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Animal Communication

Animal communication

Animal communication is any behaviour on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication, called zoosemiotics (distinguishable from anthroposemiotics, the study of human communication) has played an important part in the development of ethology, sociobiology, and the study of animal cognition. [http://acp.eugraph.com The Animal Communication Project] includes an overview of the science of animal communication (text from the book The Language of Animals) and updates about current scientific research on animal communication.

Intraspecies vs. interspecies communication

The sender and receiver of a communication may be of the same species or of different species. The majority of animal communication is intraspecific (between two or more individuals of the same species). However, there are some important instances of interspecific communication. Also, the possibility of interspecific communication, and the form it takes, is an important test of some theoretical models of animal communication.

Interspecies communication

Prey to predator

If a prey animal moves or makes a noise in such a way that a predator can detect and capture it, that fits the definition of "communication" given above. Nonetheless, we do not feel comfortable talking about it as communication. Our discomfort suggests that we should modify the definition of communication in some way, either by saying that communication should generally be to the adaptive advantage of the communicator, or by saying that it involves something more than the inevitable consequence of the animal going about its ordinary life. There are however some actions of prey species that are clearly communications to actual or potential predators. A good example is warning colouration: species such as wasps that are capable of harming potential predators are often brightly coloured, and this modifies the behaviour of the predator, who either instinctively or as the result of experience will avoid attacking such an animal. Some forms of mimicry fall in the same category: for example hoverflies are coloured in the same way as wasps, and although they are unable to sting, the strong avoidance of wasps by predators gives the hoverfly some protection. There are also behavioral changes that act in a similar way to warning colouration. For example, canines such as wolves and coyotes may adopt an aggressive posture, such as growling with their teeth bared, to indicate they will fight if necessary, and rattlesnakes use their well-known rattle to warn potential predators of their poisonous bite. Sometimes, a behavioral change and warning colouration will be combined, as in certain species of amphibians which have a brightly coloured belly, but on which the rest of their body is coloured to blend in with their surroundings. When confronted with a potential threat, they show their belly, indicating that they are poisonous in some way. A more controversial example of prey to predator communication is stotting, a highly noticeable form of running shown by some antelopes such as Thomson's gazelle in the presence of a predator; it has been argued that this demonstrates to the predator that the particular prey individual is fit and healthy and therefore not worth pursuing.

Predator to prey

Some predators communicate to prey in ways that change their behaviour and make them easier to catch, in effect deceiving them. A well-known example is the angler fish, which has a fleshy growth protruding from its forehead and dangling in front of its jaws; smaller fishes try to take the lure, and in so doing are perfectly placed for the angler fish to eat them.

Symbiotic species

Interspecies communication also occurs in various kinds of mutualism and symbiosis. For example, in the cleaner fish/grouper system, groupers signal their availability for cleaning by adopting a particular posture.

Human/animal communication

Various ways in which humans interpret the behaviour of domestic animals, or give commands to them, fit the definition of interspecific communication. Depending on the context, they might be considered to be predator to prey communication, or to reflect forms of commensalism. The recent experiments on animal language are perhaps the most sophisticated attempt yet to establish human/animal communication, though their relation to natural animal communication is uncertain.

Intraspecies communication

The majority of animal communication, however, occurs within a single species, and this is the context in which it has been most intensively studied.

Forms of communication

Most of the following forms of communication can also be used for interspecific communication. The best known forms of communication involve the display of distinctive body parts, or distinctive bodily movements; often these occur in combination, so a distinctive movement acts to reveal or emphasise a distinctive body part. An example that was important in the history of ethology was the parent Herring Gull's presentation of its bill to a chick in the nest. Like many gulls, the Herring Gull has a brightly coloured bill, yellow with a red spot on the lower mandible near the tip. When it returns to the nest with food, the parent stands over its chick and taps the bill on the ground in front of it; this elicits a begging response from a hungry chick (pecking at the red spot), which stimulates the parent to regurgitate food in front of it. The complete signal therefore involves a distinctive morphological feature (body part), the red-spotted bill, and a distinctive movement (tapping towards the ground) which makes the red spot highly visible to the chick. Investigations by Niko Tinbergen and his colleagues showed that the red colour of the bill, and its high contrast, are crucial for eliciting the appropriate response from the chick (It is unresolved whether this actually is an inborn behavior in all its complexity, or simply a combination of generalized curiosity on part of the chick, and generalized parental/feeding instincts acting together to produce a simple learning process via reward. Gull chicks peck at everything that is brightly colored, mainly red, yellow, white or shining, high-contrast objects, but the parent's bill is the only such object that will constantly yield food as a reward when pecked at. Accidental swallowing of pieces of brightly colored plastic or glass is a common cause of mortality amongst gull chicks). Another important forms of communication is bird song, usually performed mainly by males, though in some species the sexes sing in alternation (this is called duetting and serves mainly purposes of strengthening pair-bonding and repelling competitors). Bird song is just the best known case of vocal communication; other instances include the warning cries of many monkeys, the territorial calls of gibbons, and the mating calls of many species of frog. Less obvious (except in a few cases) is olfactory communication. Many mammals, in particular, have glands that generate distinctive and long-lasting smells, and have corresponding behaviours that leave these smells in places where they have been. Often the scented substance is introduced into urine or feces. Sometimes it is distributed through sweat, though this does not leave a semi-permanent mark as scents deposited on the ground do. Some animals have glands on their bodies whose sole function appears to be to deposit scent marks: for example Mongolian gerbils have a scent gland on their stomachs, and a characteristic ventral rubbing action that deposits scent from it. Golden hamsters and cats have scent glands on their flanks, and deposit scent by rubbing their sides against objects; cats also have scent glands on their foreheads. Bees carry with them a pouch of material from the hive which they release as they reenter, the smell of which indicates if they are a part of the hive and grants their safe entry.

Functions of communication

While there are as many kinds of communication as there are kinds of social behaviour, a number of functions have been studied in particular detail. They include:
- agonistic interaction: everything to do with contests and aggression between individuals. Many species have distinctive threat displays that are made during competition over food, mates or territory; much bird song functions in this way. Often there is a matched submission display, which the threatened individual will make if it is acknowledging the social dominance of the threatener; this has the effect of terminating the aggressive episode and allowing the dominant animal unrestricted access to the resource in dispute. Some species also have affiliative displays which are made to indicate that a dominant animal accepts the presence of another
- courtship rituals: signals made by members of one sex to attract or maintain the attention of potential mate, or to cement a pair bond. These frequently involve the display of body parts, body postures (gazelles assume characteristic poses as a signal to initiate mating), or the emission of scents or calls, that are unique to the species, thus allowing the individuals to avoid mating with members of another species which would be infertile. Animals that form lasting pair bonds often have symmetrical displays that they make to each other: famous examples are the mutual presentation of weed by Great-Crested Grebes, studied by Julian Huxley, the triumph displays shown by many species of geese and penguins on their nest sites and the spectacular courtship displays by birds of paradise and manakins.
- food-related signals: many animals make "food calls" that attract a mate, or offspring, or members of a social group generally to a food source. When parents are feeding offspring, the offspring often have begging responses (particularly when there are many offspring in a clutch or litter - this is well known in altricial songbirds, for example). Perhaps the most elaborate food-related signal is the dance language of honeybees studied by Karl von Frisch.
- alarm calls: signals made in the presence of a threat from a predator, allowing all members of a social group (and often members of other species) to run for cover, become immobile, or gather into a group to reduce the risk of attack.
- metacommunications: signals that modify the meaning of subsequent signals. The best known example is the play face in dogs, which signals that a subsequent aggressive signal is part of a play fight rather than a serious aggressive episode.

