Effect of lizards on spider populations: manipulative reconstruction of a natural experiment

Which species affect one another, how intensely, and the mechanisms of those effects are crucial data for understanding how ecological communities work. Tropical islands without lizards, the major top predators, have about ten times as dense web spider populations as those with lizards; processes responsible for this effect were experimentally simulated by removing lizards from randomly selected mainland plots. Spider densities in removal plots averaged 2.5 times as high as controls. Spider survival, prey abundance, and prey consumption were all negatively affected by lizards. Contrary to most studies, predator removal caused an increase in the number of spider species.     

生物进化背景下人类的可持续发展

进化、适应和选择贯穿在任何一个物种的演化过程中,这是生物与环境相互联系、相互作用的结果,是大自然固有的运动规律在生物物种演化过程中的体现。只有准确地把握进化、适应和选择3者的内涵,以生物进化为主线,以人类可持续发展为中心,把人类对环境的主动适应和自然、社会对生物物种的方向性选择结合起来,从更深的层面上理解生物的进化和在生物进化背景下人类的可持续发展,才能在理论上和实践中坚持真正的达尔文主义和现代进化观及当代可持续发展观。     

生物进化背景下人类的可持续发展(英文)

进化、适应和选择贯穿在任何一个物种的演化过程中,这是生物与环境相互联系、相互作用的结果,是大自然固有的运动规律在生物物种演化过程中的体现。只有准确地把握进化、适应和选择三者的内涵,以生物进化为主线,以人类可持续发展为中心,把人类对环境的主动适应和自然、社会对生物物种的方向性选择结合起来,从更深的层面上理解生物的进化和在生物进化背景下人类的可持续发展,才能在理论上和实践中坚持真正的达尔文主义和现代进化观及当代可持续发展观。     

七星瓢虫的研究进展

从七星瓢虫的生活习性、人工饲养及饲料、捕食功能反应、天敌及抗药性的研究等几个方面对其进行了综述,并对七星瓢虫的重要习性、生物防治、农药的选择性等方面进行了归纳分析,为充分利用自然天敌防治害虫提供理论依据。     

具有Allee效应的捕食者-食饵模型的进化动力系统

研究了具有Allee效应的捕食者-食饵种群显性特征的共同进化动力系统.得到了在对称作用下连续稳定策略和进化分支的生态条件和进化条件,食饵的分支能导致捕食者分支;证明了在对称作用下进化动力系统经历超临界Hopf分支和次临界Hopf分支,周期进化是随机突变和选择过程的可能结果.在对称作用下进化自杀不可能发生,然而,在非对称作用下当种群遭受Allee效应时,进化自杀可能发生.     

Founder effects persist despite adaptive differentiation: a field experiment with lizards

The extent to which random processes such as founder events contribute to evolutionary divergence is a long-standing controversy in evolutionary biology. To determine the respective contributions of founder effects and natural selection, we conducted an experiment in which brown anole (Anolis sagrei) lizard populations were established on seven small islands in the Bahamas, from male-female pairs randomly drawn from the same large-island source. These founding events generated significant among-island genetic and morphological differences that persisted throughout the course of the experiment despite all populations adapting in the predicted direction-shorter hindlimbs-in response to the narrower vegetation on the small islands. Thus, using a replicated experiment in nature, we showed that both founder effects and natural selection jointly determine trait values in these populations.     

Contingency and determinism in replicated adaptive radiations of island lizards

The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation of Anolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists, termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly similar evolutionary outcomes.     

Allometric engineering: a causal analysis of natural selection on offspring size

Techniques of offspring size manipulation, "allometric engineering," were used in combination with studies of natural selection to elucidate the causal relation between egg size and offspring survival of lizards. The results experimentally validate premises underlying theories of optimal egg size: fecundity selection favoring the production of large clutches of small eggs was balanced by survival selection favoring large offspring. However, large hatchlings did not always have the highest survival, contrary to most theoretical expectations. Optimizing selection on offspring size per se was the most common pattern. Moreover, matches between average and optimal egg size were qualitative, not quantitative, perhaps reflecting known functional constraints on the production of large eggs.     

