On the definition of mimicry

An operational distinction between crypsis and mimicry is made in terms of the cognitive and perceptual systems of signal-receivers. Cryptic organisms specialize in generating information of the type not attended to or filtered out (reference frame) by the receivers, whereas mimetic organisms specialize in producing information (signals) of the type sought out by and of interest to a receiver. Mimicry is defined in terms of a system of three living organisms, model, mimic and operator (signal-receiver), in which the mimic gains in fitness by the operator identifying it with the model. Some advantages and applications of the definition are briefly discussed.     

Understanding Mimicry – with Special Reference to Vocal Mimicry

The term mimicry was introduced to biology in 1862 by Henry Walter Bates in his evolutionary explanation of deceptive communication in nature, based on a three‐part interaction system of a mimicked organism or object (called model), a mimicking organism (called mimic), and one or more organisms as selecting agents. Bates gave two incongruous definitions of mimicry: one from the viewpoint of a natural agent that selects for, and in consequence is deceived by, the close resemblance of a toxic model's warning signal and the similar appearance of a palatable mimic, and another one from the viewpoint of a human taxonomist who under an evolutionary aspect focuses on convergent resemblance between model and mimic. Later definitions of Müllerian (F. Müller), arithmetic (A. Wallace) and social (M. Moynihan) mimicry abolish deception in the natural selecting agent, rely on the convergence criterion alone, fuse the roles of model and mimic but have to accept a mix of homologous and convergent resemblance amongst them for a functional explanation. The definition of vocal mimicry (E. Armstrong) refers to a learned resemblance between mimic and heterospecific model by character duplication (no convergence), so far without known (deceived or not deceived) natural selecting agents. It excludes Batesian vocal mimicry. The functional ethological understanding of mimicry as a tripartite communication system (W. Wickler) is consistent with Bates' concept and accepts deception as key element of Batesian mimicry beyond homologous and convergent resemblances. Deception is seen as caused by the divergence between a sign and its meaning for the natural selecting agent. This understanding covers mimicry in all behaviour domains, provides a generally applicable definition of mimic and model so far missing in any mimicry concept, and it distinguishes – still in line with Henry Bates – cultural from genetically determined model‐mimic‐resemblance; this applies to vocal mimicry in particular. Convergently evolved model‐mimic‐resemblance, not essential in Batesian mimicry but mandatory for its alternatives, marks a fundamental distinction between Batesian mimicry (including Mimesis) and all other conceptualized mimicries and accounts for the non‐existence of a unified meaning of the term mimicry. However, character convergence does not help to explain the mere existence of mimicry phenomena and is irrelevant for their permanence in nature. I therefore propose to remove the convergence argument from any mimicry definition.     

Causes and Consequences of a Lack of Coevolution in Müllerian mimicry

Müllerian mimicry, in which both partners are unpalatable to predators, is often used as an example of a coevolved mutualism. However, it is theoretically possible that some Müllerian mimics are parasitic if a weakly defended mimic benefits at the expense of a more highly defended model, a phenomenon known as ‘quasi-Batesian mimicry’. The theory expounded by Müller and extended here for unequal unpalatability, on the other hand, suggests that quasi-Batesian mimicry should be rare in comparison with classical, or mutualistic Müllerian mimicry. Evolutionarily, quasi-Batesian mimicry has consequences similar to classical Batesian mimicry, including unilateral ‘advergence’ of the mimic to the model, and diversifying frequency-dependent selection on the mimic which may lead to mimetic polymorphism. In this paper, theory and empirical evidence for mutual benefit and coevolution in Müllerian mimicry are reviewed. I use examples from well-known insect Müllerian mimicry complexes: the Limenitis–Danaus (Nymphalidae) system in North America, the Bombus–Psithyrus (Apidae) system in the north temperate zone, and the Heliconius–Laparus (Nymphalidae) system in tropical America. These give abundant evidence for unilateral advergence, and no convincing evidence, to my knowledge, for coevolved mutual convergence. Furthermore, mimetic polymorphisms are not uncommon. Yet classical mutualistic Müllerian mimicry, coupled with spatial (and possibly temporal) variation in model abundances convincingly explain these apparent anomalies without recourse to a quasi-Batesian explanation. Nevertheless, the case against classical Müllerian mimicry is not totally disproved, and should be investigated further. I hope that this tentative analysis of actual mimicry rings may encourage others to look for evidence of coevolution and quasi-Batesian effects in a variety of other Müllerian mimicry systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

