Bài giảng Biology - Chapter 51: Behavioral Ecology

Chapter 51Behavioral EcologyOverview: Studying BehaviorHumans have probably studied animal behaviorFor as long as we have lived on EarthAs huntersKnowledge of animal behavior was essential to human survivalCranes are birds that have captivated people’s interestPossibly because they are large and their behavior is easily observedFigure 51.1The modern scientific discipline of behavioral ecologyExtends observations of animal behavior by studying how such behavior is controlled and how it develops, evolves, and contributes to survival and reproductive successConcept 51.1: Behavioral ecologists distinguish between proximate and ultimate causes of behaviorThe scientific questions that can be asked about behavior can be divided into two classesThose that focus on the immediate stimulus and mechanism for the behaviorThose that explore how the behavior contributes to survival and reproductionWhat Is Behavior?BehaviorIs what an animal does and how it does itIncludes muscular and nonmuscular activityFigure 51.2Dorsal finAnal finLearningIs also considered a behavioral processProximate and Ultimate QuestionsProximate, or “how,” questions about behaviorFocus on the environmental stimuli that trigger a behaviorFocus on the genetic, physiological, and anatomical mechanisms underlying a behavioral actUltimate, or “why,” questions about behaviorAddress the evolutionary significance of a behaviorEthologyEthology is the scientific study of animal behaviorParticularly in natural environmentsMid 20th-century ethologistsDeveloped a conceptual framework defined by a set of questionsThese questionsHighlight the complementary nature of proximate and ultimate perspectivesFixed Action PatternsA fixed action pattern (FAP)Is a sequence of unlearned, innate behaviors that is unchangeableOnce initiated, is usually carried to completionA FAP is triggered by an external sensory stimulusKnown as a sign stimulusIn male stickleback fish, the stimulus for attack behaviorIs the red underside of an intruderFigure 51.3a(a) A male three-spined stickleback fish shows its red underside.When presented with unrealistic modelsAs long as some red is present, the attack behavior occursFigure 51.3b(b) The realistic model at the top, without a red underside, produces no aggressive response in a male three-spined stickleback fish. Theother models, with red undersides, produce strong responses.Proximate and ultimate causes for the FAP attack behavior in male stickleback fishFigure 51.4ULTIMATE CAUSE: By chasing away other male sticklebacks, a male decreasesthe chance that eggs laid in his nesting territory will be fertilized by another male.BEHAVIOR: A male stickleback fish attacks other male sticklebacks that invade its nesting territory.PROXIMATE CAUSE: The red belly of the intruding male acts as a sign stimulusthat releases aggression in a male stickleback.ImprintingImprinting is a type of behaviorThat includes both learning and innate components and is generally irreversibleImprinting is distinguished from other types of learning by a sensitive periodA limited phase in an animal’s development that is the only time when certain behaviors can be learnedAn example of imprinting is young geeseFollowing their motherKonrad Lorenz showed thatWhen baby geese spent the first few hours of their life with him, they imprinted on him as their parentThere are proximate and ultimate causes for this type of behaviorFigure 51.5BEHAVIOR: Young geese follow and imprint on their mother.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.Conservation biologists have taken advantage of imprintingIn programs to save the whooping crane from extinctionFigure 51.6Concept 51.2: Many behaviors have a strong genetic componentBiologists study the ways both genes and the environmentInfluence the development of behavioral phenotypesBehavior that is developmentally fixedIs called innate behavior and is under strong genetic influenceDirected MovementsMany animal movementsAre under substantial genetic influenceThese types of movementsAre called directed movementsKinesisA kinesisIs a simple change in activity or turning rate in response to a stimulusSow bugsBecome more active in dry areas and less active in humid areasFigure 51.7aDry open areaMoist site under leaf(a) Kinesis increases the chance that a sow bug will encounter and stay in a moist environment.TaxisA taxisIs a more or less automatic, oriented movement toward or away from a stimulusMany stream fish exhibit positive rheotaxisWhere they automatically swim in an upstream directionFigure 51.7bDirectionof rivercurrent(b) Positive rheotaxis keeps trout facing into the current, the direction from which most food comes.MigrationMany features of migratory behavior in birdsHave been found to be genetically programmedFigure 51.8Animal Signals and CommunicationIn behavioral ecologyA signal is a behavior that causes a change in another animal’s behaviorCommunicationIs the reception of and response to signalsAnimals communicate usingVisual, auditory, chemical, tactile, and electrical signalsThe type of signal used to transmit informationIs closely related to an animal’s lifestyle and environmentChemical CommunicationMany animals that communicate through odorsEmit chemical substances called pheromonesWhen a minnow or catfish is injuredAn alarm substance in the fish’s skin disperses in the water, inducing a fright response among fish in the areaFigure 51.9a, b(a) Minnows are widely dispersed in an aquarium  before an alarm substance is introduced.