Student Theses and Dissertations
Date of Award
2024
Document Type
Thesis
Degree Name
Doctor of Philosophy (PhD)
RU Laboratory
Ruta Laboratory
Abstract
In many species, males have evolved elaborate behavioral patterns to attract females or repel rival males. The neural mechanisms mediating these male behavioral traits and how females use them to guide their mating decisions remain elusive. In this thesis,I present our efforts to uncover the neural logic underlying mate selection in Drosophila melanogaster. Unlike males who display overt courtship behaviors in pursuit of a female mate, including chasing her and singing a courtship song to her, female behaviors during courtship are subtle, making it challenging to infer how a female’s sexual receptivity fluctuates based on the male’s performance.To gain insight into dynamic changes in female sexual receptivity, we explored two distinct female behaviors displayed during courtship. First, we characterized the ‘avoidance’ behaviors displayed by females in response to pursuit by an inappropriate mate, where a fast approaching visual target elicits rapid turning and acceleration but can be suppressed by male courtship song. Neural circuits underlying avoidance behavior appear to interface with those governing a female’s sexual receptivity, providing an indirect reflection of her mating preferences. Second, we analyzed female vaginal plate opening, a final motor program indicative of her sexual acceptance of a male, and how it is elicited in response to male performance. We reveal that the probability that a male’s song triggers females to open their vaginal plates varies over time, which likely reflects dynamic fluctuations in a female’s sexual receptivity. Beyond exploring how females respond to the courtship performance of individual males, we also considered how they assess and choose between alternate mates. Indeed, in the wild, Drosophila congregate on their host plants, creating a complex social environment where females are often pursued by multiple males concurrently. We demonstrate that when two males compete for a female, they rapidly alternate between courtship behaviors towards the female and agonistic behaviors towards their rival, characterized by performance of bilateral wing flicks. We show that agonistic wing flicks produce distinct acoustic signals that “jam” the auditory pathways of the female, impeding her detection of the advertising courtship song produced by rival males. Consequently, females are less likely to show receptive behaviors when serenaded by multiple males. Moreover, agonistic wing flicks serve to physically repel a male’s rivals, enabling him to overcome the acoustic interference from his competitors and gain sole access to the female. Reproductive success therefore requires that males persistently court females while also executing agonistic wing flicks to drive their competitors away. Combining optogenetic perturbations and calcium imaging in tethered males interacting with virtual fly targets, we gained insight into the circuit architecture that mediates the rapid alternation between courtship and agonistic behaviors, revealing how sex-specific sensory signals allow males to modulate their behavior on a moment- to-moment timescale and flexibly navigate complex social scenes. Together, these studies reveal the neural circuit logic underlying female mating decisions and how males adapt their courtship strategies accordingly to achieve reproductive success.
Recommended Citation
Li, Rufei, "Connecting Female Mating Decisions and Male Courtship Strategies in Drosophila" (2024). Student Theses and Dissertations. 765.
https://digitalcommons.rockefeller.edu/student_theses_and_dissertations/765
Comments
A Thesis Presented to the Faculty of The Rockefeller University in Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy