具有种群动力的时滞SI模型

对一类具有幼年和成年两个生理阶段结构和时滞的Logistic种群动力的SI传染病模型进行了分析,得到了传染病最终消除和成为地方病的阈值．     

带有年龄结构的捕食者-食饵模型研究

研究带有年龄结构的捕食者-食饵模型的渐近行为.本文所研究的模型假定捕食者从幼年阶段到成年阶段的转变率依赖于幼年种群的密度,还假定幼年捕食者捕食食饵.本文最终给出了有年龄结构的捕食者-食饵模型的捕食者持久和灭绝的若干条件.     

具有时滞和自食的非自治阶段结构竞争系统的周期解

研究了一类具有时滞和自食的非自治阶段结构竞争系统的动力学行为,其中一种群分幼年和成年两个阶段.当发生自食现象时,利用重合度理论中的延拓定理,得到该系统正周期解存在的充分条件.     

白花泡桐不定根发生过程中内源激素和RNA的变化

白花泡桐（Ｐａｕｌｏｗｎｉａｆｏｒｔｕｎｅｉ（Ｓｅｅｍ．）Ｈｅｍｓｌ．）成年型和幼年型茎切段体外培养时不定根发生过程中内源ＩＡＡ、ＣＴＫ和ＡＢＡ含量测定表明：幼年型材料中内源ＩＡＡ和ＣＴＫ的含量在诱导的第２天同时达到高峰,而成年型材料中ＩＡＡ和ＣＴＫ含量的高峰则在第４天出现．两种类型切段根原基出现的时间都与其内源ＩＡＡ和ＣＴＫ的高峰一致．幼年型材料的内源ＡＢＡ含量在第４天达到高峰,随后迅速下降．成年型材料中内源ＡＢＡ则逐步下降．成年型和幼年型材料中ＲＮＡ的变化相同,在诱导的第２天稍有下降,随后显著增加．结果显示,不定根的发生与其内源激素和ＲＮＡ的变化密切相关．     

妊娠期和哺乳期双酚A暴露对幼年子代小鼠焦虑和抑郁行为的影响

双酚A(bisphenol-A,BPA)对脑和行为发育的低剂量效应已引起广泛关注。本研究分别于妊娠最后2周和分娩后前2周母鼠灌胃BPA(0.4和4 mg/kg.d),然后以旷场、高架十字迷宫、明暗箱、镜子迷宫、强迫游泳和被动回避箱等模型,分别测试幼年期(生后21～28 d)子代小鼠的行为,探讨围生期不同阶段的BPA暴露对幼年仔鼠自发活动、探究、焦虑、抑郁和被动回避记忆等行为的影响。结果表明,围生期不同阶段的BPA暴露对这些行为的影响不同,主要表现为:妊娠期BPA暴露促进幼年仔鼠的活动性,减弱其焦虑状态,提高雄性仔鼠的探究能力,促进雌性仔鼠的被动回避记忆;哺乳期BPA暴露减少幼年仔鼠的活动性,但对其焦虑行为的影响相对较弱,不影响仔鼠的探究能力和被动回避记忆;而妊娠期和哺乳期BPA暴露均加剧幼年仔鼠的抑郁行为。以上结果提示,妊娠期和哺乳期BPA暴露均可影响幼年仔鼠的焦虑、抑郁、被动回避记忆等多种行为,而妊娠期可能是BPA影响的更敏感时期。     

琼花的离体快速繁殖

1植物名称琼花（ViburnummacrocephalumFort.f.keteleeri），又名聚八仙、八仙花。2材料类别幼胚、幼年态茎芽和成年态顶芽、腋芽。未成熟果实来自昆山亭林公园；幼年态茎芽取自实生无菌苗；成年态茎芽是江苏农学院和扬州大明寺赠送的枝条。3＿培养条件（）未成熟种子及幼胚培养基：MS＋6－BA0．l～1．0mg·L－‘（单位下同）＋GA八1～5；（2）幼年态茎芽增殖培养基：MS＋ZTI～5＋IAA0．1～1．0；（3）成年态茎芽增殖培养基：MS＋ZTI～5＋ZIP0．5～2＋IAA0．l～1．0；（4）生根培养基：l／ZMS＋IBA0．5～2．0。以上蔗糖除生根…     

湖北上白垩统马家村组的鸭嘴龙超科新材料(英文)

