Chapter 51: Animal Behavior Mrs. Valdes AP Biology

Overview: Shall We Dance? Cranes: interesting dancing behavior during courtship Animal behavior based on physiological systems and processes Behavior: nervous system’s response to stimulus; carried out by muscular or hormonal system Behavior helps animal Obtain food Find partner for sexual reproduction Maintain homeostasis Behavior subject to natural selection

Concept 51.1: Discrete sensory inputs can stimulate both simple and complex behaviors Animal’s behavior = response to external and internal stimuli Ethology: scientific study of animal behavior, particularly in natural environments According to early ethologist Niko Tinbergen, four questions should be asked about behavior: What stimulus elicits behavior, and what physiological mechanisms mediate response? How does animal’s experience during growth and development influence response mechanisms? How does behavior aid survival and reproduction? What is behavior’s evolutionary history? Proximate causation: “how” explanations, focus on Environmental stimuli that trigger behavior Genetic, physiological, and anatomical mechanisms underlying behavior Ultimate causation: “why” explanations, focus on evolutionary significance of behavior Behavioral ecology: study of ecological and evolutionary basis for animal behavior; integrates proximate and ultimate explanations for animal behavior

Fixed Action Patterns DEFINE: sequence of unlearned, innate behaviors that is unchangeable Once initiated carried to completion triggered by external cue known as sign stimulus Ex: male stickleback fish Stimulus for attack behavior: red underside of intruder Action: presented with unrealistic models, as long as some red is present, attack behavior occurs

Oriented Movement Environmental cues can trigger movement in a particular direction Kinesis: simple change in activity or turning rate in response to a stimulus Ex: sow bugs become more active in dry areas and less active in humid areas Sow bug behavior varies with humidity, sow bugs do NOT move toward or away from specific moisture levels Taxis: more or less automatic, oriented movement toward or away from a stimulus Ex: stream fish exhibit positive taxis and automatically swim in upstream direction prevents them from being swept away and keeps them facing direction from which food will come

Migration DEFINE: regular, long-distance change in location Animals can orient themselves using position of sun and their circadian clock position of North Star Earth’s magnetic field

Behavioral Rhythms Some animal behavior affected by animal’s circadian rhythm Behaviors such as migration and reproduction are linked to changing seasons, or a circannual rhythm Some behaviors linked to lunar cycles Ex: courtship in fiddler crabs occurs during new and full moon

Animal Signals and Communication Signal: behavior that causes change in another animal’s behavior Communication: transmission and reception of signals Animals communicate using visual, chemical, tactile, and auditory signals Type of signal closely related to lifestyle and environment Honeybees show complex communication with symbolic language bee returning from field performs dance to communicate information about position of food source

Pheromones Pheromones: chemicals emitted through odors effective at very low concentrations Ex: minnow or catfish injured alarm substance in fish’s skin disperses in water induce fright response among fish in area

Concept 51.2: Learning establishes specific links between experience and behavior Innate behavior: developmentally fixed; under strong genetic influence Learning: modification of behavior based on specific experiences Habituation: simple form of learning; involves loss of responsiveness to stimuli that convey little or no information Ex:, birds stop responding to alarm calls from their species if not followed by actual attack Imprinting: behavior that includes learning and innate components; generally irreversible distinguished from other learning by sensitive period limited developmental phase that is ONLY TIME when certain behaviors can be learned Ex: young geese following their mother Konrad Lorenz showed when baby geese spent first few hours of life with him imprinted on him as parent Conservation biologists taken advantage of imprinting in programs to save whooping crane from extinction Young whooping cranes imprint on humans in “crane suits” who lead crane migrations using ultralight aircraft

Spatial Learning Spatial learning: more complex modification of behavior based on experience with spatial structure of environment Niko Tinbergen showed how digger wasps use landmarks to find nest entrances Cognitive map: internal representation of spatial relationships between objects in animal’s surroundings Ex: Clark’s nutcrackers can find food hidden in caches located halfway between particular landmarks

Associative Learning DEFINE: animals associate one feature of environment with another Ex: white-footed mouse avoid eating caterpillars with specific colors after bad experience with distasteful monarch butterfly caterpillar Classical conditioning: type of associative learning in which arbitrary stimulus associated with reward or punishment Ex: dog repeatedly hears bell before being fed  salivate in anticipation at bell’s sound Operant conditioning: type of associative learning in which animal learns to associate one of its behaviors with a reward or punishment also called trial-and-error learning Ex: rat that fed after pushing lever will learn to push lever in order to receive food Ex: predator learn to avoid specific type of prey associated with painful experience

Cognition and Problem Solving Cognition: process of knowing that includes awareness, reasoning, recollection, and judgment Ex: honeybees can distinguish “same” from “different” Problem solving: process of devising strategy to overcome obstacle Ex: chimpanzees stack boxes in order to reach suspended food Some animals learn to solve problems by observing other individuals Ex: young chimpanzees learn to crack palm nuts with stones by copying older chimpanzees

