Lecture-3_Behavioral-Ecology.pdf

Chapter 51 Behavioral Ecology PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Overview: Studying Behavior Humans have probably studied animal behavior...

Chapter 51 Behavioral Ecology PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Overview: Studying Behavior Humans have probably studied animal behavior – For as long as we have lived on Earth As hunters – Knowledge of animal behavior was essential to human survival Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Cranes are birds that have captivated people’s interest – Possibly because they are large and their behavior is easily observed Figure 51.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  The modern scientific discipline of behavioral ecology – Extends observations of animal behavior by studying how such behavior is controlled and how it develops, evolves, and contributes to survival and reproductive success Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Concept 51.1: Behavioral ecologists distinguish between proximate and ultimate causes of behavior The scientific questions that can be asked about behavior can be divided into two classes – Those that focus on the immediate stimulus and mechanism for the behavior – Those that explore how the behavior contributes to survival and reproduction Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  What Is Behavior? Behavior – Is what an animal does and how it does it – Includes muscular and nonmuscular activity Dorsal fin Anal fin Figure 51.2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Learning – Is also considered a behavioral process Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Proximate and Ultimate Questions Proximate, or “how,” questions about behavior – Focus on the environmental stimuli that trigger a behavior – Focus on the genetic, physiological, and anatomical mechanisms underlying a behavioral act Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Ultimate, or “why,” questions about behavior – Address the evolutionary significance of a behavior Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Ethology Ethology is the scientific study of animal behavior – Particularly in natural environments Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Mid 20th-century ethologists – Developed a conceptual framework defined by a set of questions These questions – Highlight the complementary nature of proximate and ultimate perspectives Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Fixed Action Patterns A fixed action pattern (FAP) – Is a sequence of unlearned, innate behaviors that is unchangeable – Once initiated, is usually carried to completion Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  A FAP is triggered by an external sensory stimulus – Known as a sign stimulus Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In male stickleback fish, the stimulus for attack behavior – Is the red underside of an intruder (a) A male three-spined stickleback fish shows its red underside. Figure 51.3a Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  When presented with unrealistic models – As long as some red is present, the attack behavior occurs (b) The realistic model at the top, without a red underside, produces no aggressive response in a male three-spined stickleback fish. The other models, with red undersides, produce strong responses. Figure 51.3b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Proximate and ultimate causes for the FAP attack behavior in male stickleback fish 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 stimulus that releases aggression in a male stickleback. ULTIMATE CAUSE: By chasing away other male sticklebacks, a male decreases Figure 51.4 the chance that eggs laid in his nesting territory will be fertilized by another male. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Imprinting Imprinting is a type of behavior – That includes both learning and innate components and is generally irreversible Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Imprinting is distinguished from other types of learning by a sensitive period – A limited phase in an animal’s development that is the only time when certain behaviors can be learned Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  An example of imprinting is young geese – Following their mother Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Konrad Lorenz showed that – When baby geese spent the first few hours of their life with him, they imprinted on him as their parent Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  There are proximate and ultimate causes for this type of behavior BEHAVIOR: 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. Figure 51.5 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Conservation biologists have taken advantage of imprinting – In programs to save the whooping crane from extinction Figure 51.6 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Concept 51.2: Many behaviors have a strong genetic component Biologists study the ways both genes and the environment – Influence the development of behavioral phenotypes Behavior that is developmentally fixed – Is called innate behavior and is under strong genetic influence Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Directed Movements Many animal movements – Are under substantial genetic influence These types of movements – Are called directed movements Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Kinesis A kinesis – Is a simple change in activity or turning rate in response to a stimulus Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Sow bugs – Become more active in dry areas and less active in humid areas Moist site Dry open under leaf area (a) Kinesis increases the chance that a sow bug will encounter and stay in a moist environment. Figure 51.7a Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Taxis A taxis – Is a more or less automatic, oriented movement toward or away from a stimulus Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Many stream fish exhibit positive rheotaxis – Where they automatically swim in an upstream direction Direction of river current (b) Positive rheotaxis keeps trout facing into the current, the direction from which most food comes. Figure 51.7b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Migration Many features of migratory behavior in birds – Have been found to be genetically programmed Figure 51.8 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Animal Signals and Communication In behavioral ecology – A signal is a behavior that causes a change in another animal’s behavior Communication – Is the reception of and response to signals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Animals communicate using – Visual, auditory, chemical, tactile, and electrical signals The type of signal used to transmit information – Is closely related to an animal’s lifestyle and environment Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Chemical Communication Many animals that communicate through odors – Emit chemical substances called pheromones Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  When a minnow or catfish is injured – An alarm substance in the fish’s skin disperses in the water, inducing a fright response among fish in the area (a) Minnows are widely dispersed in an aquarium (b) Within seconds of the alarm substance being before an alarm substance is introduced. introduced, minnows aggregate near the bottom of the aquarium and reduce their movement. Figure 51.9a, b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Auditory Communication Experiments with various insects – Have shown that courtship songs are under genetic control EXPERIMENT 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. SONOGRAMS Chrysoperla plorabunda parent Volley period Standard Vibration repeating volleys unit crossed with Chrysoperla johnsoni parent Volley period Standard repeating unit The 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. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  RESULTS The 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. F1 hybrids, typical phenotype Volley period Standard repeating unit CONCLUSION The results of this experiment indicate that the songs sung by Chrysoperla plorabunda and Chrysoperla johnsoni are under genetic control. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Genetic Influences on Mating and Parental Behavior A variety of mammalian behaviors – Are under relatively strong genetic control Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Research has revealed the genetic and neural basis – For the mating and parental behavior of male prairie voles Figure 51.11 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Concept 51.3: Environment, interacting with an animal’s genetic makeup, influences the development of behaviors Research has revealed – That environmental conditions modify many of the same behaviors Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Dietary Influence on Mate Choice Behavior One example of environmental influence on behavior – Is the role of diet in mate selection by Drosophila mojavensis Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Laboratory experiments have demonstrated – That the type of food eaten during larval development influences later mate choice in females EXPERIMENT William 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. RESULTS When 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). 100 With Baja males (a) With Sonoran males 75 (b) Proportion of matings by Sonoran females 50 25 0 Artificial Organ pipe cactus Agria cactus Culture medium CONCLUSION The difference in mate selection shown by females that developed on different diets indicates that mate choice by females of Sonoran populations of D. mojavensis Figure 51.12 is strongly influenced by the dietary environment in which larvae develop. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Therese Markow and Eric Toolson proposed – That the physiological basis for the observed mate preferences was differences in hydrocarbons in the exoskeletons of the flies Figure 51.13 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Social Environment and Aggressive Behavior Cross-fostering studies in California mice and white-footed mice – Have uncovered an influence of social environment on the aggressive and parental behaviors of these mice Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Influence of cross-fostering on male mice Table 51.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Learning Learning is the modification of behavior – Based on specific experiences Learned behaviors – Range from very simple to very complex Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Habituation Habituation – Is a loss of responsiveness to stimuli that convey little or no information Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Spatial Learning Spatial learning is the modification of behavior – Based on experience with the spatial structure of the environment Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In a classic experiment, Niko Tinbergen EXPERIMENT A female digger wasp excavates and cares for four or five separate underground nests, flying to each nest daily with food – Showed how digger 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. wasps use landmarks to find the entrances to their nests Nest After the mother visited the nest and flew away, Tinbergen moved the pinecones a few feet to one side of the nest. RESULTS When 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. No Nest Nest CONCLUSION The experiment supported the hypothesis Figure 51.14 that digger wasps use landmarks to keep track of their nests. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Cognitive Maps A cognitive map – Is an internal representation of the spatial relationships between objects in an animal’s surroundings Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Associative Learning In associative learning – Animals associate one feature of their environment with another Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Classical conditioning is a type of associative learning – In which an arbitrary stimulus is associated with a reward or punishment Before stimulus Influx of alarm substances Influx of water alone Influx of pike odor Day 1 Day 3 Relative activity level Control Experimental Control Experimental group group group group Figure 51.15 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Operant conditioning is another type of associative learning – In which an animal learns to associate one of its behaviors with a reward or punishment Figure 51.16 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Cognition and Problem Solving Cognition is the ability of an animal’s nervous system – To perceive, store, process, and use information gathered by sensory receptors Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  7 Problem solving can be learned – By observing the behavior of other animals Figure 51.