Individual Recognition in Paper Wasps: Correlated Evolution of Sender Phenotypes and Receiver Cognition

Abstract

Recognition systems allow animals to discriminate among social partners on the basis of species, group membership, kinship or individual identity. Despite the fact that recognition is central to theories of social evolution, relatively little work has examined the processes by which the traits involved in recognition evolve. Notably, recognition often involves highly diverse traits used for recognition and specialized cognitive abilities, though the evolutionary origins of these traits has been largely unexplored. I consider three questions regarding the evolution of individual recognition, using Polistes wasps as a model.

First, I examine the phenotypes used for recognition. Does selection favor individuals to broadcast their identity or is recognition akin to eavesdropping? Through a series of studies I show that the variable color patterns used by P. fuscatus to recognize conspecifics have arisen as the result of selection for distinctive easily recognizable identity signals. This work provides the first evidence that selection for recognition favors individuals to broadcast their identity. Selection for efficient recognition is likely to be a prominent mechanism maintaining polymorphism in social species.

Second, I examine the specificity of cognitive processes associated with recognition. Do wasps use general learning mechanism for recognition or is it a specialized process? I demonstrate that P. fuscatus wasps have face-recognition specific learning adaptations, suggesting that cognitive evolution may be highly specific. Additionally, I show that wasps have surprisingly robust social memories despite their small brain size.

Third, it is difficult to understand how sender and receiver phenotypes are elaborated in the absence of the other. I propose that the evolution novel recognition systems may be facilitated by pre-existing sender or receiver biases. I provide initial tests of the hypotheses, finding that sender bias is likely to be a widespread mechanism facilitating the evolution of novel recognition systems. Additionally, I provide experimental evidence for a receiver bias in Polistes wasps.

The work presented in this dissertation present a multi-faceted examination of the evolution of an important social trait – individual recognition. Importantly, the results of this dissertation demonstrate that individual recognition will be an important model for studies of phenotypic polymorphic and cognitive evolution.