Aggressive mimics profit from a model-signal receiver mutualism

Mimetic species have evolved to resemble other species to avoid predation (protective mimicry) or gain access to food (aggressive mimicry). Mimicry systems are frequently tripartite interactions involving a mimic, model and 'signal receiver'. Changes in the strength of the relationship between model and signal receiver, owing to shifting environmental conditions, for example, can affect the success of mimics in protective mimicry systems. Here, we show that an experimentally induced shift in the strength of the relationship between a model (bluestreak cleaner fish, Labroides dimidiatus) and a signal receiver (staghorn damselfish, Amblyglyphidodon curacao) resulted in increased foraging success for an aggressive mimic (bluestriped fangblenny, Plagiotremus rhinorhynchos). When the parasite loads of staghorn damselfish clients were experimentally increased, the attack success of bluestriped fangblenny on damselfish also increased. Enhanced mimic success appeared to be due to relaxation of vigilance by parasitized clients, which sought cleaners more eagerly and had lower overall aggression levels. Signal receivers may therefore be more tolerant of and/or more vulnerable to attacks from aggressive mimics when the net benefit of interacting with their models is high. Changes in environmental conditions that cause shifts in the net benefits accrued by models and signal receivers may have important implications for the persistence of aggressive mimicry systems.     

Vocal mimicry in spotted bowerbirds is associated with an alarming context

Although the presence of vocal mimicry in songbirds is well documented, the function of such impressive copying is poorly understood. One explanation for mimicry in species that predominantly mimic alarm calls and predator vocal isations is that these birds use mimicry to confuse or deter potential threats or intruders, so these vocalisations should therefore be produced when the mimic is alarmed and be uncommon in other contexts. Male bowerbirds construct bowers to display to females and anecdotal reports from the Ptilonorhynchus genus suggest that males mimic alarm sounds when disturbed at their bowers. We quantified and compared the rate of mimicry during disturbance to the bower by a human and in naturally occurring social contexts in a population of spotted bowerbirds Ptilonorhynchus maculatus. Male bowerbirds produced mimicry more than thirty times more frequently in response to bower disturbance than they did in any other context. Neither conspecifics nor heterospecifics were attracted to the bower area by mimicry. These data are consistent with the hypothesis that the production of mimicry is associated with a response to an alarming situation. Additionally, the predominance of alarm mimicry by spotted bowerbirds raises the possibility that the birds learn these sounds when they experience alarming situations and they reproduce them in subsequent alarming situations.     

Distance-dependent costs and benefits of aggressive mimicry in a cleaning symbiosis

In aggressive mimicry, a 'predatory' species resembles a model that is harmless or beneficial to a third species, the 'dupe'. We tested critical predictions of Batesian mimicry models, i.e. that benefits of mimicry to mimics and costs of mimicry to models should be experienced only when model and mimic co-occur, in an aggressive mimicry system involving juvenile bluestreaked cleaner wrasse (Labroides dimidiatus) as models and bluestriped fangblennies (Plagiotremus rhinorhynchos) as mimics. Cleanerfish mimics encountered nearly twice as many potential victims and had higher striking rates when in proximity to than when away from the model. Conversely, in the presence of mimics, juvenile cleaner wrasses were visited by fewer clients and spent significantly less time foraging. The benefits to mimic and costs to model thus depend on a close spatial association between model and mimic. Batesian mimicry theory may therefore provide a useful initial framework to understand aggressive mimicry.     

