Animal Behavior 2/21/2017. What is Behavior? Understanding Behavior. Types of Behavior. Types of Behavior

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1 What is Behavior? Behavior everything an animal does & how it does it response to stimuli in its environment Animal Behavior Why Study Behavior? Evolutionary perspective part of phenotype acted upon by natural selection lead to greater fitness? lead to greater survival? lead to greater reproductive success? Causes of Behavior Proximate cause: how a behavior occurs or is modified based on its immediate interactions with the environment Understanding Behavior Male songbird what triggers singing? how does he sing? why does he sing? BEHAVIOR: A male stickleback fish attacks other male sticklebacks that invade its nesting territory. Ultimate cause: why a behavior occurs in context of natural selection - how does behavior contribute to survival and reproduction Courtship behaviors in cranes how does day length influence breeding? why do cranes breed in spring? PROXIMATE CAUSE: The red belly of the intruding male acts as a sign stimulus that releases aggression in a male stickleback. ULTIMATE CAUSE: By chasing away other male sticklebacks, a male decreases the chance that eggs laid in his nesting territory will be fertilized by another male. Is it nature or nurture? Innate behavior: behavior performed correctly and in the same way by all individuals of a species, without previous experience (genetic cause) - built in, not learned, Innate Behavior Fixed Action Pattern Fixed Action Pattern (FAP): innate behavior that occurs as an unchangeable sequence of actions - triggered by sign stimulus - conducted to completion once started - ensures that activities essential to survival are performed correctly and without practice The graylag goose responds to an egg outside her nest with a set of specific actions. Even when the egg is removed, the goose will continue to push at the air with her beak until she completes the FAP Sign Stimuli- Attack on red belly stimulus Court on swollen belly stimulus 1

2 Innate: Directed movements Taxis - change in direction - automatic movement toward (positive taxis) or away from (negative taxis) a stimulus - phototaxis -chemotaxis Kinesis - change in rate of movement in response to a stimulus Positive rheotaxis keeps trout facing into the current, the direction from which most food comes. Kinesis increases the chance that a sow bugs will encounter and stay in a moist environment. Innate: Migration Regular, long-distance change in location Environmental cues: sun, stars, earth s magnetic field, landmarks monarchs Circadian rhythm: Internal biological clock follows an approximately 24- hour natural cycle The circadian clock in the hamster brain signals a change in coat color according to season by releasing the hormone melatonin. Signal: stimulus that causes a change in behavior; basis of animal communication Pheromones chemicals emitted by members of one species that affect other members of the species (eg. Queen bee, fruit fly, fish, termites, trees, humans) Plants can have two internal clocks: one sensitive to light and the other sensitive to temperature Visual signals Warning flash of white of a mockingbird's wing Tactile (touch) Male fruit fly taps female fly Auditory signals screech of blue jay or song of warbler The Suprachiasmatic nuclei (SCN) region is located in the hypothalamus of the brain. The SCN sends signals throughout the body in response to dark and light. Honeybee dance language bee returning from the field performs a dance to communicate information about the distance and direction of a food source Minnows before alarm Minnows after alarm 2

3 Learned behaviors modified by experience variable, changeable flexible with a complex & changing environment Interaction of Genes and Experience How does inheritance and experience form a particular behavior? Biologists mated two different species to form a hybrid species Conclusion: hybrid offspring could alter inherited behavior based on experience. Types of Learning Learning: a change in an animal's behavior resulting from specific experiences Lorenz: Greylag goose experiment Control: mother rears young in nest Types of learning: 1. Habituation: type of learning in which an animal stops responding to a repeated stimulus that conveys little or no important information ex: ticking of a clock 2. Imprinting: learning that is limited to a specific time period in an animal's life and that is usually irreversible learning + innate components critical learning period : time period in which imprinting takes place Experimental: Lorenz rears young in incubator Result: Control group: normal imprinting, followed mother, had normal goose relationships Experimental group: imprinted on Lorenz, followed him, preferred human relationships to geese BEHAVIOR: Young geese follow and imprint on their mother. Types of Learning 3. Spatial Learning Cognitive Map: internal representation of spatial relationship among objects in an animal s surroundings PROXIMATE CAUSE: During an early, critical developmental stage, the young geese observe their mother moving away from them and calling. ULTIMATE CAUSE: On average, geese that follow and imprint on their mother receive more care and learn necessary skills, and thus have a greater chance of surviving than those that do not follow their mother. Birds use spatial maps to relocate nut caches 3

