Fairness modulates non-conscious facial mimicry in women

In societies with high cooperation demands, implicit consensus on social norms enables successful human coexistence. Mimicking other people's actions and emotions has been proposed as a means to synchronize behaviour, thereby enhancing affiliation. Mimicry has long been thought to be reflexive, but it has recently been suggested that mimicry might also be motivationally driven. Here, we show during an economic bargaining game that automatic happy mimicry of those making unfair offers disappears. After the bargaining game, when the proposers have acquired either a fair or unfair reputation, we observe increased angry mimicry of proposers with an unfair reputation and decreased angry mimicry of fair proposers. These findings provide direct empirical evidence that non-conscious mimicry is modulated by fairness. We interpret the present results as reflecting that facial mimicry in women functions conditionally, dependent on situational demands.     

Eye movements of stumptailed monkeys during discriminative performance: An overview

There are a number of statements that can be made about eye movements of monkeys during the learning of simple and complex discriminative problems that are probably applicable to a wide variety of visual tasks. There are systematic changes in eye movements as a function of practice. Some of these changes occur long after grosser measures of performance, such as frequency of correct choices, have reached an asymptote. Hence, short-term studies of visual information processing may be misleading. Duration of visual fixations and frequency of visual fixations are independent measures, reflecting different cognitive processes. Studies which measure only total looking time confound these two measures and, thus, may miss important information. Eye movements appear to be an important, if not essential, component of the chain of events constituting the cognitive processing underlying performance on visual tasks.     

Diversity of warning signal and social interaction influences the evolution of imperfect mimicry

Mimicry, the resemblance of one species by another, is a complex phenomenon where the mimic (Batesian mimicry) or the model and the mimic (Mullerian mimicry) gain an advantage from this phenotypic convergence. Despite the expectation that mimics should closely resemble their models, many mimetic species appear to be poor mimics. This is particularly apparent in some systems in which there are multiple available models. However, the influence of model pattern diversity on the evolution of mimetic systems remains poorly understood. We tested whether the number of model patterns a predator learns to associate with a negative consequence affects their willingness to try imperfect, novel patterns. We exposed week‐old chickens to coral snake (Micrurus) color patterns representative of three South American areas that differ in model pattern richness, and then tested their response to the putative imperfect mimetic pattern of a widespread species of harmless colubrid snake (Oxyrhopus rhombifer) in different social contexts. Our results indicate that chicks have a great hesitation to attack when individually exposed to high model pattern diversity and a greater hesitation to attack when exposed as a group to low model pattern diversity. Individuals with a fast growth trajectory (measured by morphological traits) were also less reluctant to attack. We suggest that the evolution of new patterns could be favored by social learning in areas of low pattern diversity, while individual learning can reduce predation pressure on recently evolved mimics in areas of high model diversity. Our results could aid the development of ecological predictions about the evolution of imperfect mimicry and mimicry in general.     

Eye movements in Daphnia magna

Summary Three types of behavior of the compound eye of Daphnia magna are characterized: flick, a transient rotation elicited by a brief flash of light; fixation, a maintained eye orientation in response to a stationary light stimulus of long-duration; tracking, the smooth pursuit of a moving stimulus. The magnitudes of the flick and fixation responses vary with stimulus position and are generally proportional to stimulus intensity, although at high intensities there is an attenuation of both behaviors. When the stimulus is placed at a position 80° dorsal to the eye axis, there is no response; this area is called the null region. For stationary stimuli in other positions, the direction of the response is such as to bring the stimulus closer to the null region. During tracking, the relative positions of the eye and stimulus change; the eye velocity is approximately half that of the moving stimulus. The regions of the eye in which these behaviors may be induced are different, being largest for flick and smallest for tracking. It is proposed that flick and fixation responses are a means for rotating the eye so that the stimulus is within the area surrounding the null region which is used for tracking.     

Prey community structure affects how predators select for Mullerian mimicry

Müllerian mimicry describes the close resemblance between aposematic prey species; it is thought to be beneficial because sharing a warning signal decreases the mortality caused by sampling by inexperienced predators learning to avoid the signal. It has been hypothesized that selection for mimicry is strongest in multi-species prey communities where predators are more prone to misidentify the prey than in simple communities. In this study, wild great tits (Parus major) foraged from either simple (few prey appearances) or complex (several prey appearances) artificial prey communities where a specific model prey was always present. Owing to slower learning, the model did suffer higher mortality in complex communities when the birds were inexperienced. However, in a subsequent generalization test to potential mimics of the model prey (a continuum of signal accuracy), only birds that had foraged from simple communities selected against inaccurate mimics. Therefore, accurate mimicry is more likely to evolve in simple communities even though predator avoidance learning is slower in complex communities. For mimicry to evolve, prey species must have a common predator; the effective community consists of the predator's diet. In diverse environments, the limited diets of specialist predators could create 'simple community pockets' where accurate mimicry is selected for.     

