棕榈藤育种研究进展

对国内外棕榈藤的资源保护、遗传多样性以及繁殖技术等方面的研究进行了概述 ,提出了棕榈藤研究所面临的问题 ,并借鉴其它植物育种现状提出育种策略     

Imitation, internal absorption and the reversal of local drift in stochastic evolutionary games

Evolutionary game dynamics in finite populations is typically subject to noise, inducing effects which are not present in deterministic systems, including fixation and extinction. In the first part of this paper we investigate the phenomenon of drift reversal in finite populations, taking into account that drift is a local quantity in strategy space. Secondly, we study a simple imitation dynamics, and show that it can lead to fixation at internal mixed-strategy fixed points even in finite populations. Imitation in infinite populations is adequately described by conventional replicator dynamics, and these equations are known to have internal fixed points. Internal absorption in finite populations on the other hand is a novel dynamic phenomenon. Due to an outward drift in finite populations this type of dynamic arrest is not found in other commonly studied microscopic dynamics, not even in those with the same deterministic replicator limit as imitation.     

Imitation and emulation by dogs using a bidirectional control procedure

A successful procedure for studying imitative behavior in non-humans is the bidirectional control procedure in which observers are exposed to a demonstrator that responds by moving a manipulandum in one of two different directions (e.g., left vs. right). Imitative learning is demonstrated when observers make the response in the direction that they observed it being made. This procedure controls for socially mediated effects (the mere presence of a demonstrator), stimulus enhancement (attention drawn to a manipulandum by its movement), and if an appropriate control is included, emulation (learning how the environment works). Recent research with dogs has found that dogs may not demonstrate imitative learning when the demonstrator is human. In the present research, we found that when odors were controlled for, dogs imitated the direction of a screen-push demonstrated by another dog more than in a control condition in which they observed the screen move independently while another dog was present. Furthermore, we found that dogs would match the direction of screen-push demonstrated by a human and they were equally likely to match the direction in which the screen moved independently while a human was present.     

Experimental analyses of body image in the chimpanzee

It is difficult to study body image in animals. In this study, it is assumed that the perception of the body of others reflects body image. The perception of the human face was examined in a series of six experiments with a chimpanzee. Delayed-matching-to-sample tasks were employed. Although the chimpanzee mastered the tasks and showed transfer of performance to new faces, subtle changes in the matching face resulted in the deterioration of performance. Responses of the chimpanzee were often controlled by factors other than the facial stimuli. Thus, although the chimpanzee has a body image as humans do, it may not be as clear and as segmented.     

Homosemiosis, mimicry and superficial similarity: notes on the conceptualization of independent emergence of similarity in biology

Independent phenotypic emergence of superficially similar traits is a phenomenon frequently reported from investigations in the whole biota. Superficial similarity (including mimicry) is frequently explained as results of selective forces (predation or external environment). However, the mechanisms underlying independent (polyphyletic) emergence of similar phenotypic features remain largely unknown. A part of superficial similarity may emerge due to the occasional re-activation of latent genetic and/or developmental precursors. A specific kind of superficial similarity is represented by the phenomenon of mimicry that presupposes the attendance of a particular animal-interpreter. Despite diversity of ways how mimetic patterns are generated, they are structurally similar and often bear a common semantic message for an interpreter (predator); therefore, the term “homosemiosis” is proposed for such cases of sign-mediated correspondences where congruence of meaning appears.

Evidence of somatic embryogenesis from root tip explants of the rattan Calamus manan

Summary Somatic embryogenesis of Calamus manan, a single-stemmed rattan species, in tissue culture was scientifically demonstrated for the first time. Root tips of in vitro plantlets produced friable callus when the explants were cultivated for several mo. on a Murashige and Skoog induction medium containing 7.5 mg Picloram per l (31.1 μM). Histological analyses established the presence of proembryos within the callus which differentiated subsequently into somatic embryos using the same culture medium. Histological examination revealed that these somatic embryos completely lacked starch and protein reserves, which did not prevent them, however, from germinating, and showing bipolar development. These somatic embryos further developed into young plants, similarly to zygotic embryos.     

Can we go beyond timber and manage for both timber and non‐timber forest products? The case of rattans near Kisangani,DR Congo

Rattans, one of the major non‐timber forest products used by the population in and around Kisangani (Democratic Republic of Congo), are a significant source of income and the basis of a very active informal sector focused towards supplying the city with raw canes. We present the effects of harvest and light availability on the demography of two common rattan species in the Yoko forest reserve, near Kisangani: Eremospatha haullevilleana De Wild. and Laccosperma secundiflorum (P. Beauv.) Küntze. We studied clump demography for a year, under variable light condition and harvesting regimes (control, partial harvest and complete harvest of adult stems). We show a positive effect of full and partial light availability on the dynamic of individuals for both species but with variable treatment responses. We also demonstrate that a partial harvest of two‐thirds of adults cane is beneficial or nondetrimental to the production of new shoots under partial or full‐light conditions. These results suggest opportunities for multiple‐use management that integrate timber and rattan harvesting in forest around Kisangani.     

The impact of vaccine side effects on the natural history of immunization programmes: an imitation-game approach

When the incidence and prevalence of most common vaccine preventable childhood infectious diseases are constantly low, as is the case in many industrialized countries, the incidence of vaccine-associated side effects might become a key determinant in vaccine demand. We study an SIR transmission model with dynamic vaccine demand based on an imitation mechanism where the perceived risk of vaccination is modelled as a function of the incidence of vaccine side effects. The model shows some important differences compared to previous game dynamic models of vaccination, and allows noteworthy inferences as regards both the past and future lifetime of vaccination programmes. In particular it is suggested that a huge disproportion between the perceived risk of disease and vaccination is necessary in order to achieve high coverages. This disproportion is further increased in highly industrialised countries. Such considerations represent serious challenges for future vaccination programmes.     

Evolutionary game dynamics in finite populations with strong selection and weak mutation

We study stochastic game dynamics in finite populations. To this end we extend the classical Moran process to incorporate frequency-dependent selection and mutation. For 2 x 2 games, we give a complete analysis of the long-run behavior when mutation rates are small. For 3 x 3 coordination games, we provide a simple rule to determine which strategy will be selected in large populations. The expected motion in our model resembles the standard replicator dynamics when the population is large, but is qualitatively different when the population is small. Our analysis shows that even in large finite populations the behavior of a replicator-like system can be different from that of the standard replicator dynamics. As an application, we consider selective language dynamics. We determine which language will be spoken in finite large populations. The results have an intuitive interpretation but would not be expected from an analysis of the replicator dynamics.