光周期对环青春期雄性根田鼠繁殖发育的作用与光周期信息的母体传递模式

在实验室条件下,采用析因设计,分别以长光照及短光照水平,测定根田鼠母体怀孕期、哺乳期及幼体断乳期光周期信息对环青春期雄性子代繁殖发育的作用,探讨雄性子代对光周期信息的反应及光周期信息的母体传递模式。检验的特定假设为,光周期能刺激和调节田鼠类动物雄体的繁殖发育;在其亲代与子代间存在光周期信息的母体传递。研究结果表明,在根田鼠亲代母体与子代幼体间具有光周期信息的母体传递。雄体的繁殖发育,不仅受母体传递光周期信息的作用,亦受断乳期光周期的影响。断乳后的光周期信息是影响雄体繁殖发育的主要信息。在长期的适应和进化过程中,根田鼠对高寒环境形成特殊的光周期信息传递格局和繁殖策略。     

根田鼠幼体食物选择的社群学习

社群学习为动物的一种可塑性表型行为,能使动物获得适应于栖息地的行为模式.本文在实验室条件下,通过自助餐式食物选择实验,测定栖息于青藏高原高寒草甸生态系统的根田鼠断乳幼体间食物选择的社群学习模式.结果表明,同伴对其学习个体的食物选择具有显著的作用(P<0.001).学习个体对同伴已觅食食物的摄入量占其总摄入量的71%以上.在多同伴及单同伴与学习个体相互作用4 h后,同伴对学习个体的食物选择的学习具有显著的作用(P<0.01),而在24 h后,同伴对学习个体食物选择的作用则消失.多同伴与单同伴对学习个体的食物选择作用的差异不显著(P>0.05).熟悉同伴对学习个体的食物选择具有显著的效应(P<0.01),而陌生同伴对学习个体的食物选择则无显著作用(P >0.05).     

布氏田鼠哺乳期低温经历抑制成年期神经再生

哺乳动物在出生前后所经历的环境条件对其成年后的行为和生理等具有重要影响。环境温度是影响动物后代表型的重要因素之一。本研究将分娩当天的布氏田鼠母体和幼仔在常温（23℃±1℃）或低温（4℃±1℃）饲养,断乳（21日龄）时转至常温环境,至第63日龄时再随机将两组动物各分为常温组和低温暴露组,期间检测体重、摄食量、静止代谢率、认知能力和神经细胞增殖和存活等,以验证哺乳期的低温经历可影响成年动物的代谢生理、行为表型和相关脑区神经再生的假说。结果发现：哺乳期低温经历导致成年布氏田鼠摄食量显著降低,与代谢有关的下丘脑以及学习记忆有关的海马区细胞增殖和存活数量减少。当动物在成年期面临冷暴露时,与哺乳期常温经历的动物相比,哺乳期低温经历的动物摄食量较低,在Y迷宫新异臂中的穿梭次数和停留时间显著降低,但海马和下丘脑部分核团的细 胞增殖以及海马CA的细胞存活明显升高。这表明哺乳期低温经历对布氏田鼠的能量代谢、行为和相关脑区的成体神经再生产生了持久的抑制效应,但成年后再次面对低温时,动物的代谢能力和代谢及学习记忆相关脑区的神经细胞可塑性优于哺乳期未曾经历低温的动物。     

随机限食和重喂食小鼠能量收支和生长发育的可塑性

为阐明能量收支和生长发育的可塑性对动物适应食物资源变化的作用和意义,将断乳后的雄性KM小鼠40只随机限食4周,再重喂食4周。采用封闭式流体压力呼吸计测定基础代谢率(BMR)。限食使摄食量显著增加,BMR和活动行为降低,胴体和生殖腺重量显著降低。重喂食后上述指标均恢复到对照组水平,表现出显著的可塑性变化。结果表明,KM小鼠能通过摄食量、BMR、活动行为和身体组成的可塑性调节以适应难以预测的食物资源变化。     

根田鼠哺乳期的同化能及产后生长发育过程中的能量分配

本文以食物平衡法测定了栖息于青海高原的根田鼠（Ｍｉｃｒｏｔｕｓ　ｏｅｃｏｎｏｍｕｓ）哺乳期的同化能及幼 体产后生长发育过程中的能量分配。结果显示哺乳高峰期同化能量为 ２．３ × ＢＭＲ（基础代谢率）, 很少达到其生理极限,而消化率和同化率维持在较高水平上,表明消化道形态可能有一定调节;幼 体生长发育过程中,断乳前（变温阶段）母鼠投入幼鼠生长的能量占哺乳代价（ｃｏｓｔ ｏｆ ｌａｃｔａｔｉｏｎ）的 ２５％;断乳后恒温能力发育较快时期,幼体投入生产的能量占同化能的 ８％;在恒温能力发育完善 时期,投入生产的能量占同化能的６％,表明动物自身的维持占重要地位。     

