Evolution of clutch size in birds: adaptive variation in relation to territory quality

Reproductive output from enlarged or reduced magpie broods showed that each female generally lays a clutch of optimal size. This size varies considerably between females. Approximately 85 percent of the within-years variation in clutch size was associated with differences between territories. Colonial bird species, lacking individual foraging territories, have a smaller clutch size variation than territorial species.     

Nest parasitism, productivity, and clutch size in purple martins

Mean maximum nestling weight of purple martins decreased with increase in brood size from three to five. Martins in the absence of acarine nest parasites produced young heavier than parasitized young of the same brood size; in addition, unparasitized nestlings tended to reach a maximum weight equivalent to that of young in parasitized broods of one less member. Modal brood size for parasitized and unparasitized martins was four, but there was a significant trend toward production of broods of five by mite-free birds, and of broods of three by parasitized parents. This suggests a potentially important role for nest parasitism in the determination of clutch size in martins and other birds.     

黄喉拟水龟母体大小对繁殖性能的影响

对黄喉拟水龟Mauremys mutica同一种群中3种规格（小型个体783.0 g±55.2 g、中型个体991.3 g±62.3 g和大型个体1248.5 g±122.9 g）母体的繁殖性能进行了研究。结果表明：在繁殖季节,不同规格母体的月产卵量差异较明显,其中小型母体在产卵期首月和末月产卵量所占比例相对较高;3种规格母体的平均产卵量、受精率和孵化率与母体的大小呈正相关,平均窝数与母体大小则呈负相关;窝卵数、卵重、卵宽也与母体规格呈正相关,其中窝卵数的差异极显著（P〈0.001）。在代表卵形状的卵长径与短径比值中,小规格母体产的卵略长,但差异不显著;大规格母体产的稚龟则显著大于小规格母体产的稚龟（P〈0.05）。本研究结果表明,以大规格母体作为繁殖亲本,可以获得更多的后代。     

Clutch size in birds: outcome of opposing predator and prey adaptations

A model is proposed to explain clutch size in birds as the outcome of the interaction between predatory adaptations of birds to increase their feeding efficiency and adaptations of their food resources to avoid predation. Variations in clutch size are consistent with the model. A modification that incorporates the seasonality of food resources is also discussed.     

长江师范学院校园白鹡鸰的生境分布和繁殖习性研究

2008年3～6月,对长江师范学院校园白鹅鸽的生境分布和繁殖习性进行了初步研究。研究结果表明,白鹤鸽主要分布在地面草丛（57．41％）、水域（19．44％）、楼顶（16．67％）和疏林灌丛（6．48％）,地面草丛成为白鹤鸽的最主要取食地;白鹩鸽的常见窝卵数为4枚,窝卵数为（4．00±0．32）枚,孵化期为（10．20±0．37）d,出雏数为（3．60±0．25）只,育雏期为（13．60±0．51）d;窝卵数与孵化期呈显著正相关（P=0．034,R^2=0．757）,两者呈幂函数关系,窝卵数与出雏数和育雏期相关性均不显著（P=0．166,P=0．550）;白鹤鸽对校园生境表现出极强的适应性。     

Proximate constraints on the evolution of egg size, number, and total clutch mass in lizards

Proximate constraints on egg size, number, and total clutch mass in side-blotched lizards were examined by experimentally reducing average clutch size from 4.6 eggs to one, two, and three eggs. Eggs from experimentally altered clutches were larger than those from controls, reflecting the trade-off between egg size and number. Moreover, the increased frequency of females with oviducally bound eggs or eggs that burst at oviposition suggests that egg size in clutches with very few eggs are at a functional upper size limit. These proximate constraints may also limit evolution of egg size in another group of lizards (Anolis) that only produces one-egged clutches.     

人工巢箱条件下大山雀的窝卵数与繁殖成功的关系

2004—2006年,利用人工巢箱在吉林省左家自然保护区次生林中对大山雀（Parus major）的窝卵数与繁殖成功的关系开展了研究。研究表明：大山雀对人工巢箱的利用率逐年减少,年份间差异显著（P〈0．05）。营巢成功率为74．3％,营巢失败的主要原因是人为破坏和天敌占用。大山雀的窝卵数为6—14枚,平均10．2枚,常见窝卵数为10—12枚,卵质量平均为（1．47±0．12）g,卵大小平均为16．5min×12．9min。孵化期平均为（13．8±1．4）d,平均出雏率为（88．4±1．3）％,育雏期平均为（17．3±0．9）d,平均出飞率为（78．1±2．0）％。大山雀窝卵数与孵化期、出雏率、育雏期和出飞率显著正相关.大山雀繁殖成功率逐年增加,不同年份间繁殖成功率差异极显著（P〈0．01）,窝卵数与繁殖成功率无明显相关性。     

