不同种群密度下高原鼠兔的行为模式

在2003年高原鼠兔(Ochotonacurzoniae)的繁殖初期、繁殖盛期、繁殖中期和繁殖末期,采用目标动物取样法对其不同种群密度条件下的行为模式进行研究,探讨高原鼠兔的行为变化和种群密度的相互关系。结果表明:在繁殖盛期和繁殖中期,低密度种群内雌性高原鼠兔的观望时间均显著高于高密度种群内,而在其它两个时期内无明显不同;雄性高原鼠兔的观望时间在不同密度间比较均无显著差异;同一密度条件下,雄性高原鼠兔的观望行为持续时间和发生频次均表现显著的季节性变化,而雌性高原鼠兔无明显差异。高原鼠兔的地面活动时间在不同种群密度间比较无显著差异。低密度种群内,雄性高原鼠兔的地面移动距离和频次均呈显著的季节性差异,而雌性高原鼠兔的差异不显著;高密度种群内,雌、雄个体的地面移动距离和频次都具有显著的季节性差异。在高原鼠兔的社会行为中,亲昵行为和攻击行为强度在不同种群密度间比较均无显著差异;在同一密度条件下,亲昵行为和攻击行为强度也没有表现出明显的季节性变化。以上结果说明高原鼠兔的行为变化与其繁殖期和性别有明显的关系,而在密度间无明显的差异,其主要原因是在不同的繁殖期,动物的繁殖投入不同,导致行为模式产生差异     

种群密度对高原鼠兔类固醇激素水平的影响

本研究于2003 年在野外条件下,通过比较不同密度种群间高原鼠兔的种群增长、4 种类固醇激素水平和肾上腺重量的变化,探讨种群密度与其内分泌水平间的相互关系。结果表明,在最高密度的种群内高原鼠兔种群密度增长最大,在最低密度种群内种群密度增长最小。繁殖盛期时高密度种群内雄性高原鼠兔血浆皮质酮水平显著高于低密度种群内个体,肾上腺重量在不同密度种群间也有显著差异,而血浆雌二醇、睾酮、皮质醇水平均未表现出种群密度间的显著变化。整个繁殖期内,高密度和低密度种群间高原鼠兔的皮质酮水平和肾上腺重量呈现不一致的季节变化模式,高密度种群内繁殖盛期和中期显著高于其它繁殖时期,低密度种群内则无明显变化。不同密度种群内高原鼠兔的雌二醇、睾酮、皮质醇水平的季节性变化具有相似的模式。本研究结果表明,在当前种群密度相对较低的自然情况下,高种群密度不能使高原鼠兔产生强烈的社群应激,从而限制其种群增长。     

高原鼠兔种群生产量生态学的研究Ⅲ.高原鼠兔生命率非密度制约与密度制约的种群动态趋势

本文以高原鼠兔(Ochotona curzoniae)自然种群生命表的统计参数为基础,根据非密度制约Leslie模型及具有密度制约反馈的标准Leslie修正模型,分别预测了该种群在1982-2001年间的发展趋势。在菲密度制约条件下,该种群呈指数增长。在密度制约存在肘,种群增长趋于平衡状态,且存滔率密度制约较繁殖率密度制约对种群的作用更大。存活率密度制约与非密度制约的年龄结构均为Leslie分布,繁殖率密度制约作用的种群稳定年龄分布更平均,其平衡状态的种群大小则由模型的参数决定。     

木垒草原兔尾鼠数量下降期种群结构变化

2000年9月至2001年9月在新疆木垒县分4个时段采用样方法对草原兔尾鼠(Lagurus lagurus)进行野外调查,实验室采用数学生态学方法研究草原兔尾鼠的种群年龄结构和繁殖结构变化。结果表明,随着草原兔尾鼠数量的下降,种群的年龄结构和繁殖结构都发生了明显的变化。     

塔里木兔种群遗传结构的初步探讨

塔里木兔作为中国特有种, 其种群遗传结构直到现在还未知。我们从采自于新疆维吾尔自治区3 个种群的25 号样品中扩增得到529 bp 线粒体DNA 控制区片段, 共发现存在76 个多态性位点。全部样品中定义了19 个单倍型, 每个种群都显示了很高的单倍型多态性。进一步分析表明, 3 个种群存在明显的遗传分化和较低的基因流。通过错配分布和Fu’s 中性检验分析发现, 阿克苏(AKS) , 若羌(RQ) 和疏勒(SL) 种群相对比较稳定。     

应用红外相机监测结果估计小型啮齿类物种的种群密度

红外相机(或称相机陷阱)技术可以提供物种组成、种群数量和行为等信息,广泛应用于野生动物的监测与管理。对于可以个体识别的物种,红外相机结合标志重捕法可准确估计其种群密度。但对于不可个体识别的动物,目前尚无成熟方法来估计其种群密度。建立了一个新方法,通过模拟个体运动并匹配红外相机监测数据来估计动物的种群密度。在长白山国家级自然保护区25hm2森林动态监测样地中,以每公顷一台的密度布设红外相机,调查小型啮齿动物的种群数量。在2011年和2012年冬季分别监测41d和40d。然后,设计模型模拟不同密度下啮齿类物种的运动过程,同时记录它们在25hm2的区域内被25台相机拍摄的次数。应用随机森林算法建立回归模型来匹配模拟结果与监测结果,估计啮齿类物种在样地内的密度及其置信区间。这是一种全新的利用红外相机监测数据估计种群密度的方法,可以填补对不可个体识别物种密度估计方法的空缺。     

四川藏鼠兔头骨形态的种群分化

种群分化是物种形成过程中具有决定意义的一步,是研究微进化过程的核心内容.为探讨地理隔离对小型兽类种群分化的影响,本文系统比较了四川西部3个隔离藏鼠兔Ochotona thibetana种群在头骨形态上的异同.结果表明在所测量的19个头骨形态指标中,岷山与邛崃山、邛崃山与凉山、岷山与凉山的藏鼠兔种群已分别在9、14及4个头骨变量上存在明显差异,颧宽、眶间宽、鼻骨长等变量是导致该3个山系藏鼠兔种群头骨形态发生分化的主要变量.由于藏鼠兔在各山系内部属一较为常见的物种,分析认为其头骨形态的种群分化可能与隔离状态下局部环境差异导致的选择压力不同有关.本研究揭示了在进行藏鼠兔等小型兽类种及种下阶元划分时,除数理统计手段引入的必要外,尚应充分考虑不同地理区域种群可能已产生的局部分化.     

大中型兽类种群数量估算的研究进展

大中型兽类种群数量的估算是动物生态学中重要的基本问题, 受到研究者、管理者和公众的共同关注。国际上从20世纪中期开始研究该问题, 已出现了多种研究方法和相应案例, 且还在快速发展, 但世界各地仍有很多物种的种群数量尚未知晓。在我国, 从20世纪80年代开始调查大中型兽类种群数量, 取得了重要进展, 也还有很多物种的种群数量尚不清楚。因此, 有必要归纳国际上种群数量估算的研究进展, 同时, 总结国内研究的现状、优势和趋势, 供研究者参考。本文首先选择估算大中型兽类种群数量的原理、数据来源和模型这3个要素归纳出简明的研究框架, 将现有的多种方法置于其中予以阐述。在该框架下, 根据估算原理分为4大类方法, 为距离取样法、标志重捕法、基于遇见率法和遥感影像直接计数法。针对每一大类方法, 论述其基本原理模型和模型假设, 说明能实现该原理的相应数据来源(视觉观测、红外相机拍摄、DNA微卫星识别、卫星定位跟踪、声音监测或遥感影像)的特点及如何实现该原理, 评价其适用性及优缺点, 并选择其中具有可比性的方法予以比较评价。其次, 参照该研究框架, 总结我国的研究现状, 分析未来发展的优势和趋势: 我国的红外相机数据积累充分, 可以发展以此为数据源的距离取样法、标志重捕法和基于遇见率法; 发展以粪便样品为数据来源的距离取样法和粪便DNA标志重捕法; 相比地面调查数据, 获取高分辨率遥感影像数据更容易, 尽量以此估算符合适用条件的大中型兽类的种群数量。最后, 本文提出了适用于我国大中型兽类种群数量的估算方法的选择流程, 供研究者参考。     

稻飞虱迁入初期成虫种群密度的零频率估计方法

为了在一定精度保证的前提下,简便、快捷地估计稻飞虱迁入初期成虫田间发生情况,本文基于稻飞虱成虫种群发生的田间调查数据,用种群密度m和零频率p0分别拟合Gerrard-Chiang模型、线性函数、二次函数、指数函数、幂函数和对数函数6种不同模型。结果表明,以Gerrard-Chiang模型m=1.2467（—ln p0）1.0721为最优,用其可根据零频率有效地估计稻飞虱迁入初期成虫种群密度。还确定了稻飞虱成虫不同零频率下的理论抽样数,同时进行了具体应用。     

不同烟草品种上节肢动物种群数量动态的研究

１９９８年５～７月对合肥郊区自然状态下Ｎｃ８９、Ｎｃ８２和Ｋ３２６烟草生产品种上重要节肢动物种群数量消长规律进行了系统研究．结果表明,烟田重要蜘蛛类天敌是皿蛛、狼蛛、球蛛、肖蛸蛛、蟹蛛、跳蛛和管巢蛛等,重要昆虫类天敌是烟蚜茧峰（Ａｐｈｉｄｉｕｓｇｉｆｕｅｎｓｉｓ）、瓢虫、隐翅甲、步甲、大灰食蚜蝇（Ｓｙｒｐｈａｓｃｏｒａｌａｅ）和小花蝽（Ｏｒｉｕｓｍｉｕｔｕｓ）等,重要害虫是烟蚜（Ｍｙｚｕｓｐｅｒｓｉｃａｅ）、烟青虫（Ｈｅｌｉｏｔｈｉｓａｓｕｌｔａ）、斑须蝽（Ｄｏｌｙｃｏｒｉｓｂａｃａｒｕｍ）和油葫芦（Ｇｒｙｌｕｓｔｅｓｔａｃｅｕｓ）等．烟蚜种群数量消长有两个明显的峰值,分别出现在５月１６日和６月１３～２１日前后．文中对烟蚜种群数量动态模型,烟蚜和草间小黑蛛（Ｅｒｉｇｏｎｉｄｉｕｍｇｒａｍｉｎｉｃｏｌａ）种群相互作用做了分析．烟蚜茧蜂种群平均数量Ｎｃ８９烟草品种显著高于Ｎｃ８２和Ｋ３２６,主要害虫个体总数平均数量Ｎｃ８９品种显著高于Ｋ３２６,不同烟草品种上的其它节肢动物种群平均数量均无显著差异     

Isolation and characterization of microsatellite loci in the Amami rabbit (Pentalagus furnessi)

We report on the isolation and characterization of eight polymorphic and five monomorphic microsatellites in the Amami rabbit (Pentalagus furnessi). Microsatellite polymorphism was determined using 25 individuals. There were 2–11 alleles for each polymorphic locus with heterozygosity ranging between 0.08 and 0.76. Linkage disequilibrium was not suggested between any pairs among the eight polymorphic loci. We suggest that these primers be used in future studies to monitor population size, determine dispersal patterns, and genetic diversity within and between populations of this and related species.     

The use of block counts,mark-resight and distance sampling to estimate population size of a mountain-dwelling ungulate

Population size estimates represent indispensable tools for many research programs and for conservation or management issues. Mountain ungulates in open areas are often surveyed through ground counts that normally underestimate population size. While the use of sample counts is desirable, few studies have compared different probabilistic approaches to estimate population size in this taxon. We compared the size estimates of a male population of Alpine chamois using mark-resight and line transect sampling methods, while block counts were used to obtain the minimum number of males alive in the study area. Surveys were conducted within the Gran Paradiso National Park (Italy), in August–September 2013, using block counts along purposely selected trails and vantage points, mark-resight over 5 consecutive resightings from vantage points and trails, and line transect sampling along 12 transects repeated 8 times. Block counts yielded a minimum number of males alive in the population of n = 72 individuals. This value was greater than the upper bound of the 95 % confidence interval achieved using line transect sampling {n = 54, CV = 14 % [95 % CI (40, 71)]} while mark-resight yielded a more realistic result of n = 93 individuals {CV = 18 % [95 % CI (63, 137)]}. Our results suggest that line transect sampling performed poorly in the Alpine environment, leading to underestimates of population size, likely due to violations of some assumptions imposed by the rugged nature of the terrain. The mark-resight yielded lower precision, possibly due to the limited number of marked individuals and resighting occasions, but it provided robustness and accurate estimates as marks were evenly distributed among animals.     

A theoretical approach for zone-based management of the deer population on Yakushima Island

The biological balance of Yakushima Island is currently being compromised by overpopulation of sika deer (Cervus nippon yakushimae). We predicted that the island's deer population would continue to grow unless control efforts are raised threefold from their 2012 levels. To identify the best management practice for future implementation, we evaluated and compared the performances of three different zone-based management strategies. Under the current management scenario, the median population size of the sika deer on the island would temporarily decrease, but it would subsequently rebound. Under a scenario that allows management zones to be prioritized according to the occurrence of threatened plant species and deer population size, model simulations suggested that the scenario focusing on the central zone would show the best performance based on the probability of achievement of the management goal (assuming that there is no dispersal between zones). This course of action would lead to a decrease in the median deer population size and would further ensure a high probability of achieving the 2022 target population size across most zones (up to 85 %), even if catch levels were not increased. In a future study, we would need to conduct a more detailed analysis of plants and deer density distributions.     