大型野外围栏实验揭示增食对布氏田鼠种群动态的复杂效应

尽管大多数实验都证明增加食物能提高动物的种群密度,但有关增食对动物的繁殖、存活和迁移的影响机制仍然存在争议.建立有效排除种群扩散和天敌捕食引起的复杂效应的野外大型围栏实验是目前解决这一争议必不可少的前提条件.2010~2014年,本课题组调查了增食处理对8个大型野外围栏(每个0.48 ha)内布氏田鼠(Lasiopodomys brandtii)种群动态和植物群落的影响.结果表明,增食通过增加幼体补充数量对种群密度产生正效应.然而,增食对布氏田鼠的存活产生复杂的效应:即在非繁殖季节产生正效应,在繁殖季节产生负效应.另外,增食提高了布氏田鼠植物食物的质量(蛋白质含量增加),但降低了围栏内植物群落中不喜食植物的数量.因此,增食通过增加食物的供给直接对小型啮齿类动物产生正效应.同时,食物引起的种群密度增加又通过密度制约效应间接对动物种群产生负效应,并且通过改变植物群落的结构和数量分布对啮齿动物产生长期的影响.     

植食性哺乳动物食物选择的生态学意义及行为机制

综述了植食性哺乳动物食物选择行为机制的研究进展。植食性动物的食物选择是觅食生态学研究最为活跃的领域,动物食物选择对策主要有营养选择、植物次生化合物假设、营养平衡假设、最优觅食理论和条件性气味回避假设。动物学习食物选择的行为过程中,觅食个体能通过其认知过程和感知过程来处理食物信息、学习选择食物项目是一种可塑性行为方式,有利于动物获得适应栖息地的行为模式。幼体通过社会学习自母体学习的觅食经验,在幼体一生的食物选择中均具有重要的作用。在环境条件相对稳定条件下,幼体可模仿成体的食物选择模式;在环境剧烈变化的条件下,动物通过试错学习选择的食物项目可能较模仿成体所摄取的食物项目营养含量更丰富。     

社群学习对植食性鸟类和哺乳动物觅食行为的作用

社群学习是动物的一种可塑性行为表现型式。综述了社群学习对植食性鸟类和哺乳动物觅食行为的作用,并述评了其学习机制。社群同伴对动物个体觅食地点、时间和取食方式均有影响,母体摄食的食物信息可通过胎盘和乳汁显著影响幼体的食物选择。动物通过观察学习、嗅闻学习以及味觉厌恶学习,不仅能更快找到食物资源,提高觅食效率,而且能有效降低中毒与被捕食的风险,从而提高其适合度。     

限制食粪对东方田鼠食物消化和体重生长的影响

食粪行为是植食性小型哺乳动物为满足其营养需求所采取的一种适应对策。实验室条件下,限制1月龄和12月龄东方田鼠摄食粪便,测定了限制食粪对食物消化率和体重生长的影响,旨在进一步揭示食粪行为在植食性小型哺乳动物的营养及消化对策中的作用。结果表明,限制食粪使1月龄和12月龄东方田鼠的干物质消化率分别下降27.64 %和7.89 %,粗蛋白消化率分别下降21.39 %和12.68 %;限制食粪可显著抑制东方田鼠的体重增长,且限制食粪对幼体体重的影响较成体明显。因此,研究结果充分验证了限制食粪可降低东方田鼠的食物消化率及抑制其体重生长的假设。     

单宁酸对根田鼠断乳幼体生长和存活的影响

在食物中含10％和20％蛋白质条件下,测定了单宁酸对根田鼠幼体在断乳后20d内的生长和存活的影响。结果表明,食物中含蛋白质为10％的条件下,摄食含3％和6％单宁酸食物的试验个体生长速率分别为-0．135g/d和-0．25g/d,食物利用效率均显低于对照组,断乳后20d内平均存活天数较对照组分别下降26．23％和49．36％。在食物蛋白质为20％的条件下,摄食含3％和6％单宁酸食物的试验个体生长速率分别为0．134g/d和-0．116g／d,摄食6％单宁酸食物的试验个体食物利用效率显低于摄食3％单宁酸食物的试验个体和对照组个体,断乳后20d内的平均存活天数较对照组下降39．41％,摄食3％单宁酸食物的试验个体较对照组略有下降,但不显。上述结果验证了单宁酸能显影响植食性小哺乳动物生长和存活的假设。     

Contrasting phenotypic correlations in food provision of male Tengmalm's owls (Aegolius funereus) in a temporally heterogenous environment

Summary We examined the food provision rate of male Tengmalm's owls,Aegolius funereus, during one 3 year vole cycle consisting of consecutive low, increase and peake vole years. The data were collected in the midnestling period when males provisioned the whole family. In the low vole year, males with a low loading index (g/cm²) of flying area fed their offspring more often than did males with a high loading index, whereas in the peak vole year the opposite trend was evident. Similar relationships were found in the food mass provisioned to the nest. In the increase vole year, male body size had no effect on feeding efficiency. In the peak vole year, when large voles are abundant, heavy males preyed on larger voles than were generally available in their territories, indicating that largeness may increase strike power in hunting attempts. In the low vole year, when breeding is costly due to food scarcity and extensive hunting area, small males are more economical fliers and efficient hunters than large males. The contrasting trends in correlations between male size and feeding efficiency in years of vole abundance versus scarcity suggest that no fixed phenotype may most efficiently cope with variable food supply.     

根田鼠母体捕食应激对其雄性子代性行为去雄性化的效应

母体应激效应是母体在妊娠期经历的环境变化对子代发育、繁殖及存活等特征的影响(MousseauandFox ,1 998;Bernado ,1 996 )。该效应不仅能使子代生活史特征产生迟滞性效应(Beckermanetal.,2 0 0 2 ) ,而且在密度制约过程中,导致对种群的迟滞性密度制约(Delayeddensitydependenc     

A trade-off between current and future sex allocation revealed by maternal energy budget in a small mammal

Sex-allocation theories generally assume differential fitness costs of raising sons and daughters. Yet, experimental confirmation of such costs is scarce and potential mechanisms are rarely addressed. While the most universal measure of physiological costs is energy expenditure, only one study has related the maternal energy budget to experimentally controlled offspring sex. Here, we experimentally test this in the bank vole (Myodes glareolus) by simultaneously manipulating the litter's size and sex ratio immediately after birth. Two weeks after manipulation, when mothers were at the peak of lactation and were pregnant with concurrent litters, we assessed their energy budget. We found that maternal food consumption and daily energy expenditure increased with the size of the litters being lactated. Importantly, the effects of offspring sex on energy budget depended on the characteristics of the simultaneously gestating litters. Specifically, the mothers nursing all-male litters and concurrently pregnant with male-biased litters had the highest energy expenditure. These had consequences for the next generation, as size of female offspring from the concurrent pregnancy of these mothers was compromised. Our study attests a higher cost of sons, consequently leading to a lower investment in them, and reveals the significance of offspring sex in moulding the trade-off between current and future maternal investment.     

以田鼠作为动物模型来研究社会行为的进化:基因、脑与行为

田鼠属的一些近缘种间具有独特的社会行为多态性。例如Microtusochrogaster和M .pinetorum为一夫一妻制 ,而M .montanus和M .pennsylvanicus则为独居和一夫多妻制。无论是在野外还是人工饲养的条件下 ,单配制的田鼠其雌、雄成年个体一经交配即在两者之间形成长期的配偶关系并且双亲共同哺育后代。已证明神经多肽加压素 (Vasopressin)参与了田鼠单配制行为的神经调控。本篇综述了过去以及近期关于加压素调控田鼠配偶关系形成的研究结果和进展。首先 ,阐述了加压素V1a受体 (V1aR)在脑分布的种间差异 ,并以此来鉴别特定脑区在配偶关系形成中的功能 ;其次 ,探讨了运用V1aR拮抗物的药理学方法来决定究竟哪些脑区参与配偶关系的形成 ,还描述了田鼠种间V1aR基因结构和功能的不同 ,以及这些不同对V1aR在大脑的分布和行为调控潜在的作用机制 ;最后 ,讨论了最新的研究结果 ,即对一夫多妻制田鼠进行脑V1aR基因的改造 ,从而使之表现出一夫一妻制田鼠的行为。总之 ,了解复杂的社会性行为的遗传和神经机制可以加深我们对种间和种内行为分歧进化的理解     

低数量期布氏田鼠在不同季节中对生境的选择及影响因素的研究

布氏田鼠(Microtus brandti Radde)是近年来国内外研究报道较多的鼠种之一。内蒙古锡林郭勒盟卫生防疫站(1975)、罗泽(日旬)等(1975)、黑龙江草原灭鼠办公室(1976)、刘书润(1979)、ДMиTpиeB(1980)、钟文勤等(1985)均从不同角度报道了该鼠选择生境的生态习性和数量分布特点。在前人工作的基础上,本文着重研究了布氏田鼠在低数量期对生境的选择及主要生态因子的影响。     

