Pattern of marine mass extinction near the Permian-Triassic boundary in South China

The Meishan section across the Permian-Triassic boundary in South China is the most thoroughly investigated in the world. A statistical analysis of the occurrences of 162 genera and 333 species confirms a sudden extinction event at 251.4 million years ago, coincident with a dramatic depletion of delta13C(carbonate) and an increase in microspherules.     

Increased longevities of post-Paleozoic marine genera after mass extinctions

Cohorts of marine taxa that originated during recoveries from mass extinctions were commonly more widespread spatially than those originating at other times. Coupled with the recognition of a correlation between the geographic ranges and temporal longevities of marine taxa, this observation predicts that recovery taxa were unusually long-lived geologically. We analyzed this possibility by assessing the longevities of marine genus cohorts that originated in successive substages throughout the Phanerozoic. Results confirm that several mass extinction recovery cohorts were significantly longer lived than other cohorts, but this effect was limited to the post-Paleozoic, suggesting differences in the dynamics of Paleozoic versus post-Paleozoic diversification.     

Deficits in feeding behavior after intraventricular injection of 6-hydroxydopamine in rats

Intraventricular injections of 6-hydroxydopamine produced 95 percent depletion of telencephalic norepinephrine and 62 percent depletion of striatal dopamine in rats. Treated rats maintained body weight at subnormal levels and failed to increase food intake in response to a short-term decrease in glucose utilization. After treatment with the monoamine oxidase inhibitor pargyline, 6-hydroxydopamine produced no further norepinephrine depletion but increased the dopamnine depletion to 95 percent and produced complete aphagia. These effects are comparable to events that follow bilateral electrolytic lesions of the lateral hypothalanmus.     

Mutualism among sessile invertebrates: a mediator of competition and predation

Hydroids of the genus Zanclea are epizoic on encrusting bryozoans. The bryozoans protect these hydroids with skeletal material. Zanclea polyps on the bryozoan Celleporaria brunnea sting small predators and adjacent competitors, helping Celleporaria to survive and to grow over competing species. This mutualism enables the two species to cover a larger area than they could individually.     

Organic carbon fluxes and ecological recovery from the cretaceous-tertiary mass extinction

Differences between the carbon isotopic values of carbonates secreted by planktic and benthic organisms did not recover to stable preextinction levels for more than 3 million years after the Cretaceous-Tertiary mass extinction. These decreased differences may have resulted from a smaller proportion of marine biological production sinking to deep water in the postextinction ocean. Under this hypothesis, marine production may have recovered shortly after the mass extinction, but the structure of the open-ocean ecosystem did not fully recover for more than 3 million years.     

U/Pb zircon geochronology and tempo of the end-permian mass extinction

The mass extinction at the end of the Permian was the most profound in the history of life. Fundamental to understanding its cause is determining the tempo and duration of the extinction. Uranium/lead zircon data from Late Permian and Early Triassic rocks from south China place the Permian-Triassic boundary at 251.4 +/- 0.3 million years ago. Biostratigraphic controls from strata intercalated with ash beds below the boundary indicate that the Changhsingian pulse of the end-Permian extinction, corresponding to the disappearance of about 85 percent of marine species, lasted less than 1 million years. At Meishan, a negative excursion in delta13C at the boundary had a duration of 165,000 years or less, suggesting a catastrophic addition of light carbon.     

Decoupled plant and insect diversity after the end-Cretaceous extinction

Food web recovery from mass extinction is poorly understood. We analyzed insect-feeding damage on 14,999 angiosperm leaves from 14 latest Cretaceous, Paleocene, and early Eocene sites in the western interior United States. Most Paleocene floras have low richness of plants and of insect damage. However, a low-diversity 64.4-million-year-old flora from southeastern Montana shows extremely high insect damage richness, especially of leaf mining, whereas an anomalously diverse 63.8-million-year-old flora from the Denver Basin shows little damage and virtually no specialized feeding. These findings reveal severely unbalanced food webs 1 to 2 million years after the end-Cretaceous extinction 65.5 million years ago.     

