Date of Award

Spring 2016

Project Type

Thesis

Program or Major

Zoology

Degree Name

Master of Science

First Advisor

Sandra Rehan

Second Advisor

Win Watson

Third Advisor

Larry Harris

Abstract

The formation and maintenance of eusocial insect groups, in which there are overlapping generations, cooperative brood care, and reproductive division of labor is a major evolutionary transition. To understand the origins of eusociality, simple societies must be studied. Subsociality is the simplest form of social behavior and is defined as prolonged maternal care for offspring. Studies with subsocial species can provide powerful insights into the transition from basic to advanced social behaviors. In this thesis I use the subsocial small carpenter bee Ceratina calcarata Roberton (Hymenoptera: Xylocopinae) as a model organism. Specifically I study cuticular hydrocarbons (CHCs) of this species to examine two important evolutionary questions. CHCs are long chain hydrocarbons present on the cuticle of insects and are used for signaling and communication purposes. In eusocial insects queen pheromones are CHCs that signal fertility and suppress worker reproduction. It is hypothesized that CHCs were first fertility signals in less social forms and subsequently coopted as queen pheromones in eusocial lineages. I test this hypothesis and show supportive evidence for it, as my results suggest that C. calcarata, a subsocial species, may use CHCs to signal fertility. Second, the use of CHCs to recognize non-nestmates is essential to the fitness of eusocial colonies. My results suggest that C. calcarata may possibly use CHCs as recognition cues, indicating that the use of CHCs for recognition of conspecifics is not a derived trait unique to eusocial lineages, but was probably conserved and present in less social forms. Therefore, this thesis contributes to our understanding of the factors favoring the formation and evolution of eusociality. I show that fertility signals, and the use of CHCs for non-nestmate recognition are likely to be conserved traits.

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