Behavioral Patterns

What Exactly is Behavior?

• All animal behaviors are based on physiological systems and processes.

• Behavior is the sum of an organism’s responses to external and internal stimuli.

  • In animals, behaviors are typically actions carried out by muscles under control of the nervous system.

• Examples include an animal releasing a scent to mark its territory or using its throat muscles to produce a song.

  

• Behavior is an essential part of acquiring nutrients and finding a partner for sexual reproduction.

  • It also contributes to homeostasis, a state of balance among all the body systems needed for the body to survive and function correctly.

    

• In short, all of physiology contributes to behavior, and behavior influences all of physiology.

• Many behaviors, especially involving recognition and communication, rely on specialized body structures or form.

  • Natural selection that shapes behaviors also influences the evolution of animal anatomy.

What are the Broader Functions of Animal Behaviors?

• Niko Tinbergen, a Dutch scientist and a pioneer in the study of animal behavior, asked several questions on animal behavior:

  

  • What stimulus elicits the behavior, and what physiological mechanisms mediate the response?

  • How does the animal’s experience during growth and development influence the response?

  • How does the behavior make the animal more likely to survive and reproduce?

  • What is the behavior’s evolutionary history?

• As part of his researched, he kept fish tanks of three-spined stickback fishes.

  • In this species, only males have red bellies.

    

• Male sticklebacks attack other males who invade in their nesting territories.

• Tinbergen noticed male sticklebacks behaved aggressively when a red truck passed by their view.

• He hypothesized that the color red was the cause of the attack behavior.

  • They will not attack a fish lacking red coloration.

• The territorial response of male sticklebacks is an example of a fixed action pattern.

  • These is a sequence of unlearned acts directly linked to a simple stimulus.

  • These patterns are essentially unchangeable and are usually carried to completion.

• The trigger for the behavior is an external cue called a sign stimulus.

• Environmental stimuli also provides cues that animals use to carry out behaviors.

• For example, many birds, fishes, and other animals use environmental cues to guide migration - a regular, long-distance change in location.

  

• Some migrating animals track their position relative to the sun, even though the sun’s position relative to Earth changes throughout the day.

  • Animals can adjust for these changes by a means of a circadian clock, an internal mechanism that maintains a 24-hour activity rhythm or cycle.

    

• The clock is responsible for a circadian rhythm, a daily cycle of rest and activity.

• Some behaviors like migration and reproduction reflect biological rhythms with a longer cycle, or period, than the circadian rhythm.

• Behavioral rhythms linked to the yearly cycle of seasons are called circannual rhythms.

How do Animals Communicate?

• A stimulus transmitted from one organism to another is called a signal.

  • The transmission and reception of signals between animals constitute communication, which often has a role of proximate causation of behavior.

    

• There are 4 common modes of animal communication:

  • Visual, chemical, tactile, and auditory.

• For example, a fruit fly courtship is an example of a stimulus-response chain, in which the response to each stimulus is itself the stimulus for the next behavior.

  • Male fly detects female and orients his body towards him, and then uses his senses to detect chemicals she releases in the air.

  • Then he approaches and touches her foreleg.

  • The male then extends and vibrates one wing, producing a courtship song.

  • This shows that both the male and female are of the same species.

  • If successful, the female will allow the male to attempt copulation.

    

• A rule of thumb is that the form of communication that evolves is closely related to an animal’s lifestyle and environment.

  • Like visual displays are not so effective with nocturnal animals.

  • So they rely on auditory signals, which works well in both the dark and light.

    

• It was discovered in the early 1900s by Austrian researcher Karl von Frisch that European honeybees have a unique way of communicating.

  • He and he students observed that the bees’ movements make up a “dance language” that returning foragers use to inform other bees about the distance and direction of travel to food sources.

    

• Animals that communicate through odors or tastes emit chemical substances called pheromones.

  • Pheromones are often related to reproductive behavior.

  • An example from earlier is the fruit fly courtship ritual in which the female releases pheromones.

• Pheromones are not just short-distance signaling, as it can also be used for long-distance as well.

  • Male silkworm moths can detect female moths’ pheromones from several kilometers away.

• Pheromones can also serve as alarm signals.

  

How do Animals Learn their Behaviors?

• For some behaviors, nearly all individuals in a population behave alike.

  • Such as a fixed action pattern, a courtship stimulus-response chain, or pheromone signaling.

