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 3. Learned • Learning is modification of behavior through experience • 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 • More complex learning involves the formation of new neural pathways and connections as well as changes in existing circuits 3. Learning Con’t • An animal can only learn to do what it is physically capable of doing • 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 • Communication—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 • Social species must cooperate, but not at expense of own interests such a food, mates, shelter • Aggression—offensive physical action or threat to force others to abandon something • Agonistic behavior—any activity related to fighting • Most dangerous weapons used only on prey not on own species, relying on ritualized displays to avoid injury or death • 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