How Common Are Innate Behaviors In The Animal Kingdom?

Learning Outcomes

• Define behavioral biology
• Identify different types of innate behaviors in animals

Behavior  is the change in activity of an organism in response to a stimulus. Behavioral biological science  is the study of the biological and evolutionary bases for such changes. The idea that behaviors evolved as a issue of the pressures of natural option is not new. For decades, several types of scientists accept studied fauna behavior. Biologists exercise and so in the science of ethology ; psychologists in the science of comparative psychology; and other scientists in the science of neurobiology. The first ii, ethology and comparative psychology, are the about consequential for the study of behavioral biology.

One goal of behavioral biology is to distinguish between the innate behaviors , which have a strong genetic component and are largely independent of environmental influences, from the learned behaviors , which event from environmental conditioning. Innate behavior, or instinct, is important because there is no run a risk of an incorrect beliefs existence learned. They are "hard wired" into the arrangement. On the other mitt, learned behaviors, although riskier, are flexible, dynamic, and tin exist altered according to changes in the environment.

Innate Behaviors: Motion and Migration

Innate or instinctual behaviors rely on response to stimuli. The simplest case of this is a reflex action, an involuntary and rapid response to stimulus. To test the "knee-jerk" reflex, a doctor taps the patellar tendon below the kneecap with a prophylactic hammer. The stimulation of the nerves there leads to the reflex of extending the leg at the genu. This is similar to the reaction of someone who touches a hot stove and instinctually pulls their hand away. Even humans, with our great capacity to learn, still exhibit a variety of innate behaviors.

Kinesis and Taxis

Another activity or motion of innate behavior is kinesis, or the undirected movement in response to a stimulus. Orthokinesis is the increased or decreased speed of movement of an organism in response to a stimulus. Woodlice, for example, increase their speed of movement when exposed to high or low temperatures. This move, although random, increases the probability that the insect spends less time in the unfavorable environment. Another case is klinokinesis, an increase in turning behaviors. It is exhibited by bacteria such as E. coli which, in association with orthokinesis, helps the organisms randomly find a more hospitable surroundings.

A similar, but more directed version of kinesis is taxis: the directed movement towards or abroad from a stimulus. This movement can be in response to low-cal (phototaxis), chemical signals (chemotaxis), or gravity (geotaxis) and tin be directed toward (positive) or away (negative) from the source of the stimulus. An example of a positive chemotaxis is exhibited by the unicellular protozoan Tetrahymena thermophila. This organism swims using its cilia, at times moving in a direct line, and at other times making turns. The alluring chemotactic agent alters the frequency of turning as the organism moves directly toward the source, following the increasing concentration gradient.

Fixed Action Patterns

A fixed action pattern is a series of movements elicited by a stimulus such that fifty-fifty when the stimulus is removed, the design goes on to completion. An example of such a behavior occurs in the 3-spined stickleback, a small-scale freshwater fish (Effigy 1). Males of this species develop a scarlet belly during breeding season and evidence instinctual aggressiveness to other males during this time. In laboratory experiments, researchers exposed such fish to objects that in no fashion resemble a fish in their shape, merely which were painted red on their lower halves. The male sticklebacks responded aggressively to the objects just as if they were real male sticklebacks.

Figure 1. Male person iii-spined stickleback fish exhibit a fixed action design. During mating season, the males, which develop a vivid red belly, react strongly to red-bottomed objects that in no way resemble fish.

Migration

Effigy ii. Wildebeests migrate in a clockwise fashion over 1800 miles each twelvemonth in search of rain-ripened grass. (credit: Eric Inafuku)

Migration is the long-range seasonal movement of animals. Information technology is an evolved, adjusted response to variation in resource availability, and it is a common phenomenon institute in all major groups of animals. Birds fly southward for the wintertime to go to warmer climates with sufficient food, and salmon migrate to their spawning grounds. The popular 2005 documentary March of the Penguins followed the 62-mile migration of emperor penguins through Antarctica to bring food back to their breeding site and to their young. Wildebeests (Figure ii) drift over 1800 miles each twelvemonth in search of new grasslands.

