生物数学学报第20卷2005年总目次

第1期 一个具有时滞和反请控制的单种群模型的全局稳定性(英)..…… 生抽数学中的反应扩散系统奇摄动问题(英)……,........…… 具时滞的人口模型的行波解(英).........................…… 一个广告系统的脉冲控制(英),..............…… 昨线性奇摄动多种群生态竞争一捕食系统的渐近解(英).....…… 具有反请技制的两种群竟争系统的概周期解................…… 一类可逆多分子饱和生化反应系统的非线性分析,............… 一个具有偏害关来的三种群模型的诱导控制.........……,二,二 一类带存放率的竟争扩散系统解的渐近性态.…     

一类具时滞的禽流感模型

针对具扩散和时滞的SI-SIR传染病模型,用特征分析和Lyapunov泛函方法研究了相应的具齐次Neumann边界条件反应扩散方程组解的渐近性质.最后给出数值模拟来说明如果染病鸟类的接触率和染病人类的接触率小,那么全系统的无病平衡点是全局渐近稳定的;但当染病鸟类的接触率大或者和染病人类的接触率大时,变异的禽流感将在人类中扩散.     

具常投放率的反应扩散系统的渐近性质

本文研究一类具常投放率的人口动力学中反应扩散系统的Neumann初边值问题,应用比较函数讨论其解的渐近性态,给出稳态解的存在条件．     

利用元胞自动机研究一类捕食食饵模型中的斑块扩散现象

利用概率元胞自动机模型对空间隐式的、食饵具Allee效应的一类捕食食饵模型进行模拟,发现随着相关参数的变化,种群的空间扩散前沿由连续的扩散波逐渐转变为一种相互隔离的斑块向外扩散,这种斑块扩散现象与以往的扩散模式有所不同。研究结果表明：(1)在斑块扩散的情况下,相关参数的微小变化会导致种群灭绝或者形成连续的扩散波,即斑块扩散发生在种群趋于灭绝和连续扩散之间;(2)当种群的空间扩散方式为斑块扩散时,种群的扩散速度会变慢,与其他扩散方式下的速度有着明显的区别。该研究结果对生物入侵控制和外来物种监测有重要的启发和指导作用。     

脉冲-扩散周期竞争系统解的渐近行为

研究了在周期变化环境中具有扩散及种群密度可能发生突变的两竞争种群动力系统的数学模型．模型由反应扩散方程组以及初边值及脉冲条件组成．文章建立了研究模型的上下解方法,获得了一些比较原理．利用脉冲常微分方程的比较定理以及利用相应的脉冲常微分方程的解控制和估计所讨论模型的解,研究了系统模型的解的渐近性质．     

具脉冲收获与脉冲单边扩散的单种群动力学模型研究

建立了一类具脉冲收获与脉冲单边扩散在不同固定脉冲时刻的单种群动力学模型利用离散动力系统频闪映射理论,得到了脉冲收获的阈值.该结论说明只要收获量不超过其阈值通过扩散则种群可以保持持续生存.     

强耦合竞争-竞争-互惠模型古典解的整体存在性

应用能量估计方法和bootstrap技巧证明了一类强耦合反应扩散方程系统在任意维空间中古典解的整体存在性,该系统是竞争种群含自扩散和交错扩散,互惠种群仅含自扩散的竞争-竞争-互惠模型．     

一个具有年龄结构的单种群离散反应扩散模型的波前解

利用上下解方法研究了一个具有年龄结构的单种群离散反应扩散模型波前解的存在性,并证明了存在具有临界波速的波前解.     

一类带有扩散和时滞的非自台Lotka-Volterra系统

本文讨论有时滞的扩散系统,此系统有两个种群两个斑块,其中一种种群可以在两斑块中自由扩散,另一种群被限定在斑块中不能扩散,当系数数满足一定的条件时,得到系统有持续生存和全局稳定的解。     

灰喜鹊摄食对中国沙棘种子萌发的影响

为了探明鸟类摄食中国沙棘果实后对中国沙棘种群扩散的作用,对①来自鸟粪肥的种子。②人工用酸和高温处理的种子和③作为对照的天然种子的萌发率和萌发速度进行比较,3种类型的种子均区分为具内果皮种子和不具内果皮种子两组。结果表明：酸性和高温环境对两种类型种子的萌发率影响不大,但中国沙棘果实的内果皮不仅使种子萌发推迟,而且还降低了种子的萌发率。灰喜鹊的消化作用虽然降低了中国沙棘种子的萌发率和萌发速度,但对中国沙棘种子的传播和种群的扩散仍有促进作用。     

Homosexual behavior in wild Sumatran orangutans (Pongo pygmaeus abelii).

