陕西黄龙山林区褐马鸡春季夜栖地选择

2006年4～6月,在陕西黄龙山林区,对褐马鸡(Crossoptilon mantchuricum)春季夜栖地的选择进行了研究.共记录到22个夜栖地,以夜栖树为中心做一个10 m×10 m样方,测定夜栖地海拔、坡向、坡度、坡位、地貌特征、夜栖树高度和胸径、乔木层盖度、乔木的数量、灌木层盖度、草本盖度、水源距离、人为干扰距离、林缘距离、栖枝高度和栖位上盖度等参数;通过9条样带测定54个随机样方,除栖枝高度和栖位上盖度外,指标相同.结果表明,褐马鸡春季夜栖地多偏向以坡度较大、山坡和山脊、接近水源、远离林边、人为干扰距离较远、乔木盖度和密度较大、栖树胸径较大、灌木层盖度和草本层盖度较小为主要特征的地方.主成分分析表明,前5个特征值的累积贡献率达到72.746%,可以较好地反映褐马鸡春季夜栖地生境特征.根据载荷系数绝对值大小,将褐马鸡春季夜栖地生境选择影响因子分别命名为地形和林下植被因子、气象因子、稳定性因子和水因子.影响褐马鸡夜栖地选择的关键因素是安全、舒适和栖息地转换的方便程度.     

红喉雉鹑繁殖季的夜栖行为与夜栖地选择

红喉雉鹑（Tetraophasisobscurus）是中国特有种,国家一级重点保护野生动物,研究其繁殖季的夜栖地选择,能丰富该物种的基础资料,理解其生存策略,为该物种的保护和深入研究提供科学依据。2021年和2022年的3～7月,采用跟踪观察和系统搜索法,对四川王朗国家级自然保护区繁殖期红喉雉鹑的夜栖行为和夜栖地选择进行了调查,共记录夜栖地样方34个。采用卡方检验、配对样本T检验、Mann-WhitneyU检验和逻辑斯蒂回归模型方法对数据进行分析。红喉雉鹑主要夜栖于方枝柏（Sabina saltuaria）等针叶树,常见1只单独夜栖或2只共同夜栖,未见有集群夜栖;夜栖树通常位于上坡位,距离林缘和最近乔木较近,具有较大的胸径和郁闭度,栖枝距离地面高度6.6 m左右,栖枝长度约1.66m;夜栖地具有较大的坡度和落叶盖度,而灌木盖度较小。安全因素（夜栖树胸径、坡度）和食物因素（落叶盖度）是红喉雉鹑选择夜栖地的最关键因素。     

白腹锦鸡(Chrysolophus amherstiae)的夜栖地选择

2005年4月～2006年9月,结合无线电遥测技术,采用系统搜索法和繁殖期跟踪法对四川石棉县栗子坪自然保护区白腹锦鸡的夜栖地选择进行了研究。共发现24个夜栖地。以夜栖树为中心做r=7.5m大样方,随机在其中做4个1m×1m和4个0.5m×0.5m小样方,测量乔木、灌木和草本植物的各项参数;做128个非活动区对照样方和258个日栖地样方,分别随机选取等量样方与夜栖地样方相比较。结果表明:白腹锦鸡夜栖地多在针阔混交林和针叶林中,栖树以针叶树为主,繁殖期内成对个体同树共栖的栖位距离较近,栖枝雄高雌低。影响白腹锦鸡夜栖地选择的主要因素依次为:地形、栖树、隐蔽条件和遮蔽特征。与对照样方相比,白腹锦鸡夜栖地选择较矮而疏的乔木和少量倒木的环境;与日栖地样方相比,选择较矮、疏和较低盖度灌木草本植物的环境,有一定的空间分离。     