4 Some organisms move in response to a recognized object or environmental cue, a landmark. Nest 4. Associative learning: learning to associate a stimulus with a consequence Classical conditioning - learning that a particular stimulus or a particular response is linked to a reward or punishment - rat will push a level if it receives food for pushing the level Operant conditioning - trial & error learning - associate behavior with reward or punishment ex: learning what to eat Pavlov s dogs t No nest - predator avoids specific prey associated with a painful experience Insight: the ability to respond appropriately to a new situation without previous experience 5. Cognition: process of knowing that involves awareness, reasoning, recollection, judgment Problem-solving behavior relies on cognition 6. Social learning: learning by observing others Monkeys learn correct use of alarm calls Selection for individual survival and reproductive success can explain most behaviors Foraging: food-obtaining behavior Recognize, search for, capturing, and consuming food Minimize costs / Maximize benefits Costs- energy expenditure and the risk of being eaten Crow will drop a whelk (a mollusc) from a height to break its shell Trade-off between the height and the number of times it must drop Researchers determined total flight height (energy) was minimized at 5 m Average crow flight height: 5.23 m Mating Behavior & Mate Choice Sexual selection: seeking and attracting mates, choosing and competing for mates Promiscuous Monogamous paternal care by male jawfish Polygamous (polygynous) Polyandry Partners Many One 1 M + many F 1F + many M Structure Showy Similar Showy male Showy female Care None Much Male = little Male = none Monogamous species Polygynous species Polyandrous species 4

5 Sexual seletion: ornaments correlate in general with health and vitality Mate Choice Males Agonistic behavior: threats, rituals, and sometimes combat; settles disputes over resources Courtship ritual: elaborate behavior of individuals of the same species before mating Females Mate Choice Copying: copy the mate choice of others Social Behaviors Competitive Behaviors (pack animals) Aggressive behavior: symbolic threat display or a physical struggle between individuals of the same species Genetic Basis of Behavior Certain behaviors in prairie voles are under relatively strong genetic control ADH (vasopressin) triggers pair-bond formation and aggression by male voles Differences in oxytocin (a hormone) receptors in 2 species of voles Dominance hierarchy : ranking of individuals in a group based on aggressive behavior Territorial behavior: behavior that protects territorial rights ex: chatting squirrels marking areas with urine High oxytocin levels in prairie voles (monogomous) Low oxytocin levels in montane voles (promiscuous) Altruistic Social Behavior Altruism : selfless behavior Reduce individual fitness but increase fitness of others in population i.e. bee societies; naked mole rats Inclusive fitness: total effect of producing own offspring (pass on genes) + helping close relatives Kin selection: type of natural selection; altruistic behavior enhances reproductive success of relatives Altruism can be explained by inclusive fitness Hamilton s Rule and Kin Selection: quantitative measure for predicting when natural selection would favor altruistic acts among related individuals Benefit to the recipient (B) Cost to the altruistic (C) Coefficient of relatedness: fraction of genes shared; r Hamilton s rule: rb > C 5

6 Example: Assume the average individual has two children. As a result of the sister s action: The brother can now father two children, so B 2 The sister has a 25% chance of dying and not being able to have two children, so C The brother and sister share half their genes on average, so r 0.5 If the sister saves her brother rb ( 1) C ( 0.5) Game Theory (tit for tat strategy) - Individuals always cooperate on first encounter - An individual treats another the same way it was treated the last time they met individuals will always cooperate, unless their opponent cheated them the last time they met reciprocal altruism Individuals who engage in a tit-for-tat strategy have a higher fitness than individuals who are always selfish Evolution and Human Culture Study for the test! No other species comes close to matching the social learning and cultural transmission that occur among humans Human culture is related to evolutionary theory in the distinct discipline of sociobiology Human behavior, like that of other species, results from interaction between genes and environment However, our social and cultural institutions may provide the only feature in which there is no continuum between humans and other animals 6