(b) Within seconds of the alarm substance being introduced, minnows aggregate near thebottom of the aquarium and reduce their movement.Auditory CommunicationExperiments with various insectsHave shown that courtship songs are under genetic control Charles Henry, Lucía Martínez, and ent Holsinger crossed males and females of Chrysoperla plorabunda and Chrysoperla johnsoni, two morphologically identical species of lacewings that sing different courtship songs. EXPERIMENTSONOGRAMS Chrysoperla plorabunda parentVibration volleysStandard repeating unitChrysoperla johnsoni parent Volley periodcrossed withStandard repeating unitThe researchers recorded and compared the songs of the male and female parents with those of the hybrid offspring that had been raised in isolation from other lacewings. Volley periodThe F1 hybrid offspring sing a song in which the length of the standard repeating unit is similar to that sung by the Chrysoperla plorabunda parent, but the volley period, that is, the interval between vibration volleys, is more similar to that of the Chrysoperla johnsoni parent.RESULTS The results of this experiment indicate that the songs sung by Chrysoperla plorabunda and Chrysoperla johnsoni are under genetic control.CONCLUSIONStandard repeating unitVolley periodF1 hybrids, typical phenotypeGenetic Influences on Mating and Parental BehaviorA variety of mammalian behaviorsAre under relatively strong genetic controlResearch has revealed the genetic and neural basisFor the mating and parental behavior of male prairie volesFigure 51.11Concept 51.3: Environment, interacting with an animal’s genetic makeup, influences the development of behaviorsResearch has revealedThat environmental conditions modify many of the same behaviorsDietary Influence on Mate Choice BehaviorOne example of environmental influence on behaviorIs the role of diet in mate selection by Drosophila mojavensisLaboratory experiments have demonstratedThat the type of food eaten during larval development influences later mate choice in femalesFigure 51.12William Etges raised a D. mojavensis population from Baja California and a D. mojavensis population from Sonora on three different culture media: artificial medium, agria cactus (the Baja host plant), and organ pipe cactus (the Sonoran host plant). From each culture medium, Etges collected 15 male and female Baja D. mojavensis pairs and 15 Sonoran pairs and observed the numbers of matings between males and females from the two populations.EXPERIMENTWhen D. mojavensis had been raised on artificial medium, females from the Sonoran population showed a strong preference for Sonoran males (a). When D. mojavensis had been raised on cactus medium, the Sonoran females mated with Baja and Sonoran males in approximately equal frequency (b).RESULTSThe difference in mate selection shown by females that developed on different diets indicates that mate choice by females of Sonoran populations of D. mojavensis is strongly influenced by the dietary environment in which larvae develop.CONCLUSION1007550250ArtificialOrgan pipe cactusAgria cactusCulture mediumWith Baja malesWith Sonoran males(b)Proportion of matings by Sonoran females(a)Therese Markow and Eric Toolson proposedThat the physiological basis for the observed mate preferences was differences in hydrocarbons in the exoskeletons of the fliesFigure 51.13Social Environment and Aggressive BehaviorCross-fostering studies in California mice and white-footed miceHave uncovered an influence of social environment on the aggressive and parental behaviors of these miceInfluence of cross-fostering on male miceTable 51.1LearningLearning is the modification of behaviorBased on specific experiencesLearned behaviorsRange from very simple to very complexHabituationHabituationIs a loss of responsiveness to stimuli that convey little or no informationSpatial LearningSpatial learning is the modification of behaviorBased on experience with the spatial structure of the environmentIn a classic experiment, Niko TinbergenShowed how digger wasps use landmarks to find the entrances to their nestsAfter the mother visited the nest and flew away, Tinbergen moved the pinecones a few feet to one side of the nest.Figure 51.14CONCLUSIONA female digger wasp excavates and cares for four or five separate underground nests, flying to each nest daily with food for the single larva in the nest. To test his hypothesis that the wasp uses visual landmarks to locate the nests, Niko Tinbergen marked one nest with a ring of pinecones.EXPERIMENTNestWhen the wasp returned, she flew to the center of the pinecone circle instead of to the nearby nest. Repeating the experiment with many wasps, Tinbergen obtained the same results.RESULTSThe experiment supported the hypothesis that digger wasps use landmarks to keep track of their nests. NestNo NestCognitive MapsA cognitive mapIs an internal representation of the spatial relationships between objects in an animal’s surroundingsAssociative LearningIn associative learningAnimals associate one feature of their environment with anotherClassical conditioning is a type of associative learningIn which an arbitrary stimulus is associated with a reward or punishmentFigure 51.15Before stimulusInflux of water aloneInflux of alarm substancesInflux of pike odorDay 1Day 3Control groupControl groupExperimentalgroupExperimental groupRelative activity levelOperant conditioning is another type of associative learningIn which an animal learns to associate one of its behaviors with a reward or punishmentFigure 51.16Cognition and Problem SolvingCognition is the ability of an animal’s nervous systemTo perceive, store, process, and use information gathered by sensory receptors7Problem solving can be learnedBy observing the behavior of other animalsFigure 51.17Genetic and Environmental Interaction in LearningGenetics and environment can interactTo influence the learning processConcept 51.4: Behavioral traits can evolve by natural selectionBecause of the influence of genes on behaviorNatural selection can result in the evolution of behavioral traits in populationsBehavioral Variation in Natural PopulationsWhen behavioral variation within a species Corresponds to variation in the environment, it may be evidence of past evolutionVariation in Prey SelectionDifferences in prey selection in populations of garter snakesAre due to prey availability and are evidence of behavioral evolutionFigure 51.18a, b(a) A garter snake (Thamnophis elegans)(b) A banana slug (Ariolimus californicus); not to scaleVariation in Aggressive BehaviorFunnel spiders living in different habitatsExhibit differing degrees of aggressiveness in defense and foraging behaviorFigure 51.1950403020100Time to attack (seconds)FieldLab-raised generation 1Lab-raised generation 2Desert grassland populationRiparian population60PopulationExperimental Evidence for Behavioral EvolutionLaboratory and field experimentsCan demonstrate the evolution of behaviorLaboratory Studies of Drosophila Foraging BehaviorStudies of Drosophila populations raised in high- and low-density conditionsShow a clear divergence in behavior linked to specific genesFigure 51.201412108620Average path length (cm)4L1L2L3H1H2H3H4H5D. Melanogaster lineagesLow population densityHigh population densityMigratory Patterns in BlackcapsField and laboratory studies of Blackcap birdsHave documented a change in their migratory behaviorBirds placed in funnel cagesLeft marks indicating the direction they were trying to migrateFigure 51.21a(a) Blackcaps placed in a funnel cage left marks indicating the direction in which they were trying to migrate.Migratory orientation of wintering adult birds captured in BritainWas very similar to that of laboratory-raised birdsFigure 51.21b(b) Wintering blackcaps captured in Britain and their laboratory-raised offspring had a migratory orientation toward the west, whileyoung birds from Germany were oriented toward the southwest.NESWAdults from Britain and F1 offspring of British adultsNESWYoungfrom SW GermanyMediterranean SeaBRITAINGERMANYConcept 51.5: Natural selection favors behaviors that increase survival and reproductive successThe genetic components of behaviorEvolve through natural selectionBehavior can affect fitnessThrough its influence on foraging and mate choiceForaging BehaviorOptimal foraging theoryViews foraging behavior as a compromise between the benefits of nutrition and the costs of obtaining foodEnergy Costs and BenefitsReto ZachConducted a cost-benefit analysis of feeding behavior in crowsThe crows eat molluscs called whelksBut must drop them from the air to crack the shellsZach determined that the optimal flight height in foraging behaviorCorrelated with a fewer number of drops, indicating a trade-off between energy gained (food) and energy expendedFigure 51.226050403020100Average number of drops235715Average number of dropsDrop height preferredby crows125100257550Total flight heightTotal flight height (number of drops  drop height)Height of drop (m)In bluegill sunfishPrey selection behavior is related to prey densityFigure 51.23Low prey densityHigh prey density33%33%33%32.5%32.5%35%2%40%57%100%50%35%14%33%33%33%Small preyMedium preyLarge preySmall preyMedium preyLarge preySmall preyMedium preyLarge preyPercentage availablePredicted percentage in dietObserved percentage in dietLarge prey at far distanceSmall prey at middle distanceSmall prey at close distanceRisk of PredationResearch on mule deer populations Has shown that predation risk affects where the deer choose to feedFigure 51.247060403020100Predation occurrence (%)50Relative deer useRelative deer usePredation riskOpenForest edge HabitatForest interior05101520Mating Behavior and Mate ChoiceMating behaviorIs the product of a form of natural selection call sexual selectionMating Systems and Mate ChoiceThe mating relationship between males and femalesVaries a great deal from species to speciesIn many species, mating is promiscuousWith no strong pair-bonds or lasting relationshipsIn monogamous relationshipsOne male mates with one femaleFigure 51.25a(a) Since monogamous species, such as these trumpeter swans, are often monomorphic, males and females are difficult to distinguish using external characteristics only.In a system called polygynyOne male mates with many femalesThe males are often more showy and larger than the femalesFigure 51.25bAmong polygynous species, such as elk, the male (left) is often highly ornamented.