REVISING A CLASSIC BUTTERFLY MIMICRY SCENARIO: DEMONSTRATION OF MÜLLERIAN MIMICRY BETWEEN FLORIDA VICEROYS (LIMENITIS ARCHIPPUS FLORIDENSIS) AND QUEENS (DANAUS GILIPPUS BERENICE)

Batesian and Müllerian mimicry relationships differ greatly in terms of selective pressures affecting the participants; hence, accurately characterizing a mimetic interaction is a crucial prerequisite to understanding the selective milieux of model, mimic, and predator. Florida viceroy butterflies (Limenitis archippus floridensis) are conventionally characterized as palatable Batesian mimics of distasteful Florida queens (Danaus gilippus berenice). However, recent experiments indicate that both butterflies are moderately distasteful, suggesting they may be Müllerian comimics. To directly test whether the butterflies exemplify Müllerian mimicry, I performed two reciprocal experiments using red-winged blackbird predators. In Experiment 1, each of eight birds was exposed to a series of eight queens as “models,” then offered four choice trials involving a viceroy (the putative “mimic”) versus a novel alternative butterfly. If mimicry was effective, viceroys should be attacked less than alternatives. I also compared the birds' reactions to solo viceroy “mimics” offered before and after queen models, hypothesizing that attack rate on the viceroy would decrease after birds had been exposed to queen models. In Experiment 2, 12 birds were tested with viceroys as models and queens as putative mimics. The experiments revealed that (1) viceroys and queens offered as models were both moderately unpalatable (only 16% entirely eaten), (2) some birds apparently developed conditioned aversions to viceroy or queen models after only eight exposures, (3) in the subsequent choice trials, viceroy and queen “mimics” were attacked significantly less than alternatives, and (4) solo postmodel mimics were attacked significantly less than solo premodel mimics. Therefore, under these experimental conditions, sampled Florida viceroys and queens are comimics and exemplify Müllerian, not Batesian, mimicry. This compels a reassessment of selective forces affecting the butterflies and their predators, and sets the stage for a broader empirical investigation of the ecological and evolutionary dynamics of mimicry.     

Natural selection in mimicry

Biological mimicry has served as a salient example of natural selection for over a century, providing us with a dazzling array of very different examples across many unrelated taxa. We provide a conceptual framework that brings together apparently disparate examples of mimicry in a single model for the purpose of comparing how natural selection affects models, mimics and signal receivers across different interactions. We first analyse how model–mimic resemblance likely affects the fitness of models, mimics and receivers across diverse examples. These include classic Batesian and Müllerian butterfly systems, nectarless orchids that mimic Hymenoptera or nectar‐producing plants, caterpillars that mimic inert objects unlikely to be perceived as food, plants that mimic abiotic objects like carrion or dung and aggressive mimicry where predators mimic food items of their own prey. From this, we construct a conceptual framework of the selective forces that form the basis of all mimetic interactions. These interactions between models, mimics and receivers may follow four possible evolutionary pathways in terms of the direction of selection resulting from model–mimic resemblance. Two of these pathways correspond to the selective pressures associated with what is widely regarded as Batesian and Müllerian mimicry. The other two pathways suggest mimetic interactions underpinned by distinct selective pressures that have largely remained unrecognized. Each pathway is characterized by theoretical differences in how model–mimic resemblance influences the direction of selection acting on mimics, models and signal receivers, and the potential for consequent (co)evolutionary relationships between these three protagonists. The final part of this review describes how selective forces generated through model–mimic resemblance can be opposed by the basic ecology of interacting organisms and how those forces may affect the symmetry, strength and likelihood of (co)evolution between the three protagonists within the confines of the four broad evolutionary possibilities. We provide a clear and pragmatic visualization of selection pressures that portrays how different mimicry types may evolve. This conceptual framework provides clarity on how different selective forces acting on mimics, models and receivers are likely to interact and ultimately shape the evolutionary pathways taken by mimetic interactions, as well as the constraints inherent within these interactions.     

