Multisensory integration of courtship song and taste in male Drosophila melanogaster social behavior
by Adrián Palacios-Muñoz
Date of Examination:2024-07-02
Date of issue:2025-06-24
Advisor:Prof. Dr. Jan Clemens
Referee:Prof. Dr. Tim Gollisch
Referee:Prof. Dr. Viola Priesemann
Referee:Prof. Dr. André Fiala
Referee:Prof. Dr. Ralf Heinrich
Referee:Dr. Thomas Frank
Persistent Address:
http://dx.doi.org/10.53846/goediss-11344
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Abstract
English
The integration of sensory information is essential for animals to effectively navigate and interact in their environment. For instance, the social life of male fruit flies is surrounded by various sensory modalities involved in different amounts and combinations throughout the different steps of their interactions. Due to their crowded and rapidly changing environment, fruit flies must constantly integrate all the relevant information and switch between different social behaviors and decisions accordingly. Thus, it is important to gather a rich set of information from all possible sources, to guide the male through this complex environment and achieve his goals. This sensory information will guide the males to other social targets, to display courtship and attract and mate with females, and to display aggression and repel competitors and wrongly aimed advances of other males. Two of the most prominent sensory modalities found in the social behavior of fruit flies are acoustic and taste. Both cues serve as means of communication that provide valuable information to males to shape their social interactions. As a male approaches another fly, taste cues become available and inform the male of the sex, species, and mating status of the other fly. This exchange of information has been reported to be essential in the decision of males to initiate courtship displays and choose the correct mating partner. Thus, fruit flies utilize acoustic signals in the form of courtship song to court and identify the correct partners for copulation. However, the effects of courtship song on males and its integration with taste cues has received insufficient attention. For this reason, the integration of taste and courtship song on male fruit flies is an ideal subject of study to improve the knowledge of multisensory integration and social behavior. Therefore, in this thesis, I delve into the intricate world of multisensory integration in male fruit flies, focusing on the interplay between courtship song and taste cues in the multiple aspects of their social behavior. In this study, I compared and quantified the influence of taste and courtship song on the social behavior of males and measured the main independent effects of each modality. I found that courtship song exerted a weak positive influence on social interaction, a complementary drive of courtship towards females, and an increase in aggression towards males. Meanwhile, I confirmed that male taste cues function as a suppressor of male-oriented social interaction, and female taste cues promoted social interaction and courtship display towards female targets. Furthermore, I implemented a quantitative approach to estimate the contribution of each modality in shaping social interaction, where the effect of taste had a remarkably larger magnitude than the effect of courtship song. Through this approach I also investigated the putative interaction between the two sensory modalities and explored the similarities and differences in the integration of taste and song across other aspects of social behavior, disentangling the interactions into courtship and aggression. In- terestingly, courtship song and male taste cues followed a linear summation integration in shaping social interaction, where I found that song partially overrides the strong suppression exerted by male taste cues. However, in the case of male-male interactions, aggression and courtship initiation were not affected by taste. Aggression, in particular, was promoted by courtship song, but this effect was also independent of taste ability. Meanwhile, male-female pairs showed a linear summa- tion integration of both modalities in shaping social interaction. I also confirmed that courtship song has an effect on social interactions independent of the sex of the target. Moreover, I found evidence that courtship song and female taste may have a synergistic effect, where the ability to taste impacts the display of courtship only in the presence of a song. Lastly, I closely inspected the events on which taste cues were exchanged before the initiation of courtship, which is considered a critical period for taste information in the males’ social decisions. Exposing males to courtship song increased the number of taps (sample events) to reach the decision to court. This implied a negative interaction between courtship song and the sampling of female taste cues preceding courtship initiation. In summary, I have have introduced a quantitative approach to characterize multisensory processing in free-behavior assays, and I discovered several integration strategies of courtship song and taste cues, independently modulating each aspect of the social behavior. Thus, this study contributes significantly to the understanding of multisensory integration in fruit fly social behavior, highlighting the parallel and flexible nature of multisensory processing in male fruit fly social behavior.
Keywords: multisensory integration; drosophila; gustatory; acoustic; courtship; aggression; neuroscience; behavior
