13 May 2003: Introduction to Animal Behavior

Transcription

1 13 May 2003: Introduction to Animal Behavior Why study Animal Behavior? History of Animal Behavior Levels of analysis Tools & methods Why study Animal Behavior? behavior is central to understanding all aspects of the animal s biology: it occurs at the interface of ecology, physiology, and evolution changes in behavior are good warning signs of environmental degradation behavior can have significant economic importance Why study Animal Behavior? History of Animal Behavior understanding behavior is critical for improving animal welfare consideration of behavior can improve effectiveness of wildlife conservation efforts behavior offers solutions to human social problems Pre-Darwinian views of animal behavior Charles Darwin s contribution Classical ethology Behaviorism (Comparative psychology) Behavioral ecology Sociobiology

2 History of Animal Behavior Darwin s contributions Origin of Species (1859) Darwin suggests that intricate behavior patterns could have evolved from simpler behaviors via the action of natural selection and not have spontaneously arisen via supernatural creation History of Animal Behavior Darwin s contributions Origin of Species (1859) According to Darwin, if instincts have evolved, then: more primitive species should show simpler behavior sequences we ought to be able to find gradations in behavior among related species History of Animal Behavior Descent of Man (1871) Darwin looks for evidence of human-like mental abilities in animals He presents his hypothesis of mental continuity The animal mind and human mind are points on a continuum, they do not differ qualitatively. This launches the science of comparative psychology. History of Animal Behavior Darwin s contributions He suggested that studying animals could teach us about ourselves. He believed that the expression of emotion in man and animals represents a continuum. He presented the first systematic, rigorous attempt to study comparative animal behavior and its evolution.

3 Classical ethology The study of the mediation, ecology, and evolution of behavior; originally pursued by zoologists in Europe and North America. Complex behavior usually the expression of mindless circuits of sign stimuli, innate releasing mechanism (IRM), and fixed action patterns (FAP) Behavior should be studied in natural environment, as much as possible Differences between species reflect natural selection, and are therefore interesting. Classical ethology Jacob von Uexkull ( ) Animals perceive only limited portions of the total environment with their sense organs and central nervous systems. Umwelt: the sensory-perceptual world of an animal Classical ethology Karl von Frisch ( ) honey bee dance language: animal symbolism imprinting Classical ethology Konrad Lorenz hydraulic model of motivation

4 Classical ethology Niko Tinbergen Experimental ethology, levels of analysis Ethogram complete inventory or descriptive catalog of the motor patterns exhibited by members of a particular species Ethological terms Displacement behavior Intention movement Behaviorism (comparative psychology) emphasized behavioral plasticity: learning - most animals can learn many things Originated among philosophers and psychologists in the United States. even complex behavior is forged from simple stimulus-response interactions

5 Behaviorism (comparative psychology) animal enters the laboratory as a clean slate, and the animal s current state is irrelevant a single small set of rules governs all learning in all animals species differences are insignificant studying one species = studying all species law of equipotentiality all responses are conditionable to all stimuli Behaviorism (comparative psychology) Lloyd Morgan Morgan s canon In no case may we interpret an action as the outcome of the exercise of a higher physical faculty if it can be interpreted as the outcome of the exercise of one which stands lower in the psychological scale. (Occam s razor, or the Law of Parsimony) emphasized need for non-anthropomorphic approach Behaviorism (comparative psychology) Edward Thorndike stressed systematic, replicable experiments rather than anecdotes and observation trial and error learning no deduction, via Thorndike puzzle box documented role of reinforcement species-independent laws of learning Behaviorism (comparative psychology Ivan Pavlov classical conditioning

6 Behaviorism (comparative psychology) B.F. Skinner Pros of Behaviorism & Classical Ethology Behaviorism Classical Ethology Skinner box if we cannot observe a direct behavioral response, there is no point in pondering mental events (e.g., consciousness, emotions) enormous enhancement of scientific rigor established many basic laws of learning that are good predictors of animals interactions with their environments strong grounding in evolutionary theory contributed the ethogram to the study of animal behavior studied a diversity of animal taxa and behavioral phenomena Cons of Behaviorism & Classical Ethology Behaviorism Classical Ethology Behavioral ecology dogmatic focus on environmental influence due largely to study of only a few species in arbitrary situations not grounded in evolutionary theory unrealistic view of nervous system overlooked much behavioral plasticity due to excessive focus on instincts unrealistic view of the nervous system examines the ways in which animals interact with their environments, and the adaptive value of behavior (ultimate questions). J.R. Krebs, N.B. Davies

