Aggression and discrimination among closely versus distantly related species of Drosophila.

Tarun Gupta,Sarah E Howe,Brent L Lockwood,Marlo L Zorman

doi:10.1098/rsos.190069

Abstract

Fighting between different species is widespread in the animal kingdom, yet this phenomenon has been relatively understudied in the field of aggression research. Particularly lacking are studies that test the effect of genetic distance, or relatedness, on aggressive behaviour between species. Here we characterized male–male aggression within and between species of fruit flies across the Drosophila phylogeny. We show that male Drosophila discriminate between conspecifics and heterospecifics and show a bias for the target of aggression that depends on the genetic relatedness of opponent males. Specifically, males of closely related species treated conspecifics and heterospecifics equally, whereas males of distantly related species were overwhelmingly aggressive towards conspecifics. To our knowledge, this is the first study to quantify aggression between Drosophila species and to establish a behavioural bias for aggression against conspecifics versus heterospecifics. Our results suggest that future study of heterospecific aggression behaviour in Drosophila is warranted to investigate the degree to which these trends in aggression among species extend to broader behavioural, ecological and evolutionary contexts.

Highlights

Heterospecific aggression—i.e. fighting between members of different species—is widespread in the animal kingdom [1]
The ratios of mean lunge counts (RL; heterospecific : conspecific) in closely related species pairs hovered around values of one, indicating that heterospecifics and conspecifics were likely to be targeted by aggression
The only closely related species pair interaction that showed a significant aggression bias was D. melanogaster paired with D. simulans, where D. melanogaster males were three times more likely to target heterospecifics than conspecifics

Summary

Introduction

Heterospecific aggression—i.e. fighting between members of different species—is widespread in the animal kingdom [1]. Aggressive behaviour often mediates competitive interactions between species that can have important consequences for species coexistence and the structure of ecological communities [2,3,4,5]. Most research into aggressive behaviour has focused on conspecific aggression—i.e. fighting between members of the same species [6]—with few well-characterized examples of heterospecific aggression [7], in a broad phylogenetic context [8].

Methods

Results

Conclusion