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Genetic and Environmental Interaction in Learning Genetics and environment can interact – To influence the learning process Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Concept 51.4: Behavioral traits can evolve by natural selection Because of the influence of genes on behavior – Natural selection can result in the evolution of behavioral traits in populations Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Behavioral Variation in Natural Populations When behavioral variation within a species – Corresponds to variation in the environment, it may be evidence of past evolution Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Variation in Prey Selection Differences in prey selection in populations of garter snakes – Are due to prey availability and are evidence of behavioral evolution (a) A garter snake (Thamnophis elegans) (b) A banana slug (Ariolimus Figure 51.18a, b californicus); not to scale Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Variation in Aggressive Behavior Funnel spiders living in different habitats – Exhibit differing degrees of aggressiveness in defense and foraging behavior Desert 60 grassland population 50 Riparian Time to attack (seconds) population 40 30 20 10 0 Field Lab-raised Lab-raised generation 1 generation 2 Population Figure 51.19 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Experimental Evidence for Behavioral Evolution Laboratory and field experiments – Can demonstrate the evolution of behavior Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Laboratory Studies of Drosophila Foraging Behavior Studies of Drosophila populations raised in high- and low-density conditions – Show a clear divergence in behavior linked to specific genes 14 Low population density 12 High population Average path length (cm) density 10 8 6 4 2 0 L1 L2 L3 H1 H2 H3 H4 H5 D. Melanogaster lineages Figure 51.20 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Migratory Patterns in Blackcaps Field and laboratory studies of Blackcap birds – Have documented a change in their migratory behavior Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Birds placed in funnel cages – Left marks indicating the direction they were trying to migrate (a) Blackcaps placed in a funnel cage left marks indicating the direction in which they were trying to migrate. Figure 51.21a Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Migratory orientation of wintering adult birds captured in Britain – Was very similar to that of laboratory-raised birds N Adults from BRITAIN Britain and W E F1 offspring of British S adults N (b) Wintering blackcaps captured in Britain and their laboratory-raised offspring had a migratory orientation toward the west, while young birds from Germany were oriented toward the southwest. W E Young from SW Germany S Mediterranean Sea Figure 51.21b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Concept 51.5: Natural selection favors behaviors that increase survival and reproductive success The genetic components of behavior – Evolve through natural selection Behavior can affect fitness – Through its influence on foraging and mate choice Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Foraging Behavior Optimal foraging theory – Views foraging behavior as a compromise between the benefits of nutrition and the costs of obtaining food Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Energy Costs and Benefits Reto Zach – Conducted a cost-benefit analysis of feeding behavior in crows The crows eat molluscs called whelks – But must drop them from the air to crack the shells Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Zach determined that the optimal flight height in foraging behavior – Correlated with a fewer number of drops, indicating a trade-off between energy gained (food) and energy expended 60 125 Total flight height (number of drops  drop height) 50 100 Average number of drops 40 30 Average number of drops 75 Total flight height 20 Drop height preferred 50 10 by crows 0 25 2 3 5 7 15 Height of drop (m) Figure 51.22 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In bluegill sunfish – Prey selection behavior is related to prey density Small prey at Small prey at middle distance close distance Large prey at far distance Low prey density High prey density Small prey 33% 14% Medium prey 33% 35% Large prey 33% 50% Percentage available Small prey 33% Medium prey 33% Large prey 33% 100% Predicted percentage in diet Small prey 32.5% 2% Medium prey 32.5% 40% Large prey 35% 57% Observed percentage in diet Figure 51.23 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Risk of Predation Research on mule deer populations – Has shown that predation risk affects where the deer choose to feed Relative deer use Predation 20 70 risk 60 15 Predation occurrence (%) Relative deer use 50 40 10 30 20 5 10 0 0 Open Forest edge Forest interior Habitat Figure 51.24 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Mating Behavior and Mate Choice Mating behavior – Is the product of a form of natural selection call sexual selection Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Mating Systems and Mate Choice The mating relationship between males and females – Varies a great deal from species to species Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In many species, mating is promiscuous – With no strong pair-bonds or lasting relationships Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In monogamous relationships – One male mates with one female (a) Since monogamous species, such as these trumpeter swans, are often monomorphic, males and females are difficult to distinguish using external characteristics only. Figure 51.25a Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In a system called polygyny – One male mates with many females – The males are often more showy and larger than the females (b) Among polygynous species, such as elk, the male (left) is Figure 51.25b often highly ornamented. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In polyandrous systems – One female mates with many males – The females are often more showy than the males (c) In polyandrous species, such as these Wilson’s phalaropes, females Figure 51.25c (top) are generally more ornamented than males. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  The needs of the young – Are an important factor constraining the evolution of mating systems The certainty of paternity – Influences parental care and mating behavior Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In species that produce large numbers of offspring – Parental care is at least as likely to be carried out by males as females Eggs Figure 51.26 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Sexual Selection and Mate Choice In intersexual selection – Members of one sex choose mates on the basis of particular characteristics Intrasexual selection – Involves competition among members of one sex for mates Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Mate Choice by Females Male zebra finches – Are more ornate than females, a trait that may affect mate choice by the females Figure 51.27 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Imprinting of female chicks on males with more ornamentation Experimental Groups Control Group Both parents Males Females Parents not ornamented ornamented ornamented ornamented – Affects mate selection as adults Results Females reared by Females reared by ornamented parents ornamented mothers or or ornamented fathers nonornamented parents preferred ornamented showed no preference males as mates. for either ornamented or nonornamented males. Males reared by all experimental groups showed no preference for either ornamented or nonornamented female mates. Figure 51.28 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  The size of eyestalks in stalk-eyed flies – Affects which males the females choose to mate with Figure 51.29 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Male Competition for Mates Male competition for mates – Is a source of intrasexual selection that can reduce variation among males Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Such competition may involve agonistic behavior – An often ritualized contest that determines which competitor gains access to a resource Figure 51.30 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Morphology affects the mating behavior – In isopods of the same species that are genetically distinct Large Paracerceis  males defend harems of females within intertidal sponges.      Tiny  males are able to invade and live within large harems.  males mimic female morphology and behavior and do not elicit a defensive reponse in  males and so are able to Figure 51.31 gain access to guarded harems. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Applying Game Theory Game theory evaluates alternative behavioral strategies in situations – Where the outcome depends on each individual’s strategy and the strategy of other individuals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Mating success of male side-blotched lizards – Was found to be influenced by male polymorphism and the abundance of different males in a given area Figure 51.32 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Concept 51.6: The concept of inclusive fitness can account for most altruistic social behavior Many social behaviors are selfish Natural selection favors behavior – That maximizes an individual’s survival and reproduction Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Altruism On occasion, some animals – Behave in ways that reduce their individual fitness but increase the fitness of others This kind of behavior – Is called altruism, or selflessness Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  In naked mole rat populations – Nonreproductive individuals may sacrifice their lives protecting the reproductive individuals from predators Figure 51.33 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Inclusive Fitness Altruistic behavior can be explained by inclusive fitness – The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables close relatives to produce offspring Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Hamilton’s Rule and Kin Selection Hamilton proposed a quantitative measure – For predicting when natural selection would favor altruistic acts among related individuals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  The three key variables in an altruistic act are – The benefit to the recipient – The cost to the altruist – The coefficient of relatedness Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  The coefficient of relatedness Parent A Parent B – Is the probability that two relatives  may share the same genes OR 1/ (0.5) 1/ (0.5) 2 2 probability probability Figure 51.34 Sibling 1 Sibling 2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Natural selection favors altruism when the benefit to the recipient – Multiplied by the coefficient of relatedness exceeds the cost to the altruist This inequality – Is called Hamilton’s rule Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Kin selection is the natural selection – That favors this kind of altruistic behavior by enhancing reproductive success of relatives Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  An example of kin selection and altruism – Is the warning behavior observed in Belding’s ground squirrels 300 Male Mean distance natal burrow moved from 200 (m) 100 Female 0 0 2 3 4 12 13 14 15 25 26 Age (months) Figure 51.35 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Reciprocal Altruism Altruistic behavior toward unrelated individuals – Can be adaptive if the aided individual returns the favor in the future This type of altruism – Is called reciprocal altruism Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Social Learning Social learning – Forms the roots of culture Culture can be defined as a system of information transfer through observation or teaching – That influences the behavior of individuals in a population Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Mate Choice Copying Mate choice copying – Is a behavior in which individuals in a population copy the mate choice of others Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  This type of behavior – Has been extensively studied in the guppy Poecilia reticulata Control Sample Male guppies with varying degrees of coloration Female guppies prefer males with more orange coloration. Experimental Sample Female model engaged in courtship with less orange male Female guppies prefer less orange males that are associated with another female. Figure 51.36 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Social Learning of Alarm Calls Vervet monkeys – Produce a complex set of alarm calls Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Infant monkeys give undiscriminating alarm calls at first – But learn to fine-tune them by the time they are adults Figure 51.37 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  No other species – Comes close to matching the social learning and cultural transmission that occurs among humans Figure 51.38 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Evolution and Human Culture Human culture – Is related to evolutionary theory in the distinct discipline of sociobiology Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings  Human behavior, like that of other species – Is the result of interactions 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings