A dominance signal is used in a dominance hierarchy or pecking order to indicate an animal's dominance. Dominance signals are a type of internal environment signal that demonstrate the signalers attributes [2] . Dominance signals are necessary for several species for mating, maintaining social hierarchies and defending territories [1] Dominance signals also provide information about an animals fitness. Animals have developed conflict management strategies to reduce frequency of aggressive incidents in competitive matters. This evolution is the basis of dominance signals [3].
Dominance signals can be operationally defined by (1) acts or displays produced by signalers, (2) which conveys meaning messages to recipients such that (3) the signal is met with a response and (4) the response results in dominance being displayed. [1] For example, (1) hermit claws raise their claws performing a threat signal, (2) which expresses intent to attack to challenger (3) and the challenger makes a decision to retreat which (4) reinforces signaller's dominance. [1]
The earliest study of animal signals can be attributed to Charles Darwin's "The Expressions of the Emotions in Man and Animals", which introduced the comparative study of signals across all animals [1] . Expressive abilities of the face are the basis of nonverbal expression. [2] These facial signals help maintain dominance or "status" relationships by allowing species to predict the outcome of their encounter, and calculate the cost of their own fitness. [1] Nikolaas Tinbergen furthered the essential framework for studying animal signals with his 'four questions' about the phylogeny, function, development and mechanism of signals or any other behaviour. [3]
Dominance signals are the basis of animal hierarchies and are triggered by stress environments. [1] These signals are used to maintain courtship dominance, social dominance and territorial and resource dominance both within and between different species. Dominance signals are prominent far beyond the ethology literature, as humans express them in several forms.
Animals use several modalities of communication to express dominance. Aggressive encounters between competing individuals can result in significant costs for animals. To minimize fighting costs and increase fitness, many species have evolved specialized signalling systems to assert dominance by electing specific cues or signals. [4] These signals allow individuals to gauge the status of conspecifics and not engage in combat with individuals of higher rank or strength. [5] Such signals are found in several species and can present themselves in many different ways. [5]
Visual communication is a common dominance signal among animals. They are an effective modality as they come at a low cost to the animal and minimize risk. The Gila Monster (Heloderma suspectum) for example, express bright orange splotches during territorial conflict to warn competitors that they are poisonous, and thus assert their dominance over a territory. [6]
Acoustic communication is often used by animals to express dominance. Acoustic sounds can vary substantially in amplitude, duration, and frequency structure which can influence how the signal is received. [7] Vocalizations can be effective for a species as it may decrease physical interaction, which may decrease injury costs. [8] Northern elephant seals (Mirounga angustirostris), for example, have a polygynous breeding system in which adult males establish dominance hierarchies that facilitates copulation with females. [9] Acoustic signalling is detrimental in resolving competition between males for mates. Elephant seals express unique acoustic signals that allow males to remember the violations of past rivals and recall which seals are dominant.