Effects of exotic mongoose (Herpestes javanicus) on the native fauna of Amami-Oshima Island, southern Japan, estimated by distribution patterns along the historical gradient of mongoose invasion

We examined the distribution patterns of native animals on Amami-Oshima Island, southern Japan, along a historical gradient of mongoose establishment and estimated the effects of mongoose on the native fauna. To assess the relative abundance of various ground-dwelling animals, we used the following four methods; sensor cameras for exotic mammals, nighttime driving census for nocturnal native vertebrates, line census for ground-dwelling lizards, and adhesive traps for arthropods. The results indicated that seven species with larger body size, including mammals, birds, reptiles, and amphibians, were rarely observed in mongoose-infested area. By contrast, medium-sized animals showed neutral relationships with mongoose establishment. Interestingly, the densities of smaller-sized animals were higher in mongoose-infested area. It could be interpreted that smaller species have increased in abundance through top-down cascades, i.e., decreases in native predators such as frogs and lizards caused by the mongoose have resulted in increases in the abundance of smaller animals. Predation pressures by mongoose and native predators may be canceled out for medium-sized animals, causing neutral responses to mongoose by these animals. This study appears to be the first example that shows the influence of mongoose on a wide variety of native animals. In addition, our findings indicate the importance of considering the food web structure of a recipient ecosystem and contribute to the prediction and assessment of ecological risks caused not only by mongoose, but also by other invasive top predators.     

Interactions of target population size,population parameters,and program management on viability of captive populations

When established conservation programs expand and evolve, management practices may become inconsistent with program goals. In the past decade, the American Zoo and Aquarium Association expanded species conservation programs by increasing the number of Species Survival Plans (SSP) and establishing more than 300 new Population Management Plan (PMP) programs. However, limited space in captive breeding facilities forces a competition among SSPs and less intensively managed PMPs. Regional Collection Plans establish priorities and allocate space accordingly by setting target population size for each species; species of high conservation priority (SSPs) are allocated space at the expense of lower priority species (PMPs). Because population size and genetic composition interact to impact population viability, target population size is a significant factor to a population’s prospects for long‐term survival. We examined four population parameters (current population size, target population size, current gene diversity, and mean generation time) for 46 mammalian SSPs and 17 PMPs. Relative to SSPs, PMPs combine smaller current and target population sizes, lower levels of current gene diversity, and shorter mean generation times than SSPs. Thus, the average PMP population can expect to lose gene diversity more rapidly than the average SSP population. PMPs are projected to lose 10% or more of their founding gene diversity, within only 2 years. In contrast, the average SSP population is projected to lose 10% in 40 years. Populations with small current or target population sizes require intensive management to avoid extinction. More intensive genetic management of populations typically designated as PMPs, through recruitment of potential founders and equalization of founder representation, could increase gene diversity and improve viability. Less rigorous population management should be reserved for populations whose long‐term survival is either secure or that can be readily replenished from the wild. Because PMP populations need intense genetic management similar to that currently in effect for SSPs, there should be neither a management‐level distinction between programs nor an arbitrary difference in space allocated to programs. Zoo Biol 20:169–183, 2001. © 2001 Wiley‐Liss, Inc.     

Population census of the chimpanzees in the Kalinzu Forest,Uganda: Comparison between methods with nest counts

The population of chimpanzees in the Kalinzu Forest, Uganda was censused with nest counts using the line-transect method. Four methods were examined to estimate density. The estimated densities, ranging from 2.0 to 4.7 chimpanzees per km², all indicated a high population density, in comparison with other chimpanzee habitats. Moreover, the density in the logged area of the Kalinzu Forest was higher than that in the unlogged area. Several factors are thought to contribute to the high density in the Kalinzu Forest. Notable are the mosaic forest structure dominated by mature forest with patches of logged areas, selective logging of non-food tree species of chimpanzees, and low hunting pressure. These results suggest that selective logging may be a practical means of primate conservation in places where timbers are exploited.     

Effect of the shape of forest fragments on tree population dynamics

A lattice model is used to study the influence of the shape of forest fragments on the augmentation process of a tree population following clear-cutting. Two fragments of different shapes, squarish and linear, were studied without seed immigration from the outside. Both fragments consisted initially of two patches, a 4-ha clear-cut area and a 1-ha remnant forest, mimicking a common forest management regime in Japan. Stochastic simulations using the model reveal several differences in the dynamics and equilibrium structure of the tree population between the fragments. In the squarish fragment, the forest structure reached an equilibrium state in 500–600 years, but the linear fragment took 2100–2400 years. At equilibrium, the proportion of treeless area was significantly larger in the linear fragment than in the squarish fragment. The mean area of gaps was also larger in the linear fragment. The population expansion rate from the remnant forest into the cleared area differed significantly between the two fragments: 0.63 m year^–1 in the squarish fragment, and 0.43 m year^–1 in the linear fragment. These differences are explained as arising from the spatial configuration of seed dispersal: in the linear fragment, the density of seedlings was lower by half than in the squarish fragment, because a greater proportion of seeds produced within the linear fragment were deposited outside the fragment and were lost. However, the density effect (i.e., one-sided competition among trees) mitigates the negative impact of dispersal loss on the adult population density at equilibrium. Forest fragments with linear shapes should be preferred by fugitive light-demanding species in forested landscapes.