Wild male Sumatran orangutans at two study sites engaged in homosexual behavior. These observations demonstrate that homosexual behavior is not an artifact of captivity or contact with humans. In separate instances, homosexual behavior was associated with affiliative and agonistic behaviors. These observations add orangutans to the list of primates in which homosexual behavior forms part of the natural repertoire of sexual or sociosexual behavior.     

Survey of stereotypic behavior in prosimians

Captive animals have been observed to perform a variety of stereotypic behaviors. However, little is known about stereotypic behavior in prosimians. We sent surveys to 96 AZA-accredited institutions to examine stereotypic behavior in these primates. Forty-eight surveys were returned, providing information on 440 individuals of 10 genera. According to the responses, 13.2% of the prosimians surveyed exhibited some form of stereotypic behavior. Pacing was the most common behavior. A logistic regression was used to examine intrinsic characteristics that might influence the performance of stereotypic behavior. The genus of the prosimian was a significant predictor of stereotypic behavior. Individuals of the genus Varecia and Microcebuswere more likely to engage in stereotypic behavior than members of the other genera. Rearing history, age, and sex were not significant predictors of stereotypic behavior. To examine the influence of extrinsic variables on stereotypic behavior, we transformed the data into the percentage of individuals within the enclosure that were reported to exhibit stereotypic behavior, and analyzed them at the enclosure level using a general linear model (GLM) analysis of variance (ANOVA). The only environmental variable that significantly predicted stereotypic behavior was the frequency with which enrichment was provided. Frequent enrichment was provided to those exhibits with a higher percentage of prosimians that engaged in stereotypic behavior. The results of this survey suggest that stereotypic behavior in prosimians may be associated with intrinsic factors (i.e., individual or genus differences) in addition to extrinsic factors related to housing. This knowledge may be helpful in identifying the causes of and effective treatments for stereotypic behavior in prosimians.     

Behavior of lactating rats in a dual-chambered maternity cage

Videotape sampling of behavior in a dual-chambered apparatus indicates that the continuous monitoring of the amount of time a mother spends in the cage with its litter can be taken as a valid reflection of maternal behavior. Nursing is the principal behavior of lactating females while in the compartment with their litters; lying still, consummatory behavior, and activity occur with greater frequency in the cage away from the litter. Both the time that mothers spend with their litters and nursing behavior displayed a 24-hr rhythm with crest values occurring during the period of light.     

Sickness and Aggressive Behavior in Dominant and Subordinate Mice*

Sick animals show a set of organized behavioral changes (sickness behavior), which is the result of a motivational re‐organization of the behavior as a whole. Sickness behavior display can be influenced by the social context. In this work, we sought to investigate the regulation of sickness behavior within a pair of mice in the presence of an intruder mouse. Dominant and subordinate mice were treated with the bacterial endotoxin lipopolysaccharide (LPS) and were challenged with the presence of an intruder mouse. LPS effects depended on ranking and social context. Even though dominant mice displayed more agonistic interaction towards the intruder, subordinate mice displayed agonistic behavior towards the intruder when their dominant companion was treated with LPS. The results show that, not only sickness behavior is differentially expressed among different social ranks, but also that sickness behavior is related to different reactions among surrounding animals. These data are relevant for a biological approach to the relation between sickness behavior and social behavior.     

The role of androgens in the trade-off between territorial and parental behavior in the Azorean rock-pool blenny, Parablennius parvicornis

Androgen hormones have been shown to facilitate competitive ability in courtship and territorial behavior, while suppressing paternal behavior. The rock-pool blenny, Parablennius parvicornis, provides an excellent model to study the proximate regulation of such a trade-off between territorial and parental behavior, because nest-holder males of this species display these behaviors simultaneously. A field study was carried out in which territorial nest holder males were either treated with long-lasting implants filled with 11-ketotestosterone (11-KT) or with control implants. Males treated with 11-KT showed a higher frequency of aggressive behavior, were more responsive to aggressive challenges, and were more persistent in aggressive behavior than control males. In addition, territories were larger in males treated with 11-KT than in controls. We found evidence for incompatibility between defense of a large territory and high levels of parental behavior. However, contrary to expectation, 11-KT did not suppress parental behavior. We suggest that trade-offs between territorial and parental behavior may not be regulated by androgen hormones but may result from a time constraint in the individual's activity budget.     

