Stranger danger: A meta-analysis of the dear enemy hypothesis

The dear enemy hypothesis predicts that territorial individuals will be less aggressive toward known neighbors than to strangers. This hypothesis has been well studied and there is a wealth of data demonstrating its prevelance among some taxa. However, a quantitative synthesis is needed to test the generality of the phenomenon, identify key mechanisms driving the behavior, and guide future research. Here we made a comprehensive collection of Dear Enemy data from 138 studies representing 105 species spread over eight taxonomic classes. The associated paper finds that Dear Enemy is a common phenomenon but drivers of this phenomenon are still understudied and current knowledge is unable to disentangle competing hypotheses of drivers of this behavior.