广西黑颈长尾雉对夜宿地的选择

2003年12月、2004年5月和12月、2005年4月,通过野外调查及设置样方的方法对广西金钟山鸟类保护区黑颈长尾雉的夜宿地选择进行了研究。共记录到12个夜宿地,以夜宿树为中心做一个10m×10m和5个1m×1m的样方,记录夜宿树特征(种类、胸径、栖枝高度、栖枝直径、栖枝上方盖度),测量每个样方的11个生境因子(海拔、林型、坡向、坡度、乔木层盖度、灌木层盖度、草本层盖度、距水源距离、距林缘距离、距道路距离和乔木密度);并随机设10个对照点,测量相同的生境因子。结果表明,黑颈长尾雉夜宿地主要位于阔叶林中,一般,夜间在乔木上休息,一树栖息一只,也有2—3只同宿一树。黑颈长尾雉选择有一定坡度、林下灌木和草本较少以及在森林内部远离林缘并且乔木密度较大的地方作为夜宿地,其夜栖树主要为生境内的中等大小的阔叶树,栖枝直径约为2·5—4cm,栖处高度为2—5m,黑颈长尾雉夜宿地的选择与距水源距离的远近无关。影响黑颈长尾雉夜宿地选择的因素依次为:位置及林下植被、栖枝、天气。影响黑颈长尾雉夜宿地选择的最终原因可能是安全、舒适和栖息地转换的方便程度。     

四川雉鹑的冬季夜栖地选择

四川雉鹑(Tetraophasis szechenyii)是中国特有物种,国家Ⅰ级重点保护野生动物,对其冬季夜栖地选择的了解,有助于理解物种的生存策略,为物种保护提供参考。利用徒步跟踪和无线电遥测的方法,我们于2006年9月到2007年4月在四川省雅江县帕姆岭进行了野外研究。采用卡方检验、配对样本t检验和二元逻辑斯缔回归等方法对数据进行分析。结果发现:(1)四川雉鹑利用鳞皮冷杉(Abies squamata)和大果红杉(Larix potaninii var.macrocarpa)两种树夜栖,卡方检验分析发现四川雉鹑对这两树种没有明显的选择偏好(χ2=0.745,df=1,P=0.388);(2)夜栖树的胸径为(25.8±1.3)cm,夜栖枝条离地高度为(6.3±0.3)m,直径为(3.3±0.1)cm;(3)与对照样地相比,夜栖地生境一般靠近林缘,乔木的平均胸径大、林下盖度小、倒木数量多,夜栖树胸径大、最近乔木胸径大和最近乔木距离远;(4)逻辑斯缔回归分析表明:夜栖树第一枝距地面高为冬季四川雉鹑夜栖地选择的关键因子;倒木数量、平均乔木胸径、最近林缘距离为次关键因子,该模型对夜栖地的预测正确率为80.9%。冬季四川雉鹑选择夜栖地是安全、能量和地点转移三个因素综合作用的结果,在不同的环境下,同一物种对环境会有不同的适应策略。     

广西黑颈长尾雉对夜宿地的选择

2003年12月、2004年5月和12月、2005年4月，通过野外调查及设置样方的方法对广西金钟山鸟类保护区黑颈长尾雉的夜宿地选择进行了研究。共记录到12个夜宿地，以夜宿树为中心做一个10 m×10 m和5个1 m×1 m的样方,记录夜宿树特征(种类、胸径、栖枝高度、栖枝直径、栖枝上方盖度)，测量每个样方的11个生境因子(海拔、林型、坡向、坡度、乔木层盖度、灌木层盖度、草本层盖度、距水源距离、距林缘距离、距道路距离和乔木密度)；并随机设10个对照点，测量相同的生境因子。结果表明，黑颈长尾雉夜宿地主要位于阔叶林中，一般，夜间在乔木上休息，一树栖息一只，也有2—3只同宿一树。黑颈长尾雉选择有一定坡度、林下灌木和草本较少以及在森林内部远离林缘并且乔木密度较大的地方作为夜宿地，其夜栖树主要为生境内的中等大小的阔叶树，栖枝直径约为2.5—4 cm，栖处高度为2—5 m，黑颈长尾雉夜宿地的选择与距水源距离的远近无关。影响黑颈长尾雉夜宿地选择的因素依次为：位置及林下植被、栖枝、天气。影响黑颈长尾雉夜宿地选择的最终原因可能是安全、舒适和栖息地转换的方便程度。     

