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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 • 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 • Learning – Is also considered a behavioral process Dorsal fin Figure 51.2 Anal fin 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 • Ultimate, or “why,” questions about behavior – Address the evolutionary significance of a behavior 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 • 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. Figure 51.4 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. 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 • 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 • An example of imprinting is young geese – Following their mother 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 (directed movement) 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 • Sow bugs – Become more active in dry areas and less active in humid areas Dry open 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 Moist site under leaf 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 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 – Visual, auditory, chemical, tactile, and electrical signals – Chemical communication: odors (pheremones) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Pheromones • 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 before an alarm substance is introduced. Figure 51.9a, b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (b) Within seconds of the alarm substance being introduced, minnows aggregate near the bottom of the aquarium and reduce their movement. Genetic Influences on Mating and Parental Behavior • A variety of mammalian behaviors – Are under relatively strong genetic control • 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 behavior • That environmental conditions modify many of the same behaviors • Learning is the modification of behavior – Based on specific experiences Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Habituation • Habituation – Is a loss of responsiveness to stimuli that convey little or no information 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 – Showed how digger wasps use landmarks to find the entrances to their nests EXPERIMENT A 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. 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. Nest CONCLUSION Figure 51.14 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings No Nest The experiment supported the hypothesis that digger wasps use landmarks to keep track of their nests. Cognitive Maps • A cognitive map – Is an internal representation of the spatial relationships between objects in an animal’s surroundings 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 Relative activity level Day 3 Figure 51.15 Control group Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Experimental group Control group Experimental group • 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 • Problem solving can be learned – By observing the behavior of other animals Figure 51.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Concept 51.4: Behavioral traits can evolve by natural selection • When behavioral variation within a species Time to attack (seconds) – Corresponds to variation in the environment, it may be evidence of past evolution 50 Desert grasslan d populatio n Riparian 40 populatio n 30 20 10 0 Field Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Lab-raised generation 1 Lab-raised generation 2 • Migratory orientation of wintering adult birds captured in Britain – Was very similar to that of laboratory-raised birds N BRITAIN W E S (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. N Young from SW Germany Mediterranean Sea Figure 51.21b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings E W S Adults from Britain and F1 offspring of British adults • Concept 51.5: Natural selection favors behaviors that increase survival and reproductive success • 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 Risk of Predation • Research on mule deer populations – Has shown that predation risk affects where the deer choose to feed Predation risk Relative deer use 60 15 50 40 10 30 20 5 10 0 0 Open Figure 51.24 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Forest edge Habitat Forest interior Relative deer use Predation occurrence (%) 70 20 Mating Behavior and Mate Choice • Mating behavior – Is the product of a form of natural selection called sexual selection – The mating relationship varies a great deal from species to species – mating is often promiscuous Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • In monogamous relationships – One male mates with one female • The needs of the young – • The certainty of paternity – (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 Are an important factor constraining the evolution of mating systems Influences parental care and mating behavior Sexual Selection and Mate Choice • In intersexual selection – Members of one sex choose mates on the basis of particular characteristics Figure 51.27 • Intrasexual selection – Involves competition among members of one sex for mates Figure 51.30 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 – Occasionally, altruistic behaviors arise 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 • The three key variables in an altruistic act are – The benefit to the recipient – The cost to the altruist – The coefficient of relatedness Parent A Parent B OR 1/ 1/ 2 (0.5) probab ility Figure 51.34 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sibling 1 2 (0.5) probab ility Sibling 2 • 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 • 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 Reciprocal Altruism • Altruistic behavior toward unrelated individuals – Can be adaptive if the aided individual returns the favor in the future Social Learning • Culture can be defined as a system of information transfer through observation or teaching 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 Social Learning of Alarm Calls • Vervet monkeys – Produce a complex set of alarm calls Figure 51.37 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Evolution and Human Culture • 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