一类考虑外界干扰的生物进化模型的动力学研究

依据进化动力学的理论与方法,建立了考虑外界干扰因素的Lotka-Volterra食物链进化模型,研究了中间捕食者种群表型特征的进化问题,得到了进化稳定、收敛稳定及产生进化分支的条件.最后,通过数值模拟分析了外界干扰对奇异策略的稳定性和表型特征进化分支情况的影响.     

The Ecological Significance of Sexual Dimorphism in Size in the Lizard Anolis conspersus

Adult males of Anolis conspersus capture prey of significantly larger size and occupy perches of significantly greater diameter and height than do adult females; similarly, these three dimensions of the niche are significantly larger for adult females than for juveniles. Adult males on the average eat a smaller number of prey, and the range in size of prey is larger. The relationship between the average length of the prey and that of the predator is linear when the predator size is above 36 millimeters, but becomes asymptotic when it is below that value. Subadult males as long as adult females eat significantly larger food than do the latter, but only in the larger lizards is this correlated with a relatively larger head. Anolis conspersus selects prey from a wide range of taxa and shows no obvious intraspecific specialization not connected to differences in microhabitat and prey size. The efficiency of this system for solitary species is pointed out.     

Evolution of universal grammar

Universal grammar specifies the mechanism of language acquisition. It determines the range of grammatical hypothesis that children entertain during language learning and the procedure they use for evaluating input sentences. How universal grammar arose is a major challenge for evolutionary biology. We present a mathematical framework for the evolutionary dynamics of grammar learning. The central result is a coherence threshold, which specifies the condition for a universal grammar to induce coherent communication within a population. We study selection of grammars within the same universal grammar and competition between different universal grammars. We calculate the condition under which natural selection favors the emergence of rule-based, generative grammars that underlie complex language.     

Accommodating phylogenetic uncertainty in evolutionary studies

Many evolutionary studies use comparisons across species to detect evidence of natural selection and to examine the rate of character evolution. Statistical analyses in these studies are usually performed by means of a species phylogeny to accommodate the effects of shared evolutionary history. The phylogeny is usually treated as known without error; this assumption is problematic because inferred phylogenies are subject to both stochastic and systematic errors. We describe methods for accommodating phylogenetic uncertainty in evolutionary studies by means of Bayesian inference. The methods are computationally intensive but general enough to be applied in most comparative evolutionary studies.     

Nutrient-specific foraging in invertebrate predators

Many herbivores and omnivores adjust their food selection behavior to regulate the intake of multiple nutrients. Carnivores, however, are generally assumed to optimize the rate of prey capture rather than select prey according to nutrient composition. We showed experimentally that invertebrate predators can forage selectively for protein and lipids to redress specific nutritional imbalances. This selection can take place at different stages of prey handling: The predator may select among foods of different nutritional composition, eat more of a prey if it is rich in nutrients that the predator is deficient in, or extract specific nutrients from a single prey item.     

Evolution of character displacement in Darwin's finches

Competitor species can have evolutionary effects on each other that result in ecological character displacement; that is, divergence in resource-exploiting traits such as jaws and beaks. Nevertheless, the process of character displacement occurring in nature, from the initial encounter of competitors to the evolutionary change in one or more of them, has not previously been investigated. Here we report that a Darwin's finch species (Geospiza fortis) on an undisturbed Galápagos island diverged in beak size from a competitor species (G. magnirostris) 22 years after the competitor's arrival, when they jointly and severely depleted the food supply. The observed evolutionary response to natural selection was the strongest recorded in 33 years of study, and close to the value predicted from the high heritability of beak size. These findings support the role of competition in models of community assembly, speciation, and adaptive radiations.     

环斑猛猎蝽的捕食功能反应研究

为探讨环斑猛猎蝽的捕食能力,研究了环斑猛猎蝽雌成虫对玉米螟的捕食作用及温度、空间异质性、捕食者密度和猎物密度等对功能反应的影响。结果表明:环斑猛猎蝽雌成虫对玉米螟的功能反应为HollingⅡ型;温度对环斑猛猎蝽的捕食效能影响显著,攻击率(a)、处置时间(Th)和捕食能力(a/Th)与温度之间呈二次函数关系;空间异质性对环斑猛猎蝽捕食作用有很大的影响,捕食者在捕食过程中,叶片数越多,即环境阻力越大,捕食作用率越低;环斑猛猎蝽的种内有较强的干扰作用,随着捕食者和猎物两者密度的增加,相互干扰的作用愈明显,寻找效应值也相应的降低,搜索常数Q为0.8945,干扰系数m为1.0384,E=0.8945P-1.0384。     

Predatorial borings in late precambrian mineralized exoskeletons

The late Precambrian tube-forming Cloudina, the earliest known animal to produce a mineralized exoskeleton, shows evidence of having been attacked by shell-boring organisms. Of more than 500 tubes from Shaanxi Province, China, 2.7% have rounded holes 40 to 400 micrometers in diameter. The relation between the size of the holes and the width of the bored tubes suggests that the attacking organism was a predator, selecting its prey for size. If true, this would be the oldest case of predation in the fossil record and would support the hypothesis that selection pressures from predation was a significant factor in the evolution of animal skeletons around the Precambrian-Cambrian boundary.     

Selection on major components of angiosperm genomes

Angiosperms are a relatively recent evolutionary innovation, but their genome sizes have diversified remarkably since their origin, at a rate beyond that of most other taxa. Genome size is often correlated with plant growth and ecology, and extremely large genomes may be limited both ecologically and evolutionarily. Yet the relationship between genome size and natural selection remains poorly understood. The manifold cellular and physiological effects of large genomes may be a function of selection on the major components that contribute to genome size, such as transposable elements and gene duplication. To understand the nature of selection on these genomic components, both population-genetic and comparative approaches are needed.     

Predatory fish select for coordinated collective motion in virtual prey

Movement in animal groups is highly varied and ranges from seemingly disordered motion in swarms to coordinated aligned motion in flocks and schools. These social interactions are often thought to reduce risk from predators, despite a lack of direct evidence. We investigated risk-related selection for collective motion by allowing real predators (bluegill sunfish) to hunt mobile virtual prey. By fusing simulated and real animal behavior, we isolated predator effects while controlling for confounding factors. Prey with a tendency to be attracted toward, and to align direction of travel with, near neighbors tended to form mobile coordinated groups and were rarely attacked. These results demonstrate that collective motion could evolve as a response to predation, without prey being able to detect and respond to predators.     

Human echo perception

It has been shown that human test subjects have the ability, under controlled laboratory conditions, to use echoes to detect the presence or absence of targets placed before them. In addition, blind and sighted persons have been able to detect a target monaurally, to make simple shape discriminations, and to locate a target in space. Signal, environmental, and individual variability affect performance in a measurable fashion. This research is an initial step in measuring the limits of a human being's ability to use echoes as a source of information about his physical surroundings. At this point it seems unlikely that the unaided human ear can rival the bat's auditory system for echo perception. It may be, however, that modern technology can partially bridge the evolutionary gap and bring more useful echoes to man's ear than those it now receives. Such an accomplishment would allow us to examine the extent to which man might benefit from this means of sensing his environment.     

麻类作物分子育种的研究现状与展望

麻类作物资源的保护和开发利用的成功依赖于对基因库资源遗传变异的数量、分布及其进化关系充分的了解和掌握。传统的研究方法有很大局限性,分子标记的出现弥补了传统方法的不足,成为现代科学研究的有利工具。目前关于麻类作物的遗传背景知识相对有限,但是对于作物育种又是必需的。一张高密度的遗传连锁图谱可以用于重要性状定位、重要基因克隆、比较基因组学研究和分子标记辅助育种。本文系统地论述了利用分子标记技术在6种麻类作物包括红麻、黄麻、亚麻、苎麻、大麻、剑麻的遗传连锁图谱构建及基因定位、分子标记辅助育种方面的研究进展。