Evolution of communication

The importance of communication is clear from the fact that animals have evolved elaborate body parts to facilitate it. They include some of the most striking structures in the animal kingdom, such as the peacock's tail. Birdsong appears to have not just peripheral but also brain structures entirely devoted to its production. But even the red spot on a herring gull's bill, and the modest but characteristic bowing behaviour that displays it, require evolutionary explanation. There are two aspects to the required explanation:
- identifying a route by which an animal that lacked the relevant feature or behaviour could acquire it;
- identifying the selective pressure that makes it adaptive for animals to develop structures that facilitate communication, emit communications, and respond to them. Significant contributions to the first of these problems were made by Konrad Lorenz and other early ethologists. By comparing related species within groups, they showed that movements and body parts that in the primitive forms had no communicative function could be "captured" in a context where communication would be functional for one or both partners, and could evolve into a more elaborate, specialised form. For example, Desmond Morris showed in a study of grass finches that a beak-wiping response occurred in a range of species, serving a preening function, but that in some species this had been elaborated into a courtship signal. The second problem has been more controversial. The early ethologists assumed that communication occurred for the good of the species as a whole, but this would require a process of group selection which is believed to be mathematically impossible in the evolution of sexually reproducing animals. It was the fundamental insight of sociobiology that behaviours that benefited a whole group of animals might emerge as a result of selection pressures acting solely on the individual. In the case of communication, an important discussion by John R. Krebs and Richard Dawkins established hypotheses for the evolution of such apparently altruistic or mutualistic communications as alarm calls and courtship signals to emerge under individual selection. This led to the realisation that communication might not always be "honest" (indeed, there are some obvious examples where it is not, as in mimicry). The possibility of evolutionarily stable dishonest communication has been the subject of much controversy, with Amotz Zahavi in particular arguing that it cannot exist in the long term. Sociobiologists have also been concerned with the evolution of apparently excessive signalling structures such as the peacock's tail; it is widely thought that these can only emerge as a result of sexual selection, which can create a positive feedback process that leads to the rapid exaggeration of a characteristic that confers an advantage in a competitive mate-selection situation.

Communication and understanding

Ethologists and sociobiologists have characteristically analysed animal communication in terms of more or less automatic responses to stimuli, without raising the question of whether the animals concerned understand the meaning of the signals they emit and receive. That is a key question in animal cognition. There are some signalling systems that seem to demand a more advanced understanding. A much discussed example is the use of alarm calls by vervet monkeys. Richard Seyfarth and Dorothy Cheney showed that these animals emit different alarm calls in the presence of different predators (leopards, eagles, and snakes), and the monkeys that hear the calls respond appropriately - but that this ability develops over time, and also takes into account the experience of the individual emitting the call. Metacommunication, discussed above, also seems to require a more sophisticated cognitive process.

Animal communication and human behaviour

Another controversial issue is the extent to which humans have behaviours that resemble animal communication, or whether all such communication has disappeared as a result of our linguistic capacity. Some of our bodily features - eyebrows, beards and moustaches, deep adult male voices, perhaps female breasts - strongly resemble adaptations to producing signals. Ethologists such as Iraneaus Eibl-Eibesfeldt have argued that facial gestures such as smiling, grimacing, and the eye-brow flash on greeting are universal human communicative signals that can be related to corresponding signals in other primates. Given the recency with which spoken language has emerged, it is likely that human body language does include some more or less involuntary responses that have a similar origin to the communication we see in other animals. Humans also often seek to mimic animals' communicative signals in order to interact with the animals. For example, cats have a mild affiliative response involving closing their eyes; humans often close their eyes towards a pet cat to establish a tolerant relationship. Stroking, petting and rubbing pet animals are all actions that probably work through their natural patterns of interspecific communication.

Animal communication and linguistics

For linguistics, the interest of animal communication systems lies in their similarities to and differences from human language: #Human languages are characterized for having a double articulation (in the characterization of French linguist André Martinet). It means that complex linguistic expressions can be broken down in meaningful elements (such as morphemes and words), which in turn are composed of smallest meaningless phonetic elements, or phonemes. Animal signals, however, do not exhibit this dual structure. #Animal utterances are generally reflexes of external stimuli and thus are not produced intentionally. They cannot refer to matters removed in time and space (a possible exception is the information conveyed in honeybee dance language). #Human language is learned, while animal communication systems are known largely by instinct. #Human languages combine elements to produce new messages (a property known as creativity). This is not possible in animal communication systems. #In contrast to human language, animal communication systems are not able to express conceptual generalizations.

External link

- [http://www.zoosemiotics.helsinki.fi Zoosemiotics: animal communication on the web] Category:Animal communication Category:Dog training and behavior Category:Cats Category:Semiotics Category:Zoosemiotics

Behaviour

Behavior (or behaviour) refers to the actions or reactions of an object or organism, usually in relation to the environment. Behavior can be conscious or unconscious, overt or covert, and voluntary or involuntary. Behavior is controlled by the endocrine system, and the nervous system. The complexity of the behavior of an organism is related to the complexity of its nervous system. Generally, organisms with complex nervous systems have a greater capacity to learn new responses and thus adjust their behavior. of people (and other organisms or even mechanisms) falls within a range with some behaviors being common, some unusual, some acceptable, and some outside acceptable limits. The acceptablity of behavior is evaluated relative to social norms and regulated by various means of social control. For behavior of people see human behavior. In sociology, behavior is considered as having no meaning, being not directed at other people and thus is the most basic human action. Behavior should not be mistaken with social behavior, which is more advanced action, as social behavior is behavior specifically directed at other people. Animal behavior is studied in comparative psychology, ethology, behavioral ecology and sociobiology.

External link

- [http://www.colorado.edu/epob/epob3730rlynch/01introduction.html Brain and behavior – (EPOB 3730) - University of Colorado]
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Ethology

Ethology is the scientific study of animal behavior considered as a branch of zoology. A scientist who practices ethology is called an ethologist.

Origins of the name

The term “ethology” derives from the Greek language, as ethos (ήθος) is the Greek word for "custom". Other words that derive from the Greek word ethos are: ethics and ethical. The term was first popularised in English by the American Myrmecologist William Morton Wheeler in 1902. An earlier, slightly different sense of the term was proposed by John Stuart Mill in his 1843 System of Logic. He recommended the development of a new science, "ethology," whose purpose would be the explanation of individual and national differences in character, on the basis of associationistic psychology. This use of the word was never adopted, however.

Differences and similarities with comparative psychology

Ethology can be contrasted with comparative psychology, which also studies animal behaviour, but construes its study as a branch of psychology. Thus where comparative psychology sees the study of animal behaviour in the context of what is known about human psychology, ethology sees the study of animal behaviour in the context of what is known about animal anatomy and physiology. Furthermore, early comparative psychologists concentrated on the study of learning, and thus tended to look at behaviour in artificial situations, whereas early ethologists concentrated on behaviour in natural situations, tending to describe it as instinctive. The two approaches are complementary rather than competitive, but they do lead to different perspectives and sometimes to conflicts of opinion about matters of substance. In addition, for most of the twentieth century comparative psychology developed most strongly in North America, while ethology was stronger in Europe, and this led to different emphases as well as somewhat different philosophical underpinnings in the two disciplines. A practical difference is that comparative psychologists concentrated on gaining extensive knowledge of the behaviour of very few species, while ethologists were more interested in gaining knowledge of behaviour in a wide range of species, not least in order to be able to make principled comparisons across taxonomic groups. Ethologists have made much more use of a truly comparative method than comparative psychologists ever have.

Darwinism and the beginnings of ethology

Because ethology is understood as a branch of biology, ethologists have been particularly concerned with the evolution of behaviour and the understanding of behaviour in terms of the theory of natural selection. In one sense the first modern ethologist was Charles Darwin, whose book The expression of the emotions in animals and men influenced many ethologists. However, he pursued his interest in behaviour by encouraging his protégé George Romanes, who investigated animal learning and intelligence using an anthropomorphic method that did not gain scientific support. The early ethologists, such as Oskar Heinroth and Julian Huxley instead concentrated on behaviours that can be called instinctive, or natural, in that they occur in all members of a species under specified circumstances. Their first step in studying the behaviour of a new species was to construct an ethogram, a description of the main types of natural behaviour with their frequencies of occurrence. This approach provided an objective, cumulative base of data about behaviour, which subsequent researchers could check and build on, and as a way of building a science of behaviour, it proved much more fruitful.

The Fixed Action Pattern and animal communication

An important step, associated with the name of Konrad Lorenz though probably due more to his teacher, Heinroth, was the identification of fixed action patterns (FAPs). Lorenz popularized FAPs as instinctive responses that would occur reliably in the presence of identifiable stimuli (called sign stimuli or releasing stimuli). These FAPs could then be compared across species, and the similarities and differences between behaviour compared with the similarities and differences in morphology (biology) on which taxonomy was based. An important and much quoted study of the Anatidae (ducks and geese) by Heinroth used this technique. The ethologists noted that the stimuli that released FAPs were commonly features of the appearance or behaviour of other members of their own species, and they were able to show how important forms of animal communication could be mediated by a few simple FAPs. The most sophisticated investigation of this kind was the study by Karl von Frisch of the so-called “dance language” underlying bee communication. Lorenz developed an interesting theory of the evolution of animal communication based on his observations of the nature of fixed action patterns and the circumstances in which animals emit them.