报道和描述了一些在属级别上不确定的鸭嘴龙超科材料;标本发现于湖北省西北地区与河南交界的淅川盆地西南部的上白垩统马家村组中段。鸭嘴龙超科的骨骼化石和分散的恐龙蛋共存于同一层位,大部分的骨骼化石属于未离巢晚期和幼年早期的个体发育阶段。这一状况可以很好地解释为未离巢和幼年早期阶段的个体与更年老个体所组成的群体之间的地域分隔。通过直接的形态学对比研究,确信可以识别出至少两个鸭嘴龙超科的类群:其中一个类群可能代表了一个相对进步的基干鸭嘴龙类,而另一个类群则很可能归属于鸭嘴龙亚科。鉴于北美鸭嘴龙亚科最早出现的地层时代要更晚,中桑顿期马家村组中段的鸭嘴龙亚科化石材料提供了鸭嘴龙亚科乃至鸭嘴龙科亚洲起源的新证据。     

实验藏酋猴日粮蛋白质营养水平研究

目的本试验旨在研究不同蛋白水平对实验藏酋猴生长性能和血液生化指标的影响并确定幼年实验藏酋猴的蛋白营养需要量。方法选用15只幼年实验藏酋猴随机分为5个处理组,每个处理3个重复,分别饲喂蛋白水平为11．1％、16．1％、20．5％、24．5％和29．8％的日粮,试验期90d。结果随着日粮中蛋白水平的提高,实验藏酋猴的增重、血清白蛋白、球蛋白、天门冬氨酸氨基转移酶、丙氨酸氨基转移酶和尿素氮含量显著增加（P〈0．05）,而血清总蛋白、甘油三酯、γ-谷氨酰胺转移酶和碱性磷酸酶无显著差异。应用折线法确定幼年实验藏酋猴的蛋白营养需要量为23．69％。结论日粮蛋白水平对实验藏酋猴生长性能有显著影响,从生物学和经济学角度考虑,初步认为在本试验条件下,未成年实验藏酋猴日粮蛋白水平以23．69％最合适。     

雄性猕猴血清中促黄体素的分泌水平

本文采用促黄体素（ＬＨ）体外生物测定法，对不同年龄组雄性猴血清中促黄体素分泌水平进行了分析。结果表明：幼年组为５．４±１．７ｎｇ／ｍｌ，成年组为４５．６±１２．８ｎｇ／ｍｌ，老年组为６９．２±２１．５ｎｇ／ｍｌ。提示雄性猕猴ＬＨ分泌模式与人很相似。     

禄丰古猿幼年下颌骨的研究

本文记述了１９８０年在云南省禄丰县石灰坝村禄丰古猿地点发现的最晚中新世禄丰古猿的幼年下颌骨ＰＡ８６９。作者将此标本与西瓦古猿的,南方古猿的和现生大猿的幼年下颌进行了对比,记述了禄丰古猿幼下年颌的若干特征,这些特征表明禄丰古猿幼年下颌体各部主要尺寸的比例关系本种成年的十分相似。     

Multiple periodic solutions of a delayed predator–prey model with non-monotonic functional response and stage structure

The paper studies a periodic and delayed predator–prey system with non-monotonic functional responses and stage structure. In the system, both the predator and prey are divided into immature individuals and mature individuals by two fixed ages. It is assumed that the immature predators cannot attack preys, and the case of the mature predators attacking the immature preys is also ignored. Based on Mawhin's coincidence degree, sufficient conditions are obtained for the existence of two positive periodic solutions of the system. An example is presented to illustrate the feasibility of the main results.     

Dynamics of stage-structure predator-prey systems under density-dependent effect and mortality

We develop a four dimensional predator-prey system in continuous time with stage-structure for both the communities. The reproduction rate of the prey and the transition rate for the predator, in our model, are assumed to be density-dependent. The stability results for the coexisting equilibrium are obtained by making use of Routh–Hurwitz criteria. Because of the density-dependent effects, numerical simulations are applied in complex situations. We observe that increasing values of the coefficients linked with density-dependent term promote the stability of the coexisting steady state. Our main focus is to understand the variation of stocks when mortality rates on different stage classes are increased. We verified that stable stock on mature predator increases with its increasing mortality rate in three different modeling frameworks. However, no such positive effect on the biomass of the immature predator occurs when immature predators are removed, culled or harvested. Therefore, we could conclude that the appearance of hydra effect on many unstructured predator-prey models is due to the mortality of the mature predator only. No hydra effect is also detected when mature prey is removed in several situations we discussed. Overall, the obtained results are new and could be interesting contribution in theoretical ecology.     