• Behavior that is developmentally fixed in this way is known as innate behavior.

  

• One powerful way that an animal’s environment can influence its behavior is through learning.

  • Learning is the modification of behavior as a result of specific experiences.

• The capacity for learning depends on nervous system organization established during development.

  • It involves the formation of memories by specific changes in neuronal connectivity.

  • It also follows instructions encoded in the genome.

    

• The ability of offspring to recognize and be recognized by a parent is essential for survival.

• In the young, learning comes rom imprinting, the establishment of a long-lasting behavioral response to a particular individual or object.

• Imprinting can take place only during a specific time period in development.

  • This is called the sensitive period.

    

• During the sensitive period, the young imprint on their parents and learn basic behaviors.

  • The parents also learn to recognize its offspring.

  • If bonding does not occur, the parent will not care for the offspring, and this leads to the offspring’s death and a decrease in reproductive success of the parents.

How else do Animals Learn?

• Every natural environment has spatial variation.

  • These include locations of nests, hazards, food, and prospective mates.

• An organism’s fitness may be enhanced by the capacity for spatial learning, the establishment of a memory that reflects the environment’s spatial structure.

  

• For example, Tinbergen wanted to test how animals used spatial awareness by experimenting on a female digger wasp.

• The wasp covers the entrance of her underground nest and memorizes it by learning visual landmarks that marks her location, in which pinecones are used.

  

  • Tinbergen then displaced the pinecones away from the nest, and when the wasp returned, she flew to the center of the pinecone circle.

    

• In some animals, spatial learning involves formulating a cognitive map.

  • A cognitive map is a representation in an animal’s nervous system of the spatial relationships between objects in its surroundings.

    

• By experimentally varying the distance between landmarks in the birds’ environments, researchers found that birds used the halfway point between landmarks rather than a fixed distance to find their hidden food stores.

• Learning also involves making associations between experiences.

• Associative learning is the acquired ability to associate one environmental feature (like color) with another (like danger).

  

  • Associative learning doesn’t just have to be colors.

• Research shows that some pigeons can associate danger with sound but not with a color.

  • Conversely, a rat also can learn to avoid illness-inducing foods on the basis on smells, not with sights or sounds.

• The associations an animal can readily form usually reflects relationships that often happens in nature.

• And associations that can’t be formed are unlikely to be of selective advantage in a native environment.

  

• The most complex forms of learning involve cognition - the process of knowing that involves awareness, reasoning, recollection, and judgment.

• Problem solving is the cognitive activity of devising a method to proceed from one condition to another in the face of real or apparent obstacles.

  

  • Many animals learn to solve problems by observing the behavior of other individuals.

  • This type of learning through observing is called social learning.

    

• Social learning forms the roots of culture, which can be defined as a system of information transfer through social learning or teaching that influences the behavior of individuals in a population.

  • Cultural transfer of information can alter behavior phenotypes and thereby influence the fitness of individuals.

What is Mating Behavior and Mate Choice?

• Mating behavior and mate choice play a big role in determining reproductive success.

  • These include seeking or attracting mates, choosing among potential mates, competing for mates, and caring for offspring.

• In the context of reproduction, biologists describe differences in mating systems among species, the length and number of relationships between males and females.

  • Some animals engage in monogamy (one male mating with one female) and others engage in polygamy (individual of one sex mating with several others).

    

• Sexual dimorphism, the extent to which males and females differ in appearance, also varies with the type of mating system.

• The needs of the young are an important factor constraining the evolution of mating systems.

  • Another factor influencing mating behavior and parental care is certainty of paternity.

  • The certainty of paternity is low in most species with internal fertilization because the acts of mating and birth are separated over time.

    

• Certainty of paternity is high when egg laying and mating occur together, as in external fertilization.

• Parental behavior correlated with certainty of paternity exists because it has been reinforced over generations by natural selection.

• Mate preferences of females may play a central role in the evolution of male behavior and anatomy through intersexual selection.

  • For example, studies show that during courtship, female stalk-eyed flies are more likely to mate with males that have long eyestalks.

• Things like this might correlate with health and vitality, which will help ensure the production of more offspring that survive to reproduce.

  

• The example of stalk-eyed flies can show how female choice can select for one best type of male in a given situation.

  • This typically results in low variation among males.

  • Male competition for mates can reinforce the tendency for reduced variation among males.

• This competition represents an agonistic behavior, a contest that determines which competitor gains access to a mate or other resource.