昆虫拟态的多样性

综述了昆虫拟态的常见类型及其研究动态 ,特别对光学拟态、声学拟态、化学拟态和拟态的多型现象及复杂性作了较详细的介绍     

Aggressive use of Batesian mimicry by an ant-like jumping spider

Batesian and aggressive mimicry are united by deceit: Batesian mimics deceive predators and aggressive mimics deceive prey. This distinction is blurred by Myrmarachne melanotarsa, an ant-like jumping spider (Salticidae). Besides often preying on salticids, ants are well defended against most salticids that might target them as potential prey. Earlier studies have shown that salticids identify ants by their distinctive appearance and avoid them. They also avoid ant-like salticids from the genus Myrmarachne. Myrmarachne melanotarsa is an unusual species from this genus because it typically preys on the eggs and juveniles of ant-averse salticid species. The hypothesis considered here is that, for M. melanotarsa, the distinction between Batesian and aggressive mimicry is blurred. We tested this by placing female Menemerus sp. and their associated hatchling within visual range of M. melanotarsa, its model, and various non-ant-like arthropods. Menemerus is an ant-averse salticid species. When seeing ants or ant mimics, Menemerus females abandoned their broods more frequently than when seeing non-ant-like arthropods or in control tests (no arthropods visible), as predicted by our hypothesis that resembling ants functions as a predatory ploy.     

Multi-trait mimicry and the relative salience of individual traits

Mimicry occurs when one species gains protection from predators by resembling an unprofitable model species. The degree of mimic–model similarity is variable in nature and is closely related to the number of traits that the mimic shares with its model. Here, we experimentally test the hypothesis that the relative salience of traits, as perceived by a predator, is an important determinant of the degree of mimic–model similarity required for successful mimicry. We manipulated the relative salience of the traits of a two-trait artificial model prey, and subsequently tested the survival of mimics of the different traits. The unrewarded model prey had two colour traits, black and blue, and the rewarded prey had two combinations of green, brown and grey shades. Blue tits were used as predators. We found that the birds perceived the black and blue traits to be similarly salient in one treatment, and mimic–model similarity in both traits was then required for high mimic success. In a second treatment, the blue trait was the most salient trait, and mimic–model similarity in this trait alone achieved high success. Our results thus support the idea that similar salience of model traits can explain the occurrence of multi-trait mimicry.     

Learning of salient prey traits explains Batesian mimicry evolution

Batesian mimicry evolution involves an initial major mutation that produces a rough resemblance to the model, followed by smaller improving changes. To examine the learning psychology of this process, we applied established ideas about mimicry in Papilio polyxenes asterius of the model Battus philenor. We performed experiments with wild birds as predators and butterfly wings as semiartificial prey. Wings of hybrids of P. p. asterius and Papilio machaon were used to approximate the first mutant, with melanism as the hypothesized first mimetic trait. Based on previous results about learning psychology and imperfect mimicry, we predicted that: melanism should have high salience (i.e., being noticeable and prominent), meaning that predators readily discriminate a melanistic mutant from appearances similar to P. machaon; the difference between the first mutant and the model should have intermediate salience to allow further improvement of mimicry; and the final difference in appearance between P. p. asterius and B. philenor should have very low salience, causing improvement to level off. Our results supported both the traditional hypothesis and all our predictions about relative salience. We conclude that there is good agreement between long‐held ideas about how Batesian mimicry evolves and recent insights from learning psychology about the role of salience in mimicry evolution.     