不同性别和年龄的大仓鼠对黄鼬气味的反应

将雌性成体和雌雄亚成体大仓鼠 (Cricetulustriton)长期 (4周 )暴露给过量的黄鼬 (Mustelasibirica)肛腺分泌物 ,观察其行为和生理状态的变化 ,并通过与我们以前有关黄鼬气味对成年雄鼠影响的研究结果进行比较 ,表明黄鼬气味对不同性别和不同年龄大仓鼠的胁迫效应和生殖抑制存在差异。发现黄鼬气味对雌性大仓鼠的影响较雄性小 ,对亚成体的影响较成体小 ,这与雌性和未成年动物对各种胁迫因素的反应更敏感的普遍现象相反。在成年鼠中 ,雌雄鼠的攻击行为都受到黄鼬气味的抑制 ;但天敌气味使雌性的胁腺膨大 ,对胁腺标记和肾上腺大小无影响 ;成年雄鼠的肾上腺膨大 ,胁腺萎缩 ,标记减少。在亚成体中 ,除了雄性胁腺受到抑制(与成年雄鼠相同 )外 ,雌雄鼠的肾上腺和雌性的胁腺未受影响。亚成体实验鼠的体重都比对照组低 ,但成年鼠的体重未受影响。另外 ,与以往对其它鼠类的研究结果一致 ,天敌气味并不影响成年鼠的生殖器官 ,却抑制了未成年雄鼠的附睾和未成年雌鼠的子宫。这些差异可能和生理基础的性二态以及可能面临的被捕食风险大小有关     

Intraspecific competition in immature Amblyseius fallacis,Amblyseius andersoni,Typhlodromus occidentalis and Typhlodromus pyri (Acari: Phytoseiidae)

Intraspecific competition in immature Amblyseius fallacis, Amblyseius andersoni, Typhlodromus occidentalis and Typhlodromus pyri was examined in the laboratory using small cages at five different predator densities (two, four, eight, 16 and 32) in the absence and presence of prey 100 eggs of two-spotted spider mite, Tetranychus urticae (Koch), at 25 ± 1°C, 80% RH and 16L:8D photoperiod. In the absence of spider mite prey, some individuals of immature phytoseiids showed increased development and surival with increasing predator densities up to certain limits, but none survived to the adult stage, except for a single male each of A. andersoni and A. fallacis who completed development by cannibalizing on conspecifics at a density of 32 predators per cage. In the absence of spider mite prey, the mean immature survival time was independent of the initial predator density, but the variance of survival time increased with predator density. In the presence of prey, the proportion of immatures surviving to adulthood generally decreased with initial predator density and dropped sharply to almost none at the predator density of 32 for A. fallacis, eight for A. andersoni, 16 for T. occidentalis and four for T. pyri. The number of prey consumed per predator during the first day generally decreased with predator density in all four species, as prey available per predator decreased and the competition for food increased with predator density. Our data indicate that scramble competition is operating in these four species. Although cannibalism was occasionally observed, especially after the exhaustion of prey and in the generalist predators such as A. andersoni, the immatures of these phytoseiids were less influenced by the interference of conspecifics than by the increasing difficulty of finding food at high predator densities. The implications of this study for understanding phytoseiid population dynamics and their use in biological control are discussed.     

Interspecific infanticide deters predators

It is well known that young, small predator stages are vulnerable to predation by conspecifics, intra-guild competitors or hyperpredators. It is less known that prey can also kill vulnerable predator stages that present no danger to the prey. Since adult predators are expected to avoid places where their offspring would run a high predation risk, this opens the way for potential prey to deter dangerous predator stages by killing vulnerable predator stages. We present an example of such a complex predator–prey interaction. We show that (1) the vulnerable stage of an omnivorous arthropod prey discriminates between eggs of a harmless predator species and eggs of a dangerous species, killing more eggs of the latter; (2) prey suffer a minor predation risk from newly hatched predators; (3) adult predators avoid ovipositing near killed predator eggs, and (4) vulnerable prey near killed predator eggs experience an almost fourfold reduction of predation. Hence, by attacking the vulnerable stage of their predator, prey deter adult predators and thus reduce their own predation risk. This provides a novel explanation for the killing of vulnerable stages of predators by prey and adds a new dimension to anti-predator behaviour.     