再引入黑颈长尾雉夜栖行为与夜栖地选择

2003年4月～2005年3月,通过野外观察、无线电遥测和样方调查,对广西岑王老山自然保护区再引入黑颈长尾雉的夜柄行为和夜柄地进行了研究.共观察记录到10个夜栖地,黑颈长尾雉夜间主要在树上栖息,偶尔在地上柄息,在针叶林为独栖(1只/树),在阔叶林独柄或者2～3只/树.黑颈长尾雉夜柄地选择受到柄树的高度、大小,灌术、乔木、草本层的盖度,水源距离及栖枝高度等因素的影响.黑颈长尾雉夜栖地的栖树具有一定的高度(雌:4.96±1.39 m,雄:5.52±1.95 m)和胸围大小(雌:21.4±8.29 cm,雄:23.50±8.39 cm);乔木层(78.00%±8.23%)和灌木层(44.50%±29.67%)盖度较大,草本层盖度较低的环境作为夜栖地;与水源具有一定的距离(348.50±308.30)m;夜栖地的坡度(44.80.±14.73.)和栖枝的高度(2.40±0.74 m).     

冬季白马鸡群体夜栖地特征分析

20 0 3年 1～ 4月 ,对分布于四川省甘孜藏族自治州稻城县著杰寺周围的白马鸡 (Crossoptiloncrossoptilon)群体的夜栖地特征进行了分析。随机跟踪黄昏时发现的白马鸡群体直至其上树夜栖来确定夜栖地的位置。通过系统取样的样线法调查整个研究区域环境变量的特征。共获得 1 72个 2 0 0m×2 0 0m的栅格 ,栅格中有夜栖地出现的定义为活动栅格 (37个 ) ,赋值为 1 ;反之为非活动栅格 (1 35个 ) ,赋值为 0。通过逻辑斯蒂回归建立白马鸡群体夜栖地选择的预测模型。该模型的数学表达式为Ln[P/(1 -P) ]=- 3 938+0 0 83×坡度 +0 0 37×乔木盖度 +0 1 1 6×乔木高度 - 0 0 0 3×草本盖度 (P为白马鸡群体夜栖地的出现概率 )。模型表明坡度、乔木盖度、乔木高度和草本盖度显著影响白马鸡群体的夜栖地选择。白马鸡群体的夜栖地选择与坡度、乔木盖度和乔木高度正相关 ,与草本盖度负相关。该预测模型具有较高的预测准确性。     

海南原鸡繁殖期夜栖地的选择

原鸡Gallus gallus在繁殖期的日常活动趋向于以夜栖地为中心,因此夜栖地的研究对原鸡的繁殖和保育具有重要意义.2008年2～5月在海南大田自然保护区,采用野外观察和样方调查相结合的方法,对原鸡的夜栖地利用进行了研究,共记录到15个夜栖地.结果表明: 1) 原鸡在繁殖期多结成2～6只(3.3±1.5, n=13)的繁殖群,在同一棵树或邻近几棵树上集群夜栖; 2) 落叶季雨林和灌丛草地是原鸡繁殖期夜栖的主要植被类型; 3)原鸡多以小刺竹Bambusa bambos作为夜栖树,占53.3%,其次是厚皮树Lannea coromandelica,占20.0%; 4)原鸡倾向于选择灌木生长茂密、地面草本稀疏的生境作为夜栖地,并栖息在胸径均值为8.4 cm±3.5 cm的乔木或灌木的枝条上,栖枝均高为4.4 m±0.8 m; 5)主成分分析表明,影响原鸡夜栖地选择的主要因子依次为:栖树高、栖枝高度、栖树胸径、栖枝层盖度、草本层盖度、栖枝下方盖度和栖枝上方盖度.据此分析认为:繁殖期原鸡警惕性高,夜栖地多选择易于隐蔽和转移的生境.     

基于红外相机数据的贵州高原山地环境野猪生境选择研究

近年来野猪(Sus scrofa)在我国南方山地森林生态系统中种群数量激增、生态影响强烈,是人兽冲突的典型代表,然而对其生境选择规律仍缺乏深入研究。利用2015年7月至2020年1月的长时红外相机监测数据,对贵州高原几处环境中野猪的生境选择进行了研究,共得到野猪利用样方201个,非利用样方121个。(1)Vanderploeg和Scavia选择指数分析表明,野猪喜爱活动于坡度≤20°、乔木郁闭度>0.8和草本盖度为0.2—0.4的生境类型;不喜爱的生境类型为海拔>1600 m,坡度>25°,草本盖度<0.1,距道路距离≤100 m。(2)野猪生境资源选择函数为Logit(P)=3.226-海拔×0.002-坡度×0.161+乔木郁闭度×2.078+灌木平均高×0.401+草本盖度×3.566+距道路距离×0.001+距居民点距离×0.0003,选择概率为P=e⁽logit(p))/(1+e⁽logit(p))),受试者工作特征曲线(ROC)评估模型的预测精度为87.8%,能够较好预测野猪的生境选择。(3)利用Mann-...     

