115 0,仅12.92％的变异来自种群间(AMOVA分析),基因交流值为3.85,种群间K2-P遗传距离为0.002 ～0.009,显示鲇鱼种群间没有发生明显的地理分化.NJ树揭示7个种群的个体组成2个谱系,但这2个谱系与地理分布并不相关.中性检验、错配分析和Network网络亲缘关系分析皆表明鲇鱼种群有过种群扩张,扩张时间约在0.17～0.29百万年前的中更新世中期和末期.     

珠江三角洲黄毛鼠种群数量动态的研究

本文研究农田黄毛鼠种群年度和季节数量动态。稻田区数量最高的季节为7～11月,冬春季12月～翌年6月相对来说密度较低,只是在3月份有一较小幅度增长。蕉田区黄毛鼠种群数量变化4～10月较低,11月～翌年3月数量相对较高,全年可以为呈马鞍形,即冬春较高密度,夏秋密度较低。山坡果园地小家鼠种群密度季节变化比较明显,也呈现冬春密度较高,夏秋密度较低的马鞍形曲线。     

揭示患乙肝男性比女性更易得肝癌原因

尽管早有预测认为，在未来十年全球的气候变化将会引起物种灭绝和分布地变化，但相关证据不足。近期，科学家对墨西哥蜥蜴种群进行数十年的调查后发现，自1975年来，温度上升已造成该国12％的蜥蜴种群灭绝。     

内蒙古中部小驼嗡蜣螂七个种群的遗传多样性

采用RAPD分子标记技术分析了内蒙古中部地区小驼嗡蜣螂（Onthophagus gibbulus）7个种群的遗传多样性及遗传分化。16条引物共检测到363条带,总多态位点比率为100％,Nei基因多样度为0．280,总的Shannon信息指数为0．433,结果表明,小驼嗡蜣螂种群遗传多样性丰富。在总的遗传变异中,12．57％的变异存在于种群间,87．43％的变异存在于种群内,种群间的遗传分化程度较低,种群间遗传分化系数（Gst）在0．074～0．203,基因流（Nm）在4．569～9．791,表明种群间存在广泛的基因交流。在本研究涉及的地理范围内,小驼嗡蜣螂种群的遗传距离与地理距离不相关,说明小驼嗡蜣螂种群间的分化与其生境的异质性有关。     

四合木种群生殖对策的研究

 通过研究四合木(Tetraena mongolica Maxim)种群的生殖对策,发现四合木既可进行有性生殖,又可进行营养繁殖,以有性生殖为其主要的生殖方式。有性生殖过程中具以下特征：1)具有自交和异交相结合的交配系统,异交比例(50％)高于自交比例(15％);2)具有花多果少的生殖格局,其开花率与生境、降水、植株年龄关系密切,不同种群的开花率有一定差异,种群的年龄结构对开花率有较大影响。在3～5月降水丰富的情况下,不仅开花比例高(40％～80％),且每一植株的花量很大。不同年份种群结实率普遍偏低,3～5月降雨较少的1996年平均结实率为19.8％;3～5月降雨较多的1998年为12.2％。只是由于开花基数大,对四合木种群种子的总产量不会造成较大威胁;3)胚胎发育过程中败育比率极高,只有约10％～20％的胚能发育成熟。     

东北草原羊草种群种子生产与气候波动的关系

羊草（Leymus chinensis(Trin.)Tzvel.）是一种优良的多年生禾本科牧草。东北草原羊草种群种子生产有明显的丰欠年现象。通过对3个固定样地连续12－16年的调查和测定及其与不同生长发育阶段光照时间、积温、降水量的相关分析,发现气候变化是引起羊草种群种子生产丰欠年的重要因素之一。秋季低温、多雨,翌年将是种子生产的丰年,而高温、干旱则是欠年。相反,春季高温、干旱是种子生产的丰年,而低温、多雨则是欠年。气候因子对羊草种群种子生产有明显滞后的生态效应,其影响的生态时间差可长达10－12个月之久。用前一年8－10月不同阶段的降水可预报翌年羊草种群的抽穗数量和籽实产量,但由单项降水因子引起的诸数量变化为44％－61％。     

