Ch05 Discussion Questions

Ch05 Discussion Questions - Chapter 5 The Organization of...

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Chapter 5: The Organization of Behavior: Neurons and Hormones 5.1 Figure 5.5 of the textbook shows a record of the activity of a particular neuron in a cricket’s brain that appears to act as a command cell controlling the male’s chirping call, which is produced when the male rubs his wings together. About 3 seconds into the recording, the cricket was subjected to a sharp puff of air that struck its cerci, a pair of sensory appendages that project out from the rear of the abdomen. What is the relevance of this figure to the topic that we have just discussed in the textbook? What adaptive value do you attach to the apparent proximate mechanisms that help male crickets make the behavioral decisions shown here? The cricket stopped singing immediately after sensing a tactile stimulus to the rear of its abdomen. Stimuli of this sort are associated with the rapid approach of an object, which pushes air in front of it. Predators potentially could inadvertently supply this kind of stimulation. The cricket’s control mechanisms are arranged in such a fashion as to give priority to predator avoidance over calling behavior. Thus, inputs from the cerci inhibit the calling behavior for some time. In the absence of follow-on tactile stimulation, the calling control center re-establishes its dominance and the male resumes singing for a mate. The importance of survival for crickets in a world full of dangerous predators and parasitoids, some of which track males by the sounds they produce, has evidently favored individuals that stop calling at the first sign of danger. 5.2 You may recall that the transition to foraging in honey bees depends on the makeup of the colony, such that if there is a shortage of nurse workers within the hive, older bees will delay their shift to foraging role. What prediction follows about per gene expression in the brains of these socially delayed older nurses relative to foragers of the same age from other colonies with numerous young nurse bees? Provide proximate and ultimate hypotheses for the fact that social interactions can alter circadian rhythms in honey bees—and even fruit flies [714], which do not live in highly organized societies. The shift from one behavioral program to the next must at some level be caused by changes in genetic activity. If so, we can predict that the per gene will be responsive to signals correlated with social interactions of some sort, leading to changes in the activity of the gene with corresponding changes in the daily activity patterns of foragers compared to nurses. The ultimate benefits of having a timing mechanism that can be adjusted in relation to the age of the worker and the social environment of the hive include the production of foragers that can time their foraging activity to maximum advantage. One factor that makes it useful for foragers to have a circadian rhythm is the circadian pattern of flower opening and nectar production that characterizes so many flowering plant species. Fruit flies resemble honey bees in having circadian proximate
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This note was uploaded on 03/27/2008 for the course BIO 325 taught by Professor Chepko-sade during the Fall '06 term at SUNY Oswego.

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Ch05 Discussion Questions - Chapter 5 The Organization of...

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