Selection with Partial Selfing. I. Mass Selection

The expected responses to mass selection carried out before or after reproduction in a population whose members all have a fixed probability of self pollination (s) are formulated using covariances of relatives and their component quadratic functions for a model with arbitrary additive and dominance effects. The response measured in the first generation offspring after selection (immediate gain) can differ from that retained when the population has regained equilibrium (permanent gain). The population mean behaves in a predictable manner during the return to equilibrium, and its value at any time can be predicted from earlier generations. The permanent gain from selection after reproduction is always (1 + s)/2 times as large as that from selection before reproduction, but the relationship of the immediate gains depends on the genetic model assumed. Numerical analysis applied to a model with two alleles per locus and varying allele frequencies, dominance ratios and numbers of loci showed that the proportion of the immediate gain retained at equilibrium was reduced with the large inbreeding depression associated with increasing dominance levels and numbers of loci and was generally lower for selection after reproduction than before. In the absence of information as to the magnitude of genetic variances and inbreeding depression in species reproducing by partial selfing, the importance of this phenomenon is unknown.     

Interaction between Natural Selection for Heterozygotes and Directional Selection

Significant correlations between allelic frequencies and environmental variables in a number of insect species have been demonstrated by multivariate techniques. Since many environmental variables show a strong relationship to geographic location and since gene flow between populations can also produce patterns of gene frequencies which are related to the geographic location, both selection and gene-flow hypotheses are consistent with the observed correlations. The genetic variables can be corrected for geographic location and so for linear gene-flow patterns. If, after correction, the genetic variables still show significant correlations with similarly corrected environmental variables, then these correlations are consistent with hypotheses of selection but not of gene flow. The data of Johnson and Schaffer (1973) have been reanalyzed using the method of canonical correlation after correction for geographical location by means of multiple regression. Five of the nine loci studied exhibit significant canonical correlations. These results, under the assumption of linear gene flow, support hypotheses of selective action of environmental variables in the genotype-environment relationships observed.     

Determination of the Selection Capacity of Antibiotics for Gene Selection

Choosing a potent selection antibiotic (SA), is a crucial success factor when creating stably transfected cell lines using an antibiotic selection marker. The selection capacity of this antibiotic is defined as its ability to kill sensitive, untransfected parental cells, while leaving resistant, transfected cells unharmed. Currently, no procedure has been described to determine this selection capacity. Therefore, a protocol to obtain a numerical value, called the “selectivity factor” (SF), that defines the selection capacity of SAs is developed. The SF is determined by using a modified MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐diphenyltetrazolium bromide) assay for both sensitive and resistant cells, and applies to commonly used cell lines. To prove the concept, the SF of the SA G418 and hygromycin B (HmB) on several cell lines is determined. The SF of G418 on BHK‐21 cells is very high, indicating that G418 is an ideal SA for transfected BHK‐21 cells. For HeLa cells, the SF of G418 is very low suggesting G418 is not an optimal SA for selecting transfected HeLa cells. For these cells, HmB would be a better choice. These conclusions are confirmed by an independent cell death assay. The SF identifies the most optimal SA for a certain cell line, reduces the risk of selecting spontaneously resistant cell clones, and streamlines the process of generating stable cell lines. Most importantly, the method is especially time saving when obtaining stable cell lines expressing toxic genes, and reduces culture times for generating large numbers of cell lines from the same parental cell line.     

Simultaneous Selection of Extreme Populations: A Subset Selection Approach

The problem of selecting a “best” (largest mean, or smallest mean) population from a collection of k independent populations was formulated and solved by Bechhofer (1954). Gupta (1965) solved another important problem, that of selecting a subset of populations containing the “best” population from the original collection of populations. Since then many variations of the problem have been considered. Tong (1969) and Lewis (1980) have investigated the problem of selecting extreme populations (populations with a largest, and populations with a smallest, mean) with respect to one and two standard populations, respectively. In this paper we study the selection of extreme populations in absence of any standard population. We formulate subset-selection procedures when variances are known and equal, and also in the most general case when they are unknown and unequal. Nonexistence of a single-stage procedure is noted for this latter case (even if variances are equal). A two-stage procedure and some of its associated properties are discussed. Tables needed for application are provided, as is a worked example.     