Use of keyed character string data structures and operators in models of primate groups

Many primate populations exhibit forms of organization that are both complex and highly dynamic. A prototype of a general purpose primate population computer modelling system has been developed; this modelling system provides data structures and operators that facilitate computer representation of many static and dynamic features of primate population organization. In this system, primate group structures are represented by text strings known as key strings. A key string begins with a label or key character that identifies its population element type. The label character is followed by data fields contained between bounds marker characters. Nested key strings can be used to concisely represent many of the structural features of social groups in different primate species. Changes in group structures are accomplished by key string insertion, deletion and move operations. Models of structures and processes in island, rhesus monkey and hamadryas baboon populations built with this prototype modelling system are discussed. In these pilot applications, use of key string data structures and operators greatly simplifies many aspects of model construction.     

华山松木蠹象自然种群的生命表

华山松木蠹象Pissodes punctatus Langor et Zhang在云南分布广泛,在曲靖市国营海寨林场对华山松的危害面积达6670hm2。在该林场连续6年对该虫的自然种群消长规律进行研究,将华山松木蠹象的生长发育过程分为卵期、1期幼虫期、2期幼虫期、蛹期、成虫期5个阶段。通过林间观察及室内饲养,得到该虫自然种群生命表。并通过回归分析,得到该虫消亡的关键因子主要为2期幼虫和蛹期的白僵菌,其次为2期幼虫和蛹期寄生蜂。     

Metabolomic changes in cats with renal disease and calcium oxalate uroliths

Metabolomics - The global population is aging. Preserving function and independence of our aging population is paramount. A key component to maintaining independence is the preservation of...     

气象因子对落叶松毛虫种群数量的影响

为探究落叶松毛虫种群数量与气象因子的关系,利用大兴安岭地区落叶松毛虫发生年度监测数据与气象数据构建线性回归模型,以赤池信息量准则为评价依据,通过逐步回归的方式从拟合优度和复杂度两方面权衡选取最优模型.采用相对权重法确定影响落叶松毛虫种群数量的关键气象因子,并量化了关键气象因子对松毛虫种群数量的影响.结果表明: 低龄幼虫期和繁殖期是影响落叶松毛虫种群数量的关键时期,而中龄幼虫期和高龄幼虫期的影响较弱; 低龄幼虫期日相对湿度均值、低龄幼虫越冬期日均温小于-22 ℃积温和繁殖期降水总量是影响落叶松毛虫种群数量的关键气象因子; 低龄幼虫期日相对湿度均值和繁殖期降水总量的标准差每增加1倍,落叶松毛虫种群数量的标准差分别减少62%和35%;低龄幼虫越冬期日均温小于-22 ℃积温的标准差每增加1倍,落叶松毛虫种群数量的标准差增加40%.表明全球气候变暖趋势下落叶松毛虫的爆发特点等可能呈现出新的形式,建立长期的种群数量监测体系尤为重要.     

Current dynamics and predicted vulnerability to sea‐level rise of a threatened Bittern Botaurus stellaris population

The decline of the Bittern Botaurus stellaris has long been symbolic of wetland habitat loss and fragmentation across western Europe. Wetland restoration and creation activity, targeted at Bittern, has been ongoing in the UK for more than 10 years and the overall numbers of occupied sites has increased five‐fold in that time. The strong recovery, whilst cause for celebration, disguises the continued precariousness of the population. This recovery has predominantly been fuelled by chick productivity from three sites in coastal Suffolk and there is increasing awareness that these sites are in immediate danger from rising sea levels. A key question is whether any loss of these key sites to coastal flooding matters to the UK Bittern population. A cautious approach to mathematical modelling of the sensitivity of the UK Bittern population to sea‐level rise events suggests that we should be concerned about the long‐term future. Our models demonstrate the sensitivity of the UK population to changes in chick survival and suggest that the growth of the UK Bittern population would be negatively affected by the loss of even a proportion of nests from these three key sites. These findings prompt the need for a multi‐layered conservation strategy to meet this dynamic challenge. A potential way forward is discussed.     

