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- All Subjects: Biology
- All Subjects: Social Insect
- Member of: Theses and Dissertations
- Status: Published
Much is still unknown about dominance hierarchies. Many different species form dominance hierarchies and each species have very different ways of forming these hierarchies. Some engage in various different dominance interactions to establish a dominant position. This experiment aims to use the ant species, Harpegnathos saltator, as a model to explore what sets dominant individuals, or gamergates in this case, apart from non-dominant individuals, or non-gamergates. H. saltator ants perform various different behaviors such as dueling, which is a mutually beneficial behavior, dominance biting, which is an aggressive behavior, and policing which is used to bring down those who are dominant. These behaviors can be used to study the importance of initiation and aggression in hierarchy formation. This experiment will explore how aggression through dominance biting, duel initiation, group size, and time period affect the formation of gamergates. To do so, socially unstable colonies of 15, 30, and 60 ants were video recorded for days until gamergates were established. Then, from the recordings, a period of high activity was selected and observed for dueling, duel initiation, dominance biting, dominance bite downs, and policing. The results showed that gamergates tended to perform dominance biting and dominance bite downs far more than non-gamergates during the period of high activity, but not as clearly with duelling and duel initiations. It was inconclusive whether or not the combination of both dueling and dominance biting was what set gamergates apart from non gamergates as different groups showed different results. Gamergates performed visibly more dominance bite downs than non-gamergates, so aggression may be important in setting gamergates apart from non-gamergates. In terms of group size, the smallest group had the least number of gamergates and the least activity, and the medium and large group had a similar number of gamergates and activity.
An intimate view of the unique architecture of Harpegnathos saltwater nest using aluminum nest casts
Given the incredible variety in ant nest architecture, this experiment sought to evaluate how the nest architecture of Harpegnathos saltator differs from other species’ nests. To achieve the ability to evaluate the structure of H. saltator nest, we created experimental colonies varying in size from 20, 40, 60, 80 workers of Harpegnathos saltator in five-gallon buckets of sand and then allowing the colonies to grow for four months and twelve days. To create the nest casts, we developed a charcoal kiln out of a galvanized trash can and used a ceramic crucible to hold the aluminum being melted. Using molten aluminum to create nest casts of each colony produced, we obtained three poorly developed nests and one decent nest. The decent nest cast, the 80 worker H. saltator nest, was lacking key features of H. saltator nests that have been excavated in the field. However, they do share many of the same structures such as the shaping of the chambers. The ability of the experimental colonies to excavate the soil provided in the buckets to them was likely halted by poor penetration of water into superficial layers of the soil, thus making the soil too difficult to excavate and form the structures that are key elements of the species nest architecture. Despite these key challenges which the colonies faced, the 80-worker colony showed extensive vertical development and did display features associated with natural H. saltator colonies. Thus, given the display of some key features associated with characteristics of the H. saltator nests excavated in the field, it can be said that with some modification to technique that this is a viable avenue for future study of nest architecture and colony structure.