Imprinting

A second important finding of Lorenz concerned the early learning of young nidifugous birds, a process he called imprinting. Lorenz observed that the young of birds such as geese and chickens spontaneously followed their mothers from almost the first day after they were hatched, and he discovered that this following response could be transferred to an arbitrary stimulus if the eggs were incubated artificially and the stimulus was presented during a critical period (now called a sensitive period) that covered the few days after hatching. The concept of imprinting has been widely adopted in developmental psychology.

Tinbergen's four questions for ethologists

Lorenz’s collaborator, Niko Tinbergen, argued that ethology always needed to pay attention to four kinds of explanation of any instance of behaviour:
- Function: how does the behaviour impact on the animal’s chances of survival and reproduction?
- Causation: what are the stimuli that elicit the response, and how has it been modified by recent learning?
- Development: how does the behaviour change with age, and what early experiences are necessary for the behaviour to be shown?
- Evolutionary history: how does the behaviour compare with similar behaviour in related species, and how might it have arisen through the process of phylogeny?

The flowering of ethology

Through the work of Lorenz and Tinbergen, ethology developed strongly in continental Europe in the years before World War II. After the war, Tinbergen moved to the University of Oxford, and ethology became stronger in the UK, with the additional influence of William Thorpe, Robert Hinde and Patrick Bateson at the Sub-department of Animal Behaviour of the University of Cambridge, located in the village of Madingley. In this period, too, ethology began to develop strongly in North America. Lorenz, Tinbergen, and von Frisch were jointly awarded the Nobel Prize in 1973 for their work in developing ethology.

Social ethology and recent developments

In 1970, the English ethologist John H. Crook published an important paper in which he distinguished comparative ethology from social ethology, and argued that much of the ethology that had existed so far was really comparative ethology, looking at animals as individuals, whereas in the future, ethologists would need to concentrate on the behaviour of social groups of animals and the social structure within them. This was prescient. E. O. Wilson’s book ‘’Sociobiology’’ appeared in 1975, and since that time the study of behaviour has been much more concerned with social aspects. It has also been driven by the stronger, but more sophisticated, Darwinism associated with Wilson and Richard Dawkins. The related development of behavioral ecology has also helped transform ethology. At the same time a substantial rapprochement with comparative psychology has occurred, so the modern scientific study of behaviour offers a more or less seamless spectrum of approaches, from animal cognition, more traditional comparative psychology, ethology, sociobiology and behavioural ecology.

Notes

- There are often mismatches between human senses and those of the organisms they are observing. To compensate, ethologists often reach all the way back to epistemology to give them the tools to predict and avoid misinterpretation of data.

List of ethologists

People who have made notable contributions to the field of ethology:

Animal cognition

Animal cognition is the title given to a modern approach to the mental capacities of animals. It has developed out of comparative psychology, but has also been strongly influenced by the approach of ethology and behavioral ecology. Much of what used to be considered under the title of animal intelligence is now thought of under this heading.

Historical background

For most of the twentieth century, the dominant approach to animal psychology was to use experiments on intelligence in animals to uncover simple processes (such as classical conditioning and operant conditioning) that might then account for the apparently more complex intellectual abilities of human beings. This reductionist philosophy was combined with a strongly behaviorist methodology, in which overt behavior was taken as the only valid data for the study of psychology, and in its more extreme forms (the radical behaviorism of B. F. Skinner and his experimental analysis of behavior) behavior was taken as the only topic of interest. In effect, the mental processes that we experience in ourselves were viewed as epiphenomena. The success of cognitive psychology in addressing human mental processes, from the late 1950s on, led to a re-evaluation of the research paradigm, and researchers began to address animal mental processes from the opposite direction, by taking what is known about human mental processes and looking for evidence of comparable processes in other species. In a sense this was a return to the approach of Darwin's protegé George Romanes, arguably the first comparative psychologist of the modern era. However, whereas Romanes relied heavily on anecdote and an anthropomorphic projection of human capacities onto other species, modern researchers in animal cognition are in most cases firmly behaviorist in methodology, even though they differ sharply from the behaviourist philosophy. There are some exceptions to the rule of behaviourist methodology, such as John Lilly and, some would argue, Donald Griffin, who have been prepared to take a strong position that other animals do have minds and that we should approach the study of their cognition accordingly. However their claims have not found wide acceptance in the scientific community, though they have attracted an enthusiastic following among lay people. The development of animal cognition was also strongly influenced by:
- increased use of and interest in primates (and also cetaceans) rather than the rats and pigeons that had become the classic species of the comparative psychology laboratory, and by developments within primatology;
- advancing knowledge of animals' behaviour in their natural environments through studies in ethology, sociobiology and behavioral ecology; such studies often showed that animals needed certain cognitive abilities in order to adapt to their ecological niche (as for example in studies of caching birds such as Clark's Nutcracker), or appeared to use cognitive abilities under natural conditions (for example in Jane Goodall's studies of chimpanzees);
- one or two high profile projects, in particular Allen and Beatrice Gardner's Washoe project in which a chimpanzee learned at least some elements of American Sign Language.
- advancing understanding of brain function through work in physiological psychology and cognitive neuropsychology This account of the history of the study of animal cognition is inevitably oversimplified. From Romanes on, there have always been comparative psychologists who have been more or less cognitively inclined: obviously examples are Wolfgang Köhler, famous for his studies of insight in chimpanzees, and Edward C. Tolman, who introduced into psychology, as an explanation of the behaviour of rats in mazes, two ideas that have been immensely influential in human cognitive psychology - the cognitive map and the idea of decision-making in risky choice according to expected value.

Methodology

Research in animal cognition continues to use some of the established research techniques of comparative psychology and the experimental analysis of behavior, such as mazes and Skinner boxes, though it employs them in new varieties (such as the 8-arm maze and water maze that have been used in many studies of spatial memory) and in new ways. However it complements those with observation of animals in their natural environments, or quasi-natural environments and also with field experiments. It has also been characterised by a number of very long term projects, such as the Washoe project and other ape-language experiments (e.g. project Nim), Irene Pepperberg's extended series of studies with the African Gray Parrot Alex, and studies of long-term memory in pigeons in which birds were shown to remember pictures for periods of several years. Some researchers have made effective use of a Piagetian methodology, taking tasks which human children are known to master at different stages of development, and investigating which of them can be performed by particular species. Others have been inspired by concerns for animal welfare and the management of domestic species: for example Temple Grandin has harnessed her unique expertise in animal welfare and the ethical treatment of farm livestock to highlight underlying similarites between humans and other animals.

Research questions

Given the broad programme of animal cognition, of looking for the animal analogues of human cognitive processes, the areas of study in animal cognition follow more or less from those in human cognitive psychology. However progress in the different areas has been variable. Among the fields of interest are:

Attention

Research has focused on animals' ability to distribute attention between different aspects of a stimulus, and on visual search. As in humans, it appears that sharing attention between stimulus features reduces the capacity to detect any one of them, though there are some ecologically relevant visual search tasks at which particular species show remarkable abilities (for example, pigeons have an extraordinary capacity to pick out grain from substrate).

Categorisation

Following pioneering research by Richard Herrnstein, there has been a mass of research on birds' ability to discriminate between categories of stimuli, including the kinds of ill-defined category that are used in everyday human speech. Birds have been found to learn this kind of task easily, and to transfer correct responding readily to new instances of the categories.

Memory

The categories that have been developed to analyse human memory (short term memory, long term memory, working memory) have been applied to the study of animal memory, and some of the phenomena characteristic of human short term memory (e.g. the serial position effect) have been detected in animals particularly monkeys. However most progress has been made in the analysis of spatial memory, partly in relation to studies of the physiological basis of spatial memory and the role of the hippocampus, and partly in relation to scatter-hoarding animals such as Clark's Nutcracker, certain jays, and certain squirrels, whose ecological niches require them to remember to locations of thousands of caches, often following radical changes in the environment.

Tool use

There are some species that use particular tools as an essential part of their foraging behaviour, for example the Woodpecker Finch of the Galapagos Islands. However these behaviours are often quite inflexible and cannot be applied effectively in new situations. Several species have now been shown to be capable of more flexible tool use. A well known example is Jane Goodall's observation of chimpanzees "fishing" for termites in their natural environment, and captive great apes are often observed to use tools effectively; several species of corvids have also been trained to use tools in controlled experiments.