赤松毛虫消长规律生命表分析

赤松毛虫消长规律生命表分析慕宗昭倪玉乐,孙家江（山东省林业厅,济南２５００１４）（山东省文登市林业局,２６４４００）ＬｉｆｅＴａｂｌｅＡｎａｌｙｓｉｓｏｆＤｅｎｄｒｏｌｉｍｕｓｓｐｅｃｔａｂｉｌｉｓＧｒｏｗｔｈａｎｄＤｅｃｌｉｎｅＰａｔｔｅｒｎｓ．￥...     

Of lemmings and snowshoe hares: the ecology of northern Canada

Two population oscillations dominate terrestrial community dynamics in northern Canada. In the boreal forest, the snowshoe hare (Lepus americanus) fluctuates in cycles with an 8-10 year periodicity and in tundra regions lemmings typically fluctuate in cycles with a 3-4 year periodicity. I review 60 years of research that has uncovered many of the causes of these population cycles, outline areas of controversy that remain and suggest key questions to address. Lemmings are keystone herbivores in tundra ecosystems because they are a key food resource for many avian and mammalian predators and are a major consumer of plant production. There remains much controversy over the role of predation, food shortage and social interactions in causing lemming cycles. Predation is well documented as a significant mortality factor limiting numbers. Food shortage is less likely to be a major limiting factor on population growth in lemmings. Social interactions might play a critical role in reducing the rate of population growth as lemming density rises. Snowshoe hares across the boreal forest are a key food for many predators and their cycles have been the subject of large-scale field experiments that have pinpointed predation as the key limiting factor causing these fluctuations. Predators kill hares directly and indirectly stress them by unsuccessful pursuits. Stress reduces the reproductive rate of female hares and is transmitted to their offspring who also suffer reduced reproductive rates. The maternal effects produced by predation risk induce a time lag in the response of hare reproductive rate to density, aiding the cyclic dynamics.     

Comparative analysis of external factors affecting the population of wild reindeer in Taimyr

This paper surveys external ecological factors that have an impact on the population of wild reindeer on the Taimyr Peninsula. These factors are estimated according to their influence on the abundance of the reindeer population. The key factors are examined with relation to bioenergetics. The population conservation strategy in view of the potential resumption of anthropogenic influence due to further industrial development of Taimyr is proposed.     

Cancer stem cells as the engine of unstable tumor progression

Genomic instability is considered by many authors the key engine of tumorigenesis. However, mounting evidence indicates that a small population of drug resistant cancer cells can also be a key component of tumor progression. Such cancer stem cells would define a compartment effectively acting as the source of most tumor cells. Here we study the interplay between these two conflicting components of cancer dynamics using two types of tissue architecture. Both mean field and multicompartment models are studied. It is shown that tissue architecture affects the pattern of cancer dynamics and that unstable cancers spontaneously organize into a heterogeneous population of highly unstable cells. This dominant population is in fact separated from the low-mutation compartment by an instability gap, where almost no cancer cells are observed. The possible implications of this prediction are discussed.     

密度对不同类型玉米源库关系及产量的调控

通过对不同类型玉米品种在4个不同生态条件下的密度定额试验发现,随着密度的增加,群体库源也随着增加,但两者增加幅度不同,群体库的增加幅度超过群体源的增加幅度。高密度下群体源不足是产量提高的主要限制因素。保证一定总粒数,增加吐丝后干物质积累量,提高成粒率,强源促库是玉米高产的关键。