Becoming a Sign: The Mimic’s Activity in Biological Mimicry

From a semiotic perspective biological mimicry can be described as a tripartite system with a double structure that consists of ecological relations between species and semiotic relations of sign. In this article the focus is on the mimic who is the individual benefiting from its resemblance to the cues or signals of other species or to the environment. In establishing the mimetic resemblance the question of mimic’s activity becomes crucial, and the activity can range from the fixed bodily patterns to fully dynamic behavioural displays. The mimic’s activity can be targeted at two other participants of the mimicry system—either at the model or at the receiver. The first possibility is quite common in camouflage and there are several possibilities for mimic’s activity to occur: selecting a resting place or habitat based on conformity with the environment, changing body coloration to correspond to the surrounding environment, covering oneself with particles of the soil. In its activity aimed at the model, the mimic develops a strong semiotic connection with its specific perceptual environment or part of it and obtains a representational character. In the second possibility the activity of a mimetic organism is aimed at the receiver who is confused by the resemblance, and between the two participants an active communicative interaction is established. Such type of mimicry can be exemplified by abstract threat displays found in various groups of animals, for instance a toad’s upright posture as a response to the presence of a snake. From the semiotic viewpoint it can be interpreted as the motive of fear in the predator’s Umwelt being entered into the mimic’s subjective world and manifested in its behaviour. The mimetic organism ends up in an ambiguous position, where it needs to pretend to be something other than it is. In the final part of the article it is argued that the mimetic sign is basically a false designator as the mimic’s activity to become a sign is aimed at a specific type of signs. Rather than signifying belonging to its own species or group, a mimetic sign indicates that its carrier belongs to the type of some other species. The tension between the form and behaviour of mimetic organisms arises from the discrepancy between the type of organism that it essentially is and the type of organism that the mimetic sign it carries imposes on it.     

Facultative mimicry: cues for colour change and colour accuracy in a coral reef fish

Mimetic species evolve colours and body patterns to closely resemble poisonous species and thus avoid predation (Batesian mimicry), or resemble beneficial or harmless species in order to approach and attack prey (aggressive mimicry). Facultative mimicry, the ability to switch between mimic and non-mimic colours at will, is uncommon in the animal kingdom, but has been shown in a cephalopod, and recently in a marine fish, the bluestriped fangblenny Plagiotremus rhinorhynchos, an aggressive mimic of the juvenile cleaner fish Labroides dimidiatus. Here we demonstrate for the first time that fangblennies adopted mimic colours in the presence of juvenile cleaner fish; however, this only occurred in smaller individuals. Field data indicated that when juvenile cleaner fish were abundant, the proportion of mimic to non-mimic fangblennies was greater, suggesting that fangblennies adopt their mimic disguise depending on the availability of cleaner fish. Finally, measurements of spectral reflectance suggest that not only do mimic fangblennies accurately resemble the colour of their cleaner fish models but also mimic other species of fish that they associate with. This study provides insights into the cues that control this remarkable facultative mimicry system and qualitatively measures its accuracy.     

Perspectives and Debates: Mimicry,Signalling and Co‐Evolution (Commentary on Wolfgang Wickler – Understanding Mimicry – With special reference to vocal mimicry)

In his stimulating discussion, Wolfgang Wickler criticizes fuzzy usage of term mimicry by drawing attention to its original definition by H. Bates. Mimicry refers to functional ‘model–mimic–selecting agent’ trinity (with varying number of species involved) when the selecting agent (i.e. signal receiver) responds similarly to mimic and model to the advantage of the mimic. Concurring with Wickler I argue that convergence is neither necessary nor sufficient to support similarity as evidence for mimicry and that it is artificial and unproductive to classify mimicry with respect to ontogeny (innate vs. learned similarity) or model species identity (learning from conspecifics vs. heterospecifics). Using butterfly ‘eye’‐spots, I argue that just identifying each of the supposed model, the mimic and the selective agent, and even demonstrating that mimic‐model similarity affects the agent's behaviour, provides no conclusive evidence for mimicry. Even a demonstration that the mimic benefits from receiver response may not provide conclusive evidence for mimicry. Using avian brood parasite–host egg and nestling mimicry, I emphasize that without experimental manipulation of the hypothesized mimetic traits, it is impossible to test the mimicry hypothesis robustly. Due to fundamental constraints on human perception, some cases of mimicry may in fact be just a by‐product of human inability to perceive relevant differences between animal phenotypes (what is similar for human eye, nose or ear may not be viewed, smelled or heard as similar for relevant animal observers), whereas many cases of real mimicry may escape our attention from the same reason (‘hidden’ mimicry). Surprisingly, the same mimetic phenotype may show completely different effects on selective agents under different ecological circumstances. Finally, relatively dissimilar species may be more mimetic than highly similar model–mimic pairs because mimicry may be more fruitfully understood as a co‐evolutionary process rather than a similarity.     