Evidence for recent groundwater seepage and surface runoff on Mars

Relatively young landforms on Mars, seen in high-resolution images acquired by the Mars Global Surveyor Mars Orbiter Camera since March 1999, suggest the presence of sources of liquid water at shallow depths beneath the martian surface. Found at middle and high martian latitudes (particularly in the southern hemisphere), gullies within the walls of a very small number of impact craters, south polar pits, and two of the larger martian valleys display geomorphic features that can be explained by processes associated with groundwater seepage and surface runoff. The relative youth of the landforms is indicated by the superposition of the gullies on otherwise geologically young surfaces and by the absence of superimposed landforms or cross-cutting features, including impact craters, small polygons, and eolian dunes. The limited size and geographic distribution of the features argue for constrained source reservoirs.     

黄苇鳽筑巢、产卵、孵化及雏鸟生长的初步研究

对云龙湖黄苇鳽(Ixobrychus sinensis)的筑巢、产卵、孵化进行了研究,并测定了黄苇鳽雏鸟阶段的几个生长指标。结果表明,黄苇鳽的筑巢期从5月下旬至6月下旬,巢用水烛叶织,并营建于水烛丛中上部;巢底距离水面1.16±0.29 m,巢-岸距离10.7±3.87 m,巢-敞水区距离2.25±1.01 m;同域巢间距平均为37.5 m;巢深4.0±0.9 cm,巢内面积161.1±48.1 cm~2;窝卵数4.6±0.9个,卵体积6.75±0.51 cm~3,卵重9.41±0.73 g;窝卵数与总卵重呈正相关,窝卵数与巢内面积相关性不显著,窝总卵重与巢内面积相关性也不显著;孵化期为15~18 d,孵化率约为82%;各项形体指标随发育日龄而增长,其中翅长增长较快。     

Evidence for DNA loss as a determinant of genome size

Eukaryotic genome sizes range over five orders of magnitude. This variation cannot be explained by differences in organismic complexity (the C value paradox). To test the hypothesis that some variation in genome size can be attributed to differences in the patterns of insertion and deletion (indel) mutations among organisms, this study examines the indel spectrum in Laupala crickets, which have a genome size 11 times larger than that of Drosophila. Consistent with the hypothesis, DNA loss is more than 40 times slower in Laupala than in Drosophila.     

黑水鸡营巢、产卵、孵化及雏鸟生长的初步研究

在江苏省徐州市云龙湖观察了黑水鸡(Gallinula chloropus L.)的营巢、产卵、孵化过程,测定了黑水鸡雏鸟阶段的几个生长指标。结果表明,黑水鸡的营巢期从5月初至5月末,巢营建于芦苇[Phragmites australis(Cav.)Trin.ex Steud.]和水烛(Typha angustifolia L.)丛下部,并以芦苇和水烛茎叶织巢;巢底距离水面(10.7±5.4)cm,巢-岸距离(7.38±2.18)m,巢-敞水区距离(2.58±2.13)m;巢密度为0.25~0.40个/100 m~2;巢深(5.5±1.3)cm,巢内面积(241.4±79.6)cm~2;窝卵数(8.9±3.1)个,卵体积(20.15±2.57)cm~3,卵重(20.72±2.46)g;窝卵数与巢内面积呈正相关(r=0.678 5),窝卵数与总卵重呈正相关(r=0.941 8);孵化期为20~21 d,孵化率大于90%;各项形体指标随发育日龄而增长,其中体重增幅逐渐大于体长。由此对黑水鸡栖息地的管理和保护提出了建议。     

Anatomy and dynamics of a supramolecular membrane protein cluster

Most plasmalemmal proteins organize in submicrometer-sized clusters whose architecture and dynamics are still enigmatic. With syntaxin 1 as an example, we applied a combination of far-field optical nanoscopy, biochemistry, fluorescence recovery after photobleaching (FRAP) analysis, and simulations to show that clustering can be explained by self-organization based on simple physical principles. On average, the syntaxin clusters exhibit a diameter of 50 to 60 nanometers and contain 75 densely crowded syntaxins that dynamically exchange with freely diffusing molecules. Self-association depends on weak homophilic protein-protein interactions. Simulations suggest that clustering immobilizes and conformationally constrains the molecules. Moreover, a balance between self-association and crowding-induced steric repulsions is sufficient to explain both the size and dynamics of syntaxin clusters and likely of many oligomerizing membrane proteins that form supramolecular structures.     

Abiotic forcing of plankton evolution in the Cenozoic

We characterize the evolutionary radiation of planktic foraminifera by the test size distributions of entire assemblages in more than 500 Cenozoic marine sediment samples, including more than 1 million tests. Calibration of Holocene size patterns with environmental parameters and comparisons with Cenozoic paleoproxy data show a consistently positive correlation between test size and surface-water stratification intensity. We infer that the observed macroevolutionary increase in test size of planktic foraminifera through the Cenozoic was an adaptive response to intensifying surface-water stratification in low latitudes, which was driven by polar cooling.     