Hunting behavior of a marine mammal beneath the antarctic fast Ice

The hunting behavior of a marine mammal was studied beneath the Antarctic fast ice with an animal-borne video system and data recorder. Weddell seals stalked large Antarctic cod and the smaller subice fish Pagothenia borchgrevinki, often with the under-ice surface for backlighting, which implies that vision is important for hunting. They approached to within centimeters of cod without startling the fish. Seals flushed P. borchgrevinki by blowing air into subice crevices or pursued them into the platelet ice. These observations highlight the broad range of insights that are possible with simultaneous recordings of video, audio, three-dimensional dive paths, and locomotor effort.     

珍贵濒危蝴蝶——中华虎凤蝶幼虫的取食行为

中华虎凤蝶五龄幼虫的取食活动是非连续的，且一般无明显的昼夜节律．日取食平均１８．００～２９．４０次，取食间隔１９．００～３０．４０次．日取食次数、取食总时间和一次取食时间一般似随日龄增长而增多或延长，近化蛹时则明显下降；一次取食间隔时间则反之．一次取食时间长短与其前后取食间隔总时间具极显著的相关性．取食时间和取食间隔时间的分布都是聚集的，说明其取食起始与终止是受内在因子调控的     

基于自动饲喂系统的肉鸡采食行为与生产性能的相关性

【目的】研究肉鸡采食行为对生产性能的影响,为鸡饲养管理提供参考依据。【方法】采用由自动饲喂系统收集的45日龄黄羽肉鸡采食行为和生产性能数据,通过统计描述鸡采食行为24 h的变化规律,对鸡群的各个采食行为和生产性能进行相关性分析。【结果】鸡群1 d中存在2个采食高峰,分别是06:00—10:00和17:00—19:00;在采食高峰期前期或末期鸡群的平均单只采食速率更高,最高约为3.0 g·min~(–1);鸡只的单次采食行为(单次采食量、单次采食时长、单次采食速率)与生产性能(日均采食量、平均日增质量、饲料转化率)存在显著相关;鸡只的日均采食次数与平均日增质量存在显著负相关,与饲料转化率存在显著正相关;鸡只日均采食时长与生产性能无显著相关。【结论】鸡的单次采食行为与生产性能之间联系紧密,选育采食次数少的鸡只可提高生产性能。     

Inhibitory and facilitatory effect of two related peptides on extinction of avoidance behavior

The polypeptide chain which constitutes the first ten amino acids of the ACTH molecule inhibits extinction of a shuttle-box avoidance response. If the phenylalanine molecule in the 7th position of this peptide is replaced by its dextrorotatory form, extinction is facilitated.     

A direct and active influence of gravity on the behavior of a marine invertebrate larva

Larvae of the bryozoans Bugula neritina and Bugula stolonifera exhibit an apparent negative geotaxis under conditions of darkness and constant temperature. This behavior cannot be accounted for by buoyancy since the larvae are negatively bouyant, nor is it a consequence of gradients in the partial pressures of dissolved gases since the response occurs under conditions where the gradient is reversed or when experiments are conducted in chambers with interfaces of only glass and water. Pressure bomb experiments indicate that the behavior is not a barokinesis. Centrifuge experiments, however, showed that larvae of Bugula stolonifera orient directly and actively to gravity, while those of Bugula neritina have some other measure of geographic up. Since bryozoan larvae lack statocysts, the sensory apparatus mediating the gravity response in Bugula stolonifera is still unknown.     