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 mimicry under constraints

The resemblance between mimetic organisms and their models varies from near perfect to very crude. One possible explanation, which has received surprisingly little attention, is that evolution can improve mimicry only at some cost to the mimetic organism. In this article, an evolutionary game theory model of mimicry is presented that incorporates such constraints. The model generates novel and testable predictions. First, Batesian mimics that are very common and/or mimic very weakly defended models should evolve either inaccurate mimicry (by stabilizing selection) or mimetic polymorphism. Second, Batesian mimics that are very common and/or mimic very weakly defended models are more likely to evolve mimetic polymorphism if they encounter predators at high rates and/or are bad at evading predator attacks. The model also examines how cognitive constraints acting on signal receivers may help determine evolutionarily stable levels of mimicry. Surprisingly, improved discrimination abilities among signal receivers may sometimes select for less accurate mimicry.     

Mimicry in plant-parasitic fungi

Mimicry is the close resemblance of one living organism (the mimic) to another (the model), leading to misidentification by a third organism (the operator). Similar to other organism groups, certain species of plant-parasitic fungi are known to engage in mimetic relationships, thereby increasing their fitness. In some cases, fungal infection can lead to the formation of flower mimics (pseudo flowers) that attract insect pollinators via visual and/or olfactory cues; these insects then either transmit fungal gametes to accomplish outcrossing (e.g. in some heterothallic rust fungi belonging to the genera Puccinia and Uromyces) or vector infectious spores to healthy plants, thereby spreading disease (e.g. in the anther smut fungus Microbotryum violaceum and the mummy berry pathogen Monilinia vaccinii-corymbosi). In what is termed aggressive mimicry, some specialized plant-parasitic fungi are able to mimic host structures or host molecules to gain access to resources. An example is M. vaccinii-corymbosi, whose conidia and germ tubes, respectively, mimic host pollen grains and pollen tubes anatomically and physiologically, allowing the pathogen to gain entry into the host's ovary via stigma and style. We review these and other examples of mimicry by plant-parasitic fungi and some of the mechanisms, signals, and evolutionary implications.     

Juvenile Snooks (Centropomidae) as Mimics of Mojarras (Gerreidae), with a Review of Aggressive Mimicry in Fishes

Aggressive mimicry has been proposed for several unrelated fish species both in freshwater and marine environments. I describe herein a few additional examples, including the first ones from brackish water. In one well documented case, juvenile snooks, Centropomus mexicanus (Centropomidae) join bottom-foraging groups of the superficially similar mojarras, Eucinostomus melanopterus (Gerreidae) and prey on small fishes and crustaceans under such disguise. Two other snook species and two species of groupers (Serranidae), are here suggested as additional instances of aggressive mimicry. Furthermore, I review published examples of aggressive mimicry in fishes and indicate trends in the relationships between the mimics, their feeding tactics, and their putative models. Three large families, Serranidae, Cichlidae, and Blenniidae display most of the examples of aggressive mimicry, serranids being largely represented by the genus Hypoplectrus and blenniids by the tribe Nemophini only. Three major trends are here indicated for aggressive mimics: (1) fish species that feed on prey smaller than themselves tend to mimic and join fish species harmless to their prospective prey; (2) fish species that feed on prey larger than themselves tend to mimic mostly beneficial fish species (cleaners) or, less frequently, join species harmless to their prospective prey; (3) fish species that feed on prey about their own size tend to mimic their prospective prey species, the perfect wolf in a sheep's clothes disguise type. The latter deceit is recorded mostly for scale and fin-feeding freshwater fishes.     

Context-dependent vocal mimicry in a passerine bird

How do birds select the sounds they mimic, and in what contexts do they use vocal mimicry? Some birds show a preference for mimicking other species' alarm notes, especially in situations when they appear to be alarmed. Yet no study has demonstrated that birds change the call types they mimic with changing contexts. We found that greater racket-tailed drongos (Dicrurus paradiseus) in the rainforest of Sri Lanka mimic the calls of predators and the alarm-associated calls of other species more often than would be expected from the frequency of these sounds in the acoustic environment. Drongos include this alarm-associated mimicry in their own alarm vocalizations, while incorporating other species' songs and contact calls in their own songs. Drongos show an additional level of context specificity by mimicking other species' ground predator-specific call types when mobbing. We suggest that drongos learn other species' calls and their contexts while interacting with these species in mixed flocks. The drongos' behaviour demonstrates that alarm-associated calls can have learned components, and that birds can learn the appropriate usage of calls that encode different types of information.     