7 Sociobiology applies the principles of evolutionary biology to the study of social behavior in animals a synthesis of behavioral ecology and the study of social organisms which relies heavily on the comparative approach E.O. Wilson Sociobiology: the new synthesis Levels of analysis: Tinbergen s 4 questions Proximate: What are the mechanisms that cause the behavior? How does the behavior develop? Ultimate: Why - what is the survival (& reproductive) value of the behavior? How did the behavior evolve? Methods, tools, and concerns in the scientific study of animal behavior science is only one way of knowing other ways include religion, art, etc. science is based on two assumptions physical reality exists there are physical explanations for events. science is a systematic way of seeking, but never finding, truths Methods and tools: strong inference (hypothesis testing) method begin with an observed, described phenomenon state the questions clearly. create natural explanations for the phenomenon (hypotheses), including a null hypothesis generate testable predictions/outcomes from the explanations/hypotheses; if possible generate mutually exclusive predictions

8 whenever possible, avoid predictions which support the hypothesis in favor of predictions which would falsify the hypothesis disproof is stronger than proof. test the hypotheses collect data and compare it to the predictions reject the hypotheses that did not predict the observed data continue until only one hypothesis not rejected then test this one! example: Timothy Clutton-Brock (& others) sentinel behavior among meerkats (Suricata suricata) observation individual meerkats appear to take turns at sentinel duty, watching out for predators and giving an alarm call if one is seen.

9 question Why (in adaptive sense) do meerkats take turns at sentinel duty? H 1 : because sentinels can save the lives of relatives, sentinal duty & warning is favored by kin selection. H 2 : reciprocal altruism (I scratch your back...) H 3 : sentinel behavior is selfish, warning is cheap H 1 : because sentinels can save the lives of relatives, behavior is favored by kin selection P 1 : group members closely related nope, group members not closely related, on average P 2 : sentinel more frequently when near close relatives nope, individuals sentinel when near completely unrelated animals therefore, H 1 is not true. H 2 : reciprocal altruism (I scratch your back...) P 1 : group members serve sentinel duty in regular order, they take turns... nope, no regular order of sentinel duty therefore, H 2 is not true H 3 : selfish behavior is selfish, warning is cheap P 1 : sentinel only when full & don t need to eat Yep P 2 : sentinel behavior is not risky Yep P 3 : perform sentinel behavior whether alone or in a group Yep P 4 : perform sentinel behavior when in group and no one else on guard Yep therefore, H 3 is not rejected

10 Methods and tools: design of an animal Will the study describe a phenomenon or test hypotheses? If the latter, clearly define the behavior. Identify the independent and dependent variables, and the control groups (if necessary). Which of Tinbergen s four questions will be addressed? Methods and tools: design of an animal Will the study be performed in a laboratory or field setting? lab concerns animal procurement (captured v. bred) housing and care experimental conditions experimental techniques How will the variables be measured/codified? What will be the study species? What is the level of investigation? Methods and tools: design of an animal lab experimental techniques Classical conditioning apparatus Methods and tools: design of an animal lab experimental techniques Skinner box

11 Methods and tools: design of an animal lab experimental techniques Thorndike puzzle box Methods and tools: design of an animal Will the study be performed in a laboratory or field setting? field concerns: non-invasive data collection methods» ad libitum» zero-one» scan» focal animal survey (FAS) invasive? how to be minimally invasive how to identify individuals, if necessary how to find/track animals experimental techniques data collection & recording tools legal & ethical concerns external validity How well can you generalize from your results? How well do your results represent the real world? internal validity How well can you replicate your results? How well can you establish cause & effect? impact the smallest number of animals as possible detect and reduce animal stress & pain weigh the potential gain in knowledge against the consequences to the individual animals and populations use the appropriate control groups, test sequences, and statistical analysis consider different Umwelts