基于形状与纹理特征的鱼类摄食状态检测方法

在水产养殖中,检测鱼类的摄食状态对于投喂控制具有重要意义。以镜鲤为实验对象,提出了一种基于鱼群图像的形状及纹理特征和BP神经网络的鱼群摄食行为检测方法。首先,对采集到的图片进行背景减、灰度化、二值化等处理,得到图像形状与纹理信息,然后计算鱼群图像的形状参数和图像熵,最后利用BP神经网络建模,对鱼群的摄食状态进行检测识别。结果显示,本方法的正确识别率达到98.0%。与单一的基于纹理的检测方法相比,不仅可以把因水面抖动、水花等不利因素的干扰作为纹理的特有属性进行分析,而且考虑了图像的形状信息,提高了检测的准确性,可以用于指导水产养殖中的精准投喂控制。     

Striatal nondopaminergic neurons: possible involvement in feeding and drinking behavior

Intracaudate injections of kainic acid destroy striatal neurons containing acetylcholine and gamma-aminobutyric acid but leave dopaminergic nerve terminals in this brain region intact. Rats injected with the drug are aphagic and adipsic, and have other behavioral abnormalities strikingly similar to those seen in animals with lesions in the dopaminergic nigrostriatal bundle.     

葫芦素B对甜菜夜蛾幼虫取食和成虫产卵的影响

测定了葫芦素B对甜菜夜蛾1～3龄幼虫取食和成虫产卵的影响.结果表明,当质量浓度达到16 0 0 μg·mL-1时,葫芦素B对1龄幼虫有拒食作用,并降低其存活率,干扰作用控制指数(IIPC)为0 70 0 ;在相同质量浓度下,葫芦素B抑制成虫产卵,产卵抑制率达5 5 5 % ,IIPC为0 4 4 5 .     

石斛篓象的取食行为与防治研究

石斛篓象成虫有其独特的取食行为习性:喜食叶片柄端(0～1/3)、茎干顶端(2/3～1),成虫一般只从叶的背面取食.应加强石斛苗移栽前的处理以及移栽后的监测和管理;可在石斛篓象幼虫、成虫的盛发期,依据特有的危害症状分别对其进行人工防治;可在石斛篓象成虫产卵高峰期后(1月底)采收3年生及以上石斛植株,从而减少田间虫口基数.化学农药防治成虫时,要重点喷施在叶片背面和茎干顶端.     

Abrupt and gradual extinction among Late Permian land vertebrates in the Karoo basin, South Africa

The Karoo basin of South Africa exposes a succession of Upper Permian to Lower Triassic terrestrial strata containing abundant terrestrial vertebrate fossils. Paleomagnetic/magnetostratigraphic and carbon-isotope data allow sections to be correlated across the basin. With this stratigraphy, the vertebrate fossil data show a gradual extinction in the Upper Permian punctuated by an enhanced extinction pulse at the Permian-Triassic boundary interval, particularly among the dicynodont therapsids, coinciding with negative carbon-isotope anomalies.     

不同种群云斑天牛对寄主取食和产卵的行为差异

【目的】研究不同种群云斑天牛Batocera horsfieldi对寄主植物的适应性。【方法】通过室内取食和产卵试验,测定余姚种群云斑天牛和临安种群云斑天牛对4种寄主植物(黄连木Pistacia chinensis、女贞Ligustrum lucidum、白蜡Fraxinus chinensis和大叶杨Populus lasiocarpa)的取食和产卵行为差异。【结果】取食试验结果显示:余姚种群云斑天牛与临安种群云斑天牛对4种寄主植物表现出不同的取食偏好性。余姚种群取食偏好性从高到低依次为黄连木、女贞、白蜡和大叶杨,余姚种群最喜欢取食黄连木。在选择性条件和无选择性条件下,取食量分别为(1 520.00±34.79)和(1 815.50±42.13) mm²。临安种群取食偏好性从高到低依次为女贞、黄连木、白蜡和大叶杨。临安种群最喜欢取食女贞,在选择性条件和无选择性条件下,取食量分别为(1 347.33±51.95)和(1 173.00±75.54) mm²。产卵结果试验显示:余姚种群和临安种群云斑天牛对4种寄主植物表现出比较一致的产卵偏好性,都...