Reasoning and problem solving

Closely related to tool use is the study of reasoning and problem solving. Many of the data on these issues come from earlier comparative psychologists such as Wolfgang Köhler, rather than recent experiments. It is clear that animals of quite a range of species are capable of solving a range of problems that are argued to involve abstract reasoning; modern research has tended to show that the performances of Köhler's chimpanzees, who could achieve spontaneous solutions to problems without training, were by no means unique to that species, and that apparently similar behaviour can be found in animals usually thought of as much less intelligent, if appropriate training is given.

Language

In addition to the ape-language experiments mentioned above, there have also been more or less successful attempts to teach language or language-like behaviour to some non-primate species, including cetaceans, the parrot Alex, and Great Spotted Woodpeckers.

Consciousness

The sense in which animals can be said to have consciousness or a self-concept has been hotly debated; it is often referred to as the debate over animal minds. The best known research technique in this area is the mirror test devised by Gordon Gallup, in which an animal's skin is marked in some way while it is asleep or sedated, and it is then allowed to see its reflection in a mirror; if the animal spontaneously directs grooming behaviour towards the mark, that is taken as an indication that it is aware of itself. Self-awareness, by this criterion, has been reported for chimpanzees and also for some other great apes, and some cetaceans, but not for monkeys. However both the interpretation of such data, and the data themselves, remain controversial.

Deception, empathy, and theory of mind

Related to the issue of self-consciousness is the question of whether an animal can show empathy, i.e. can understand what another animal is thinking. It is usually argued that to show empathy requires you to have a theory of mind, i.e. to attribute mental processes to other individuals, and that without a theory of mind it is impossible for an animal or person to show tactical deception. Experiments to test for theory of mind in animals have mainly been carried out on primates. No convincing evidence has been found for theory of mind in any primate species other than the great apes; the interpretation of the data from great apes is currently controversial, but some researchers are convinced that they do show theory of mind.

Continuing controversy

The broad programme of research into animal cognition has achieved a good deal. Nonetheless, its results and philosophy continue to be debated, on a number of grounds:
- Particular issues within animal cognition, particularly the interpretation of language-learning and self-awareness experiments, have generated major controversies both about the extent of the animals' achievements, and about the correct interpretation of the behaviour observed.
- Many non-experts in the field, and a small minority of experts, find the scientific approach too cautious, and feel that it tends to underrate the intellectual achievements of animals by insisting on behavioural evidence. Studies that demonstrate limited intellectual ability in popular species such as dogs, horses, or dolphins are particularly likely to come under this kind of attack.
- Cognitive psychologists interested in work with humans frequently discount studies of animal cognition. To some extent this may be an effect of history - in the 1950s and 1960s cognitive psychology had to struggle to assert itself against the dominance of behaviorism and animal learning, and the attitudes of those days remain entrenched in influential figures in the field.
- Cognitive scientists have been interested in comparing and contrasting human cognition with artificial intelligence or machine cognition, but have been less interested in including animal cognition in the analysis - despite the fact that the common biological origins of human and animal cognition suggest that there might be greater resemblance, at least in some respects, between human and animal cognition than between human and machine cognition. There is also a minority of cognitive scientists who simply neglect accumulated psychological knowledge about cognition, whether animal or human.
- Those psychologists who are committed to radical behaviourism and the experimental analysis of behaviour discount cognitive analyses of animal behaviour. This is not surprising since for the most part they also reject cognitive analyses of human behaviour, and it is perhaps a category error: in so far as the study of animal cognition exposes new behavioural phenomena, it simply provides more that a radical behaviourist must explain without using mentalistic language.

External links

- [http://www.pigeon.psy.tufts.edu/avc/ Avian Visual Cognition, a cyber book edited by Robert G. Cook]

References

- Wynne, C. D. L. (2001). Animal Cognition. Basingstoke: Palgrave
- Sebeok (1990). Essays in Zoosemiotics. Toronto: Toronto Semiotic Circle. ISSN 08385858. Category:Zoosemiotics Category:cognition Category:Animal intelligence Category:Animal cognition

Species

In biology, a species is the basic unit of biodiversity. In scientific classification, a species is assigned a two-part name in Latin. The genus is listed first (and capitalized), followed by a specific epithet. For example, humans belong to the genus Homo, and are in the species Homo sapiens. The name of the species is the whole binomial not just the second term (the specific epithet). The binomial, and most other purely formal aspects of the biological codes of nomenclature, were formalized by Carolus Linnaeus in the 1700's and as a result are called the "Linnaean system". At that time, species were thought to represent independent acts of creation by God, and were therefore considered objectively real and immutable. Since the advent of the theory of evolution, the conception of species has undergone vast changes in biology, however no consensus on the definition of the word has yet been reached. The most commonly cited definition of "species" was first coined by Ernst Mayr. By this definition, called the biological species concept or isolation species concept, species are "groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups". However, many other species concepts are also used (see other definitions of species below). The scientific name of a species is properly typeset in italics. When an unknown species is being referred to this may be done by using the abbreviation "sp." in the singular or "spp." in the plural in the place of the second part of the scientific name. Note that the word "specie" is not the singular of "species". It refers to coined money.

Definitions of species

The definition of a species given above as taken from Mayr, is somewhat idealistic. Since it assumes sexual reproduction, it leaves the term undefined for a large class of organisms that reproduce asexually. Biologists frequently do not know whether two morphologically similar groups of organisms are "potentially" capable of interbreeding. Further, there is considerable variation in the degree to which hybridization may succeed under natural and experimental conditions, or even in the degree to which some organisms use sexual reproduction between individuals to breed. Consequently, several lines of thought in the definition of species exist: ; Typological species : A group of organisms in which individuals are members of the species if they sufficiently conform to certain fixed properties. The clusters of variations or phenotypes within specimens (ie: longer and shorter tails) would differentiate the species. This method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, we now know that different phenotypes do not always constitute different species (e.g.: a 4-winged Drosophila born to a 2-winged mother is not a different species). Species named in this manner are called morphospecies. ; Morphological species : A population or group of populations that differs morphologically from other populations. For example, we can distinguish between a chicken and a duck because they have different shaped bills and the duck has webbed feet. Species have been defined in this way since well before the beginning of recorded history. This species concept is much criticised because more recent genetic data reveals that genetically distinct populations may look very similar and, contrarily, large morphological differences sometimes exist between very closely-related populations. Nonetheless, most species known have been described solely from morphology. ; Biological / Isolation species : A set of actually or potentially interbreeding populations. This is generally the most useful formulation for scientists working with living examples of the higher taxa like mammals, fish, and birds, but meaningless for organisms that do not reproduce sexually. It does not distinguish between the theoretical possibility of interbreeding and the actual likelihood of gene flow between populations and is thus impractical in instances of allopatric (geographically isolated) populations. The results of breeding experiments done in artificial conditions may or may not reflect what would happen if the same organisms encountered each other in the wild, making it difficult to gauge whether or not the results of such experiments are meaningful in reference to natural populations. ; Mate-recognition species : A group of organisms that are known to recognise one another as potential mates. Like the isolation species concept above, it applies only to organisms that reproduce sexually. Unlike the isolation species concept, it focuses specifically on pre-mating reproductive isolation. ; Phylogenetic / Evolutionary / Darwinian species : A group of organisms that shares an ancestor; a lineage that maintains its integrity with respect to other lineages through both time and space. At some point in the progress of such a group, members may diverge from one another: when such a divergence becomes sufficiently clear, the two populations are regarded as separate species. ; Microspecies : Species that reproduce without meiosis or mitosis so that each generation is genetically identical to the previous generation. See also apomixis. In practice, these definitions often coincide, and the differences between them are more a matter of emphasis than of outright contradiction. Nevertheless, no species concept yet proposed is entirely objective, or can be applied in all cases without resorting to judgement. Given the complexity of life, some have argued that such an objective definition is in all likelihood impossible, and biologists should settle for the most practical definition. For most vertebrates, this is the biological species concept, and to a lesser extent (or for different purposes) the phylogenetic species concept. Many BSC subspecies are considered species under the PSC; the difference between the BSC and the PSC can be summed up insofar as that the BSC defines a species as a consequence of manifest evolutionary history, while the PSC defines a species as a consequence of manifest evolutionary potential. Thus, a PSC species is "made" as soon as an evolutionary lineage has started to separate, while a BSC species starts to exist only when the lineage separation is complete.