Positive Selection Vectors

ABSTRACT:?

This review describes information concerning positive selection vectors on their mechanism, classification, property, and limitation. A total of 72 positive selection vectors collected were discussed. Positive selection vectors can reduce background and directly screen transformants containing cloned DNA fragments. The mechanisms to perform positive selection include insertional inacti-vation and the replacement of functional genes of the vectors. In general, the former is much more convenient than the latter. The functional genes are controlled either by their promoters or by heter-ologous promoters introduced. On the basis of the structures, positive selection vectors could be classified into five groups. The positive selection vectors are commonly based on the mechanisms of lethal genes and the sensitivity of compounds. The vectors, with molecular weights ranging from 2.6 to 17.0?kb, have diverse genetic markers and wide host ranges, including Escherichia coli, Bacillus, Streptomyces, lactic acid bacteria, yeasts, and mammalian cells. Although some limitations exist for using some positive selection vectors, they are useful in recombinant DNA experiments.     

The Units of Selection Revisited: The Modules of Selection

Richard Lewontin's (1970) early work on the units of selection initiated the conceptual and theoretical investigations that have led to the hierarchical perspective on selection that has reached near consensus status today. This paper explores other aspects of his work, work on what he termed continuity and quasi-independence, that connect to contemporary explorations of modularity in development and evolution. I characterize such modules and argue that they are the true units of selection in that they are what evolution by natural selection individuates, selects among, and transforms.     

Selection and sticklebacks

Over the last decade, there has been increasing circumstantial evidence for the action of natural selection in the genome, arising largely from molecular genetic surveys of large numbers of markers. In nonmodel organisms without densely mapped markers, a frequently used method is to identify loci that have unusually high or low levels of genetic differentiation, or low genetic diversity relative to other populations. The paper by Mäkinen et al. (2008a) in this issue of Molecular Ecology reports the results of a survey of microsatellite allele frequencies at more than 100 loci in seven populations of the three‐spined stickleback (Gasterosteus aculeatus). They show that a microsatellite locus and two indel markers located within the intron of the Eda gene, known to control the number of lateral plates in the stickleback ( Fig. 1 ), tend to be much more highly genetically differentiated than other loci, a finding that is consistent with the action of local selection. They identify a further two independent candidates for local selection, and, most intriguingly, they further suggest that up to 15% of their loci may provide evidence of balancing selection.

Figure 1 Open in figure viewer PowerPoint Three‐spined stickleback (Gasterosteus aculeatus).     

Selection index updating

Summary When traits become evident at different ages or there are large differences in the costs of measuring various traits, selection by independent culling levels may give a higher aggregate economic return than index selection because not all traits need to be measured on all individuals. The problems with optimum independent culling selection is that general solutions are not possible and numerical integration is needed for specific cases. Recently, Xu and Muir (1991) developed a new independent culling level procedure by use of orthogonal transformation of the original characters. With their procedure, explicit solutions for optimum truncation points are possible without numerical integration. As such, the procedure is proficient for any number of stages, and generalized theoretical comparisons of alternative breeding strategies are possible. However, their procedure was limited to the case where selection is for one character at each stage. In this paper, our previous results are extended to the general case of multi-stage index selection, called selection index updating. This procedure is called selection index updating because as traits become available in latter stages, each subsequent index contains all of the traits available up to that stage.The procedure is to develop sequential indices for each stage such that correlations among indices at different stages are zero. Optimum culling points are obtained for the updating procedure by using Xu and Muir's (1991) iterative equations. Due to the property of orthogonality of the updated indices, aggregate gain can be partitioned into gains due to various stages of selection. Partitioning of aggregate economic gain is useful to breeders who desire to adjust individual trait selection intensity based on facilities available at that stage. Methods are discussed to modify the procedure to obtain maximum aggregate economic return per unit of cost associated with obtaining measures on each trait. An application of multi-stage selection is demonstrated using a set of data for Rhode Island Red layer type chickens. A second example demonstrates the use of multi-stage selection optimized with respect to aggregate economic gain and costs associated with obtaining measurements.Journal Paper No. 12813 of the Purdue University Agricultural Experiment Station