Courtship learning in Drosophila melanogaster: Diverse plasticity of a reproductive behavior |
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| Authors: | Leslie C. Griffith Aki Ejima |
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| Affiliation: | 1.Department of Biology, National Center for Behavioral Genomics and Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02493, USA;;2.Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Kyoto, Japan 606-8501 |
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| Abstract: | ![]()
Mechanisms for identifying appropriate mating partners are critical for species propagation. In many species, the male uses multiple sensory modalities to search for females and to subsequently determine if they are fit and receptive. Males can also use the information they acquire in this process to change their courtship behavior and reduce courtship of classes of targets that are inappropriate or unreceptive. In Drosophila, courtship plasticity, in the form of both nonassociative and associative learning, has been documented—the type of learning depending on the nature of the trainer. The conditions in which the male is presented with the training target can profoundly alter the cues that he finds salient and the longevity of the memory that he forms. With the exception of habituation and sensitization, these types of plasticity have an operant component in that the male must be courting to respond to the behavior-altering cues. Courtship plasticity is therefore a complex and rich range of behaviors rather than a single entity. Our understanding of these plastic behaviors has been enhanced by recent advances in our understanding of the circuitry underlying courtship itself and the identification of chemical cues that drive and modify the behavior. Courtship learning is providing a window into how animals can use a variety of sensory inputs to modulate a decision making process at many levels.When confronted with a potential mate, Drosophila melanogaster males perform a stereotyped courtship ritual. This behavior serves at least two obvious functions for the male. The first is to prime conspecific females for copulation. During courtship, the female is assessing the male''s suitability, and if the song he sings (Burnet et al. 1971; von Schilcher 1976a) and pheromones he emits (Grillet et al. 2006; Kurtovic et al. 2007) are correct for her species and of sufficient quality, her willingness to copulate is increased. She will slow her locomotion, present her abdomen to the male, and then spread her wings and genital plates to allow him to mount (Lasbleiz et al. 2006). A second function of courtship is that it allows a male to accumulate information about the target courtship object to assess its suitability and receptiveness. The male uses auditory, mechanosensory, visual, and chemosensory signals from the target to make this assessment (for review, see Villella and Hall 2008; Ejima and Griffith 2009).Since D. melanogaster males will avidly initiate courtship of a wide variety of inappropriate and/or unreceptive targets, including immature males, sexually immature virgin females, mated females, and heterospecific females, the information obtained during courtship is critical to deciding whether to increase the intensity of his effort or terminate pursuit of the target. In the last several years, courtship has become a favored model for those researchers interested in how the nervous system specifies “innate” behaviors. While it is true that a male does not have to be instructed to produce adequate courtship (Hall 1994; Clyne and Miesenbock 2008), this apparently stereotyped behavior is far from static: It can be modified in a dizzying number of ways by experience. In this paper, we will discuss how information gathered during courtship can allow males to learn about specific types of courtship objects and broadly modify future behavioral responses to a particular class of target. |
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