Although migration is thought of as innate behavior, only some migrating species always migrate (obligate migration). Animals that exhibit facultative migration can choose to migrate or not. Additionally, in some animals, only a portion of the population migrates, whereas the rest does not migrate (incomplete migration). For example, owls that live in the tundra may migrate in years when their food source, small rodents, is relatively scarce, just not migrate during the years when rodents are plentiful.

Foraging

Figure 3. The painted stork uses its long nib to forage. (credit: J.Thousand. Garg)

Foraging is the human activity of searching for and exploiting food resources. Feeding behaviors that maximize energy gain and minimize energy expenditure are chosen optimal foraging behaviors, and these are favored by natural department. The painted stork, for example, uses its long beak to search the bottom of a freshwater marshland for crabs and other food (Figure 3).

Innate Behaviors: Living in Groups

Not all animals live in groups, but even those that alive relatively solitary lives, with the exception of those that can reproduce asexually, must mate. Mating unremarkably involves one animal signaling some other so as to communicate the desire to mate. In that location are several types of energy-intensive behaviors or displays associated with mating, called mating rituals. Other behaviors plant in populations that live in groups are described in terms of which animal benefits from the behavior. In selfish behavior, only the beast in question benefits; in altruistic behavior, 1 animal'southward actions do good some other animal; cooperative behavior describes when both animals do good. All of these behaviors involve some sort of communication between population members.

Communication within a Species

Animals communicate with each other using stimuli known equally signals. An instance of this is seen in the three-spined stickleback, where the visual signal of a ruddy region in the lower half of a fish signals males to become aggressive and signals females to mate. Other signals are chemical (pheromones), aural (sound), visual (courtship and ambitious displays), or tactile (touch). These types of communication may exist instinctual or learned or a combination of both. These are not the same every bit the communication we associate with language, which has been observed only in humans and mayhap in some species of primates and cetaceans.

A pheromone is a secreted chemical signal used to obtain a response from another private of the same species. The purpose of pheromones is to elicit a specific beliefs from the receiving individual. Pheromones are peculiarly common amid social insects, just they are used by many species to attract the opposite sexual activity, to sound alarms, to mark food trails, and to elicit other, more complex behaviors. Even humans are thought to respond to certain pheromones called axillary steroids. These chemicals influence human perception of other people, and in one study were responsible for a group of women synchronizing their menstrual cycles. The role of pheromones in man-to-human communication is still somewhat controversial and continues to be researched.

Songs are an instance of an aural betoken, 1 that needs to be heard by the recipient. Possibly the all-time known of these are songs of birds, which identify the species and are used to attract mates. Other well-known songs are those of whales, which are of such low frequency that they can travel long distances underwater. Dolphins communicate with each other using a broad diverseness of vocalizations. Male crickets make chirping sounds using a specialized organ to attract a mate, repel other males, and to announce a successful mating.

Effigy 4. This stork's courtship brandish is designed to attract potential mates. (credit: Linda "jinterwas"/Flickr)

Courtship displays are a series of ritualized visual behaviors (signals) designed to attract and convince a member of the opposite sex to mate. These displays are ubiquitous in the fauna kingdom. Oftentimes these displays involve a series of steps, including an initial brandish by one fellow member followed past a response from the other. If at any point, the display is performed incorrectly or a proper response is not given, the mating ritual is abandoned and the mating attempt volition be unsuccessful. The mating display of the common stork is shown in Figure four.

Aggressive displays are also common in the animal kingdom. An instance is when a canis familiaris bares its teeth when it wants another dog to dorsum down. Presumably, these displays communicate not but the willingness of the animal to fight, but also its fighting ability. Although these displays practise bespeak aggression on the part of the sender, it is thought that these displays are actually a mechanism to reduce the amount of actual fighting that occurs betwixt members of the same species: they allow individuals to assess the fighting ability of their opponent and thus decide whether it is "worth the fight." The testing of certain hypotheses using game theory has led to the conclusion that some of these displays may overstate an animal's actual fighting ability and are used to "bluff" the opponent. This blazon of interaction, fifty-fifty if "dishonest," would be favored by natural choice if information technology is successful more than times than non.

Distraction displays are seen in birds and some fish. They are designed to attract a predator away from the nest that contains their young. This is an example of an altruistic beliefs: it benefits the young more than the individual performing the display, which is putting itself at risk by doing then.

Many animals, especially primates, communicate with other members in the group through touch on. Activities such as grooming, touching the shoulder or root of the tail, embracing, lip contact, and greeting ceremonies have all been observed in the Indian langur, an One-time World monkey. Like behaviors are found in other primates, particularly in the dandy apes.

The killdeer bird distracts predators from its eggs past faking a broken wing display in this video taken in Boise, Idaho. Note that this video has no narration.

You lot can view the descriptive transcript for "Killdeer – Broken-Fly Brandish, Boise, Idaho" here (opens in new window).

Altruistic Behaviors

Behaviors that lower the fettle of the private but increase the fitness of some other individual are termed donating. Examples of such behaviors are seen widely across the animal kingdom. Social insects such as worker bees have no power to reproduce, yet they maintain the queen and so she can populate the hive with her offspring. Meerkats keep a lookout man standing baby-sit to warn the balance of the colony about intruders, even though the sentry is putting itself at take chances. Wolves and wild dogs bring meat to pack members non present during a hunt. Lemurs accept care of infants unrelated to them. Although on the surface, these behaviors appear to be altruistic, it may non exist so uncomplicated.

There has been much discussion over why donating behaviors exist. Do these behaviors atomic number 82 to overall evolutionary advantages for their species? Do they aid the donating individual pass on its own genes? And what about such activities between unrelated individuals? One explanation for altruistic-type behaviors is constitute in the genetics of natural selection. In the 1976 volume, The Selfish Cistron, scientist Richard Dawkins attempted to explain many seemingly altruistic behaviors from the viewpoint of the gene itself. Although a gene patently cannot be selfish in the human sense, it may appear that mode if the sacrifice of an individual benefits related individuals that share genes that are identical by descent (nowadays in relatives because of common lineage). Mammal parents make this sacrifice to accept care of their offspring. Emperor penguins migrate miles in harsh conditions to bring nutrient back for their young. Selfish cistron theory has been controversial over the years and is all the same discussed among scientists in related fields.

Fifty-fifty less-related individuals, those with less genetic identity than that shared by parent and offspring, benefit from seemingly donating behavior. The activities of social insects such as bees, wasps, ants, and termites are proficient examples. Sterile workers in these societies accept intendance of the queen considering they are closely related to it, and equally the queen has offspring, she is passing on genes from the workers indirectly. Thus, it is of fitness do good for the worker to maintain the queen without having any direct chance of passing on its genes due to its sterility. The lowering of individual fitness to raise the reproductive fitness of a relative and thus one'south inclusive fettle evolves through kin selection. This phenomenon can explicate many superficially altruistic behaviors seen in animals. However, these behaviors may not exist truly divers as altruism in these cases because the actor is really increasing its own fettle either straight (through its ain offspring) or indirectly (through the inclusive fitness it gains through relatives that share genes with it).

Unrelated individuals may also human activity altruistically to each other, and this seems to defy the "selfish gene" caption. An example of this observed in many monkey species where a monkey will nowadays its back to an unrelated monkey to have that private pick the parasites from its fur. After a certain corporeality of time, the roles are reversed and the first monkey now grooms the second monkey. Thus, at that place is reciprocity in the beliefs. Both benefit from the interaction and their fitness is raised more than if neither cooperated nor if i cooperated and the other did not cooperate. This beliefs is still not necessarily altruism, as the "giving" behavior of the actor is based on the expectation that information technology will be the "receiver" of the behavior in the future, termed reciprocal altruism. Reciprocal altruism requires that individuals repeatedly come across each other, oft the result of living in the same social group, and that cheaters (those that never "requite back") are punished.

Evolutionary game theory, a modification of classical game theory in mathematics, has shown that many of these so-called "altruistic behaviors" are non altruistic at all. The definition of "pure" altruism, based on human behavior, is an activeness that benefits another without any straight benefit to oneself. Most of the behaviors previously described do not seem to satisfy this definition, and game theorists are practiced at finding "selfish" components in them. Others have argued that the terms "selfish" and "altruistic" should be dropped completely when discussing animal behavior, equally they describe human beliefs and may not be directly applicable to instinctual beast activity. What is clear, though, is that heritable behaviors that improve the chances of passing on one's genes or a portion of one's genes are favored by natural selection and volition be retained in future generations as long equally those behaviors convey a fitness reward. These instinctual behaviors may then exist applied, in special circumstances, to other species, as long as information technology doesn't lower the beast's fitness.

Finding Sexual activity Partners

Non all animals reproduce sexually, merely many that exercise take the same challenge: they need to notice a suitable mate and often have to compete with other individuals to obtain one. Pregnant free energy is spent in the procedure of locating, attracting, and mating with the sex partner. Two types of selection occur during this process and tin atomic number 82 to traits that are of import to reproduction called secondary sexual characteristics: intersexual selection, the choosing of a mate where individuals of i sexual practice cull mates of the other sex, and intrasexual option, the contest for mates between species members of the same sex. Intersexual selection is often circuitous because choosing a mate may be based on a diverseness of visual, aural, tactile, and chemical cues. An example of intersexual selection is when female person peacocks cull to mate with the male with the brightest plumage. This type of selection ofttimes leads to traits in the chosen sexual practice that exercise not heighten survival, but are those traits most attractive to the opposite sex (oft at the expense of survival). Intrasexual selection involves mating displays and ambitious mating rituals such as rams butting heads—the winner of these battles is the one that is able to mate. Many of these rituals employ up considerable free energy but result in the selection of the healthiest, strongest, and/or most ascendant individuals for mating. Three general mating systems, all involving innate every bit opposed to learned behaviors, are seen in animal populations: monogamous, polygynous, and polyandrous.

Watch this informative video on sexual selection.

In monogamous  systems, one male and one female are paired for at least ane breeding season. In some animals, such as the greyness wolf, these associations tin last much longer, even a lifetime. Several theories may explain this type of mating system. The "mate-guarding hypothesis" states that males stay with the female person to foreclose other males from mating with her. This behavior is advantageous in such situations where mates are scarce and difficult to detect. Another explanation is the "male-assist hypothesis," where males that help guard and rear their immature will have more and healthier offspring. Monogamy is observed in many bird populations where, in addition to the parental care from the female person, the male is also a major provider of parental intendance for the chicks. A third explanation for the evolutionary advantages of monogamy is the "female-enforcement hypothesis." In this scenario, the female ensures that the male person does not accept other offspring that might compete with her own, so she actively interferes with the male's signaling to attract other mates.

Polygynous  mating refers to one male mating with multiple females. In these situations, the female must exist responsible for virtually of the parental intendance as the single male is not capable of providing intendance to that many offspring. In resourced-based polygyny, males compete for territories with the all-time resources, and and so mate with females that enter the territory, drawn to its resource richness. The female person benefits past mating with a dominant, genetically fit male; however, it is at the cost of having no male person help in caring for the offspring. An example is seen in the yellowish-rumped honeyguide, a bird whose males defend beehives considering the females feed on their wax. As the females approach, the male defending the nest volition mate with them. Harem mating structures are a type of polygynous organisation where certain males dominate mating while controlling a territory with resources. Harem mating occurs in elephant seals, where the alpha male person dominates the mating within the group. A third type of polygyny is a lek system. Here in that location is a communal courting area where several males perform elaborate displays for females, and the females cull their mate from this group. This behavior is observed in several bird species including the sage grouse and the prairie chicken.

In polyandrous mating systems, 1 female mates with many males. These types of systems are much rarer than monogamous and polygynous mating systems. In pipefishes and seahorses, males receive the eggs from the female, fertilize them, protect them within a pouch, and give nascence to the offspring (Figure v). Therefore, the female is able to provide eggs to several males without the burden of carrying the fertilized eggs.

Figure 5. Polyandrous mating, in which one female mates with many males, occurs in the (a) seahorse and the (b) pipefish. (credit a: modification of work by Brian Gratwicke; credit b: modification of work by Stephen Childs)

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