灰树花深层培养的生长动力学与计算机模拟

研究了灰树花的生长特性,建立了灰树花的生长速率模型和基质消耗动力学模型;并运用SIMULINK仿真环境,建立了灰树花在培养过程中的主要因素通气量和pH对菌丝生物影响的模型,结果表明,模拟结果较理想。     

Likelihood-Based Modeling and Analysis of Data Underdispersed Relative to the Poisson Distribution

By using a generalization of the Poisson process, distributions can be constructed that show appropriate amounts of underdispersion relative to the Poisson distribution that may be apparent from observed data. These are then used to examine the differences between the distributions of numbers of fetal implants in mice corresponding to different doses of the herbicide 2,4,5-T.     

Drift dispersal of mayfly nymphs in the presence of chemical and visual cues from diurnal drift- and nocturnal benthic-foraging fishes

1. The drift of Baetis thermicus nymphs in the presence of chemical, visual and hydrodynamic cues, considered individually and in combination, produced by different predatory fishes was examined experimentally in laboratory streams. Masu salmon ( Oncorhynchus masou ) and freshwater sculpin ( Cottus nozawae ) are typical drift- and benthic-foraging fishes, respectively.
2. Observations of fish swimming in the streams revealed differing diel periodicity between the species; sculpin were nocturnal foragers and salmon diurnal.
3. The drift rate of Baetis by night increased in the presence of chemical cues from sculpin, with other cues having no interactive effects. In contrast, the drift rate increased primarily in the presence of both chemical and, particularly, visual cues from salmon, although no additional effects were found for any non-visual cues. Visual cues could enable Baetis to assess precisely the predation risk from foraging salmon by day, whereas Baetis could not use visual cues to detect sculpin either at night, because of the low light intensity, or during the day, because of the low activity of sculpin at that time.
4. In natural streams, which are often inhabited by several predatory fish employing different modes of foraging, invertebrates may be able to precisely assess the risk and effectively to avoid predators by using cues unique to each.     

Simulating secondary contact in allopatric speciation: an empirical test of premating isolation

Allopatric populations of Geospiza difficilis, the Sharp‐beaked Ground Finch, differ morphologically in association with different habitats to an extent unrivalled by any other species of Darwin's finch. The question arises as to whether they have diverged so much that they would not interbreed if they became sympatric; in other words, have they become separate species while remaining allopatric? In other species of Darwin's finches, it is known that a sexual imprinting‐like process based on early learning of song constrains breeding to conspecifics in sympatry. Therefore we used song playback experiments on Isla Genovesa to test the potential of G. difficilis to respond to songs from two other populations of the species on other, ecologically similar, islands. We found strong responses by males to songs of their own population, and heterogeneous but overall weaker responses to the structurally similar songs of G. difficilis from Isla Darwin. Tested birds did not respond to G. difficilis songs from Isla Wolf, songs of G. fuliginosa from Isla Pinta and control Cassin's finch songs. Female responses were infrequent and weak, apparently inhibited by the presence of responding males in most instances. Thus, assuming that females exercise similar discriminations to those of males, the Genovesa population of G. difficilis appears to be well advanced along the path of speciation: reproductively isolated from the Wolf population by a premating barrier to gene exchange that is culturally inherited, but not reproductively isolated from the Darwin population. We discuss the implications of imprinting for the process of speciation, the reasons for divergence of songs in allopatry, and the outcome of a hypothetical secondary contact in terms of coexistence, competition and interbreeding. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 76 , 545–556.     

酶法降解植物纤维素技术研究

用正交试验法探讨了以麦秸为原料进行纤维素酶降解的工艺条件。正交试验的结果表明,影响麦秸纤维素降解的因素的主次顺序为A（酶添加量）＞B（底物浓度）＞E（时间）＞C（温度）＞D（pH值）,纤维素酶解麦秸纤维素的最佳组合为A3B1E3C3D2,即纤维素酶的添加量为0．2％,底物浓度为5％,反应时间为2h,反应温度50℃,pH5.0时为最佳条件。在比常规酶解法时间缩短12－30倍的条件下,能使纤维素降解葡萄糖的转化率达22．3％。     

Nucleation and facilitation in salt pans in Mediterranean salt marshes

Abstract. Arthrocnemum macrostachyum is a perennial species acting as a primary colonizer of salt pans in Mediterranean high salt marshes. Salicornia ramosissima, an annual, occurs in salt pans under Arthrocnemum canopies and in open areas. The aim of this study was to analyse, in wild populations and a transplant experiment, how S. ramosissima population dynamics and growth are affected by A. macrostachyum. The environmental conditions within the patches of Arthrocnemum were less stressful than in the open areas, with lower radiation levels and salinity concentrations. In the inner areas of A. macrostachyum patches, density‐dependent mortality processes of S. ramosissima seedlings led to low densities of adult individuals with greater morphological development and reproductive success than in open areas. However, at the edges of Arthrocnemum patches facilitation of seedling survival favoured high densities. Environmental stress hindered development, decreased reproduction and premature death. These results are in agreement with the general theory of factors controlling vegetation distribution that biotic interactions dominate in low stress environments, while abiotic interactions dominate under harsher environmental conditions. A. macrostachyum plays an essential role in the succession in these salt pans, facilitating seed production and stimulating nucleation processes in S. ramosissima.     

自组织作用在生物进化中的模拟研究

生物的进化可以看作是在基因随机突变的驱动下,通过自组织作用而形成高级有序结构的过程。生物进货研究只能看到进货的结果,而不能对进货的过程进行定量分析和检验。采用进化计算的算法框架对进化现象进行,模拟随机初始条件及环境突变条件下种群的分化和物种形成过程,研究地域分布对物种分化和形成的影响,以及过渡物种的分布特点,并对有限地域条件下地域面积和物种数量的关系进行了模拟研究。