Animal Behavior

Chapter 36

I.

Science of Animal Behavior A. Ethology

• Ethology—study of animal behavior in its natural habitat • Behavior is the way an animal acts in response to a stimulation; usually involve finding food, interacting in social groups, avoiding predators, and reproducing • Idea that behaviors can be isolated and measured to trace their evolution • Proximate causation—physiological reasons for animal behavior • Ultimate causation-selective adaptations are the reasons for certain animal behaviors • Interested in tracing behavior across species

B. Sociobiology

• Study of social behavior • E.O. Wilson father of sociobiology • Reciprocal communication between individuals in a group of the same species that is cooperative and permits the group to become organized • Differing levels of complexity • individuals that act as 1 large individual,like Portuguese man-o-war • Social insects like bees, ants, termites • Groups like elephants, dolphins, primates • humans

C. Behavioral Ecology

• Individual behavior that maximizes reproductive success • Mate choice, foraging, parenting are all studied

II.

Principles of Ethology A. Stereotypical Behavior

• Konrad Lorenz & Niko Tinbergen were pioneers • Automatic programmed responses to a stimulus in the environment that may mimic intelligent behavior (usually most effective in the wild); these are instincts • Releaser—any stimulus that triggers a certain behavior • Sign stimulus—one specific part of the stimulus that the animal responds to • Examples—parent’s call releasing the freeze response in a chick; male stickleback becoming aggressive in presence of other male’s red coloration

B. Control of Behavior 1. Innate

• Predictable stereotyped behaviors that are inherited • Independent of learning but does depend on interactions during development • Important for survival, especially in animals that do not have parental care • Reflexes are simplest type and usually protective; instinctive behavior is more complex series of actions • Longer lived animals may also develop additional social and learned behaviors since have time to acquire them

2. Genetics

• Inheritance of innate behavior depends on many interacting genes • Some, however, like honeybee hygiene, are just 1 gene; bees that were recessive for 1 gene, uncapped cells that contained decaying larvae; those that were recessive for another gene carried out the decayed larvae • Sometimes crossing purebred dominants and recessives for certain traits creates hybrids that have confused behavior

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3. Learned

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Learning is modification of behavior through experience

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Habituation —animal learns to ignore a stimulus (perceived as harmless or unrewarding) and does not react to it; repeated stimulation diminishes the release of neurotransmitters from sensory neurons to motor neurons resulting in no reaction Conditioning —animal connects a certain stimulus with a certain behavior; used in training animals usually with a reward Sensitization —a noxious stimulus is added to an initial stimulus resulting in a response; later only initial stimulus need be given to have same result

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More complex learning involves the formation of new neural pathways and connections as well as changes in existing circuits

3. Learning Con’t

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An animal can only learn to do what it is physically capable of doing

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Imprinting —young animal exposed to object during critical window of development; bond then lasts for life; ”mother”; learning bird songs Trial-and-error learning or operant learning —animal relates its past experience to new stimulus

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Communication

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—the sharing of information that results in a behavior change Language —using symbols to represent ideas

III. Social Behavior A. Examples

• Response of one animal of a species to another of the same species • Males fighting over female; breeding may sometimes be the only social interaction • Monogamy—relationship for life • Mother mammals and birds usually form bond with young until weaned or fledged • Social aggregations for feeding, warmth, protection

B. Advantages

• Passive and active defense since safer in group than alone • More animals in a group, less likely will be eaten • Brings together males and females for breeding; contact may also bring about necessary endocrinal changes needed for breeding • Survival of young increases • Hunting, protection from weather, division of labor, potential for learning and transmitting useful information

C. Disadvantages

• If depend on camouflage for protection, better off dispersed • Large predators need great quantities of food • Habitat may not support large numbers of individuals in a certain area

D. Aggression & Dominance

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Social species must cooperate, but not at expense of own interests such a food, mates, shelter

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Aggression —offensive physical action or threat to force others to abandon something Agonistic behavior —any activity related to fighting

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Most dangerous weapons used only on prey not on own species, relying on ritualized displays to avoid injury or death

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Ritualized display —behavior that has been modified through evolution to make it effective in communication; may be used to gain access to food, mates, or territory; loser runs away or signals defeat by subordination ritual Dominance hierarchy —establishes a “pecking” order; weaker members typically die in times of scarce resources

E. Territoriality

• Territory—fixed area from which intruders of same species are excluded • May be an alternate behavior to dominance • Ensures food supply • Provides protected area for mating and rearing young • Sometimes costs of maintaining a territory outweighs benefits • Birds tend to form territories; mammals typically have home ranges

F. Mating Systems

• Monogamy--1 male and 1 female mating at a time • Polygamy—general term for any system that has multiple partners • Polygyny—1 male mates with more than 1 female; male may hold critical resources to attract several mates (resource defense); females may aggregate making them easily defensible (female defense); female may pick male from group of males based on display (male dominance) • Polyandry—1 female mates with more than 1 male

G. Altruistic Behavior & Kin Selection

• Inclusive fitness—relative number of individual’s alleles that are passed on to future offspring or that of related individuals • Some insect workers, that are haplodiploid, give up reproduction and aid the queen in reproducing; they are 75% related to sister queen’s offspring, rather than only 50% if mated and had own offspring • In these systems, it is important to be able to distinguish kin from non-kin

IV. Animal Communication A. Chemical Signals

• One animal influences the behavior of another though sounds, scents, touch, and movement • A signal conveys one message and can not be rearranged to construct new kinds of information (in contrast to language) • Chemical signals evolve easily since there is selection for better detectors • Pheromones are chemical signals used to attract mates • Female moths emit pheromones; males use antennae that detect it and then locate female

B. Displays 1. Bees

• Communicate location of food through the Waggle Dance • Figure eight pattern done in comb of hive • Waggle in middle part of the 8 indicates direction of food source relative to the sun • The speed of the waggle is inversely proportional to the distance the food is from the hive • If food is close to hive, a found dance is used instead • Dancing less common when food is plentiful; more intense when food is scarce

2. Other Organisms

• Courtship dances of birds repeat many displayed behaviors so that a commitment to courtship is ensured

C. Language

• Animal cognition—mental function, perception, thinking, and memory • Studies try to detect extent to which animals are self aware and levels of reasoning • Humans have a hard time determining this in other animals • Chimps have learned 132 words in ASL • Parrots can vocalize like humans which aids in measuring cognition; can identify shapes, colors, and numbers