Tactile signals occur when physical contact is made between two competing animals and can only be transmitted over very short distances. [10] Tactile communication is often very important in building and maintaining relationship among social animals as it can establish hierarchies. [10] Snakes (Serpentes) engage in tactile communication to compete for dominance. This communication is often referred to as a combat ritual. [10] It involves interaction sequences between two male snakes and has been recorded in four groups of snakes including colubrids, elapids, viperines and crotalines. [10] During competition, the male snakes will exert pressures through pushing, flipping or entwining, which will result in one physically subduing the other. The dominant male will then proceed to copulate with the females. [10]
Electric signalling is a mode of communication often used by aquatic animals living in murky water. Electric signalling can minimize fighting costs and allow dominance to be exerted in low visibility conditions. [11] In electric fish (Sternarchorhynchus), the frequency of electric organ discharge signals the dominance status of individuals. [11]
Dominance signals, like other animal behaviours, have internal underlying mechanisms that allow for the external display to occur. Underlying mechanisms may include hormones, sensory organs, cognitive maps, spatial memory, associative learning, brain structure, mental representations and neural morphology. [12]
Dominance signalling in animals is often a result of hormone changes. Hormones can work in either positive feedback loops or negative feedback loops and can alter the phenotypes of behaviour. [13] In Australasian swamphen (Porphyrio porphyrio melanotus), for example, badge display is an indicator of dominance. It has been found that altering a bird's badge can actually change androgen circulation and can cause feedback effects on the individuals physiology. [13] In a field study by Cody Dey, researchers found that birds which had the apparent size of their frontal shield decreased, received more aggression and also decreased their true shield relative to individuals who did not have their apparent shield size altered. [13]
Dominance signals used during courtship are driven by interactions between a male's fitness and a female's preference. Dominance signals influence a female's choice of mate because the power of a signal may be a reflection of the male's genetic success. [14]
Dominance signals are elicited in wild turkeys during courtship. Wild turkeys fundamentally follow a dominant hierarchy as a way to increase their inclusive fitness. [14] The dominant subordinate relationship occurs between two brothers. One brother, the dominant, copulates while the other male, the subordinate, helps. [14]
After birth, the physical appearance of the male turkeys is used to indicate dominance. Physical characters such as height, bulk, and density are evaluated. [14]
Electric fish express dominance signals during courtship by exerting electric organ discharge "chirps". [11] The "chirps" are an indicator of a male's aggressiveness and size. The more "chirps" a male electric fish produces, increases his likelihood of reproductive success. Continual bouts of chirping can last hours on evenings prior to courting. The electric chirps stimulate females to spawn. [11] The chirp involves a slight increase in frequency followed by a cessation of the male dominant frequency. [11] Chirps are normally short and abrupt during aggressive encounters when courting females, however, become softer during actual copulation. [11]
Social dominance is formed through dominance hierarchies. Such hierarchies arise when a member of social group elicits a dominance signal to initiate competitive interaction. [15]
Gorilla's chest-drumming is a signal used to demonstrate social dominance. [16] This non-verbal, rapid chest-drumming creates a sound because gorillas have air sacks on both sides of their throat. The drumming is often accompanied by screaming and non-specified sounds. [16] This signal is used as a warning signal to young gorilla to back-down if they are trying to join their tribe. [16] This signal will only cease if the young male backs-down or if they engage in battle. [16] The young males are not challenging the dominant for courtship behaviour alone, but rather are trying for group-wide control. [17] Chest-drumming is also used a sign of victory after a battle and demonstrates who is the male dominant. [17] As gorillas are male dominant, females do not produce these dominance signals. Silverback gorillas also use chest-drumming to command their family to follow them, reinforcing familial dominance. [16]
Dominance signals that reinforce hierarchy are crucial for survival for animals like gorillas who are extremely aggressive. A Gorilla's chest drumming, for example, reduces intra-species aggression by making the dominant-subordinate relationship clear. For social animals like gorillas, having and maintaining a dominant male is crucial to maintain their way of life. [16]
Dominance signals are often elicited over competition for territory. Dominance over a territory can be highly beneficial as it would provide abundant recourse. However, the cost of holding a territory can also be quite high. Dominance signals allow signalers to convey the dominant-subordinate relationship to a receiver avoiding physical contact.
Dominance signals used by Atlantic Salmon allow for territory to be defended. When an Atlantic salmon is challenged by another salmon for territory and resources, a physical change in colour display occurs. [18] When a subordinate male enters the territory of a dominant male, it will become darker after assessment of the dominant male, while the dominant male remains his original colour. [18] This change in colour has been recorded in the sclera of the eye and the overall body coloration. The darkening is a sign of submission and is beneficial for both males as it minimizes the risk of potential injury during prolonged fights. [18]
Dominance signals are typically associated with ethology. However, humans display such signals as it is an innate characteristic. Fundamentally, all social species must have expressions of dominance and engage in hierarchy systems to function. [19] Men exhibiting greater dominance signals often have higher success mating with women.
Human voice pitch is one of the most prevalent dominance signal and has evolutionary ties to non-human primates. [20] Physically, men's vocal folds and vocal tracts are longer than those of women, which produces a lower fundamental frequency and closer spacing of formant frequencies in men. [20] These differences are not fully clear from an evolutionary perspective; However, it has been suggested that voice pitch is linked to male dominance competition. [20] Current research on male voice pitch suggests that lower pitch is perceived as increasing dominance. [20] Lower pitch voices also tend to be indicators of physical and social dominance. [20] Other vocalization signals include loud rapid speaking tempo and clear articulation. [20] Empirical evidence shows that women perceive deep-voiced men to be more dominant and desirable for mating. [21]
Physical size is one of the most prevalent dominance signals a human can elicit. Height, weight, bulk, and muscularity send signals of strength and can hold power over subordinate males. [20] Other non-verbal signals that are perceived as signs of dominance are rapid gait, straight postures, firm and strong stances, animated gesturing, and clothing or hair styles that create a bulkier appearance. [22] Women generally view men who display great muscularity and strength to be more attractive. [23] When observing the male wrestling competitions of the indigenous Mehinaku tribe of the Amazon rainforest, anthropologist Thomas Gregor noted that males who are "heavily muscled" and "imposingly built" have higher mating access to females, while small men, who are derogatorily referred to as peristsi, "fare badly". [21] He reports that powerful male wrestlers are both frightening to villagers and the most sexually desirable to females. [21]
Facial expression is used as a dominance signal in humans. Derived from our primate ancestors, faces of mature members have broader faces with a more defined jaw, smaller ratio of eye size to face size and larger noses. [20] Younger members are perceived as having baby-faced features which includes rounder, softer faces, larger eyes when compared to face ratio, and smaller noses. [20] These facial features can be used as dominance signals as baby-faced individuals are perceived as weak and submissive compared to mature faces which can indicate physical and social dominance. [22] In a study where women viewed mixed-martial arts fights, male winners whose faces indicated victory and dominance were perceived to be more attractive, stronger, aggressive, and masculine compared to the male losers. [24]
More subtle dominance signals have also been suggested such as head nods, less arm wrap, increasing gestures, and more left leg lean. [25] These subtle differences are associated with perception of dominance among males. [20] Little research has been conducted regarding how or if, women elicit subtle dominance signals to express dominance. [19]
Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex. These two forms of selection mean that some individuals have greater reproductive success than others within a population, for example because they are more attractive or prefer more attractive partners to produce offspring. Successful males benefit from frequent mating and monopolizing access to one or more fertile females. Females can maximise the return on the energy they invest in reproduction by selecting and mating with the best males.
Animal communication is the transfer of information from one or a group of animals to one or more other animals that affects the current or future behavior of the receivers. Information may be sent intentionally, as in a courtship display, or unintentionally, as in the transfer of scent from predator to prey with kairomones. Information may be transferred to an "audience" of several receivers. Animal communication is a rapidly growing area of study in disciplines including animal behavior, sociology, neurology and animal cognition. Many aspects of animal behavior, such as symbolic name use, emotional expression, learning and sexual behavior, are being understood in new ways.
In the zoological field of ethology, a dominance hierarchy is a type of social hierarchy that arises when members of animal social groups interact, creating a ranking system. A dominant higher-ranking individual is sometimes called an alpha, and a submissive lower-ranking individual is called a beta. Different types of interactions can result in dominance depending on the species, including ritualized displays of aggression or direct physical violence. In social living groups, members are likely to compete for access to limited resources and mating opportunities. Rather than fighting each time they meet, individuals of the same sex establish a relative rank, with higher-ranking individuals often gaining more access to resources and mates. Based on repetitive interactions, a social order is created that is subject to change each time a dominant animal is challenged by a subordinate one.
Phoca is a genus of the earless seals, within the family Phocidae. It now contains just two species, the common seal and the spotted seal. Several species formerly listed under this genus have been split into the genera Pusa, Pagophilus, and Histriophoca. Until recently, Phoca largha has been considered a subspecies of Phoca vitulina but now is considered its own species. For this reason, the fossil history of the genus is unclear, and it has formerly been used as wastebasket taxon for a number of fossils of uncertain affinity.
The pant-hoot is a loud, structurally complex vocalization of chimpanzees. The call is generally divided into four distinct, successive phases: introduction, build-up, climax and let-down. This introductory phase begins with soft, breathy, low-frequency 'hoo's' that transition into the build-up phase; a series of increasingly rapid, low-frequency in-and-out pants. Following the build-up phase, the call quickly builds into the climax, consisting of loud, high-frequency screams that eventually slow into the let-down phase, similar in structure to the build-up, but with decreasing amplitude and pace until the call is complete.
Cats communicate for a variety of reasons, including to show happiness, express anger, solicit attention, and observe potential prey. Additionally, they collaborate, play, and share resources. When cats communicate with humans, they do so to get what they need or want, such as food, water, attention, or play. As such, cat communication methods have been significantly altered by domestication. Studies have shown that domestic cats tend to meow much more than feral cats. They rarely meow to communicate with fellow cats or other animals. Cats can socialize with each other and are known to form "social ladders," where a dominant cat is leading a few lesser cats. This is common in multi-cat households.
Display behaviour is a set of ritualized behaviours that enable an animal to communicate to other animals about specific stimuli. Such ritualized behaviours can be visual, but many animals depend on a mixture of visual, audio, tactical and chemical signals. Evolution has tailored these stereotyped behaviours to allow animals to communicate both conspecifically and interspecifically which allows for a broader connection in different niches in an ecosystem. It is connected to sexual selection and survival of the species in various ways. Typically, display behaviour is used for courtship between two animals and to signal to the female that a viable male is ready to mate. In other instances, species may make territorial displays, in order to preserve a foraging or hunting territory for its family or group. A third form is exhibited by tournament species in which males will fight in order to gain the 'right' to breed. Animals from a broad range of evolutionary hierarchies avail of display behaviours - from invertebrates such as the simple jumping spider to the more complex vertebrates like the harbour seal.
Teleogryllus oceanicus, commonly known as the Australian, Pacific or oceanic field cricket, is a cricket found across Oceania and in coastal Australia from Carnarvon in Western Australia and Rockhampton in north-east Queensland
Agonism is a broad term which encompasses many behaviours that result from, or are triggered by biological conflict between competing organisms. It is defined as "survivalist animal behaviour that includes aggression, defense, and avoidance". Approximately 23 shark species are capable of producing such displays when threatened by intraspecific or interspecific competitors, as an evolutionary strategy to avoid unnecessary combat. The behavioural, postural, social and kinetic elements which comprise this complex, ritualized display can be easily distinguished from normal, or non-display behaviour, considered typical of that species' life history. The display itself confers pertinent information to the foe regarding the displayer's physical fitness, body size, inborn biological weaponry, confidence and determination to fight. This behaviour is advantageous because it is much less biologically taxing for an individual to display its intention to fight than the injuries it would sustain during conflic. Agonistic displays are essential to the social dynamics of many biological taxa, extending far beyond sharks.
The Mozambique tilapia is an oreochromine cichlid fish native to southeastern Africa. Dull colored, the Mozambique tilapia often lives up to a decade in its native habitats. It is a popular fish for aquaculture. Due to human introductions, it is now found in many tropical and subtropical habitats around the globe, where it can become an invasive species because of its robust nature. These same features make it a good species for aquaculture because it readily adapts to new situations. It is known as black tilapia in Colombia and as blue kurper in South Africa.
A courtship display is a set of display behaviors in which an animal, usually a male, attempts to attract a mate; the mate exercises choice, so sexual selection acts on the display. These behaviors often include ritualized movement ("dances"), vocalizations, mechanical sound production, or displays of beauty, strength, or agonistic ability.
Seismic or vibrational communication is a process of conveying information through mechanical (seismic) vibrations of the substrate. The substrate may be the earth, a plant stem or leaf, the surface of a body of water, a spider's web, a honeycomb, or any of the myriad types of soil substrates. Seismic cues are generally conveyed by surface Rayleigh or bending waves generated through vibrations on the substrate, or acoustical waves that couple with the substrate. Vibrational communication is an ancient sensory modality and it is widespread in the animal kingdom where it has evolved several times independently. It has been reported in mammals, birds, reptiles, amphibians, insects, arachnids, crustaceans and nematode worms. Vibrations and other communication channels are not necessarily mutually exclusive, but can be used in multi-modal communication.
