Natural selection predicts that each individual should strive to maximize its genetic contribution to the next generation. However, in eusocial organisms, many individuals give up some or all of their reproduction to help another individual. In highly eusocial organisms, like the honeybee, workers are partially or completely sterile and could not found their own colony. However, in primitively eusocial organisms like Polistes, workers are capable of reproducing and founding their own colonies. In addition, mated females often accept worker-like roles on new colonies rather than founding their own colonies. This opens the question of why an individual that could reproduce would choose, instead, to help another individual. To address this question I looked at the energetic costs of being a worker or a dominant, solitary, or subordinate foundress, as well as the metabolic differences among these individuals. I measured the cost of different behaviors, including interactions between individuals, flight, grooming and nest care. I found that foraging related behaviors (performed by solitary and subordinate foundress and workers) were quite expensive, while interactions (performed primarily by dominants) were relatively low cost. I also looked at the thermoregulation necessary for some of these behaviors, and found that flying Polistes thermoregulate, another energetically costly behavior. When I compared the cost of maintaining ovarian development among these different roles, I found that workers and subordinate foundresses spent more energy to maintain the same level of ovarian development, suggesting that they would need to expend more energy to create a colony, and, therefore, be less able than the average solitary foundress to maintain a successful colony. Finally, I created an energy budget for each role. I found that workers used more energy than any other role, but, after that, solitaries with workers used approximately the same amount of energy on tasks as subordinates. Solitaries prior to worker emergence would be expected to use even more energy. This suggests that an individual with low resources and a high energetic cost of egg maintenance might be have a low success as a solitary foundress, and, therefore, be better off taking a subordinate role and helping a sister.
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|Advisor:||Starks, Philip T.|
|Commitee:||Lewis, Sara, Prestwich, Ken, Reed, Michael, Woods, William A.|
|School Location:||United States -- Massachusetts|
|Source:||DAI-B 72/09, Dissertation Abstracts International|
|Keywords:||Behavior, Energy budget, Eusocial paper wasp, Hymenoptera, Metabolism, Polistes fuscatus, Thermoregulation|
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