Incorporating Motion into Investigations of mimicry

During the past thirty years, natural selection due to predation has been investigated with regard to prey motion in three areas that are relevant to the evolution of mimicry: (1) anti-apostatic selection, (2) locomotor mimicry, and (3) escape mimicry. Anti-apostatic selection, or selection against the odd individuals, arises when prey are at very high densities or when prey are Müllerian mimics. When prey are at high densities, motion of the prey increases selection against odd individuals. When the prey are Müllerian mimics, motion may also play an important role in strengthening selection against odd individuals. This may explain locomotor mimicry between Müllerian mimics. Locomotor mimicry arises when two distantly-related prey species appear alike in behaviour, and there is a corresponding suite of morphological, physiological, and biomechanical traits that the prey have in common. Locomotor mimicry has been demonstrated in Müllerian mimics. It is also predicted to occur in Batesian mimics but with important limitations due to selection by the predator for the prey to maintain the ability to escape if detected. Locomotor mimicry may also occur between palatable species that are alike as a result of unprofitable prey (or escape) mimicry. Escape mimicry arises when prey are difficult to capture. By frustration learning, the predator associates the colour of the prey with unprofitability. In all three instances, dis-similarity in colour or motion probably increases selection against the odd individual. In addition, the interaction of colour and motion gives rise to greater reliability of the signals to a specialist predator. However for a generalist predator, multiple component signals of the prey lead to errors in signal perception and greater risk of cheating. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dynamics of mimicry evolution

We simulated mimicry evolution by allowing three populations to cocvolvc: two populations of senders and one of receivers. Artificial neural networks were used to model receivers, and it was assumed that recognition was inherited. The senders' signals consisted of nine dimensions. Changes to receivers and senders were caused by random mutations during the course of the simulation. Whereas it paid both types of senders to elicit the same response from the receiver, it benefited the receiver to respond in this way only towards one of the sender types. The receiver was thus in conflict with one of the senders, e.g. as in Batesian mimicry. Monotonically increasing response gradients caused the appearance of the model and the mimic to move in the same direction. Mimicry evolved because the mimic approached the model faster than the model moved away. Even after mimicry was established the model and the mimic were constantly changing in appearance. Our results conform with what is known in comparative psychology and ethology about how animals respond to stimuli. Several of our results arc a direct consequence of recognition and have not, to our knowledge, been reported before, showing the importance of considering the recognition mechanism in detail when studying mimicry.     

Mutualistic mimicry enhances species diversification through spatial segregation and extension of the ecological niche space

Species richness varies among clades, yet the drivers of diversification creating this variation remain poorly understood. While abiotic factors likely drive some of the variation in species richness, ecological interactions may also contribute. Here, we examine one class of potential contributors to species richness variation that is particularly poorly understood: mutualistic interactions. We aim to elucidate large‐scale patterns of diversification mediated by mutualistic interactions using a spatially explicit population‐based model. We focus on mutualistic Müllerian mimicry between conspicuous toxic prey species, where convergence in color patterns emerges from predators' learning process. To investigate the effects of Müllerian mimicry on species diversification, we assume that some speciation events stem from shifts in ecological niches, and can also be associated with shift in mimetic color pattern. Through the emergence of spatial mosaics of mimetic color patterns, Müllerian mimicry constrains the geographical distribution of species and allows different species occupying similar ecological niches to exist simultaneously in different regions. Müllerian mimicry and the resulting spatial segregation of mimetic color patterns thus generate more balanced phylogenetic trees and increase overall species diversity. Our study sheds light on complex effects of Müllerian mimicry on ecological, spatial, and phylogenetic diversification.     

The evolution of imperfect mimicry

Examples of imperfect resemblance between Batesian mimics andtheir models appear widespread in the natural world, but sofar few quantitative models have been proposed to explain thephenomenon. I used a simple signal detection model to showthat the relationship between model—mimic similarity and mimic effectiveness is typically nonlinear. In particular, Ifound that there will be little or no further selection toimprove model—mimic resemblance beyond a certain levelif the model species is costly to attack, if the mimic speciesis not particularly profitable (e.g., hard to catch), or ifthe mimic is relatively rare. When there are two different sympatricmodel species, then mimics should usually evolve a phenotypicsimilarity to one or the other model species, but not to both.In contrast, when several model species occur in differentareas (or emerge at different times) and individual mimicsuse each of these areas, then the optimal phenotype should bea "jack-of-all-trades" intermediate phenotype that does notclosely resemble any particular model species. Somewhat surprisingly,the theory predicts that if mimics spend an equal amount oftime with each model species, then the optimal intermediatephenotype should more closely resemble the least numerous andleast noxious model. This phenomenon arises because a vague similarity to an extremely noxious species is usually sufficientto guarantee significant protection, whereas a much closerresemblance to a mildly noxious model species is necessaryto afford a similar level of benefit.     