Importance in biological classification

The idea of species has a long history. It is one of the most important levels of classification, for several reasons:
- It often corresponds to what lay people treat as the different basic kinds of organism - dogs are one species, cats another.
- It is the standard binomial nomenclature (or trinomial nomenclature) by which scientists typically refer to organisms.
- It is the only taxonomic level which has empirical content, in the sense that asserting that two animals are of different species is saying something more than classificatory about them. After thousands of years of use, the concept remains central to biology and a host of related fields, and yet also remains at times ill-defined and controversial.

Implications of assignment of species status

The naming of a particular species should be regarded as a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be confirmed or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as the same species. When two named species are discovered to be of the same species, the older species name is usually retained, and the newer species name dropped, a process called synonymization, or convivially, as lumping. Dividing a taxon into multiple, often new, taxons is called splitting. Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognizing differences or commonalities between organisms (see lumpers and splitters). Traditionally, researchers relied on observations of anatomical differences, and on observations of whether different populations were able to interbreed successfully, to distinguish species; both anatomy and breeding behavior are still important to assigning species status. As a result of the revolutionary (and still ongoing) advance in microbiological research techniques, including DNA analysis, in the last few decades, a great deal of additional knowledge about the differences and similarities between species has become available. Many populations which were formerly regarded as separate species are now considered to be a single taxon, and many formerly grouped populations have been split. Any taxonomic level (species, genus, family, etc.) can be synonymized or split, and at higher taxonomic levels, these revisions have been still more profound. From a taxonomical point of view, groups within a species can be defined as being of a taxon hierarchically lower than a species. In zoology only the subspecies is used, while in botany the variety, subvariety, and form are used as well.

The isolation species concept in more detail

In general, for large, complex, organisms that reproduce sexually (such as mammals and birds), one of several variations on the isolation or biological species concept is employed. Often, the distinction between different species, even quite closely related ones, is simple. Horses (Equus caballus) and donkeys (Equus asinus) are easily told apart even without study or training, and yet are so closely related that they can interbreed after a fashion. Because the result, a mule or hinny, is not usually fertile, they are clearly separate species. But many cases are more difficult to decide. This is where the isolation species concept diverges from the evolutionary species concept. Both agree that a species is a lineage that maintains its integrity over time, that is diagnosably different to other lineages (else we could not recognise it), is reproductively isolated (else the lineage would merge into others, given the chance to do so), and has a working intra-species recognition system (without which it could not continue). In practice, both also agree that a species must have its own independent evolutionary history—otherwise the characteristics just mentioned would not apply. The species concepts differ in that the evolutionary species concept does not make predictions about the future of the population: it simply records that which is already known. In contrast, the isolation species concept refuses to assign the rank of species to populations that, in the best judgement of the researcher, would recombine with other populations if given the chance to do so.

The isolation question

There are, essentially, two questions to resolve. First, is the proposed species consistently and reliably distinguishable from other species? Secondly, is it likely to remain so in the future? To take the second question first, there are several broad geographic possibilities.
- The proposed species are sympatric—they occupy the same habitat. Observation of many species over the years has failed to establish even a single instance of two diagnostically different populations that exist in sympatry and have then merged to form one united population. Without reproductive isolation, population differences cannot develop, and given reproductive isolation, gene flow between the populations cannot merge the differences. This is not to say that cross breeding does not take place at all, simply that it has become negligible. Generally, the hybrid individuals are less capable of successful breeding than pure-bred individuals of either species.
- The proposed species are allopatric—they occupy different geographical areas. Obviously, it is not possible to observe reproductive isolation in allopatric groups directly. Often it is not possible to achieve certainty by experimental means either: even if the two proposed species interbreed in captivity, this does not demonstrate that they would freely interbreed in the wild, nor does it always provide much information about the evolutionary fitness of hybrid individuals. A certain amount can be inferred from other experimental methods: for example, do the members of population A respond appropriately to playback of the recorded mating calls of population B? Sometimes, experiments can provide firm answers. For example, there are seven pairs of apparently almost identical marine snapping shrimp (Altheus) populations on either side of the Isthmus of Panama, which did not exist until about 3 million years ago. Until then, it is assumed, they were members of the same seven species. But when males and females from opposite sides of the isthmus are placed together, they fight instead of mating. Even if the isthmus were to sink under the waves again, the populations would remain genetically isolated: therefore they are now different species. In many cases, however, neither observation nor experiment can produce certain answers, and the determination of species rank must be made on a 'best guess' basis from a general knowledge of other related organisms.
- The proposed species are parapatric—they have breeding ranges that abut but do not overlap. This is fairly rare, particularly in temperate regions. The dividing line is often a sudden change in habitat (an ecotone) like the edge of a forest or the snow line on a mountain, but can sometimes be remarkably trivial. The parapatry itself indicates that the two populations occupy such similar ecological roles that they cannot coexist in the same area. Because they do not crossbreed, it is safe to assume that there is a mechanism, often behavioral, that is preventing gene flow between the populations, and that therefore they should be classified as separate species.
- There is a hybrid zone where the two populations mix. Typically, the hybrid zone will include representatives of one or both of the 'pure' populations, plus first-generation and back-crossing hybrids. The strength of the barrier to genetic transmission between the two pure groups can be assessed by the width of the hybrid zone relative to the typical dispersal distance of the organisms in question. The dispersal distance of oaks, for example, is the distance that a bird or squirrel can be expected to carry an acorn; the dispersal distance of Numbats is about 15 kilometres, as this is as far as young Numbats will normally travel in search of vacant territory to occupy after leaving the nest. The narrower the hybrid zone relative to the dispersal distance, the less gene flow there is between the population groups, and the more likely it is that they will continue on separate evolutionary paths. Nevertheless, it can be very difficult to predict the future course of a hybrid zone; the decision to define the two hybridizing populations as either the same species or as separate species is difficult and potentially controversial.
- The variation in the population is clinal; at either extreme of the population's geographic distribution, typical individuals are clearly different, but the transition between them is seamless and gradual. For example, the Koalas of northern Australia are clearly smaller and lighter in colour than those of the south, but there is no particular dividing line: the further south an individual Koala is found, the larger and darker it is likely to be; Koalas in intermediate regions are intermediate in weight and colour. In contrast, over the same geographic range, black-backed (northern) and white-backed (southern) Australian Magpies do not blend from one type to another: northern populations have black backs, southern populations white backs, and there is an extensive hybrid zone where both 'pure' types are common, as are crossbreeds. The variation in Koalas is clinal (a smooth transition from north to south, with populations in any given small area having a uniform appearance), but the variation in magpies is not clinal. In both cases, there is some uncertainty regarding correct classification, but the consensus view is that species rank is not justified in either. The gene flow between northern and southern magpie populations is judged to be sufficiently restricted to justify terming them subspecies (not full species); but the seamless way that local Koala populations blend one into another shows that there is substantial gene flow between north and south. As a result, experts tend to reject even subspecies rank in this case.

The difference question

Obviously, when defining a species, the geographic circumstances become meaningful only if the populations groups in question are clearly different: if they are not consistently and reliably distinguishable from one another, then we have no grounds for believing that they might be different species. The key question in this context, is "how different is different?" and the answer is usually "it all depends". In theory, it would be possible to recognise even the tiniest of differences as sufficient to delineate a separate species, provided only that the difference is clear and consistent (and that other criteria are met). There is no universal rule to state the smallest allowable difference between two species, but in general, very trivial differences are ignored on the twin grounds of simple practicality, and genetic similarity: if two population groups are so close that the distinction between them rests on an obscure and microscopic difference in morphology, or a single base substitution in a DNA sequence, then a demonstration of restricted gene flow between the populations will probably be difficult in any case. More typically, one or other of the following requirements must be met:
- It is possible to reliably measure a quantitative difference between the two groups that does not overlap. A population has, for example, thicker fur, rougher bark, longer ears, or larger seeds than another population, and although this characteristic may vary within each population, the two do not grade into one another, and given a reasonably large sample size, there is a definite discontinuity between them. Note that this applies to populations, not individual organisms, and that a small number of exceptional individuals within a population may 'break the rule' without invalidating it. The less a quantitative difference varies within a population and the more it varies between populations, the better the case for making a distinction. Nevertheless, borderline situations can only be resolved by making a 'best-guess' judgement.
- It is possible to distinguish a qualitative difference between the populations; a feature that does not vary continuously but is either entirely present or entirely absent. This might be a distinctively shaped seed pod, an extra primary feather, a particular courting behaviour, or a clearly different DNA sequence. Sometimes it is not possible to isolate a single difference between species, and several factors must be taken in combination. This is often the case with plants in particular. In eucalypts, for example, Corymbia ficifolia cannot be reliably distinguished from its close relative Corymbia calophylla by any single measure (and sometimes individual trees cannot be definitely assigned to either species), but populations of Corymbia can be clearly told apart by comparing the colour of flowers, bark, and buds, number of flowers for a given size of tree, and the shape of the leaves and fruit. When using a combination of characteristics to distinguish between populations, it is necessary to use a reasonably small number of factors (if more than a handful are needed, the genetic difference between the populations is likely to be insignificant and is unlikely to endure into the future), and to choose factors that are functionally independent (height and weight, for example, should usually be considered as one factor, not two).

