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Animal Behavior What is behavioral ecology? Behavioral ecology studies how behavior is controlled and how it develops, evolves, and contributes to survival Behavior is everything an animal does and how it does it Ethology is the scientific study of how animals behave, especially in natural environments Understanding Behavior Questions that must be asked to understand any behavior: What is the mechanistic basis of the behavior (chemical, anatomical, and physiological mechanisms)? How does development of the animal, from zygote to mature individual, influence behavior? What is the evolutionary history of the behavior? How does the behavior contribute to survival and reproduction (fitness)? Fixed Action Patterns One type of behavior studied by ethologists is the fixed action pattern (FAP) An FAP is a sequence of unlearned behavioral acts that is essentially unchangeable and, once started, is usually carried to completion Triggered by a sign stimulus (some external sensory stimuli that triggers the behavior Example: Aggressive behavior in male stickleback fish in response to the red underside of an intruder fish The following models were used to induce aggressive behavior. The realistic model did nothing, but the shapes with red bottoms caused aggressive behavior Imprinting Imprinting is a type of behavior that includes both learning and innate components and is irreversible There is a limited phase in an animal’s development which is the only time when certain behaviors can be learned (sensitive period) Incubator-hatched goslings imprinted on scientist (Konrad Lorenz) during first few hours of life and followed him Nature vs. Nurture? In biology, it’s not an either/or scenario Genes and the environment both influence behavior Some behaviors can be altered based on the environment (still set behavior, but the behavior changes based on changing external conditions) Other behaviors are virtually identical in a population . . . regardless of external stimuli Innate behavior is behavior that is developmentally fixed, regardless of the environment Directed Movements Animal movements can have substantial genetic influence (directed movements) Examples: Kinesis Taxis Migration Directed Movements Kinesis: a simple change in activity or turning rate in response to a stimulus Example: pillbugs live best in moist conditions; they move around more in dry areas and less in moist/humid areas More movement increases likelihood they will encounter a moist area Directed Movements Taxis = a more or less automatic, oriented movement toward or away from a stimulus Example: fish swimming against the current Migration Animal Signals & Communication Many interactions between organisms are a result of sending and receiving information that alters behavior A signal is a behavior that causes a change in another animal’s behavior Communication involves the transmission of, reception of, and response to signals between animals Types of Communication Chemical Communication: Pheromones – chemically emitted odors that may attract organisms from several kilometers away. Particularly important in reproduction behavior Auditory Communication: Bird songs and insect songs are also important in reproduction Drosophila males produce a characteristic “song” by beating their wings Environment & Genetics Environmental factors, such as the quality of the diet, the nature of social interactions, and opportunities for learning can influence the development of behaviors in every group of animals Example: Variations in diet led to rejection of mates in Drosophila Learning (start here) Learning is the modification of behavior based on specific experiences Learning has a large range of expression From simple imprinting to “learn” to recognize a parent to extremely complex . . . i.e. AP Biology Habituation: loss of responsiveness to stimuli that convey little or no information If you poke a hydra, it will contract into itself. Yet, if you keep poking the hydra (not very nice), eventually it will ignore the stimuli if it is not harmed Evolutionarily it is believed this prevents organisms from wasting energy on stimuli that are not pertinent to survival or reproduction Learning Spatial Learning: the modification of behavior based on experience with the spatial structure of the environment, including the location of nest sites, hazards, food, and prospective mates Example: Organisms being able to recognize landmarks This is a much more sophisticated form of learning because it involves “learning” stimulus that may vary in an environment Learning By putting together several landmarks in a spatial learning scheme, organisms could traverse to a variety of different environmental locations Another possibility is the use of cognitive maps, an internal representation of the surrounding environment with spatial relations to each other (a mental map) Sometimes it is difficult to determine if an organism is using spatial learning or relying on a cognitive map Associative Learning Another type of learning has to do with an organism learning behaviors based on experiential factors Associative learning is the ability of many animals to associate one feature of the environment with another Example: Associating eating one type of insect with a bad taste Types of Associative Learning Classical Conditioning an arbitrary stimulus is associated with a reward or punishment Example: Pavlov’s Experiment Operant Conditioning “trial-and-error learning” Example: Mouse eating distasteful caterpillar OR a coyote getting a face full of quills from a porcupine Cognition & Problem Solving Some behaviors show more sophisticated levels of learning Cognition is the ability of an animal’s nervous system to perceive, store, process, and use information gathered by sensory receptors Cognitive ethology studies how an animal’s nervous system and behavior interact Example: chimpanzees cracking open oil palm nuts by observing an experienced chimpanzee performing the task Natural Selection & Behaviorism The genetic components of behavior evolve through natural selection Natural selection favors behaviors that increase survival and reproductive success Foraging behavior – Balance between benefits of nutrition and cost of finding food (predation, energy, etc.) Cost-benefit analysis Mating systems and parental care Most animals are promiscuous (no strong pairbonding relationship) Monogamous Polygamous (usually single male with many females) Reasons for mating systems Finding mates, caring for young, and passing on genetic traits are strong determining factors in mate selection Monogamy is important in birds. It takes a lot of work to feed and care for young that are relatively helpless. Both male and female are needed to provide for young, so they stick together Polygamy occurs when the young can care for themselves at a young age. Males seek to maximize reproductive success There are many other factors that influence behavior Sexual selection Reminder: Intersexual selection: one sex chooses a mate based on some characteristic of the other sex (female usually makes the selection and males vie for selection) Intrasexual selection: competition of one sex for mates (males fight each other to “win” a female) Evolutionary impact A lot of male behaviors, or anatomical features, may be due to intersexual selection Females choose traits and those traits become selected for Peacock feathers, birdsong, long eyestalks in male stalk-eyed flies Male behaviors, or anatomical features, may also be due to intrasexual selection Agonisitic behaviors are ritualized competitions that teach males to fight for mates Altruism & Inclusive Fitness Most social behaviors are selfish Altruism = when an animal behaves in a way that reduces its individual fitness but increases the fitness of the other individuals in the population Example: squirrels alarm call, worker bees Helps close relatives (children, siblings, etc.), thereby increasing the individual’s genetic representation in the next generation (saving close relatives) – “inclusive fitness” Reciprocal Altruism Sometimes animals will behave altruistically to other animals that are not related This behavior can be adaptive if it aids the animal in the future, reciprocal altruism Reciprocal altruism is rare in animals Limited largely to same species that live in a social group, but not always related (chimpanzees) Social Learning In addition to genetic and environmental influences, learning can be influenced by social contact Social learning is learning from observing the behaviors of others Social learning forms the roots of culture Mistakenly, we believe social learning only occurs in humans. It may also occur in animal populations Social Learning Example: Mate choice copying Female guppies have been seen to mate with males that have been successful in attracting other females Example: Alarm calls Monkeys learn different calls to symbolize different predators (leopards, eagles, snakes) When young these calls are inaccurate (any bird may be given the “eagle” call Yet, as they mature and “learn” to discriminate species, their calls become more accurate What about us? Biology is not limited to the study of just animal behaviors Some scientists study how evolutionary theory applies to human culture, sociobiology This field is highly controversial Could be used to justify status quo human societies (caste systems) Risk of oversimplification