Aggressive mimicry in neonates of the sidewinder rattlesnake,Crotalus cerastes (Serpentes: Viperidae): stimulus control and visual perception of prey luring

Aggressive mimicry in vertebrates remains understudied relative to other categories of mimetic systems, such as Batesian mimicry. Prey attraction through caudal luring (CL) is a type of aggressive mimicry that constitutes a tripartite relationship in which a predator (mimic, S2), typically a snake, produces a highly specific tail display in the presence of a prey species (receiver or operator, R) to produce a resemblance to a prey animal (model, S1), such as a worm or insect, that the receiver mistakes for food and attempts to capture. Most reports of CL in snakes, however, are not hypothesis‐based and provide limited information on the cognitive interplay between predator and prey. In two experiments, CL was studied using a large sample (N = 40) of neonatal sidewinder rattlesnakes (Crotalus cerastes) and lizards (N = 12 species) to investigate stimulus control and visual perception. In experiment 1, CL was elicited in 110 trials using lizards that were either syntopic (N = 6 species) or nonsympatric (N = 6 species) to C. cerastes, and CL occurred at a significantly greater frequency when using syntopic taxa. Similarly, syntopic lizards were attracted to luring snakes significantly more than their nonsympatric counterparts. The presence of CL in C. cerastes was not ubiquitous and we provide preliminary evidence that this behaviour varies geographically and thus has a genetic basis. In experiment 2, a potential predator (live toad) was introduced to subjects that had been stimulated to lure by means of a prey‐dummy and, in all (N = 8) trials, there was an immediate shift in the behaviour of the snakes. The most notable changes were termination of CL and a transition to species‐typical defensive displays, which included rapid tail vibration and audible rattling in individuals with two (or more) rattle segments. We discuss future directions of CL research in snakes, especially with regard to expanding the types of cognitive tests. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 81–91.     

The evolution of multicomponent mimicry

The relative sizes of phenotypic mutations contributing to evolutionary change has long been the subject of debate. We describe how mimicry research can shed light on this debate, and frame mimicry studies within the general context of macromutationism and micromutationism, and punctuated versus gradual evolution. Balogh and Leimar [Müllerian mimicry: an examination of Fisher's theory of gradual evolutionary change. Proc. Roy. Soc. Lond. B Biol. Sci. 272, 2269-2275] have recently used a model to readdress the question of whether or not mimicry evolves gradually along a single dimension. We extend their approach, and present the first model to consider the effect of predator generalization along multiple components on the evolution of mimicry. We find that the gradual evolution of mimicry becomes increasingly less likely as the number of signal components increases, unless predators generalize widely over all components. However, we show that the contemporary two-step hypothesis (punctuated evolution followed by gradual refinement) can explain the evolution of Müllerian mimicry under all tested conditions. Thus, although the gradual evolution of mimicry is possible, the two-step hypothesis appears more generally applicable.     

A population dynamic model of Batesian mimicry

A population dynamic model of Batesian mimicry, in which populations of both model and mimetic species were considered, was analyzed. The probability of a predator catching prey on each encouter was assumed to depend on the frequency of the mimic. The change in population size of each species was considered to have two components, growth at the intrinsic growth rate and carrying capacity, and reduction by predation. For simplicity in the analyses, three assumptions were made concerning the carrying capacities of each population: (1) with no density effects on the mimic population growth rate; (2) with no density effects on the model species; and (3) with density effects on both species. The first and second cases were solved analytically, whereas the last was, for the most part, investigated numerically. Under assumption (1), two stable equilibria are possible, in which both species either coexist or go to extinction. Under assumption (2), there are also two stable equilibria possible, in which either only the mimic persists or both go to extinction. These results explain the field records of butterflies (Pachliopta aristolochiae and its mimic Papilio polytes) in the Ryukyu Islands, Japan.     

昆虫拟态的历史发展

昆虫的拟态理论是由英国自然学家Bates于1862年提出的,Fisher称其为"达尔文后自然选择最重要的依据之一".大量的科学研究表明,昆虫的拟态行为最晚出现在石炭纪,自那时起昆虫与捕食者、昆虫与植物之间开始出现了共同的演变和进化.拟态的模仿方式一般包括颜色、花纹以及形态,但是也可以单指行为方面,且拟态大部分情况下可能模仿的是一个动物群体或者只是另外一种动物身上的一部分.拟态包括多种定义,不同的定义之间用小同的标准来区分拟态现象和非拟态现象,如贝茨氏拟态、缪勒氏拟态、侵略性拟态和瓦曼氏拟态等.本文从其中广义拟态的角度,对当前不同类群昆虫化石中拟态现象的研究进展进行了简要总结.