枣基因组大小研究

采用流式细胞技术,以4个酸枣类型、9个枣品种的新鲜幼嫩叶片为材料,以Otto为解离液,日本晴（Oryza sativa ssp.japonica cv.Nipponbare）为外标,测定其基因组大小（2C值）,比较枣和酸枣的2C值差异。结果表明,枣的基因组大小为(360.70±4.73)Mb,小于酸枣的基因组（388.20±8.32 Mb）;枣品种间基因组大小无显著差异,酸枣类型间差异显著,说明酸枣具有更高的基因组变异,且酸枣到枣的进化中可能伴随着基因组的缩减。     

Preliminary results of the pioneer venus small probe net flux radiometer experiment

Net radiation measurements in the atmosphere of Venus indicate that the bulk of the atmosphere is radiatively cooling at high latitudes and heating at low latitudes. Similarity of features observed by all three probes indicate planetwide stratification. Flux variations within the clouds provide evidence of significant differences in cloud structure. A feature of unusually large opacity found near 60 kilometers at the north probe site is probably related to the unique circulation regime revealed by ultraviolet and infrared imagery. A stable layer between the cloud bottoms and about 35 kilometers contains several features in the flux profiles probably resulting from large-scale compositional stratifications rather than clouds. In the layer below 35 kilometers unexpectedly large fluxes were observed.     

Corotating variations of cosmic rays near the South heliospheric pole

Three-dimensional simulations of the heliospheric modulation of galactic cosmic ray protons show that corotating variations in the intensity can persist to quite high heliographic latitudes. Variations are seen at latitudes considerably higher than the maximum latitude extension of the heliographic current sheet, in regions where the solar wind velocity and magnetic field show no significant variation. Similar conclusions may apply also to lower energy particles, which may be accelerated at lower latitudes. Cosmic ray variations caused by corotating interaction regions present at low heliographic latitudes can propagate to significantly higher latitudes.     

香猪早期生长性能及生理生化指标测定研究

对本基地一世代和三世代香猪的早期生长性能及生理生化指标进行了测定 ,结果表明 :香猪体型小 ,生长性能稳定 ,生长速度与原产地香猪基本一致 ;两个世代香猪 (4月龄 )的体温、呼吸次数和心率相似 ,也与原产地香猪相近 ,且公、母猪之间差异不显著 (P >0 0 5 ) ;两个世代香猪的血清谷丙转氨酶、血糖、血清钙、血清无机磷、血清总蛋白含量等基本一致。由于香猪体型小、生长性能稳定 ,生理指标和血清生化值与人类相近 ,因而是理想的医学研究用实验动物     

不同移栽方式对水稻产量及效益的影响

[目的]就不同移栽方式对水稻产量及其效益的影响进行分析。[方法]以丹粳253、沈农6014为试材,采用乳苗抛栽、抛秧、插秧、大垄双行水和水直播(对照)5种移栽方式,比较研究了不同移栽方式对水稻群体的产量性状及其效益的影响。[结果]不同纬度地区不同栽培方式产量差异极显著。在沈阳地区,不同栽培方式水稻产量排序依次为插秧>抛秧>乳苗>大垄双行>水直播;在丹东地区,不同栽培方式水稻产量排序依次为大垄双行>抛秧>乳苗>插秧>水直播。乳苗抛栽的产量在不同纬度地区差异很大。丹东地区的乳苗抛栽水稻的产量较沈阳的高3 486.45 kg/hm2。乳苗抛栽平均可比插秧栽培节约1 018.5元/hm2,比抛秧栽培节约726.0元/hm2。[结论]不同栽培方式之间产量差异达到了极显著水平,产量与每公顷穗数、每穗颖花数、成粒率、千粒重的正相关达极显著水平。     

苹果梨授粉柱头数对座果率和果实性状的影响

苹果梨授粉柱头数超过二个时．幼果期果形指数显著增加，有形成大果的基础.随授粉柱头数的增加，座果率增加．种子数增多．单果重有上升趋势，除涂抹四个柱头的和其他的种子数有显著差异外均无显著差异，徐沫柱头组种子数所产生的显著差异，是否由涂抹药剂引起，有待进一步研究证实．苹果梨种子数和单果重及果形间经测验无显著相关关系．     

碟形弹簧的性能优化

变形能是弹簧的一个值得注意的特性。本文以拖拉机离合器碟形弹簧为例,说明这种弹簧优化设计的一般方法。优化结果表明,弹簧在离合器接合和分离过程中的变形能随其结构参数和性能参数有某种变化规律。