Chapter 51 Behavioral Ecology Overview Studying Behavior The modern scientific discipline of behavioral ecology studies how behavior develops evolves and contributes to survival and reproductive success Concept 51 1 Behavioral ecologists distinguish between proximate and ultimate causes of behavior Scientific questions that can be posed about any behavior can be divided into two classes those that focus on the immediate stimulus and mechanism for the behavior and those that explore how the behavior contributes to survival and reproduction What is behavior Behavioral traits are an important part of an animal s phenotype Most of what we call behavior results from an animal s muscular activity such as a predator chasing a prey In some behaviors muscular activity is less obvious as in bird song Some nonmuscular activities are also behaviors as when an animal secretes a pheromone to attract a member of the opposite sex Learning is also a behavioral process Put simply behavior is everything an animal does and how it does it Proximate and Ultimate Questions Proximate questions are referred to as how questions As we observe a behavior we may ask both proximate and ultimate questions Proximate questions about behavior focus on the environmental stimuli if any that that trigger a behavior as well as the genetic physiological and anatomical mechanisms underlying a behavioral act Ultimate questions address the evolutionary significance of a behavior and why natural selection favors this behavior A proximate question about the timing of breeding by this species might ask How does day length Red crowned cranes breed in spring and early summer Ultimate questions are referred to as why questions influence breeding by red crowned cranes A reasonable hypothesis for the proximate cause of this behavior is that breeding is triggered by the effect of increased day length on the crane s production of and response to particular hormones An ultimate hypothesis might be that red crowned cranes reproduce in spring and early summer because that is when breeding is most productive At that time of year parent birds can find an ample supply of food for rapidly growing offspring providing an advantage in reproductive success compared to birds that breed in other seasons These two levels of causation are related Proximate mechanisms produce behaviors that evolved because they reflect fitness in some way For example increased day length has little adaptive significance for red crowned cranes but because it corresponds to seasonal conditions that increase reproductive success such as the availability of food for feeding young birds breeding when days are long is a proximate mechanism that has evolved in cranes Ethology In the mid 20th century a number of pioneering behavioral biologists developed the discipline of ethology In 63 Niko Tinbergen ethologist suggested 4 questions that must be answered to understand any the scientific study of how animals behave particularly in their natural environments behavior 1 mechanisms 2 3 4 Tinbergen s list includes both proximate and ultimate questions How does development of the animal from zygote to mature individual influence the behavior What is the evolutionary history of the behavior How does the behavior contribute to survival and reproduction fitness What is the mechanistic basis of the behavior including chemical anatomical and physiological The first two which concern mechanism and development are proximate questions while the second two are ultimate or evolutionary questions Fixed Action Patterns 1 In the red spined stickleback the male attacks other males that invade his nesting territory The stimulus for the attack is the red underside of the intruder A male stickleback will attack any model that has some red visible on it A fixed action pattern FAP is a sequence of unlearned behavioral acts that is essentially unchangeable and once initiated is usually carried to completion A FAP is triggered by an external sensory stimulus called a sign stimulus A proximate explanation for this aggressive behavior is that the red belly of the intruding male acts as a sign stimulus that releases aggression in a male stickleback An ultimate explanation is that by chasing away other male sticklebacks a male decreases the chance that eggs laid in his nesting territory will be fertilized by another male Imprinting Imprinting is a type of behavior that includes learning and innate components and is generally irreversible Imprinting is distinguished from other types of learning by having a sensitive period a limited phase in an animal s development that is the only time that certain behaviors can be learned An example of imprinting is young geese following their mother In species that provide parental care parent offspring bonding is a critical time in the life cycle During the period of bonding the young imprint on their parent and learn the basic behavior of the species while the parent learns to recognize its offspring Among gulls the sensitive period for parental bonding on young lasts one or two days If bonding does not occur the parent will not initiate care of the infant leading to certain death of the offspring and decreasing the parent s reproductive success How do young gulls know on whom or what to imprint The tendency to respond is innate in birds The world provides the imprinting stimulus and young gulls respond to and identify with the first object they encounter that has certain key characteristics In greylag geese the key stimulus is movement of the object away from the young A proximate explanation for young geese following and imprinting on their mother is that during an early critical developmental stage the young geese observe their mother moving away from them and calling An ultimate explanation is that 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 ultimate causes of behavior Early study of imprinting and fixed action patterns helped make the distinction between proximate and They also helped to establish a strong tradition of experimental approaches in behavioral ecology Concept 51 2 Many behaviors have a strong genetic component Behavioral traits like other aspects of a phenotype are the result of complex interactions between genetic In biology the nature versus nurture issue is not about whether genes or environment influence