Chapter-51-Behavioral-Ecology - Chapter 51 Behavioral...

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Chapter 51 Behavioral Ecology Lecture Outline Overview: Studying Behavior Humans have studied animal behavior for as long as we have lived on Earth. As hunter and hunted, knowledge of animal behavior was essential to human 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. Many behaviors result 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 questions are mechanistic, concerned with the environmental stimuli that trigger a behavior, as well as the genetic, physiological, and anatomical mechanisms underlying a behavioral act. Proximate questions are referred to as “how?” questions. Ultimate questions address the evolutionary significance of a behavior and why natural selection favors this behavior. Ultimate questions are referred to as “why?” questions. Red-crowned cranes breed in spring and early summer. A proximate question about the timing of breeding by this species might ask, “How does day length 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 increase fitness in some way.
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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. Classical ethology presaged an evolutionary approach to behavioral biology.
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Chapter-51-Behavioral-Ecology - Chapter 51 Behavioral...

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