Collective action or individual choice: Spontaneity and individuality contribute to decision-making in Drosophila

Abstract

Our own unique character traits make our behavior consistent and define our individuality. Yet, this consistency does not entail that we behave repetitively like machines. Like humans, animals also combine personality traits with spontaneity to produce adaptive behavior: consistent, but not fully predictable. Here, we study an iconically rigid behavioral trait, insect phototaxis, that nevertheless also contains both components of individuality and spontaneity. In a light/dark T-maze, approximately 70% of a group of Drosophila fruit flies choose the bright arm of the T-Maze, while the remaining 30% walk into the dark. Taking the photopositive and the photonegative subgroups and re-testing them reveals the spontaneous component: a similar 70–30 distribution emerges in each of the two subgroups. Increasing the number of choices to ten choices, reveals the individuality component: flies with an extremely negative series of first choices were more likely to show photonegative behavior in subsequent choices and vice versa. General behavioral traits, independent of light/dark preference, contributed to the development of this individuality. The interaction of individuality and spontaneity together explains why group averages, even for such seemingly stereotypical behaviors, are poor predictors of individual choices.

Precise Quantification of Behavioral Individuality From 80 Million Decisions Across 183,000 Flies

“…High-throughput, automated behavioral assays have been used to investigate the variability of Drosophila behavior ( Mollá-Albaladejo and Sánchez-Alcañiz, 2021 ; Mueller et al, 2021 ; Steymans et al, 2021 ; Werkhoven et al, 2021 ). The species’ deep genetic toolkit facilitates the study of proximate mechanisms controlling variability such as neurotransmitters ( Kain et al, 2012 ; Honegger et al, 2020 ), neural circuits ( Buchanan et al, 2015 ; Skutt-Kakaria et al, 2019 ; Honegger et al, 2020 ; Linneweber et al, 2020 ), genes ( Kain et al, 2012 ; Ayroles et al, 2015 ; Wu et al, 2018 ), environmental variation ( Akhund-Zade et al, 2019 ), and social effects ( Alisch et al, 2018 ; Versace et al, 2020 ).…”