Learning and problem solving Fig. 51-UN1 Imprinting Learning and problem solving Spatial learning Cognition Associative learning Social learning

Concept 51.3: Both genetic makeup and environment contribute to the development of behaviors Animal behavior governed by complex interactions between genetic and environmental factors Cross-fostering studies help behavioral ecologists identify contribution of environment to animal’s behavior Cross-fostering study: places young from one species in care of adults from another species California mice and white-footed mice study uncovered influence of social environment on aggressive and parental behaviors Cross-fostered mice developed some behaviors that were consistent with their foster parents Humans: twin studies allow researchers to compare relative influences of genetics and environment on behavior

Regulatory Genes and Behavior Master regulatory gene can control many behaviors Ex: single gene controls many behaviors of male fruit fly courtship ritual Multiple independent genes can contribute to a single behavior Ex: Green lacewings: courtship song unique to each species; multiple independent genes govern different components of courtship song

Genetically Based Behavioral Variation in Natural Populations Behavioral variation within species corresponds to environmental variation evidence of past evolution Example: Most blackcaps (birds) that breed in Germany winter in Africa, but some winter in Britain two migratory populations are genetically distinct Example: Natural diet of western garter snakes varies by population Coastal populations feed mostly on banana slugs, while inland populations rarely eat banana slugs Studies show differences in diet are genetic two populations differ in ability to detect and respond to specific odor molecules produced by banana slugs!

Influence of Single-Locus Variation Differences at single locus can sometimes have a large effect on behavior Ex: male prairie voles pair-bond with their mates, while male meadow voles do not level of specific receptor for neurotransmitter determines which behavioral pattern develops

Concept 51.4: Selection for individual survival and reproductive success can explain most behaviors Genetic components of behavior evolve through NATURAL SELECTION!!!!! Behavior can affect fitness by influencing foraging and mate choice Natural selection refines behaviors that enhance efficiency of feeding Foraging: food-obtaining behavior; includes recognizing, searching for, capturing, and eating food items Drosophila melanogaster, variation in gene dictates foraging behavior in larvae Larvae with one allele travel farther while foraging than larvae with other allele Larvae in high-density populations benefit from foraging farther for food Larvae in low-density populations benefit from short-distance foraging Natural selection favors different foraging behavior depending density of the population

Optimal Foraging Model Optimal foraging model: views foraging behavior as compromise between benefits of nutrition and costs of obtaining food costs of obtaining food include energy expenditure and risk of being eaten while foraging Natural selection should favor foraging behavior that minimizes costs and maximizes benefits Optimal foraging behavior demonstrated by Northwestern crow crow will drop whelk (a mollusc) from height to break shell and feed on soft parts crow faces trade-off between height from which it drops whelk and number of times it must drop whelk Researchers determined experimentally that total flight height (which reflects total energy expenditure) minimized at drop height of 5 m AND… average flight height for crows is 5.2 m. BOOM. SCIENCE.

Average number of drops Fig. 51-19 125 60 50 100 40 Average number of drops Average number of drops 30 75 Total flight height (number of drops  drop height in m) Total flight height 20 Drop height preferred by crows = 5.23 m 50 Figure 51.19 Energy costs and benefits in foraging behavior 10 25 2 3 5 7 15 Drop height (m)

Mating Behavior and Mate Choice Mating behavior includes seeking or attracting mates, choosing among potential mates, and competing for mates Mating behavior results from type of natural selection called sexual selection Promiscuous: no strong pair-bonds or lasting relationships; many animals Monogamous relationships: one male mates with one female Males and females with monogamous mating systems have similar external morphologies Polygamous relationships: individual of one sex mates with several individuals of other sex; species usually sexually dimorphic: males and females have different external morphologies Polygyny: one male mates with many females Males usually more showy and larger than females Polyandry: one female mates with many males; RARE Females often more showy than males

Paternal certainty relatively low species with internal fertilization Needs of young important factor constraining evolution of mating systems Ex: Bird species chicks need continuous supply of food A male maximizes his reproductive success by staying with his mate, and caring for his chicks (monogamy) Ex: Bird species chicks soon able to feed and care for self A male maximizes his reproductive success by seeking additional mates (polygyny) Females certain eggs laid / young born contain her genes; however, paternal certainty depends on mating behavior Paternity certainty influences parental care and mating behavior Paternal certainty relatively low species with internal fertilization mating and birth separated over time Paternal certainty much higher when egg laying and mating occur together, as in external fertilization parental care is at least as likely to be by males as by females

Sexual Selection and Mate Choice Intersexual selection: members of one sex choose mates on basis of certain traits Female Choice Intrasexual selection: involves competition between members of same sex for mates Mate Choice by Females Females drive sexual selection by choosing males with specific behaviors or features of anatomy Ex: female stalk-eyed flies choose males with relatively long eyestalks Ornaments, such as long eyestalks, often correlate with health and vitality Ex: Female zebra finch chicks who imprint on ornamented fathers are more likely to select ornamented mates Experiments suggest mate choice by female zebra finches play key role in evolution of ornamentation in male zebra finches