(b)In polyandrous systemsOne female mates with many malesThe females are often more showy than the malesFigure 51.25c(c) In polyandrous species, such as these Wilson’s phalaropes, females (top) are generally more ornamented than males.The needs of the youngAre an important factor constraining the evolution of mating systemsThe certainty of paternityInfluences parental care and mating behaviorIn species that produce large numbers of offspringParental care is at least as likely to be carried out by males as femalesFigure 51.26EggsSexual Selection and Mate ChoiceIn intersexual selectionMembers of one sex choose mates on the basis of particular characteristicsIntrasexual selectionInvolves competition among members of one sex for matesMate Choice by FemalesMale zebra finchesAre more ornate than females, a trait that may affect mate choice by the femalesFigure 51.27Imprinting of female chicks on males with more ornamentationAffects mate selection as adultsFigure 51.28Experimental GroupsControl GroupParents not ornamentedBoth parents ornamentedMalesornamentedFemalesornamentedResultsFemales reared byornamented parentsor ornamented fatherspreferred ornamentedmales as mates.Females reared byornamented mothers ornonornamented parentsshowed no preferencefor either ornamented ornonornamented males.Males reared by all experimental groups showed nopreference for either ornamented or nonornamentedfemale mates.The size of eyestalks in stalk-eyed fliesAffects which males the females choose to mate withFigure 51.29Male Competition for Mates Male competition for matesIs a source of intrasexual selection that can reduce variation among malesSuch competition may involve agonistic behaviorAn often ritualized contest that determines which competitor gains access to a resourceFigure 51.30Morphology affects the mating behaviorIn isopods of the same species that are genetically distinctFigure 51.31Large Paracerceis  males defend harems of females within intertidal sponges.Tiny  males are able to invadeand live withinlarge harems. males mimic female morphology and behavior and do not elicit a defensive reponse in  males and so are able to gain access to guarded harems.Applying Game TheoryGame theory evaluates alternative behavioral strategies in situations Where the outcome depends on each individual’s strategy and the strategy of other individualsMating success of male side-blotched lizardsWas found to be influenced by male polymorphism and the abundance of different males in a given areaFigure 51.32Concept 51.6: The concept of inclusive fitness can account for most altruistic social behaviorMany social behaviors are selfishNatural selection favors behaviorThat maximizes an individual’s survival and reproductionAltruismOn occasion, some animalsBehave in ways that reduce their individual fitness but increase the fitness of othersThis kind of behaviorIs called altruism, or selflessnessIn naked mole rat populationsNonreproductive individuals may sacrifice their lives protecting the reproductive individuals from predatorsFigure 51.33Inclusive FitnessAltruistic behavior can be explained by inclusive fitnessThe total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables close relatives to produce offspringHamilton’s Rule and Kin SelectionHamilton proposed a quantitative measureFor predicting when natural selection would favor altruistic acts among related individualsThe three key variables in an altruistic act areThe benefit to the recipientThe cost to the altruistThe coefficient of relatednessThe coefficient of relatednessIs the probability that two relatives may share the same genesFigure 51.34Parent AParent BORSibling 1Sibling 21/2 (0.5) probability1/2 (0.5) probabilityNatural selection favors altruism when the benefit to the recipientMultiplied by the coefficient of relatedness exceeds the cost to the altruistThis inequalityIs called Hamilton’s ruleKin selection is the natural selectionThat favors this kind of altruistic behavior by enhancing reproductive success of relativesAn example of kin selection and altruismIs the warning behavior observed in Belding’s ground squirrelsMaleFemaleAge (months)Mean distance moved from natal burrow (m)30020010000234121314152526Figure 51.35Reciprocal AltruismAltruistic behavior toward unrelated individualsCan be adaptive if the aided individual returns the favor in the futureThis type of altruismIs called reciprocal altruismSocial LearningSocial learningForms the roots of cultureCulture can be defined as a system of information transfer through observation or teachingThat influences the behavior of individuals in a populationMate Choice CopyingMate choice copying Is a behavior in which individuals in a population copy the mate choice of othersThis type of behaviorHas been extensively studied in the guppy Poecilia reticulataFigure 51.36Male guppieswith varying degrees ofcolorationControl SampleFemale guppies prefermales with more orangecoloration.Experimental SampleFemale modelengaged incourtship withless orangemaleFemale guppies prefer lessorange males that are associatedwith another female.Social Learning of Alarm CallsVervet monkeysProduce a complex set of alarm callsInfant monkeys give undiscriminating alarm calls at firstBut learn to fine-tune them by the time they are adultsFigure 51.37No other speciesComes close to matching the social learning and cultural transmission that occurs among humansFigure 51.38Evolution and Human CultureHuman cultureIs related to evolutionary theory in the distinct discipline of sociobiologyHuman behavior, like that of other speciesIs the result of interactions between genes and environmentHowever, our social and cultural institutionsMay provide the only feature in which there is no continuum between humans and other animals