A single social defeat reduces aggression in a highly aggressive strain of Drosophila

Abstract

Genes and prior experience both influence the behavior of animals, but the relative contribution of each to fighting behavior in Drosophila remains unclear. To address this issue, we bred hyperaggressive flies by selecting winners of fights over 34-37 generations. Males of this strain initiate fights sooner, retaliate more often, and regularly defeat opponents from the nonselected parent Canton-S strain. After a defeat, however, these highly aggressive flies lose their second fights against socially naïve counterparts. Defeated flies also lunge and retaliate less after experiencing a loss, suggesting that the subsequent losses result from flies becoming less aggressive. Remarkably, flies that were once capable of engaging in highintensity boxing and tussling patterns of behavior for extended periods of time often do not even engage in mid-intensity lunging after a single defeat. Furthermore, these formerly highly aggressive flies lose all competitive advantage over nonselected Canton-S after experiencing a loss. Lastly, females were more likely to copulate with males from the nonselected parent line than with the hyperaggressive strain.behavior | fighting | flies | learning | memory

Handling alters aggression and “loser” effect formation inDrosophila melanogaster

“…With this model system, a "loser mentality" originally was demonstrated in a larger chamber than the one used in this study. In addition, male flies were pretest handled and longer fighting periods with greater interval times between fights were required (Yurkovic et al 2006;Penn et al 2010). In the present study, where flies were not handled prior to experiments, we showed that clear hierarchical relationships could be established after only 20 min.…”

“…Few studies, however, have reported such effects on Drosophila Cold Spring Harbor Laboratory Press on May 9, 2018 -Published by learnmem.cshlp.org Downloaded from (Yurkovic et al 2006;Penn et al 2010). With this model system, a "loser mentality" originally was demonstrated in a larger chamber than the one used in this study.…”

“…In Drosophila, after hierarchical relationships have been established, a loser-like mentality develops in defeated flies that likely involves learning and memory (Yurkovic et al 2006;Penn et al 2010). In most cases, one fly (the winner) lunges more and retreats less while the other (the loser) does not lunge at all and instead retreats following each attack.…”

Social structure and indirect genetic effects: genetics of social behaviour

“…(8) We are seeing progress in determining interactive phenotypes which are affected by the social environment ['group' to individual ] and interactive phenotypes that are determined between individuals [individual to individual (Penn et al, 2010;Bailey & Hoskins, 2014)]. Our hope is that molecular, physiological and quantitative approaches not only continue to investigate the effects of being 'social', but also converge to create an integrative social paradigm.…”

“…Although a significant 'winner' effect exists in other insects, notably crickets (Rillich & Stevenson, 2011), studies in D. melanogaster have classically failed to demonstrate aggressive advantages in subsequent fights (Yurkovic et al, 2006;Penn, Zito & Kravitz, 2010), although a recent study reveals that this advantage is present but disrupted easily by handling (Trannoy, Chowdhury & Kravitz, 2015). Nevertheless, the outcome of aggression between flies creates a dominance relationship, with a clear 'loser' effect.…”