Historical development of the species concept

In the earliest works of science, a species was simply an individual organism that represented a group of similar or nearly identical organisms. No other relationships beyond that group were implied. Aristotle used the words genus and species to mean generic and specific categories. Aristotle and other pre-Darwinian scientists took the species to be distinct and unchanging, with an "essence", like the chemical elements. When early observers began to develop systems of organization for living things, they began to place formerly isolated species into a context. To the modern mind, many of the schemes delineated are whimsical at best, such as those that determined consanguinity based on color (all plants with yellow flowers) or behavior (snakes, scorpions and certain biting ants). In the 18th century Carolus Linnaeus classified organisms according to differences in the form of reproductive apparatus. Although his system of classification sorts organisms according to degrees of similarity, it made no claims about the relationship between similar species. At the time, it was still widely believed that there is no organic connection between species, no matter how similar they appear; every species was individually created by God, a view today called creationism. This approach also suggested a type of idealism: the notion that each species exists as an "ideal form". Although there are always differences (although sometimes minute) between individual organisms, Linnaeus considered such variation problematic. He strove to identify individual organisms that were exemplary of the species, and considered other non-exemplary organisms to be deviant and imperfect. By the 19th century most naturalists understood that species could change form over time, and that the history of the planet provided enough time for major changes. As such, the new emphasis was on determining how a species could change over time. Jean-Baptiste Lamarck suggested that an organism could pass on an acquired trait to its offspring, i.e., the giraffe's long neck was attributed to generations of giraffes stretching to reach the leaves of higher treetops (this well-known and simplistic example, however, does not do justice to the breadth and subtlety of Lamarck's ideas). Lamarck's most important insight may have been that species can be extraordinarily fluid; his 1809 Zoological Philosophy contained one of the first logical refutations of creationism. With the acceptance of the work of Charles Darwin in the 1860s, Lamarck's view of evolution was quickly eclipsed. It was not until the late 20th century that his work began to be reexamined, and took its place as a fundamental stepping stone to the modern theory of adaptive mutation. Lamarck's long-discarded ideas of the goal-oriented evolution of species, also known the teleological process, have also received renewed attention, particularly by proponents of artificial selection. Charles Darwin and Alfred Wallace provided what scientists now consider the most powerful and compelling theory of evolution. Basically, Darwin argued that it is populations that evolve, not individuals. His argument relies on a radical shift in perspective from Linnaeus: rather than defining species in ideal terms (and searching for an ideal representative and rejecting deviations), Darwin considered variation among individuals to be natural. He further argued that variation, far from being problematic, actually provides the explanation for the existence of distinct species. Darwin's work drew on Thomas Malthus' insight that the rate of growth of a biological population will always outpace the rate of growth of the resources in the environment, such as the food supply. As a result, Darwin argued, not all the members of a population will be able to survive and reproduce. Those that did will, on average, be the ones possessing variations—however slight—that make them slightly better adapted to the environment. If these variable traits are heritable, then the offspring of the survivors will also possess them. Thus, over many generations, adaptive variations will accumulate in the population, while counter-adaptive will be eliminated. It should be emphasized that whether a variation is adaptive or non-adaptive depends on the environment: different environments favor different traits. Since the environment effectively selects which organisms live to reproduce, it is the environment (the "fight for existence") that selects the traits to be passed on. This is the theory of evolution by natural selection. In this model, the length of a giraffe's neck would be explained by positing that proto-giraffes with longer necks would have had a significant reproductive advantage to those with shorter necks. Over many generations, the entire population would be a species of long-necked animals. In 1859, when Darwin published his theory of natural selection, the mechanism behind the inheritance of individual traits was unknown. Although Darwin made some speculations on how traits are inherited (pangenesis), his theory relies only on the fact that inheritable traits exist, and are variable (which makes his accomplishment even more remarkable.) Although Gregor Mendel's paper on genetics was published in 1866, its significance was not recognized. It was not until 1900 that his work was rediscovered by Hugo de Vries, Carl Correns and Erich von Tschermak, who realised that the "inheritable traits" in Darwin's theory are genes. The theory of the evolution of species through natural selection has two important implications for discussions of species -- consequences that fundamentally challenge the assumptions behind Linnaeus' taxonomy. First, it suggests that species are not just similar, they may actually be related. Some students of Darwin argue that all species are descended from a common ancestor. Second, it supposes that "species" are not homogeneous, fixed, permanent things; members of a species are all different, and over time species change. This suggests that species do not have any clear boundaries but are rather momentary statistical effects of constantly changing gene-frequencies. One may still use Linnaeus' taxonomy to identify individual plants and animals, but one can no longer think of species as independent and immutable. The rise of a new species from a parental line is called speciation. There is no clear line demarcating the ancestral species from the descendant species. Although the current scientific understanding of species suggests there is no rigorous and comprehensive way to distinguish between different species in all cases, biologists continue to seek concrete ways to operationalize the idea. One of the most popular biological definitions of species is in terms of reproductive isolation; if two creatures cannot reproduce to produce fertile offspring, then they are in different species. This definition captures a number of intuitive species boundaries, but nonetheless has some problems, however. It has nothing to say about species that reproduce asexually, for example, and it is very difficult to apply to extinct species. Moreover, boundaries between species are often fuzzy: there are examples where members of one population can produce fertile offspring with a second population, and members of the second population can produce fertile offspring with members of a third population, but members of the first and third population cannot produces fertile offspring. Consequently, some people reject this notion of species. In recent years we have witnessed the drastic reduction in the size of breeding populations and the geographical range of many physically large mammals. In earlier times it was assumed that every species existed in at least a few thousand living individuals, except very rare relic, isolated groups. In the present, many well know mammal & bird species are so stressed by habitat loss, and other effects of the modern world, that only a very few breeding males may contribute the genetic material to a small number of breeding females. In these highly stressed conditions, the likelihood of change is very much greater. Mammals may become smaller, have darker fur, more stripes, more cautious behavior, even over time learn to co-exist with the human world. Very likely, evolution is radically accelerated, and we are only beginning to notice it. Species in transition before our eyes. It is possible that this severe stress is essential to the creation of new species, and may have been a prime factor throughout biological history, from other population reducing influences. Richard Dawkins defines two organisms as conspecific if and only if they have the same number of chromosomes and, for each chromosome, both organisms have the same number of nucleotides (The Blind Watchmaker, p. 118). However, most if not all taxonomists would strongly disagree. For example, in many amphibians, most notably in New Zealand's Leiopelma frogs, the genome consists of "core" chromosomes which are mostly invariable and accessory chromosomes, of which exist a number of possible combinations. Even though the chromosome numbers are highly variable between populations, these can interbreed successfully and form a single evolutionary unit. In plants, polyploidy is extremely commonplace with few restrictions on interbreeding; as individuals with an odd number of chromosome sets are usually sterile, depending on the actual number of chromosome sets present, this results in the odd situation where some individuals of the same evolutionary unit can interbreed with certain others and some cannot, with all populations being eventually linked as to form a common gene pool. The classification of species has been profoundly affected by technological advances that have allowed researchers to determine relatedness based on molecular markers, starting with the comparatively crude blood plasma precipitation assays in the mid-20th century and coming into full swing with Charles Sibley's ground-breaking DNA-DNA hybridisation studies in the 1970s. The results of the technique caused revolutionary changes in the higher taxonomic categories (such as phyla and classes), resulting in the reordering of many branches of the phylogenetic tree (see also: molecular phylogeny). For taxonomic categories below genera, the results have been mixed so far; the pace of evolutionary change on the molecular level is rather slow, yielding clear differences only after considerable periods of reproductive separation. Instances of hybridization can result in misleading molecular data, the Pomarine Skua - Great Skua phenomenon being a famous example. Turtles have been determined to evolve with just one-eighth of the speed of other reptiles on the molecular level, and the rate of molecular evolution in albatrosses is half of what is found in the rather closely related storm-petrels. The hybridization technique is however no longer considered a good technique and more reliable computational techniques for sequence comparison are now used for. Molecular taxonomy does not directly measure the evolutionary processes, but rather the overall change brought upon by these processes. The processes that lead to the generation and maintenance of variation such as mutation, crossover and selection are not uniform (see also molecular clock). DNA is only extremely rarely a direct target of natural selection rather than changes in the DNA sequence enduring over generations being a result of the latter; for example, silent transition-transversion combinations would alter the melting point of the DNA sequence, but not the sequence of the encoded proteins and thus are a possible example where, for example in microorganisms, a mutation confers a change in fitness all by itself.