根田鼠的熟悉性及其自然动情下的配偶选择

报道了在室内雌鼠自然动情条件下根田鼠两性个体配偶选择的3种熟悉性效应的5组实验结果,包括雌性对熟悉和陌生雄鼠、配偶和陌生雄鼠、配偶和熟悉雄鼠的择偶行为实验 , 雄性对熟悉和陌生雌鼠、配偶和陌生雌鼠的择偶行为实验。在实验前, 将1对性成熟的雌雄鼠 (非亲缘关系) 每天关养8 h 共8 d 建立熟悉性; 配对雌雄鼠至少生育1胎则为配偶关系。在 Y 形迷宫内的30 min 实验中, 两个被选择鼠分别以项链拴在横跨选择箱顶端中央的一根铁丝上, 限制它们在各自箱内活动; 而允许异性选择鼠从中立箱自由进入两个选择箱。记录选择鼠对异性被选择鼠的访问、社会探究、攻击、交配和友好行为的频次和时间。经Wilcoxon 关联样本 T 检验发现, 除交配行为不显著外, 雌性根田鼠均选择熟悉性较高的雄鼠; 而雄鼠不具这种选择性。该结果提示雌雄根田鼠的不同择偶行为也许就是反映该种婚配制度特征的直接行为过程。因此, 在择偶行为中, 雌性根田鼠表现的单配性倾向和雄鼠的多配性倾向, 只能以其婚配制度为一雄多雌制的假设来解释。我们的实验还说明在多配制田鼠中, 一雄多雌制与混交制在雌鼠择偶行为上是不同的, 而与单配制的相似或相近, 故简单地比较多配制与单配制则不能反映田鼠亚科动物婚配制度的多样性。     

Delayed dispersal in the Zaisan mole vole (Ellobius tancrei): helping or extended parental investment?

The highly social subterranean voles of genus Ellobius (mole vole) represent a unique model to compare with both social bathyergids and surface-dwelling voles. Unlike most arvicolines, mole voles display the prolonged obligatory delay of dispersal. In subterranean rodents, this delay may be associated with benefits of cooperation (weaned offspring help their parents), an extended parental investment (parents care for weaned offspring), or both. To identify the role offspring aged <3 months play in mole vole families, we estimated their contribution to important group activities. We found that juveniles contributed very little to daily living activities up to the age of approximately 2 months. The older offspring carried objects at least as frequently as breeders, but they engaged in gnawing obstacles less frequently than their fathers. Male breeders and non-breeders engaged in gnawing more than the respective categories of females. Although young mole voles clearly did not surpass their parents in performing the more energetically costly activities, they gained body mass by 26 g (130 %) between days 30 and 90, often surpassing their parents in weight. Based on our results, in E. tancrei an extremely prolonged infancy is followed by intensive building of body reserves. This ontogenetic trajectory appears to be distinct from the patterns described for social bathyergids and for most voles.     

Maternal Food Restriction During Lactation Affects Body Weight and Sexual Behavior of Male Offspring in Meadow Voles (Microtus pennsylvanicus)

Little is known about the occurrence of individual variation in sexual behavior and how maternal nutrition can affect this variation. We tested the hypothesis that male offspring of female meadow voles, Microtus pennsylvanicus, that were 30% food restricted (FR) during days 1–7 of lactation (FR 1–7), days 8–14 of lactation (FR 8–14), or late days 15–21 of lactation (FR 15–21) lactation show persistent, negative effects on their sexual behavior as adults relative to male offspring of females that were not food restricted. We measured three components of sexual behavior, attractivity, proceptivity, and receptivity, beginning when the males were 98 d of age. Food restriction during middle lactation (FR 8–14) but not during early (FR 1–7) and late lactation (FR 15–21) was sufficient to induce adult male voles to produce anogenital marks that were not as attractive as those produced by control males. Food restriction during lactation did not affect the proceptive behavior of male voles but did affect their receptivity. Only four of 12 FR 8–14 male voles mated compared to nine of 12 FR 1–7 males, eight of 12 FR 15–21 males, and eight of 11 control males. However, no differences existed in their copulatory behavior among the males that did mate. The body weight of FR 1–7 and FR 8–14 males was lower than that of FR 15–21 and control males when they were between 22 d of age (weaning) and 48 d of age (puberty) but was similar when the males were 98 d of age. Food intake was similar for the FR and control males between day 22 and day 98. It remains unclear, however, whether this type of maternal effect represents strategic programing of offspring behavior in response to the environment experienced by mothers or is a product of developmental processes of food restriction prior to weaning (Evolution 58 , 2004, 2574).