A hypothesis to explain accuracy of wasp resemblances

Mimicry is one of the oldest concepts in biology, but it still presents many puzzles and continues to be widely debated. Simulation of wasps with a yellow‐black abdominal pattern by other insects (commonly called “wasp mimicry”) is traditionally considered a case of resemblance of unprofitable by profitable prey causing educated predators to avoid models and mimics to the advantage of both (Figure 1a). However, as wasps themselves are predators of insects, wasp mimicry can also be seen as a case of resemblance to one's own potential antagonist. We here propose an additional hypothesis to Batesian and Müllerian mimicry (both typically involving selection by learning vertebrate predators; cf. Table 1) that reflects another possible scenario for the evolution of multifold and in particular very accurate resemblances to wasps: an innate, visual inhibition of aggression among look‐alike wasps, based on their social organization and high abundance. We argue that wasp species resembling each other need not only be Müllerian mutualists and that other insects resembling wasps need not only be Batesian mimics, but an innate ability of wasps to recognize each other during hunting is the driver in the evolution of a distinct kind of masquerade, in which model, mimic, and selecting agent belong to one or several species (Figure  1b). Wasp mimics resemble wasps not (only) to be mistaken by educated predators but rather, or in addition, to escape attack from their wasp models. Within a given ecosystem, there will be selection pressures leading to masquerade driven by wasps and/or to mimicry driven by other predators that have to learn to avoid them. Different pressures by guilds of these two types of selective agents could explain the widely differing fidelity with respect to the models in assemblages of yellow jackets and yellow jacket look‐alikes.     

An overview of the relationships between mimicry and crypsis

There have been many different and conflicting definitions of mimicry. Some of the definitions of mimicry include crypsis and others do not. Each definition includes different groups of phenomena and uses different criteria to distinguish mimetic from non-mimetic phenomena. The confusion is eliminated by a consideration of the criteria of all definitions. This shows that there are in fact three major criteria dividing six phenomona, rather than a single dichotomy between mimicry and crypsis (Table 2). The criteria are defined by the results of a mistake in discrimination between the model and mimìc: (a) the mistake does or does not depend upon relationship between mimic and background; (b) the mistake has or has no effect on the population dynamics or evolution of the model and (c) the mistake affects dynamics or evolution of one or of many models. The main reason for the contusion about mimicry and crypsis is that each author's definition includes differing and partially overlapping subsets of the six classes: crypsis; masquerade; Batesism; Müllerism; polymorphism and convergence.     

Batesian mimics influence mimicry ring evolution

Mathematical models of mimicry typically involve artificial prey species with fixed colorations or appearances; this enables a comparison of predation rates to demonstrate the level of protection a mimic might be afforded. Fruitful theoretical results have been produced using this method, but it is also useful to examine the possible evolutionary consequences of mimicry. To that end, we present individual-based evolutionary simulation models where prey colorations are free to evolve. We use the models to examine the effect of Batesian mimics on Müllerian mimics and mimicry rings. Results show that Batesian mimics can potentially incite Müllerian mimicry relationships and encourage mimicry ring convergence.     

A preliminary revision of the supraspecific classification of Kobresia Willd. (Cyperaceae)

Previous supraspecific classifications of the genus Kobresia are evaluated. The evolution of the genus is discussed, and a preliminary revised supraspecific classification based on putative evolution is proposed. Previous classifications were mostly based on inflorescence characters. The spicate inflorescence might have evolved in parallel from a paniculate one, and unisexual spikelet might also be the result of parallel evolution from bisexual spikelets. Therefore, the subgenera or sections Elyna and Hemicarex , which were recognized by previous authors and characterized by the spicate inflorescence (the former with bisexual spikelets and the latter with unisexual ones), may be polyphyletic. In the classification presented here, three subgenera are recognized. A new subgenus Blysmocarex (N. A. Ivanova) S. R. Zhang is proposed. A key to subgenera and sections is included, and types, synonymies and representative species are given under each supraspecific rank.