External links

- http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Speciation.html
- [http://www.sciencedaily.com/releases/2003/12/031231082553.htm 2003-12-31, ScienceDaily: Working On The 'Porsche Of Its Time': New Model For Species Determination Offered] Quote: "...two species of dinosaur that are members of the same genera varied from each other by just 2.2 percent. Translation of the percentage into an actual number results in an average of just three skeletal differences out of the total 338 bones in the body. Amazingly, 58 percent of these differences occurred in the skull alone. "This is a lot less variation than I'd expected", said Novak..."
- [http://www.sciencedaily.com/releases/2003/08/030808081854.htm 2003-08-08, ScienceDaily: Cross-species Mating May Be Evolutionarily Important And Lead To Rapid Change, Say Indiana University Researchers] Quote: "...the sudden mixing of closely related species may occasionally provide the energy to impel rapid evolutionary change..."
- [http://www.sciencedaily.com/releases/2004/01/040109064407.htm 2004-01-09 ScienceDaily: Mayo Researchers Observe Genetic Fusion Of Human, Animal Cells; May Help Explain Origin Of AIDS] Quote: "...The researchers have discovered conditions in which pig cells and human cells can fuse together in the body to yield hybrid cells that contain genetic material from both species... "What we found was completely unexpected", says Jeffrey Platt, M.D."
- [http://www.sciencedaily.com/releases/2000/09/000913211733.htm 2000-09-18, ScienceDaily: Scientists Unravel Ancient Evolutionary History Of Photosynthesis] Quote: "...gene-swapping was common among ancient bacteria early in evolution..."
- [http://plato.stanford.edu/entries/species/ Stanford Encyclopedia of Philosophy entry]
- [http://www.barcodinglife.org/ Barcoding of species] rank22 rank22 ms:Spesies ja:種 (生物) th:สปีชีส์

Wasp

See text. A wasp is any insect of the order Hymenoptera and suborder Apocrita that is not a bee, sawfly, or an ant. Less familiar, the suborder Symphyta includes the sawflies and wood wasps, which differ from the Apocrita by having a broad connection between the thorax and abdomen. Also, Symphyta larvae are mostly herbivorous and "caterpillarlike", whereas those of Apocrita are largely predatory or parasitic. Most familiar wasps belong to the Aculeata, a division of the Apocrita, whose ovipositors are modified into a venomous stinger. Aculeata also contains ants and bees. In this sense, the species called "velvet ants" (Mutillidae) are actually wasps. A narrower meaning of the term wasp is any member of the Aculeate family Vespidae. This includes the yellowjackets (Vespula, Dolichovespula spp.) and hornets (Vespa spp.).

Characteristics

hornet]] hornet The following characteristics are present in most wasps:
- Two pairs of wings (exception: female Mutillidae)
- A stinger (only present in females because it derives from the ovipositor)
- Few or no hairs (in contrast to bees); exception: Mutillidae
- Predators or parasitoids, mostly on other insects; some species of Pompilidae, such as the tarantula hawk, specialize in using spiders as a host Wasps are critically important in natural biocontrol. Almost every pest insect species has a wasp species that is predator or parasite upon it. Wasps are also increasingly used in agricultural pest control.

Families

- Chrysididae - cuckoo wasps
- Crabronidae
- Mutillidae - velvet ants
- Orussidae, and Syntexidae
- Pompilidae - spider wasps
- Rhopalosomatidae - rhopalosomatid wasps
- Sapygidae - club-horned wasps
- Scoliidae - scoliid wasps
- Sierolomorphidae - sierolomorphid wasps
- Sphecidae - digger wasps, e.g. the Cicada killer wasp
- Tiphiidae - flower wasps
- Vespidae - yellowjackets, hornets, paper wasps.
- Xiphydriidae

External links

- [http://www.pollinator.com/beneficials/trypaxylon_politum.htm A pictorial life cycle of organ pipe wasps]
- [http://paipm.cas.psu.edu/BenefInsects/beneficials_Parastd.htm Links to many parasitic wasps and other insects used for biological control]
- [http://research.amnh.org/entomology/social_insects/training/hymintro.html Phylogeny of the order Hymenoptera] contrasting the groups discussed in this article
- [http://www.nlm.nih.gov/medlineplus/ency/article/000033.htm Medline Encyclopedia] N.I.H. - Insect bites and stings
- [http://dermnetnz.org/arthropods/bites.html New Zealand Dermatological Society Incorporated] - Insect bites and stings and how to prevent them Category:Insects Category:Vespoidea

Hoverfly

- Eristalinae
- Microdontinae
- Syrphinae 200 genera
about 5,000 species The flower-flies or hover-flies are a family of flies (Diptera), scientifically termed the Syrphidae. As one of their names suggests, they are most often seen around flowers; the adults feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprophytes, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores and prey on aphids, thrips, and other plant-sucking insects. Aphids alone cause tens of millions of dollars of damage to crops worldwide every year, and so aphid-feeding hover-flies are being recognised as important natural enemies of pests, and potential agents for use in biological control. Adult syrphid flies are important pollinators. pollinator Some syrphids, such as Volucella pellucens, mimic bees or wasps in appearance, sometimes bearing an alarming resemblance, both in shape and coloration to those insects. It is thought that this mimicry protects hover-flies from falling prey to birds and other insectivores which avoid eating true wasps because of their sting. However a flower-fly and a wasp can be distinguished by counting the wings. The flies have two wings, and the wasps and bees have four. About 6,000 species in 200 genera have been described. One species, Eristalis gatesi, is named after Bill Gates [http://www.sel.barc.usda.gov/diptera/syrphid/gates.htm].

Gallery

Image:Schwebfliege.jpg|Episyrphus balteatus Image:FlowerFly-BeeType.jpg|Episyrphus balteatus Image:Hoverfly.jpg Image:Volucella_inanis_fg1.jpg|Volucella inanis

External links

- [http://www.sel.barc.usda.gov/diptera/syrphid/gates.htm Flower-fly named after Bill Gates]
- [http://www.syrphidae.com Syrphidae species in Europe, with photos, range maps and literature]
- [http://www.sel.barc.usda.gov/diptera/syrphid/syrphid.htm USDA Entomology site]
- [http://www.bioimages.org.uk/HTML/T661.HTM Large numbers of Syrphidae photos]
- [http://home.hccnet.nl/mp.van.veen/hf_index.html Northwest European Hoverflies: identification keys and photos] Category:Flies Category:Pollination

Wolf

: The Gray Wolf (Canis lupus), known in Europe as the Grey Wolf, is a mammal of the Canidae family. Although there are different species with "wolf" in its name, the Gray Wolf is the most common understanding of "wolf" in the English language. Depending on researcher, the wolf either shares a common ancestry with, or is a member of, the same species as the domestic dog (Canis familiaris or C. lupus familiaris). Wolves once had a nearly worldwide range, but are now limited primarily to North America, Eurasia, and the Middle East. The habitat of wolves include forests, tundra, taigas, plains, and mountains. In the Northern Hemisphere, human habitat destruction and hunting have drastically reduced their range. The wolf is frequently involved in conflicts between competing interests: tourism versus industry, city versus country, as well as conservationism versus urban development. Since the wolf is an apex predator, its state usually depends on the state of its habitat. Wolves are still endangered after being hunted to near extinction in many parts of the world in the 17th century. Carolus Linnaeus gave the wolf the scientific name Canis lupus in the 18th century.