An evaluation of behavior inferences from Bayesian state‐space models: A case study with the Pacific walrus

State‐space models offer researchers an objective approach to modeling complex animal location data sets, and state‐space model behavior classifications are often assumed to have a link to animal behavior. In this study, we evaluated the behavioral classification accuracy of a Bayesian state‐space model in Pacific walruses using Argos satellite tags with sensors to detect animal behavior in real time. We fit a two‐state discrete‐time continuous‐space Bayesian state‐space model to data from 306 Pacific walruses tagged in the Chukchi Sea. We matched predicted locations and behaviors from the state‐space model (resident, transient behavior) to true animal behavior (foraging, swimming, hauled out) and evaluated classification accuracy with kappa statistics (κ) and root mean square error (RMSE). In addition, we compared biased random bridge utilization distributions generated with resident behavior locations to true foraging behavior locations to evaluate differences in space use patterns. Results indicated that the two‐state model fairly classified true animal behavior (0.06 ≤ κ ≤ 0.26, 0.49 ≤ RMSE ≤ 0.59). Kernel overlap metrics indicated utilization distributions generated with resident behavior locations were generally smaller than utilization distributions generated with true foraging behavior locations. Consequently, we encourage researchers to carefully examine parameters and priors associated with behaviors in state‐space models, and reconcile these parameters with the study species and its expected behaviors.     

Steroid regulation of sexual behavior.

A review of experimental data on the steroid regulation of sexual behavior in the rat suggests that estrogen is involved in the control of both male and female sexual behavior. Female sexual behavior is stimulated by estrogen alone or in combination with progesterone and by aromatizable androgens. In the male, testosterone, androstenediol, and androstenedione were effective in the control of male sexual behavior. Estrogen alone may initiate and restore full masculine copulatory behavior in sexually castrated males. Estrogen may also synergize with nonaromatizable androgens and control behavior. While antiestrogens are ineffective in inhibiting sexual behavior, aromatization blockers (primarily aminoglutethimide) can block sexual response in the presence of aromatizable androgens.     

Differential effects of testosterone and progesterone on the activation and retention of courtship behavior in sexual and parthenogenetic whiptail lizards

Both testosterone (T) and progesterone (P) facilitate the expression of male-typical sexual behavior in a variety of animals, including rodents and lizards. In two species of whiptail lizards, Cnemidophorus inornatus and C. uniparens, both hormones elicit the full repertoire of courtship behavior. However, the relative efficacy of the two hormones is unknown. In Experiments 1 and 2 we assessed differences in capacity of exogenous T and P to induce male-typical courtship behavior in gonadectomized whiptail lizards. In both species, individuals implanted with T showed more frequent courtship behavior relative to those implanted with P or cholesterol. In Experiments 3 and 4 we examined whether T and P differentially affected the retention of courtship behavior following implant removal. In both species, individuals implanted with T showed more courtship behavior following implant removal than those previously given P. In these experiments, implants were removed at a time when individuals in both groups were behaviorally similar; therefore, the differences in behavior following implant removal were not due to differences in the amount of courtship experience. Taken together, the hormone that was more effective at activating courtship behavior was also more effective at maintaining courtship behavior following implant removal. In summary, though both T and P can elicit identical sexual behaviors in both whiptail species, T has a greater and more lasting effect on courtship behavior and possibly on the neural circuits underlying courtship behavior.     

Effect of visual cues from female on the postejaculatory operant behavior of male rat

Bar-press response reinforced by the contact with estrous female were investigated in male rats in two experimental situations, when the visual communication with female was prevented or when it was permitted. After the instrumental responses directly preceded by ejaculations, depending on the increasing duration of response latency, three categories of male behavior were observed: avoiding of the contact with female, precopulatory behavior, or copulatory behavior. The enabling the visual communication with a female caused the significant increase of occurrence of copulatory behavior and significant decrease of contact-avoiding behavior, whereas the precopulatory behavior showed unsignificant increase. It is suggested that when prevented to see the female male rats can perform the instrumental response even when the sexual arousal is to low for precopulatory behavior. Such unrewarded responses lead to the appearance of frustration. On the contrary, when the female is visible the instrumental response is delayed up to the moment when the visual cues coming from female can evoke at least precopulatory behavior.     

Is maternal behavior correlated with later explorative behavior of young guinea pigs (Cavia aperea f. porcellus)?

The results of previous studies, mostly involving primates, have shown a correlation between mothering styles and later explorative behavior of the young. On the basis of our previous study on the existence of mothering styles in guinea pigs we conclude that three main components of maternal behavior are useful for these kinds of studies: locomotion, affiliative behavior, and aggressive behavior. In the present study we examined the extent to which these components were correlated with later explorative behavior of guinea-pig pups. The later explorative behavior of 48 pups from 16 mothers was measured after weaning in a series of tests designed to highlight different aspects of exploration. The results indicate that maternal behavior does not have a predominant correlation with later explorative behavior of the pups. Correlations were not found between the affiliative and aggressive behavior of the mothers and the later explorative behavior of the pups. Mothers scoring high on locomotion had pups that showed more explorative behavior than did the pups of mothers scoring low on locomotion. This correlation, however, was not linear and was significant for only one parameter. Received: 28 April 1999 / Received in revised form: 27 October 1999 / Accepted: 10 November 1999