Experimental Groups of Parental Pairs Control Group Fig. 51-24 Experimental Groups of Parental Pairs Control Group Both parents ornamented Males ornamented Females ornamented Parents not ornamented Offspring Offspring Mate preference of female offspring: ornamented male Figure 51.24 Sexual selection influenced by imprinting Mate preference of female offspring: none

Male Competition for Mates source of intrasexual selection that can reduce variation among males may involve agonistic behavior often ritualized contest that determines which competitor gains access to resource (lady or land that lady likes)

Applying Game Theory Sexual selection driven evolution of alternative mating behavior and morphology in males Fitness of particular phenotype (behavior or morphology) depends on phenotypes of other individuals in population Game theory: evaluates alternative strategies where outcome depends on each individual’s strategy and strategy of other individuals Ex: each side-blotched lizard has blue, orange, or yellow throat each color associated with specific strategy for obtaining mates genetic basis to throat color and mating strategy Like rock-paper-scissors, each strategy will outcompete one strategy, but be outcompeted by other strategy THUS! success of each strategy depends on frequency of all of strategies; THIS drives frequency-dependent selection

Concept 51.5: Inclusive fitness can account for the evolution of altruistic social behavior Natural selection favors behavior that maximizes individual’s survival and reproduction These behaviors are often selfish Altruism: Occasionally some animals behave in ways that reduce their individual fitness but increase fitness of others AKA selflessness Ex: under threat from predator, individual Belding’s ground squirrel make alarm call to warn others, even though calling increases chances that caller is killed Ex: naked mole rat populations, nonreproductive individuals sacrifice lives protecting their reproductive queen and kings from predators

Inclusive Fitness Altruism explained by inclusive fitness Inclusive fitness: total effect individual has on proliferating its genes by producing offspring and helping close relatives produce offspring

Hamilton’s Rule and Kin Selection William Hamilton proposed quantitative measure for predicting when natural selection would favor altruistic acts among related individuals Three key variables in altruistic act: Benefit to recipient (B) Cost to altruist (C) Coefficient of relatedness (fraction of genes that, on average, are shared; r) Natural selection favors altruism when: rB > C Hamilton’s rule: this inequality Kin selection: natural selection that favors this kind of altruistic behavior by enhancing reproductive success of relatives Ex: warning behavior in Belding’s ground squirrels In group, most of females closely related to each other Most alarm calls given by females who aiding close relatives Ex: Naked mole rats living within colony are closely related Nonreproductive individuals increase their inclusive fitness by helping reproductive queen and kings (their close relatives) to pass their genes to the next generation

Mean distance (m) moved from birthplace Fig. 51-29 300 Male 200 Mean distance (m) moved from birthplace 100 Figure 51.29 Kin selection and altruism in Belding’s ground squirrels Female 1 2 3 4 12 13 14 15 25 26 Age (months)

Reciprocal Altruism Reciprocal altruism: altruistic behavior toward unrelated individuals can be adaptive if aided individual returns favor in future limited to species with stable social groups where individuals meet repeatedly, and cheaters (who don’t reciprocate) are punished used to explain altruism between unrelated individuals in humans

Social Learning DEFINE: learning through observation of others and forms roots of culture Culture: system of information transfer through observation or teaching that influences behavior of individuals in population can alter behavior and influence fitness of individuals Mate-choice copying: individuals in population copy mate choice of others This type of behavior extensively studied in guppy Poecilia reticulata Females who mate with males attractive to other females more likely to have sons that are attractive to other females “Sexy Son” Hypothesis

Evolution and Human Culture No other species comes close to matching social learning and cultural transmission that occurs among humans Human culture related to evolutionary theory in distinct discipline of sociobiology Human behavior results from interactions between genes and environment However, social and cultural institutions may provide ONLY feature in which there is NO continuum between humans and other animals

You should now be able to: State Tinbergen’s four questions and identify each as a proximate or ultimate causation Distinguish between the following pairs of terms: kinesis and taxis, circadian and circannual behavioral rhythms, landmarks and cognitive maps, classical and operant conditioning Suggest a proximate and an ultimate cause for imprinting in newly hatched geese Explain how associative learning may help a predator avoid toxic prey Describe how cross-fostering experiments help identify the relative importance of environmental and genetic factors in determining specific behaviors Describe optimal foraging theory Define and distinguish among promiscuous, monogamous, and polygamous mating systems Describe how the certainty of paternity may influence the development of mating systems Distinguish between intersexual and intrasexual selection Explain how game theory may be used to evaluate alternative behavioral strategies Define altruistic behavior and relate the coefficient of relatedness to the concept of altruism Distinguish between kin selection and reciprocal altruism Define social learning and culture