Sexual selection in birds concerns how birds have evolved a variety of mating behaviors, with the peacock tail being perhaps the most famous example of sexual selection and the Fisherian runaway. Commonly occurring sexual dimorphisms such as size and color differences are energetically costly attributes that signal competitive breeding situations. Many types of avian sexual selection have been identified; intersexual selection, also known as female choice; and intrasexual competition, where individuals of the more abundant sex compete with each other for the privilege to mate. Sexually selected traits often evolve to become more pronounced in competitive breeding situations until the trait begins to limit the individual's fitness. Conflicts between an individual fitness and signaling adaptations ensure that sexually selected ornaments such as plumage coloration and courtship behavior are "honest" traits. Signals must be costly to ensure that only good-quality individuals can present these exaggerated sexual ornaments and behaviors.
Sexual selection in amphibians involves sexual selection processes in amphibians, including frogs, salamanders and newts. Prolonged breeders, the majority of frog species, have breeding seasons at regular intervals where male-male competition occurs with males arriving at the waters edge first in large number and producing a wide range of vocalizations, with variations in depth of calls the speed of calls and other complex behaviours to attract mates. The fittest males will have the deepest croaks and the best territories, with females making their mate choices at least partly based on the males depth of croaking. This has led to sexual dimorphism, with females being larger than males in 90% of species, males in 10% and males fighting for groups of females.
An alternative mating strategy is a strategy used by male or female animals, often with distinct phenotypes, that differs from the prevailing mating strategy of their sex. Such strategies are diverse and variable both across and within species. Animal sexual behaviour and mate choice directly affect social structure and relationships in many different mating systems, whether monogamous, polygamous, polyandrous, or polygynous. Though males and females in a given population typically employ a predominant reproductive strategy based on the overarching mating system, individuals of the same sex often use different mating strategies. Among some reptiles, frogs and fish, large males defend females, while small males may use sneaking tactics to mate without being noticed.
Allofeeding is a type of food sharing behaviour observed in cooperatively breeding species of birds. Allofeeding refers to a parent, sibling or unrelated adult bird feeding altricial hatchlings, which are dependent on parental care for their survival. Allofeeding also refers to food sharing between adults of the same species. Allofeeding can occur between mates during mating rituals, courtship, egg laying or incubation, between peers of the same species, or as a form of parental care.
Social rank theory provides an evolutionary paradigm that locates affiliative and ranking structures at the core of many psychological disorders. In this context, displays of submission signal to dominant individuals that subordinate group members are not a threat to their rank within the social hierarchy. This helps to achieve social cohesion. According to social rank theory, anxiety and depression are natural experiences that are common to all mammalian species. It is the pathological exaggeration of anxiety and depression that contributes to psychological disorders.
Primate sociality is an area of primatology that aims to study the interactions between three main elements of a primate social network: the social organisation, the social structure and the mating system. The intersection of these three structures describe the socially complex behaviours and relationships occurring among adult males and females of a particular species. Cohesion and stability of groups are maintained through a confluence of factors, including: kinship, willingness to cooperate, frequency of agonistic behaviour, or varying intensities of dominance structures.
Communication occurs when an animal produces a signal and uses it to influences the behaviour of another animal. A signal can be any behavioural, structural or physiological trait that has evolved specifically to carry information about the sender and/or the external environment and to stimulate the sensory system of the receiver to change their behaviour. A signal is different from a cue in that cues are informational traits that have not been selected for communication purposes. For example, if an alerted bird gives a warning call to a predator and causes the predator to give up the hunt, the bird is using the sound as a signal to communicate its awareness to the predator. On the other hand, if a rat forages in the leaves and makes a sound that attracts a predator, the sound itself is a cue and the interaction is not considered a communication attempt.