Anatomy

18th century The wolf's anatomy differs from the dog's in several ways. The wolf usually has golden-yellow eyes, longer legs, larger paws, more-pronounced jaws, a longer muzzle, and a brain that is typically 30 percent larger than that of a dog. Also noticeable is a pre-caudal gland on the over side of the tail, close to the base, that is not present on dogs. Wolves are also distinguished from dogs by characteristics of the skull, particularly the orbital angle, which is the angle formed between lines drawn across the top and side of the skull at the eye socket. This angle is larger (53 degrees or more) in dogs, and smaller (45 degrees or less) in wolves. Lastly, while the elbows of many dogs stick more out to the sides of their bodies, the elbows of a wolf point inwards towards their stomach, almost touching. This allows wolves to run at speeds of 8 kilometers per hour (km/h) (5 miles per hour) (mph) for hours on end. A wolf often seems more massive than a dog of comparable weight due to the extra bulk of the coat. The coat is built up of two layers, with hard guard hairs to repel water and dirt and a thick, woolly undercoat to keep the animal warm. The wolf changes coat two times a year, in spring and autumn. Females tend to keep the winter coat further into the spring than males. Wolves and most larger dogs share the same tooth configuration: The upper jaw has six incisors, two canines, eight premolars, and four molars. The bottom jaw has six incisors, two canines, eight premolars, and six molars. The canine teeth are by far most important, as they are used to catch and hold prey. One common reason that wolves starve is due to tooth damage after suffering a kick by larger prey. Wolves stand approximately 0.66–0.8 meters (26–32 in) at the shoulder and weigh 25–52 kilograms (55–115 lb, with extremes being 195 pounds [88 kg]). Females are about twenty percent smaller than males. They measure 1–1.5 meters (40–58 in) long, with the tail consisting roughly a third of their body length (0.67–0.5 meter, 26–20 in). The body of the wolf is built for long-distance running, with a rather thin chest and powerful back and leg muscles which allow them to run at 72 km/h (45 mph) with strides of up to sixteen feet. Wolves can also travel over great distances, and their wide paws ensure deep snow hampers them less than their prey. Coloration runs from gray to gray-brown but can vary through the canine spectrum of white, red, brown, and black.A wolf's coat usually lacks any clear patterns save for markings around the eyes. Fur colors often mimic the colors of a wolf's surroundings; for example, in regions where there is continual snowfall, white wolves are far more common. Aging wolves acquire a grayish tint in their coat.

Social structure

Packs

snow Wolves function as social predators and hunt in packs organized according to a strict social hierarchy and led by an alpha male and alpha female. This social structure was originally thought to allow the wolf to take prey many times its size. However, emerging new theories suggest the pack strategy has less to do with hunting than with reproductive success. The size of the pack may change over time and is controlled by several factors, including habitat, personalities of individual wolves within a pack, and food supply. Packs can contain between two and 20 wolves, though an average pack consists of six or seven. The hierarchy of the pack is relatively strict, with the alphas at the top and the omega at the bottom. The hierarchy affects all activity in the pack, from which wolf eats first to which is allowed to breed (generally only the alpha pair). New packs are formed when a wolf leaves its birth pack and claims a territory. Wolves searching for other wolves with which to form packs can travel very long distances in search of suitable territories. Dispersing individuals must avoid the territories of other wolves because intruders on "owned" territories are chased away or killed. This possibly explains wolf "predation" of dogs. Most dogs, except perhaps large, specially bred attack dogs, do not have much of a chance against a wolf protecting its territory from the unwanted intrusion.

Rank order

The alpha pair has the most social freedom of all the animals in a pack, but they are not "leaders" in the sense humans usually think of the term. They do not give the other wolves orders; the alphas simply have the most liberty to choose where they would like to go and what they would like to do, and the rest of the pack usually follows. In larger packs, there may be betas, a second in command to the alphas, and the omegas, the lowest-ranking member of the pack. While most alpha pairs are monogamous with each other, there are exceptions. An alpha animal may preferentially mate with a lower-ranking animal, especially if the other alpha is closely related (a brother or sister, for example). The death of one alpha does not affect the status of the other alpha, who will usually take another mate. Usually, only the alpha pair is able to successfully rear a litter of pups. (Other wolves in a pack may breed, and may even produce pups, but usually they lack the freedom or the resources to raise the pups to maturity.) All the wolves in the pack assist in raising wolf pups. Some pups may choose to stay in the original pack to reinforce it and help rear more pups while others disperse. Rank order is established and maintained through a series of ritualized fights and posturing best described as ritual bluffing. Wolves prefer psychological warfare to actual fighting, and high-ranking status is based more on personality or attitude than on size or physical strength. Rank, who holds it, and how it is enforced varies widely between packs and between individual animals. In large packs full of easygoing wolves, or in a group of juvenile wolves, rank order may shift almost constantly, or even be circular (e.g., animal A dominates animal B, who dominates animal C, who dominates animal A). Loss of rank can happen gradually or suddenly. An older wolf may simply choose to give way when an ambitious challenger presents itself, and rank will shift without bloodshed. On the other hand, the older animal may choose to fight back, with varying degrees of intensity. While an extremely high percentage of wolf aggression is non-damaging and ritualized, a high-stakes fight can result in injury. The loser of such a damaging fight is frequently chased away from the pack or, rarely, may be killed as other aggressively aroused wolves attempt to join in. This kind of dominance fight is more common in the winter months, when mating occurs.

Body language

injury injury Wolves communicate not only by sound (such as yipping, growling, and howling), but also by body language. This ranges from subtle signals–such as a slight shift in weight–to the obvious, like rolling on the back as a sign of submission.
- Dominance – A dominant wolf stands stiff legged and tall. The ears are erect and forward, and the hackles bristle slightly. Often the tail is held vertical and curled toward the back. This display shows the wolf's rank to all others in the pack. A dominant lupine may stare penetratingly at a submissive one, pin the other to the ground, or even stand on its hind legs.
- Submission (active) – In active submission, the entire body is lowered, and the lips and ears are drawn back. Sometimes active submission is accompanied by a rapid thrusting out of the tongue and lowering of the hindquarters. The tail is placed down, or halfway or fully between the legs, and the muzzle often points up to the more dominant animal. The back may be partially arched as the submissive wolf humbles itself to its superior. (A more arched back and more tucked tail indicate a greater level of submission.)
- Submission (passive) – Passive submission is more intense than active submission. The wolf rolls on its back and exposes its vulnerable throat and underside. The paws are drawn into the body. This is often accompanied by whimpering.
- Anger – An angry lupine's ears are erect, and its fur bristles. The lips may curl up or pull back, and the incisors are displayed. The wolf may also snarl.
- Fear – A frightened wolf tries to make its body look small and therefore less conspicuous. The ears flatten down against the head, and the tail may be tucked between the legs, as with a submissive wolf. There may also be whimpering or barks of fear, and the wolf may arch its back.
- Defensive – A defensive wolf flattens its ears against its head.
- Aggression – An aggressive wolf snarls and its fur bristles. The wolf may crouch, ready to attack if necessary.
- Suspicion – Pulling back of the ears shows a lupine is suspicious. In addition, the wolf narrows its eyes. The tail of a wolf that senses danger points straight out, parallel to the ground.
- Relaxedness – A relaxed wolf's tail points straight down, and the wolf may rest sphinxlike or on its side. The wolf's tail may also wag. The further down the tail droops, the more relaxed the wolf is.
- Tension – An aroused wolf's tail points straight out, and the wolf may crouch as if ready to spring.
- Happiness – As dogs do, a lupine may wag its tail if it is in a joyful mood. The tongue may loll out of the mouth.
- Hunting – A wolf that is hunting is tensed, and therefore the tail is horizontal and straight.
- Playfulness – A playful lupine holds its tail high and wags it. The wolf may frolic and dance around, or bow by placing the front of its body down to the ground, while holding the rear high, sometimes wagged. This is reminiscent of the playful behavior executed in domestic dogs.

Howling

frolic Wolves are noted for their distinctive howl. There are several possible reasons for the howling. It can be said at the outset that wolves do not howl when attacking their prey. In fact, it has been shown that prey animals do not even react to the sound. Perhaps they simply fail to make the connection between noise and predator. The most obvious reason for wolves to howl is to keep in touch; it is difficult to think of a better way for a lupine pack to communicate in a thickly forested area or over great distances. Howls are also employed to summon pack members to a location. However, howling also occurs when a pack is together, so there must be some other purpose. Observations of wolf packs suggest that howling often occurs at summer sunsets preceding the adults' departure to the hunt. This is repeated when they return at sunup. Some scientists speculate that these group howling sessions strengthen the wolves' social bonds and comradeship—similar to community singing among humans. Howling may also be a form of territorial advertisement and declaration. Studies have shown that the dominant animals in a pack are more likely to answer a human imitation of a "rival" pack when residing in an area that is indisputably theirs. Wolves howl more frequently in the evening and the early morning, especially during winter and spring breeding and pup rearing. The pups themselves, however, towards th