带有阶段结构的时滞捕食-被捕食动力系统的全局稳定性和最优收获量

讨论捕食和被捕食动力系统时,把生物种群分为幼年和成年两个阶段,仅成年有捕食能力。还考虑了种群相互作用中不可避免的时滞和密度制约作用,以及在捕食一被捕食模型中更切合实际的“比率依赖”理论。通过对系统的分析和构造李雅普诺夫函数,分别得出在适当条件下系统非负平衡位置的局部稳定性和全局稳定性。并研究了成熟种群的最优收获量。     

The effectiveness of post-contact defenses in a prey with no pre-contact detection

Most empirical and theoretical papers on prey–predator interactions are for animals with long-range detection, animals that can detect and react to predators long before these touch the prey. Heavy-bodied and chemically defended harvestmen (Arachnida, Opiliones) are an exception to this general pattern and rely on contact to detect arthropod predators. We examined the interactions between the Brazilian wandering spider Ctenus ornatus with harvestmen (Mischonyx cuspidatus) or control prey (Gryllus sp. and M. cuspidatus immature, both with soft integuments). Considering a prey–predator system in which fleeing from or reacting to a predator at a distance is not possible, we predicted both a high survival value of near-range defense mechanisms and that mortality would be higher in the absence of such defense mechanisms. We also expected the predator to behave differently when interacting with harvestmen or with a control prey without such defense mechanisms. Our results from laboratory experiments partially matched our predictions: First of all, histological sections showed that the integument of adult harvestmen is thicker than that of immature harvestmen and that of crickets. Adult harvestmen were less preyed upon than the control prey; the heavy armature increases the survival rate but the secretions from the scent glands do not. The predator did behave differently when attacking harvestmen compared to crickets. Despite the large size difference between predator and harvestmen, the protection provided by the armature allowed some of the harvestmen to survive encounters without pre-contact detection, thus greatly reducing the reliance on long-range detection to survive encounters with predators. Harvestmen call for theoretical and empirical work on prey–predator interactions that take into account the possibility that prey may not detect the predator before contact is established.     

Impact of temperature and prey density on the predacious capacity and behaviour of Stethorus punctillum Weise

Temperature had various effects on the predacious efficacy of immature and mature stages of the coccinellid predator, Stethorus punctillum on the two-spotted spider mite, Tetranychus urticae. In the case of immature stages, food consumption at the lowest tested temperature (15°C) was significantly higher than that at higher temperatures (25 and 35°C). On the contrary, positive correlation between food consumption and temperature was evaluated in the case of adult predator. Regarding predator responses to different prey density, a high positive correlation between food consumption and prey density was evaluated among 4^th instar larvae of the predator, followed by adult predator, while younger instars did not show reasonable increases with increasing prey densities. These results confirm that larval and adult stages of S. punctillum exhibit “Type II” functional response. In conclusion, the 4^th instar larvae and adult predator are the most preferable stages in winter and summer crops to control T. urticae, respectively.     

Compensatory growth following transient intraguild predation risk in predatory mites

Compensatory or catch‐up growth following growth impairment caused by transient environmental stress, due to adverse abiotic factors or food, is widespread in animals. Such growth strategies commonly balance retarded development and reduced growth. They depend on the type of stressor but are unknown for predation risk, a prime selective force shaping life history. Anti‐predator behaviours by immature prey typically come at the cost of reduced growth rates with potential negative consequences on age and size at maturity. Here, we investigated the hypothesis that transient intraguild predation (IGP) risk induces compensatory or catch‐up growth in the plant‐inhabiting predatory mite Phytoseiulus persimilis. Immature P. persimilis were exposed in the larval stage to no, low or high IGP risk, and kept under benign conditions in the next developmental stage, the protonymph. High but not low IGP risk prolonged development of P. persimilis larvae, which was compensated in the protonymphal stage by increased foraging activity and accelerated development, resulting in optimal age and size at maturity. Our study provides the first experimental evidence that prey may balance developmental costs accruing from anti‐predator behaviour by compensatory growth.